Silver halide light sensitive emulsion layer having enhanced photographic sensitivity

This invention comprises a photographic element comprising at least one silver halide emulsion layer in which the silver halide is sensitized with a compound of the formula X--H, wherein X is an electron donor moiety to which a base, B.sup.-, is covalently linked and H is a leaving hydrogen atom, and wherein: PA1 1) X--H has an oxidation potential between 0 and about 1.4 V; and PA1 2) the oxidized form of X--H undergoes deprotonation reaction with the base B.sup.-, to give the radical X.sup..cndot. and the protonated base B-H. In a preferred embodiment of the invention, the radical X.cndot. has an oxidation potential <-0.7V.

FIELD OF THE INVENTION 
This invention relates to a photographic element comprising at least one 
light sensitive silver halide emulsion layer which has enhanced 
photographic sensitivity. 
BACKGROUND OF THE INVENTION 
A variety of techniques have been used to improve the light-sensitivity of 
photographic silver halide materials. 
Chemical sensitizing agents have been used to enhance the intrinsic 
sensitivity of silver halide. Conventional chemical sensitizing agents 
include various sulfur, gold, and group VIII metal compounds. 
Spectral sensitizing agents, such as cyanine and other polymethine dyes, 
have been used alone, or in combination, to impart spectral sensitivity to 
emulsions in specific wavelength regions. These sensitizing dyes function 
by absorbing long wavelength light that is essentially unabsorbed by the 
silver halide emulsion and using the energy of that light to cause latent 
image formation in the silver halide. 
Many attempts have been made to further increase the spectral sensitivity 
of silver halide materials. One method is to increase the amount of light 
captured by the spectral sensitizing agent by increasing the amount of 
spectral sensitizing agent added to the emulsion. However, a pronounced 
decrease in photographic sensitivity is obtained if more than an optimum 
amount of dye is added to the emulsion. This phenomenon is known as dye 
desensitization and involves sensitivity loss in both the spectral region 
wherein the sensitizing dye absorbs light, and in the light sensitive 
region intrinsic to silver halide. Dye desensitization has been described 
in The Theory of the Photographic Process, Fourth Edition, T. H. James, 
Editor, pages 265-266, (Macmillan, 1977). 
It is also known that the spectral sensitivity found for certain 
sensitizing dyes can be dramatically enhanced by the combination with a 
second, usually colorless organic compound that itself displays no 
spectral sensitization effect. This is known as the supersensitizing 
effect. 
Examples of compounds which are conventionally known to enhance spectral 
sensitivity include sulfonic acid derivatives described in U.S. Pat. Nos. 
2,937,089 and 3,706,567, triazine compounds described in U.S. Pat. Nos. 
2,875,058 and 3,695,888, mercapto compounds described in U.S. Pat. No. 
3,457,078, thiourea compounds described in U.S. Pat. No. 3,458,318, 
pyrimidine derivatives described in U.S. Pat. No. 3,615,632, 
aminothiatriazoles as described in U.S. Pat. No. 5,306,612 and hydrazines 
as described in U.S. Pat. Nos. 2,419,975, 5,459,052 and 4,971,890 and 
European Patent Application No. 554,856 A1. The sensitivity increases 
obtained with these compounds generally are small, and many of these 
compounds have the disadvantage that they have the undesirable effect of 
deteriorating the stability of the emulsion or increasing fog. 
Various electron donating compounds have also been used to improve spectral 
sensitivity of silver halide materials. U.S. Pat. No. 3,695,588 discloses 
that the electron donor ascorbic acid can be used in combination with a 
specific tricarbocyanine dye to enhance sensitivity in the infrared 
region. The use of ascorbic acid to give spectral sensitivity improvements 
when used in combination with specific cyanine and merocyanine dyes is 
also described in U.S. Pat. No. 3,809,561, British Patent No. 1,255,084, 
and British Patent No. 1,064,193. U.S. Pat. No. 4,897,343 discloses an 
improvement that decreases dye desensitization by the use of the 
combination of ascorbic acid, a metal sulfite compound, and a spectral 
sensitizing dye. 
Electron donating compounds that are covalently attached to a sensitizing 
dye or a silver-halide adsorptive group have also been used as 
supersensitizing agents. U.S. Pat. Nos. 5,436,121 and 5,478,719 disclose 
sensitivity improvements with the use of compounds containing 
electron-donating styryl bases attached to monomethine dyes. Spectral 
sensitivity improvements are also described in U.S. Pat. No. 4,607,006 for 
compounds containing an electron-donating group derived from a 
phenothiazine, phenoxazine, carbazole, dibenzophenothiazine, ferrocene, 
tris(2,2'-bipyridyl)ruthenium, or a triarylamine skeleton which are 
connected to a silver halide adsorptive group. However, these latter 
compounds generally have no silver halide sensitizing effect of their own 
and provide only minus-blue sensitivity improvements when used in 
combination with a sensitizing dye. 
PROBLEM TO BE SOLVED BY THE INVENTION 
There is a continuing need for materials which, when added to photographic 
emulsions, increase their sensitivity. Ideally such materials should be 
useable with a wide range of emulsion types, their activity should be 
controllable and they should not increase fog beyond acceptable limits. 
This invention provides such materials. 
SUMMARY OF THE INVENTION 
We have now discovered that an electron donating compound that upon 
donating an electron undergoes a deprotonation reaction can be used to 
sensitize a silver halide emulsion. The terms "sensitize" and 
"sensitization" is used in this patent application to mean an increase in 
the photographic response of the silver halide emulsion layer of a 
photographic element and the term "sensitizer" is used to mean a compound 
that provides sensitization when present in a silver halide emulsion 
layer. 
One aspect of this invention comprises a photographic element comprising at 
least one silver halide emulsion layer in which the silver halide is 
sensitized with a compound of the formula X--H, wherein X is an electron 
donor moiety to which a base, B.sup.-, is covalently linked and H is a 
leaving hydrogen atom, and wherein: 
1) X--H has an oxidation potential between 0 and about 1.4 V; and 
2) the oxidized form of X--H undergoes deprotonation reaction with a base 
B.sup.-, to give the radical X.sup..cndot. and the protonated base B-H. 
In this patent application, oxidation potentials are reported as "V" which 
represents "volts versus a saturated calomel reference electrode". 
Another aspect of this invention comprises a photographic element 
comprising at least one silver halide emulsion layer in which the silver 
halide is sensitized with a compound of the formula X--H, wherein X is an 
electron donor moiety to which a base, B.sup.-, is covalently linked and H 
is a leaving hydrogen atom, and wherein: 
1) X--H has an oxidation potential between 0 and about 1.4 V; 
2) the oxidized form of X--H undergoes deprotonation reaction with a base, 
B.sup.-, to give the radical X.sup..cndot. and the protonated base B-H; 
and 
3) the radical X.sup..cndot. has an oxidation potential .ltoreq.-0.7V (that 
is, equal to or more negative than about -0.7V). 
Compounds which meet criteria (1) and (2) but not (3) are capable of 
donating one electron and are referred to herein as deprotonating 
one-electron donors. Compounds which meet all three criteria are capable 
of donating two electrons and are referred to herein as deprotonating 
two-electron donors. 
Another aspect of this invention comprises a photographic element 
comprising at least one silver halide emulsion layer in which the silver 
halide is sensitized with a compound of the formula: 
EQU A-(L-X--H).sub.k 
or 
EQU (A-L).sub.k -X--H 
wherein A is a silver halide adsorptive group that contains at least one 
atom of N, S, P, Se, or Te that promotes adsorption to silver halide, and 
L represents a linking group containing at least one C, N, S or O atom, k 
is 1 or 2, and X--H is a deprotonating one-electron or two-electron donor 
group as defined above. 
Another aspect of this invention comprises a photographic element 
comprising at least one silver halide emulsion layer in which the silver 
halide is sensitized with a compound of the formula: 
EQU Z-(L-X--H).sub.k 
wherein Z is a light absorbing group including, for example, cyanine dyes, 
complex cyanine dyes, merocyanine dyes, complex merocyanine dyes, 
homopolar cyanine dyes, styryl dyes, oxonol dyes, hemioxonol dyes, and 
hemicyanine dyes; L represents a linking group containing at least one C, 
N, S or O atom; and X--H is a deprotonating one-electron or two-electron 
donor group as defined above. 
Another aspect of this invention comprises a photographic element 
comprising at least one silver halide emulsion layer in which the silver 
halide is sensitized with a compound of the formula: 
EQU Q-X--H 
wherein Q represents the atoms necessary to form a chromophore comprising 
an amidinium-ion, a carboxyl-ion or dipolar-amidic chromophoric system 
when conjugated with X--H, and X--H is a deprotonating one-electron or 
two-electron donor group as defined above. 
Another aspect of this invention comprises a photographic element 
comprising at least one silver halide emulsion layer in which the silver 
halide is sensitized with a compound of the formula: 
EQU A-(X--H).sub.k 
or 
EQU (A).sub.k -X--H 
wherein A is a silver halide adsorptive group as described above that 
contains at least one atom of N, S, P, Se, or Te that promotes adsorption 
to silver halide, k is 1 or 2, and X--H is a deprotonating one-electron or 
two-electron donor group as defined above. 
Another aspect of this invention comprises a photographic element 
comprising at least one silver halide emulsion layer in which the silver 
halide is sensitized with a compound of the formula: 
EQU Z-(X--H).sub.k 
or 
EQU (Z).sub.k -X--H 
wherein Z is a light absorbing group as described above which includes, for 
example, cyanine dyes, complex cyanine dyes, merocyanine dyes, complex 
merocyanine dyes, homopolar cyanine dyes, styryl dyes, oxonol dyes, 
hemioxonol dyes, and hemicyanine dyes; k is 1 or 2; and X--H is a 
deprotonating one-electron or two-electron donor group as defined above. 
Electron-donating compounds that undergo a fragmentation reaction, i. e., a 
bond cleavage reaction, subsequent to oxidation have been described in 
above-mentioned commonly assigned copending U.S. patent applications Ser. 
Nos. 08/740,536, 08/739,911 and 08/739,921, filed Oct. 30, 1996, the 
entire disclosures of which are incorporated herein by reference. The 
fragmentation reaction preferably results in the formation of a reducing 
radical. In these applications, fragmentation of a variety of bonds in the 
donor compound was described (e.g. carbon-carbon, carbon-silicon, 
carbon-boron). 
ADVANTAGEOUS EFFECT OF THE INVENTION 
This invention provides a silver halide photographic emulsion containing an 
organic electron donor capable of enhancing both the intrinsic sensitivity 
and, if a dye is present, the spectral sensitivity of the silver halide 
emulsion. The activity of these compounds can be easily varied with 
substituents to control their speed and fog effects in a manner 
appropriate to the particular silver halide emulsion in which they are 
used. An important feature of the electron donor compounds used is that 
after donating an electron they undergo a deprotonation reaction which 
results in irreversible transformation of the oxidized donor. The utility 
of deprotonating electron donor compounds has not been previously 
described. 
DETAILED DESCRIPTION OF THE INVENTION 
The photographic element of this invention comprises a silver halide 
emulsion layer which contains a deprotonating electron donor of the 
formula X--H, in which X is an electron donor moiety to which a base, 
B.sup.-, is covalently linked and H is a leaving hydrogen atom. The 
deprotonating electron donor X--H enhances the sensitivity of a silver 
halide emulsion. 
The following represents the reactions believed to take place when the 
compound X--H undergoes oxidation and deprotonation to the base, B.sup.-, 
to produce a radical X.sup..cndot., which in a preferred embodiment 
undergoes further oxidation. 
##STR1## 
The base, B.sup.-, is the conjugate base of an acid, B-H, which preferably 
has a pKa in the range about 1 to about 8, preferably about 2 to about 7. 
The deprotonation reactions with conjugate bases for acids with 
significantly lower pKa values tend to be too slow to be useful. If the 
pKa of the acid, B-H, is significantly larger than about 8, then the base 
is likely to be already protonated in the medium, and will therefore not 
be capable of deprotonating the oxidized molecule X--H.sup..cndot.+. As 
mentioned above, the base, B.sup.-, is covalently attached to the X--H 
molecule. 
The important characteristics of the X--H molecule are its oxidation 
potential, the oxidation potential of the radical X.cndot., and the rate 
of deprotonation of the oxidized molecule X--H.sup..cndot.+. Here are 
shown 4 preferred general structures for X--H (I-IV) which are designed to 
accommodate these required characteristics. For simplicity, and because of 
multiple possible sites, the attachment of the base, B.sup.-, is not 
specifically indicated in the structures. The sites of attachment of the 
base are discussed below. In certain instances where there is another 
abstractable H atom, it is not clear which H atom is in fact abstracted. 
Specific structures for X--H compounds are provided hereinafter. 
##STR2## 
The symbol "R" (that is R without a subscript) is used in all structural 
formulae in this patent application to represent a hydrogen atom or an 
unsubstituted or substituted alkyl group. In the structures of this patent 
application a designation such as --OR(N(R).sub.2) indicates that either 
--OR or --N(R).sub.2 can be present. Unless otherwise specified the symbol 
"n" is an integer of 1 to 8. 
In structure (I): 
m: 0, 1; 
Z.sub.1 : O, S, Se, Te; 
Ar: aryl group (e.g., phenyl, naphthyl, phenanthryl, anthryl); or 
heterocyclic group (e.g., pyridine, indole, benzimidazole, thiazole, 
benzothiazole, thiadiazole, etc.); 
R.sub.1 : R, carboxyl, amide, sulfonamide, halogen, N(R).sub.2, (OH).sub.f, 
(OR').sub.f, or (SR).sub.f ; 
R': alkyl or substituted alkyl; 
f: 1-3; 
R.sub.2 : R, Ar'; 
Ar': aryl group such as phenyl, substituted phenyl, or heterocyclic group 
(e.g., pyridine, benzothiazole, etc.) 
R.sub.3 : R, Ar'; 
R.sub.2 and R.sub.3 : together can form 5- to 8-membered ring; 
R.sub.2 and Ar: can be linked to form 5- to 8-membered ring; 
R.sub.3 and Ar: can be linked to form 5- to 8-membered ring; 
In structure (II): 
Ar: aryl group (e.g., phenyl, naphthyl, phenanthryl); or heterocyclic group 
(e.g., pyridine, benzothiazole, etc.); 
R.sub.4 : a substituent having a Hammett sigma value of -1 to +1, 
preferably -0.7 to +0.7, e.g., R, OR, SR, halogen, CHO, C(O)R, COOR, 
CON(R).sub.2, SO.sub.3 R, SO.sub.2 N(R).sub.2, SO.sub.2 R, SOR, C(S)R, 
etc; 
R.sub.5 : R, Ar' 
R.sub.6 and R.sub.7 : R, Ar' 
R.sub.5 and Ar: can be linked to form 5- to 8-membered ring; 
R.sub.6 and Ar: can be linked to form 5- to 8-membered ring (in which case, 
R.sub.6 can be a hetero atom); 
R.sub.5 and R.sub.6 : can be linked to form 5- to 8-membered ring; 
R.sub.6 and R.sub.7 : can be linked to form 5- to 8-membered ring; 
Ar': aryl group such as phenyl, substituted phenyl, heterocyclic group; 
R: hydrogen atom or an unsubstituted or substituted alkyl group. 
A discussion on Hammett sigma values can be found in C. Hansch and R. W. 
Taft Chem. Rev. Vol 91, (1991) p 165, the disclosure of which is 
incorporated herein by reference. 
In structure (III): 
Z.sub.2 : O, S, Se; 
Ar: aryl group (e.g., phenyl, naphthyl, phenanthryl, anthryl); or 
heterocyclic group (e.g., indole, benzimidazole, etc.) 
R.sub.8 : R, carboxyl, N(R).sub.2, (OR).sub.f, or (SR).sub.f (f=1-3); 
R.sub.9 and R.sub.10 : R, Ar'; 
R.sub.9 and Ar: can be linked to form 5- to 8-membered ring; 
Ar': aryl group such as phenyl substituted phenyl or heterocyclic group; 
R: a hydrogen atom or an unsubstituted or substituted alkyl group. 
In structure (IV): 
"ring" represents a substituted or unsubstituted 5-, 6-, or 7-membered 
unsaturated ring, preferrably a heterocyclic ring. 
Since X is an electron donor moiety (i.e., an electron rich organic group), 
the substituents on the aromatic groups (Ar and/or Ar'), for any 
particular X group should be selected so that X remains electron rich. For 
example, if the aromatic group is highly electron rich, e.g. anthracene, 
electron withdrawing substituents can be used, providing the resulting 
X--H compound has an oxidation potential of 0 to about 1.4 V. Conversely, 
if the aromatic group is not electron rich, electron donating substituents 
should be selected. 
When reference in this application is made to a substituent "group" this 
means that the substituent may itself be substituted or unsubstituted (for 
example "alkyl group" refers to a substituted or unsubstituted alkyl). 
Generally, unless otherwise specifically stated, substituents on any 
"groups" referenced herein or where something is stated to be possibly 
substituted, include the possibility of any groups, whether substituted or 
unsubstituted, which do not destroy properties necessary for the 
photographic utility. It will also be understood throughout this 
application that reference to a compound of a particular general formula 
includes those compounds of other more specific formula which specific 
formula falls within the general formula definition. Examples of 
substituents on any of the mentioned groups can include known 
substituents, such as: halogen, for example, chloro, fluoro, bromo, iodo; 
alkoxy, particularly those with 1 to 12 carbon atoms (for example, 
methoxy, ethoxy); substituted or unsubstituted alkyl, particularly lower 
alkyl (for example, methyl, trifluoromethyl); alkenyl or thioalkyl (for 
example, methylthio or ethylthio), particularly either of those with 1 to 
12 carbon atoms; substituted and unsubstituted aryl, particularly those 
having from 6 to 20 carbon atoms (for example, phenyl); and substituted or 
unsubstituted heteroaryl, particularly those having a 5- or 6-membered 
ring containing 1 to 3 heteroatoms selected from N, O, S or Se (for 
example, pyridyl, thienyl, furyl, pyrrolyl and their corresponding benzo 
and naptho analogs); and others known in the art. Alkyl substituents 
preferably contain 1 to 12 carbon atoms and specifically include "lower 
alkyl", that is having from 1 to 6 carbon atoms, for example, methyl, 
ethyl, and the like. Further, with regard to any alkyl group, alkylene 
group or alkenyl group, it will be understood that these can be branched 
or unbranched and include ring structures. 
As indicated above, a base, B-, is covalently linked to X. The base is 
preferably the conjugate base of an acid of pKa between about 1 and about 
8. Collections of pKa values are available (see, for example: Dissociation 
Constants of Organic Bases in Aqueous Solution, D. D. Perrin 
(Butterworths, London, 1965); CRC Handbook of Chemistry and Physics, 77th 
ed, D. R. Lide (CRC Press, Boca Raton, Fla., 1996)). Examples of useful 
bases are included in Table I. 
Table I 
pKa's in Water of the Conjugate Acids of Some Useful Bases 
TABLE I 
__________________________________________________________________________ 
pKa's in water of the conjugate acids of some useful bases 
__________________________________________________________________________ 
CH.sub.3 --CO.sub.2 .sup.- 
4.76 
CH.sub.3 --COS.sup.- 
3.33 
C.sub.2 H.sub.5 --CO.sub.2 .sup.- 4.87 
- (CH.sub.3).sub.2 CH--CO.sub.2 .sup.- 4.84 
3.73 ## 
- (CH.sub.3).sub.3 C--CO.sub.2 .sup.- 5.03 
4.88 ## 
- HO--CH.sub.2 --CO.sub.2 .sup.- 3.83 
- 
3.48 ## 
4.01 ## 
- CH.sub.3 --CO--NH--CH.sub.2 --CO.sub.2 .sup.- 3.67 
- 
4.19 ## 
4.7 ## 
- 
4.96 ## 
- 
4.65 0## 
- 
6.61 1## 
- 
5.25 2## 
- 
6.15 3## 
- 
2.44 4## 
- 
5.5315## 
__________________________________________________________________________ 
Preferably the base is a carboxylate, sulfate and amine oxide. 
As mentioned above the base is covalently attached to X--H. The attached 
base should be appropriately situated to deprotonate X--H by reaction with 
the proton indicated by the symbol H in the preferred general structures 
I-IV given above. The base may be directly attached to X, or more 
preferably the base is attached using a linking group. The linking group 
is preferably an organic linking group containing at least one C, N, S, or 
O atom. Preferred examples of the linkage group include, an alkylene 
group, an arylene group, an alkylene group in which one or more of the 
carbon atoms is replaced by --O--, --S--, --C.dbd.O, --SO.sub.2 --, --NH, 
--P.dbd.O, and --N.dbd.. Each of these linking components can be 
optionally substituted and can be used alone or in combination. The length 
of the linkage group can be limited to a single atom or can be much 
longer, for instance up to 10 atoms in length. Some preferred examples of 
these linkage groups are: 
##STR16## 
where n=1-8, (n.sub.1 +n.sub.2)=1-8, and n.sub.3 =1-3. 
The linking group positions the base so that the desired deprotonation can 
occur. If the base is the carboxylate anion, then the linking group should 
not be a simple methylene group, since such a compound may undergo a 
decarboxylation reaction upon 1 electron oxidation, as described in 
commonly assigned copending U.S. patent applications Ser. Nos. 08/740,536, 
08/739,911 and 08/739,921, filed Oct. 30, 1996, the entire disclosures of 
which are incorporated herein by reference, Specific examples of the 
attachment of the base to the X--H compound are shown in the illustrative 
examples of the general structures I-IV given below. In these examples, 
the attached base is the carboxylate group (--CO.sub.2.sup.-). The 
following examples are illustrative. It is clear that via appropriate 
substitution chemistry, the attached carboxylate group could be replaced 
by an other base, for example, those included in Table I. The present 
invention should not be construed as being limited to these illustrative 
examples. 
The following are illustrative examples of the general structure I: 
##STR17## 
where n=1-8. 
The following are illustrative examples of the general structure II: 
##STR18## 
R.sub.11 through R.sub.13 are independently chosen from H, alkyl (such as 
methyl, ethyl, butyl, isopropyl, tert-butyl, cyclohexyl), substituted 
alkyl, halo, alkoxy, alkylthio, carboxyl, amido, sulfonyl, formyl, acyl, 
or R.sub.11 and R.sub.13 or R.sub.12 and R.sub.13 are fused 5- to 
8-membered ring. 
EQU Z.sub.3 =S, O, Se, NR, C(R).sub.2 
The following are illustrative examples of the general structure III: 
##STR19## 
wherein n'=0 to 3. 
The following is an illustrative example of the general structure IV: 
##STR20## 
wherein n'=0 to 3. 
In the above formulae, counterion(s) required to balance the charge of the 
X--H moiety are not shown as any counterion can be utilized. Common 
counterions are sodium, potassium, triethylammonium (TEA.sup.+), 
tetramethylguanidinium (TMG.sup.+), diisopropylammonium (DIPA.sup.+), and 
tetrabutylammonium (TBA.sup.+). 
Illustrative examples of the preferred X--H compounds are of the formula: 
##STR21## 
wherein: 
one or both of R.sub.11 and R.sub.12 is a group that has a steric parameter 
which is equal to or larger than that of fluorine; 
R.sub.13 is a substituent having a Hammett sigma value of -1 to +1; 
R.sub.11 and R.sub.13 can form a fused 5- to 8-membered, saturated or 
unsaturated ring that may contain heteroatoms; 
More preferred are compounds according to the above structure wherein: 
R.sub.11 or R.sub.12 or both R.sub.11 and R.sub.12 are independently chosen 
to be a halogen atom, a substituted or unsubstituted alkyl, an alkoxy 
group, an alkylthio group, an aryl group, a heterocyclic moiety, a 
carboxylate group or an acyl group; 
R.sub.13 is a hydrogen atom, a halogen atom, a substituted or unsubstituted 
alkyl group, a carboxylate group, an amido group, a formyl group, an acyl 
group, a sulfonate or sulfonamide group, an alkoxy or an alkylthio group. 
R.sub.11 and R.sub.12 can form a fused 5- to 8-membered, saturated or 
unsaturated ring that may contain heteroatoms. 
Steric parameters are listed in R. W. Taft, Progress in Physical Organic 
Chemistry, vol 12, p 92 to 98 (Wiley & Sons, New York, 1976). 
The following are preferred examples of X--H compounds: 
______________________________________ 
#STR22## 
Compound No. 
R.sub.14 R.sub.15 R.sub.16 
R.sub.17 
______________________________________ 
1 Bu (CH.sub.2).sub.2 --CO.sub.2 .sup.- H H 
2 Me (CH.sub.2).sub.3 --CO.sub.2 .sup.- H H 
3 Me (CH.sub.2).sub.5 --CO.sub.2 .sup.- H H 
4 (CH.sub.2).sub.2 --CO.sub.2 .sup.- (CH.sub.2).sub.2 --CO.sub.2 .sup.- 
H H 
5 (CH.sub.2).sub.3 --CO.sub.2 .sup.- (CH.sub.2).sub.3 --CO.sub.2 .sup.- 
H H 
6 (CH.sub.2).sub.2 --CO.sub.2 .sup.- (CH.sub.2).sub.2 --CO.sub.2 .sup.- 
Me H 
7 (CH.sub.2).sub.3 --CO.sub.2 .sup.- (CH.sub.2).sub.3 --CO.sub.2 .sup.- 
Me H 
8 (CH.sub.2).sub.2 --CO.sub.2 .sup.- (CH.sub.2).sub.2 --CO.sub.2 .sup.- 
OMe OMe 
______________________________________ 
#STR23## 
Compound No. R.sub.18 R.sub.19 
______________________________________ 
9 CH.sub.3 H 
10 C.sub.2 H.sub.5 H 
11 CH(CH.sub.3).sub.2 H 
12 C(CH.sub.3).sub.3 H 
13 C.sub.6 H.sub.5 H 
14 (CH.sub.2).sub.2 OH H 
15 CH.sub.2 --CN H 
16 CH.sub.2 --Ph H 
17 (CH.sub.2).sub.2 --NMe.sub.2 H 
18 CO--Ph H 
19 CO.sub.2 Et H 
20 O--Ph H 
- 21 
H TR24## 
- 22 
H TR25## 
- 23 CH.sub.3 CH.sub.3 
24 CH.sub.3 Br 
25 Br CH.sub.3 
26 Cl H 
27 F H 
______________________________________ 
#STR26## 
#STR27## 
- 
#STR28## 
#STR29## 
- 
#STR30## 
#STR31## 
- 
#STR32## 
#STR33## 
- 
#STR34## 
Compound No. R.sub.20 R.sub.21 
______________________________________ 
35 CH.sub.3 H 
36 C.sub.2 H.sub.5 H 
37 CH(CH.sub.3).sub.2 H 
38 C(CH.sub.3).sub.3 H 
39 C.sub.6 H.sub.5 H 
40 (CH.sub.2).sub.2 OH H 
41 CH.sub.3 CH.sub.3 
42 Br CH.sub.3 
______________________________________ 
#STR35## 
Compound No. R.sub.22 R.sub.23 
______________________________________ 
43 (CH.sub.2).sub.2 --CO.sub.2 .sup.- H 
44 (CH.sub.2).sub.3 --CO.sub.2 .sup.- H 
45 (CH.sub.2).sub.4 --CO.sub.2 .sup.- H 
46 (CH.sub.2).sub.5 --CO.sub.2 .sup.- H 
47 (CH.sub.2).sub.6 --CO.sub.2 .sup.- H 
48 (CH.sub.2).sub.3 --CO.sub.2 .sup.- CH.sub.3 
49 (CH.sub.2).sub.3 --CO.sub.2 .sup.- Br 
______________________________________ 
#STR36## 
Compound No. R.sub.24 R.sub.25 
______________________________________ 
50 C.sub.2 H.sub.5 CH.sub.3 
51 CH(CH.sub.3).sub.2 CH.sub.3 
52 Cl CH.sub.3 
53 Cl Cl 
______________________________________ 
#STR37## 
- 
#STR38## 
- 
#STR39## 
Compound No. R.sub.26 R.sub.27 
______________________________________ 
56 (CH.sub.2).sub.2 --CO.sub.2 .sup.- H 
57 (CH.sub.2).sub.3 --CO.sub.2 .sup.- H 
58 (CH.sub.2).sub.4 --CO.sub.2 .sup.- H 
59 (CH.sub.2).sub.5 --CO.sub.2 .sup.- H 
60 (CH.sub.2).sub.6 --CO.sub.2 .sup.- H 
61 (CH.sub.2).sub.3 --CO.sub.2 .sup.- CH.sub.3 
62 (CH.sub.2).sub.3 --CO.sub.2 .sup.- Br 
______________________________________ 
#STR40## 
- 
#STR41## 
- 
#STR42## 
- 
#STR43## 
- 
#STR44## 
- 
#STR45## 
- 
#STR46## 
- 
#STR47## 
- 
#STR48## 
- 
##STR49## 
______________________________________ 
The deprotonating electron donors X--H can be deprotonating one-electron 
donors which meet the first two criteria described above or deprotonating 
two-electron donors which meet all three criteria described above. The 
first criterion relates to the oxidation potential of the X--H species 
(E.sub.ox1). E.sub.ox1 is preferably no higher than about 1.4 V and 
preferably less than about 1.0 V. The oxidation potential is preferably 
greater than 0, more preferably greater than about 0.3 V. E.sub.ox1 is 
preferably in the range of about 0 to about 1.4 V, and more preferably 
from about 0.3 V to about 1.0 V. 
Oxidation potentials are well known and can be found, for example, in 
"Encyclopedia of Electrochemistry of the Elements", Organic Section, 
Volumes XI-XV, A. Bard and H. Lund (Editors) Marcel Dekkar Inc., NY 
(1984). E.sub.ox1 can be measured by the technique of cyclic voltammetry. 
In this technique, the electron donor is dissolved in a solution of 
80%/20% by volume acetonitrile to water containing 0.1 M lithium 
perchlorate. Oxygen is removed from the solution by passing nitrogen gas 
through the solution for 10 minutes prior to measurement. A glassy carbon 
disk is used for the working electrode, a platinum wire is used for the 
counter electrode, and a saturated calomel electrode (SCE) is used for the 
reference electrode. Measurement is conducted at 25.degree. C. using a 
potential sweep rate of 0.1 V/sec. The oxidation potential vs. SCE is 
taken as the peak potential of the cyclic voltammetric wave. Oxidation 
potentials of some example X--H compounds are summarized in Table II. 
Table II 
Oxidation Potentials of Example X--H Compounds 
TABLE II 
______________________________________ 
Oxidation Potentials of Example X-H conpounds 
Compound E.sub.oxl (V vs SCE) 
______________________________________ 
1 0.632 
9 0.695 
11 0.715 
12 0.760 
37 0.625 
38 0.625 
43 0.712 
44 0.670 
45 0.685 
46 0.710 
47 0.750 
56 0.665 
57 0.660 
58 0.680 
59 0.680 
60 0.790 
______________________________________ 
The second criterion defining the compounds useful in accordance with our 
invention is the requirement that the oxidized form of X--H, that is the 
radical cation X--H.sup.+.cndot., undergoes deprotonation to the attached 
base, to give the radical X.sup..cndot. and the B-H moiety. It is widely 
known that radical species, and in particular radical cations formed by a 
one-electron oxidation reaction, may undergo a multitude of reactions, 
some of which are dependent upon their concentration and on the specific 
environment wherein they are produced. As described in "Kinetics and 
Mechanisms of Reactions of Organic Cation Radicals in Solution", Advances 
in Physical Organic Chemistry, vol 20, 1984, pp 55-180, and "Formation, 
Properties and Reactions of Cation Radicals in Solution", Advances in 
Physical Organic Chemistry, vol 13, 1976, pp 156-264, V. Gold Editor, 
1984, published by Academic Press, NY, the range of reactions available to 
such radical species includes: dimerization, deprotonation, nucleophilic 
substitution, disproportionation, and bond cleavage. With compounds useful 
in accordance with our invention, the oxidized form of X--H undergoes a 
deprotonation reaction. In some instances where there is another 
abstractable H atom in the molecule, for example, compounds 56-64 which 
have either an NH or an OH group, it is not clear which H atom is in fact 
abstracted. 
The rate constant of the deprotonation reaction, k.sub.dp, can be measured 
by conventional laser flash photolysis. The general technique of laser 
flash photolysis as a method to study properties of transient species is 
well known (see, for example, "Absorption Spectroscopy of Transient 
Species" W. Herkstroeter and I. R. Gould in Physical Methods of Chemistry 
Series, second Edition, Volume 8, page 225, edited by B. Rossiter and R. 
Baetzold, John Wiley & Sons, New York, 1993). The specific experimental 
apparatus we used to measure deprotonation rate constants and radical 
oxidation potentials is described in detail below. The rate constant of 
deprotonation in compounds useful in accordance with this invention is 
preferably faster than about 10 per second (i.e., k.sub.dp should be 10 
s.sup.-1 or higher, or, in other words, the lifetime of the radical cation 
X--H.sup.+.cndot. should be 0.1 sec or less). The deprotonation rate 
constants can be considerably higher than this, namely in the 10.sup.2 to 
10.sup.13 s.sup.-1 range. The deprotonation rate constant is preferably 
about 10.sup.3 sec.sup.-1 to about 10.sup.13 s.sup.-1, more preferably 
about 10.sup.4 to about 10.sup.11 s.sup.-1. 
Table III 
Rate Constants for Deprotonation of the Radical Cations of Some Example 
X--H Compounds in CH.sub.3 CN/H.sub.2 O (4:1) 
TABLE III 
______________________________________ 
Rate Constants for 
Deprotonation of the Radical Cations of some Example X-H 
Compounds in CH.sub.3 CN/H.sub.2 O (4:1) 
Compound k.sub.dp (s.sup.-1) 
______________________________________ 
2 ca. 1 .times. 10.sup.3 
3 ca. 1 .times. 10.sup.3 
4 &lt;1 .times. 10.sup.5 
5 &lt;1 .times. 10.sup.5 
9 2 .times. 10.sup.5 
10 6 .times. 10.sup.5 
11 2 .times. 10.sup.6 
12 ca. 3 .times. 10.sup.7 
13 3 .times. 10.sup.5 
25 ca. 5 .times. 10.sup.4 
26 1.1 .times. 10.sup.6 
27 7.9 .times. 10.sup.4 
28 2.4 .times. 10.sup.5 
29 9 .times. 10.sup.4 
32a 2.4 .times. 10.sup.7 
43 1.8 .times. 10.sup.6 
44 ca 1 .times. 10.sup.8 
45 1.3 .times. 10.sup.7 
46 1.4 .times. 10.sup.6 
47 2.3 .times. 10.sup.5 
54 ca. 1 .times. 10.sup.5 
118 &gt;3 .times. 10.sup.5 
______________________________________ 
In a preferred embodiment of the invention, the X--H compound is a 
deprotonating two-electron donor and meets a third criterion, that the 
radical X.sup..cndot. resulting from the deprotonation reaction has an 
oxidation potential, E.sub.ox2, equal to or more negative than -0.7V, 
preferably more negative than about -0.9 V. This oxidation potential is 
preferably in the range of from about -0.7 to about -2 V, more preferably 
from about -0.8 to about -2 V and most preferably from about -0.9 to about 
-1.6 V. 
The oxidation potential of many radicals have been measured by transient 
electrochemical and pulse radiolysis techniques as reported by Wayner, D. 
D.; McPhee, D. J.; Griller, D. in J. Am. Chem. Soc. 1988, 110, 132; Rao, 
P. S,; Hayon, E. J. Am. Chem. Soc. 1974, 96, 1287 and Rao, P. S,; Hayon, 
E. J. Am. Chem. Soc. 1974, 96, 1295. The data demonstrate that for carbon 
centered radicals, the oxidation potentials of tertiary substituted 
species are less positive (i.e., the radicals are stronger reducing 
agents) than those of the corresponding secondary radicals, which in turn 
are more negative than those of the corresponding primary radicals. For 
example, the oxidation potential of benzyl radical decreases from 0.73V to 
0.37 V to 0.16 V upon replacement of one or both hydrogen atoms by methyl 
groups. 
##STR50## 
A considerable decrease in the oxidation potential of the radicals is 
achieved by a hydroxy or alkoxy substituents. For example the oxidation 
potential of the benzyl radical (+0.73 V) decreases to -0.44 when one of 
the a hydrogen atoms is replaced by a methoxy group. 
##STR51## 
An .alpha.-amino substituent decreases the oxidation potential of the 
radical to values of about -1 V. There are almost no data available for 
oxidation potentials of heteroatom centered radicals. Based simply on the 
fact that the electronegativities of atoms such as nitrogen and oxygen are 
larger than for carbon, it would be expected that radicals centered on 
nitrogen and oxygen would be harder to oxidize than carbon centered 
radicals. In addition, stabilization via .alpha.-substitution such as 
described above for carbon radicals would be less beneficial for nitrogen 
and oxygen radicals simply because of the reduced number of valence sites 
for these atoms. 
The oxidation potential of the transient species X.cndot., can be 
determined using a laser flash photolysis technique as described in 
greater detail below. In this technique, the compound X--H is oxidized by 
an electron transfer reaction initiated by a short laser pulse. The 
oxidized form of X--H then undergoes the deprotonation reaction to give 
the radical X.sup..cndot.. X.sup..cndot. is then allowed to interact with 
various electron acceptor compounds, Ac, of known reduction potential. The 
sequence of events is illustrated below for the example of X--H compound 
2. The ability of X.sup..cndot. to reduce a given Ac indicates that the 
oxidation potential of X.sup..cndot. is nearly equal to or more negative 
than the reduction potential of Ac. The experimental details are set forth 
more fully below. 
##STR52## 
In accordance with our invention we have discovered that compounds which 
provide a radical X.cndot. having an oxidation potential more negative 
than -0.7 are particularly advantageous for use in sensitizing silver 
halide emulsions. Oxidation potentials (E.sub.ox2) for radicals derived 
from typical compounds useful in accordance with our invention, i.e. 
having oxidation potentials more negative than -0.7, are given in Table 
III. Where only limits on potentials could be determined, the following 
notation is used: &lt;-0.90 V should be read as "more negative than -0.90 V" 
and &gt;-0.40 V should be read as "less negative than -0.40 V". Some 
comparative examples of compounds which provide radicals with E.sub.ox2 
less negative than -0.7 V are also included. 
Table IV 
Oxidation Potentials, E.sub.ox2, for Radicals Derived From Typical X--H 
Compounds 
TABLE IV 
______________________________________ 
Oxidation Potentials, E.sub.ox2, 
for Radicals Derived From Typical X-H Compounds 
#STR53## 
X-H compound R.sub.28 
E.sub.ox2 
______________________________________ 
10 C.sub.2 H.sub.5 &lt;-0.9 
11 CH(CH.sub.3).sub.2 &lt;-0.9 
12 C(CH.sub.3).sub.3 &lt;-0.9 
13 C.sub.6 H.sub.5 &lt;-0.9 
26 Cl &lt;-0.9 
27 F &lt;-0.9 
______________________________________ 
#STR54## 
X-H compound 
E.sub.ox2 
______________________________________ 
28 &lt;-0.9 
______________________________________ 
#STR55## 
X-H compound n.sub.1 
E.sub.ox2 
______________________________________ 
43 2 &lt;-0.9 
45 4 &lt;-0.9 
46 5 &lt;-0.9 
______________________________________ 
#STR56## 
X-H compound n.sub.2 
E.sub.ox2 
______________________________________ 
2 3 &lt;-0.9 
3 5 &lt;-0.9 
______________________________________ 
#STR57## 
X-H compound R.sub.29 E.sub.ox2 
______________________________________ 
6 (CH.sub.2).sub.2 CO.sub.2.sup.- &lt;-0.9 
7 (CH.sub.2).sub.3 CO.sub.2.sup.- &lt;-0.9 
______________________________________ 
#STR58## 
X-H compound R.sub.30 
E.sub.ox2 
______________________________________ 
25 Br &lt;-0.9 
27 F &lt;-0.9 
______________________________________ 
#STR59## 
X-H compound 
E.sub.ox2 
______________________________________ 
29 &lt;-0.9 
______________________________________ 
#STR60## 
X-H compound 
E.sub.ox2 
______________________________________ 
32a &lt;-0.9 
______________________________________ 
#STR61## 
X-H compound 
E.sub.ox2 
______________________________________ 
54 &lt;-0.9 
______________________________________ 
#STR62## 
X-H compound R.sub.31 E.sub.ox2 
______________________________________ 
37 CH(CH.sub.3).sub.2 &gt;-0.45 
38 C(CH.sub.3).sub.3 &gt;-0.45 
______________________________________ 
#STR63## 
X-H compound 
E.sub.ox2 
______________________________________ 
58 &gt;-0.45 
______________________________________ 
#STR64## 
X-H compound 
E.sub.ox2 
______________________________________ 
64 &gt;-0.45 
______________________________________ 
#STR65## 
X-H compound R.sub.x 
E.sub.ox2 
______________________________________ 
120 H &lt;-0.9 
117 SO.sub.3.sup.- &lt;-0.9 
______________________________________ 
#STR66## 
X-H compound 
E.sub.ox2 
______________________________________ 
119 &lt;-0.9 
______________________________________ 
#STR67## 
X-H compound 
E.sub.ox2 
______________________________________ 
118 &lt;-0.9 
______________________________________ 
#STR68## 
X-H compound R.sub.y 
E.sub.ox2 
______________________________________ 
121 H &lt;-0.9 
122 CHO &lt;-0.9 
______________________________________ 
In another aspect of this invention, the deprotonating donor compound X--H 
can be attached to a silver halide adsorbing group, A, via a linking group 
L. Such an attached donor can be represented by the formula: 
EQU A-(L-X--H).sub.k 
or 
EQU (A-L).sub.k -X--H 
In these formulae, the X--H symbol represents a group which has a structure 
and properties which are identical to those described for the unattached 
X--H compounds described above. The linking group is described in detail 
below. 
The group A may be a silver-ion ligand moiety or a cationic surfactant 
moiety. Silver-ion ligands include: i) sulfur acids and their Se and Te 
analogs, ii) nitrogen acids, iii) thioethers and their Se and Te analogs, 
iv) phosphines, v) thionamides, selenamides, and telluramides, and vi) 
carbon acids. The aforementioned acidic compounds should preferably have 
acid dissociation constants, pKa, greater than about 5 and smaller than 
about 14. More specifically, the silver-ion ligand moieties which may be 
used to promote adsorption to silver halide are the following: 
i) Sulfur acids, more commonly referred to as mercaptans or thiols, which 
upon deprotonation can react with silver ion thereby forming a silver 
mercaptide or complex ion. Thiols with stable C--S bonds that are not 
sulfide ion precursors have found use as silver halide adsorptive 
materials as discussed in The Theory of the Photographic Process, fourth 
Edition, T. H. James, editor, pages 32-34, (Macmillan, 1977). Substituted 
or unsubstituted alkyl and aryl thiols with the general structure shown 
below, as well as their Se and Te analogs may be used: 
EQU R"--SH and R'"--SH 
The group R" is an aliphatic, aromatic, or heterocyclic group, and may be 
substituted with functional groups comprising halogen, oxygen, sulfur or 
nitrogen atoms, and R'" is an aliphatic, aromatic, or heterocyclic group 
substituted with a SO.sub.2 functional group. When the group R'" is used 
the adsorbing group represents a thiosulfonic acid. 
Heterocyclic thiols are the more preferred type in this category of 
adsorbing groups and these may contain O, S, Se, Te, or N as heteroatoms 
as given in the following general structures: 
##STR69## 
wherein: Z.sub.4 represents the remaining members for completing a 
preferably 5- or 6-membered ring which may contain one or more additional 
heteroatoms, such as nitrogen, oxygen, sulfur, selenium or tellurium atom, 
and is optionally benzo- or naphtho-condensed. 
The presence of an --N.dbd. adjacent to, or in conjugation with the thiol 
group introduces a tautomeric equilibrium between the mercaptan 
[--N.dbd.C--SH] and the thionamide structure [--HN--C.dbd.S]. The 
triazolium thiolates of U.S. Pat. No. 4,378,424 represent related 
mesoionic compounds that cannot tautomerize but are active Ag.sup.+ 
ligands. Preferred heterocyclic thiol silver ligands for use in this 
invention, which include those common to silver halide technology, are 
mercaptotetrazole, mercaptotriazole, mercaptothiadiazole, 
mercaptoimidazole, mercaptooxadiazole, mercaptothiazole, 
mercaptobenzimidazole, mercaptobenzothiazole, mercaptobenzoxazole, 
mercaptopyrimidine, mercaptotriazine, phenylmercaptotetrazole, 
1,4,5-trimethyl-1,2,4-triazolium 3-thiolate, and 
1-methy-4,5,-diphenyl-1,2,4-triazolium-3-thiolate. 
ii) Nitrogen acids which upon deprotonation can serve as silver-ion 
ligands. A variety of nitrogen acids which are common to silver halide 
technology may be used, but most preferred are those derived from 5- or 
6-membered heterocyclic ring compounds containing one or more of nitrogen, 
or sulfur, or selenium, or tellurium atoms and having the general formula: 
##STR70## 
wherein: Z.sub.4 represents the remaining members for completing a 
preferably 5- or 6-membered ring which may contain one or more additional 
heteroatoms, such as a nitrogen, oxygen, sulfur, selenium or tellurium 
atom, and is optionally benzo- or naphtho-condensed, 
Z.sub.5 represents the remaining members for completing a preferably 5- or 
6-membered ring which contains at least one additional heteroatom such as 
nitrogen, oxygen, sulfur, selenium or tellurium and is optionally benzo or 
naptho-condensed, 
Preferred are heterocyclic nitrogen acids including azoles, purines, 
hydroxy azaindenes, and imides, such as those described in U.S. Pat. No. 
2,857,274, the disclosure of which is incorporated herein by reference. 
The most preferred nitrogen acid moieties are: uracil, tetrazole, 
benzotriazole, benzothiazole, benzoxazole, adenine, rhodanine, and 
substituted 1,3,3a,7-tetraazaindenes, such as 
5-bromo-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene. 
iii) Cyclic and acyclic thioethers and their Se and Te analog. Preferred 
members of this ligand category are disclosed in U.S. Pat. No. 5,246,827, 
the disclosure of which is incorporated herein by reference. Structures 
for preferred thioethers and analogs are given by the general formulae: 
EQU --(CH.sub.2).sub.a --S--(CH.sub.2).sub.b --CH.sub.3 
EQU --(CH.sub.2).sub.a --Se--(CH.sub.2).sub.b --CH.sub.3 
EQU --(CH.sub.2).sub.a --Te--(CH.sub.2).sub.b --CH.sub.3 
EQU --(CH.sub.2).sub.a --S--(CH.sub.2).sub.b --S--(CH.sub.2).sub.c --CH.sub.3 
##STR71## 
wherein: a=1-30, b=1-30, c=1-30 with the proviso that a+b+c is .ltoreq. to 
30, and Z.sub.6 represents the remaining members for completing a 5- to 
18-membered ring, or more preferably a 5- to 8-membered ring. The cyclic 
structures incorporating Z.sub.6 may contain more than one S, Se, or Te 
atom. R" is an aliphatic, aromatic, or heterocyclic group, and may be 
substituted with functional groups comprising a halogen, oxygen, sulfur or 
nitrogen atom. Specific examples of this class include: --CH.sub.2 
CH.sub.2 SCH.sub.2 CH.sub.3, 
1,10-dithia-4,7,13,16-tetraoxacyclooctadecane, --CH.sub.2 CH.sub.2 
TeCH.sub.2 CH.sub.3, --CH.sub.2 CH.sub.2 SeCH.sub.2 CH.sub.3, --CH.sub.2 
CH.sub.2 SCH.sub.2 CH.sub.2 SCH.sub.2 CH.sub.3, and thiomorpholine. 
iv) Phosphines that are active silver halide ligands in silver halide 
materials may be used. Preferred phosphine compounds are of the formula: 
EQU (R").sub.3 --P 
wherein each R" is independently an aliphatic, aromatic, or heterocyclic 
group, and may be substituted with functional groups comprising halogen, 
oxygen, sulfur or nitrogen atoms. Particularly preferred are P(CH.sub.2 
CH.sub.2 CN).sub.3, and m-sulfophenyl-dimethylphosphine. 
v) Thionamides, thiosemicarbazides, telluroureas, and selenoureas of the 
general formulae: 
##STR72## 
wherein: 
U.sub.1 represents --NH.sub.2, --NHR", --NR".sub.2, --NH--NHR", --SR", OR"; 
D and D' represent R" or, may be linked together, to form the remaining 
members of a 5- or 6-membered ring; and 
Many such thionamide Ag.sup.+ ligands are described in U.S. Pat. No. 
3,598,598, the disclosure of which is incorporated herein by reference. 
Preferred examples of thionamides include N,N'-tetraalkylthiourea, 
N-hydroxyethyl benzthiazoline-2-one, and phenyldimethyldithiocarbamate, 
and N-substituted thiazoline-2-one. 
vi) Carbon acids derived from active methylene compounds that have acid 
dissociation constants greater than about 5 and less than about 14, such 
as bromomalonitrile, 1-methyl-3-methyl-1,3,5-trithiane bromide, and 
acetylenes. Canadian Patent 1,080,532 and U.S. Pat. No. 4,374,279 (both of 
which are incorporated herein by reference) disclose silver-ion ligands of 
the carbon acid type for use in silver halide materials. Because the 
carbon acids have, in general, a lower affinity for silver halide than the 
other classes of adsorbing groups discussed herein, the carbon acids are 
less preferred as an adsorbing group. General structures for this class 
are: 
##STR73## 
wherein: F" and G" are independently selected from --CO.sub.2 R", --COR", 
CHO, CN, SO.sub.2 R", SOR", NO.sub.2, such that the pKa of the CH is 
between 5 and 14. 
Cationic surfactant moieties that may serve as the silver halide adsorptive 
group include those containing a hydrocarbon chain of at least 4 or more 
carbon atoms, which may be substituted with functional groups based on 
halogen, oxygen, sulfur or nitrogen atoms, and which is attached to at 
least one positively charged ammonium, sulfonium, or phosphonium group. 
Such cationic surfactants are adsorbed to silver halide grains in 
emulsions containing an excess of halide ion, mostly by coulombic 
attraction as reported in J. Colloid Interface Sci., volume 22, 1966, pp. 
391. Examples of useful cationic moieties are: dimethyldodecylsulfonium, 
tetradecyltrimethylammonium, N-dodecylnicotinic acid betaine, and 
decamethylenepyridinium ion. 
Preferred examples of A include an alkyl mercaptan, a cyclic or acyclic 
thioether group, benzothiazole, tetraazaindene, benzotriazole, 
tetralkylthiourea, and mercapto-substituted hetero ring compounds 
especially mercaptotetrazole, mercaptotriazole, mercaptothiadiazole, 
mercaptoimidazole, mercaptooxadiazole, mercaptothiazole 
mercaptobenzimidazole, mercaptobenzothiazole, mercaptobenzoxazole, 
mercaptopyrimidine, mercaptotriazine, phenylmercaptotetrazole, 
1,2,4-triazolium thiolate, and related structures. 
Most preferred examples of A are: (specific structures for linked A-L-X--H 
compounds are provided hereinafter): 
##STR74## 
The point of attachment of the linking group L to the silver halide 
adsorptive group will vary depending on the structure of the adsorptive 
group, and may be at one (or more) of the heteroatoms, at one (or more) of 
the aromatic or heterocyclic rings. 
The linkage group represented by L which connects the silver halide 
absorptive group to the deprotonating electron donator moiety X--H by a 
covalent bond is preferably an organic linking group containing a least 
one C, N, S, or O atom. Preferred examples of the linkage group include, 
an alkylene group, an arylene group, --O--, --S--, --C.dbd.O, --SO.sub.2 
--, --NH--, --P.dbd.O, and --N.dbd.. Each of these linking components can 
be optionally substituted and can be used alone or in combination. 
Examples of preferred combinations of these groups are: 
##STR75## 
where c=1-30, and d=1-10 
The length of the linkage group can be limited to a single atom or can be 
much longer, for instance up to 30 atoms in length. A preferred length is 
from about 2 to 20 atoms, and most preferred is 3 to 10 atoms. Some 
preferred examples of L can be represented by the general formulae 
indicated below: 
##STR76## 
e and f=1-30, with the proviso that e+f.ltoreq.30. 
Shown below are preferred illustrative compounds which have a deprotonating 
X--H group linked to a silver halide adsorptive group according to the 
general structures A-(L-X--H).sub.k and (A-L).sub.k -X--H. 
______________________________________ 
#STR77## 
Compound No. 67 
- 
#STR78## 
- 68 
- 
#STR79## 
- 69 
- 
#STR80## 
- 70 
- 
#STR81## 
- 71 
- 
#STR82## 
- 72 
- 
#STR83## 
- 73 
- 
#STR84## 
- 74 
______________________________________ 
#STR85## 
Compound no. 
X 
______________________________________ 
109 3 
111 4 
113 5 
115 6 
______________________________________ 
#STR86## 
Compound no. 
X 
______________________________________ 
110 3 
112 4 
114 5 
116 6 
______________________________________ 
In another aspect of the present invention, the deprotonating donor 
compound X--H can be attached to a light absorbing group, Z. Such an 
attached donor can be represented by the formula: 
EQU Z-(L-X--H).sub.k 
In this formula, the X--H symbol represents a group which has a structure 
and properties which are identical to those described for the unattached 
X--H compounds described above. 
In this formula, the L symbol represents a linking group which is described 
above. 
The light absorbing group Z is preferably a spectral sensitizing dye 
typically used in color sensitization technology including, for example, 
cyanine dyes, complex cyanine dyes, merocyanine dyes, complex merocyanine 
dyes, homopolar cyanine dyes, styryl dyes, oxonol dyes, hemioxonol dyes, 
and hemicyanine dyes. Representative spectral sensitizing dyes are 
discussed in Research Disclosure, Item 36544, September 1994, the 
disclosure of which, including the disclosure of references cited therein 
are incorporated herein by reference. These dyes may be synthesized by 
those skilled in the art according to the procedures described herein or 
F. M. Hamer, The Cyanine Dyes and Related Compounds (Interscience 
Publishers, New York, 1964). Particularly preferred as a light absorbing 
group is a cyanine or merocyanine dye represented by the general formulae 
75-79 below: 
##STR87## 
wherein: 
E.sub.1 and E.sub.2 represent the atoms necessary to form a substituted or 
unsubstituted hetero ring and may be the same or different, 
each J independently represents a substituted or unsubstituted methine 
group, 
q is a positive integer of from 1 to 4, 
p and r each independently represents 0 or 1, 
D.sub.1 and D.sub.2 each independently represents substituted or 
unsubstituted alkyl or unsubstituted aryl, and 
W.sub.2 is a counterion as necessary to balance the charge; 
##STR88## 
wherein E.sub.1, D.sub.1, J, p, q and W.sub.2 are as defined above for 
formula 75 and G represents 
##STR89## 
wherein E.sub.4 represents the atoms necessary to complete a substituted 
or unsubstituted heterocyclic nucleus, and F and F' each independently 
represents a cyano group, an ester group, an acyl group, a carbamoyl group 
or an alkylsulfonyl group; 
##STR90## 
wherein D.sub.1, E.sub.1, J, p, q and W.sub.2 are as defined above for 
formula 75, and G.sub.2 represents a substituted or unsubstituted amino 
group or a substituted or unsubstituted aryl group; 
##STR91## 
wherein D.sub.1, E.sub.1, D.sub.2, E.sub.1, J, p, q, r and W.sub.2 are as 
defined for formula 75 above, and E.sub.3 is defined the same as E.sub.4 
for formula 76 above; 
##STR92## 
wherein D.sub.1, E.sub.1, J, G, p, q, r, W.sub.2 and E.sub.3 are as 
defined above. 
In the above formulas, E.sub.1 and E.sub.2 each independently represents 
the atoms necessary to complete a substituted or unsubstituted 5- or 
6-membered heterocyclic nucleus. These include a substituted or 
unsubstituted: thiazole nucleus, oxazole nucleus, selenazole nucleus, 
quinoline nucleus, tellurazole nucleus, pyridine nucleus, thiazoline 
nucleus, indoline nucleus, oxadiazole nucleus, thiadiazole nucleus, or 
imidazole nucleus. This nucleus may be substituted with known 
substituents, such as halogen (e.g., chloro, fluoro, bromo), alkoxy (e.g., 
methoxy, ethoxy), substituted or unsubstituted alkyl (e.g., methyl, 
trifluoromethyl), substituted or unsubstituted aryl, substituted or 
unsubstituted aralkyl, sulfonate, and others known in the art. 
In one embodiment of the invention, when dyes according to formula 75 are 
used E.sub.1 and E.sub.2 each independently represent the atoms necessary 
to complete a substituted or unsubstituted thiazole nucleus, a substituted 
or unsubstituted selenazole nucleus, a substituted or unsubstituted 
imidazole nucleus, or a substituted or unsubstituted oxazole nucleus. 
Examples of useful nuclei for E.sub.1 and E.sub.2 include: a thiazole 
nucleus, e.g., thiazole, 4-methylthiazole, 4-phenylthiazole, 
5-methylthiazole, 5-phenylthiazole, 4,5-dimethyl-thiazole, 
4,5-diphenylthiazole, 4-(2-thienyl)thiazole, benzothiazole, 
4-chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 
7-chlorobenzothiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 
6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 
5-phenylbenzothiazole, 6-phenylbenzothiazole, 4-methoxybenzothiazole, 
5-methoxybenzothiazole, 6-methoxybenzothiazole, 4-ethoxybenzothiazole, 
5-ethoxybenzothiazole, tetrahydrobenzothiazole, 
5,6-dimethoxybenzothiazole, 5,6-dioxymethylbenzothiazole, 
5-hydroxybenzothiazole, 6-5-dihydroxybenzothiazole, 
naphtho[2,1-d]thiazole, 5-ethoxynaphtho[2,3-d]thiazole, 
8-methoxynaphtho[2,3-d]thiazole, 7-methoxynaphtho[2,3-d]thiazole, 
4'-methoxythianaphtheno-7', 6'-4,5-thiazole, etc.; an oxazole nucleus, 
e.g., 4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, 
4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, 5-phenyloxazole, 
benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 
5-phenylbenzoxazole, 6-methylbenzoxazole,, 5,6-dimethylbenzoxazole, 
4,6-dimethylbenzoxazole, 5-ethoxybenzoxazole, 5-chlorobenzoxazole, 
6-methoxybenzoxazole, 5-hydroxybenzoxazole, 6-hydroxybenzoxazole,, 
naphtho[2,1-d]oxazole, naphtho[1,2-d]oxazole, etc.; a selenazole nucleus, 
e.g., 4-methylselenazole, 4-phenylselenazole, benzoselenazole, 
5-chlorobenzoselenazole, 5-methoxybenzoselenazole, 
5-hydroxybenzoselenazole, tetrahydrobenzoselenazole, 
naphtho[2,1-d]selenazole, naphtho[1,2-d]selenazole, etc.; a pyridine 
nucleus, e.g., 2-pyridine, 5-methyl-2-pyridine, 4-pyridine, 
3-methyl-4-pyridine, 3-methyl-4-pyridine, etc.; a quinoline nucleus, e.g., 
2-quinoline, 3-methyl-2-quinoline, 5-ethyl-2-quinoline, 
6-chloro-2-quinoline, 8-chloro-2-quinoline, 6-methoxy-2-quinoline, 
8-ethoxy-2-quinoline, 8-hydroxy-2-quinoline, 4-quinoline, 
6-methoxy-4-quinoline, 7-methyl-4-quinoline, 8-chloro-4-quinoline, etc.; a 
tellurazole nucleus, e.g., benzotellurazole, 
naphtho[1.2-d]benzotellurazole, 5,6-dimethoxybenzotellurazole, 
5-methoxybenzotellurazole, 5-methylbenzotellurazole; a thiazoline nucleus, 
e.g., thiazoline, 4-methylthiazoline, etc.; a benzimidazole nucleus, e.g., 
benzimidazole, 5-trifluoromethylbenzimidazole, 5,6-dichlorobenzimidazole; 
and indole nucleus, 3,3-dimethylindole, 3,3-diethylindole, 
3,3,5-trimethylindole; or a diazole nucleus, e.g., 
5-phenyl-1,3,4-oxadiazole, 5-methyl-1,3,4-thiadiazole. 
F and F' are each a cyano group, an ester group such as ethoxy carbonyl, 
methoxycarbonyl, etc., an acyl group, a carbamoyl group, or an 
alkylsulfonyl group such as ethylsulfonyl, methylsulfonyl, etc. Examples 
of useful nuclei for E.sub.4 include a 2-thio-2,4-oxazolidinedione nucleus 
(i.e., those of the 2-thio-2,4-(3H,5H)-oxaazolidinone series) (e.g., 
3-ethyl-2-thio-2,4 oxazolidinedione, 3-(2-sulfoethyl)-2-thio-2,4 
oxazolidinedione, 3-(4-sulfobutyl)-2-thio-2,4 oxazolidinedione, 
3-(3-carboxypropyl)-2-thio-2,4 oxazolidinedione, etc.; a thianaphthenone 
nucleus (e.g., 2-(2H)-thianaphthenone, etc.), a 
2-thio-2,5-thiazolidinedione nucleus (i.e., the 
2-thio-2,5-(3H,4H)-thiazoledeione series) (e.g., 
3-ethyl-2-thio-2,5-thiazolidinedione, etc.); a 2,4-thiazolidinedione 
nucleus (e.g., 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 
3-phenyl-2,4-thiazolidinedione, 3-a-naphthyl-2,4-thiazolidinedione, etc.); 
a thiazolidinone nucleus (e.g., 4-thiazolidinone, 
3-ethyl-4-thiazolidinone, 3-phenyl-4-thiazolidinone, 
3-a-naphthyl-4-thiazolidinone, etc.); a 2-thiazolin-4-one series (e.g., 
2-ethylmercapto-2-thiazolin-4-one, 2-alkylphenyamino-2-thiazolin-4-one, 
2-diphenylamino-2-thiazolin-4-one, etc.) a 2-imino-4-oxazolidinone (i.e., 
pseudohydantoin) series (e.g., 2,4-imidazolidinedione (hydantoin) series 
(e.g., 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, 
3-phenyl-2,4-imidazolidinedione, 3-a-naphthyl-2,4-imidazolidinedione, 
1,3-diethyl-2,4-imidazolidinedione, 
1-ethyl-3-phenyl-2,4-imidazolidinedione, 
1-ethyl-2-a-naphthyl-2,4-imidazolidinedione, 
1,3-diphenyl-2,4-imidazolidinedione, etc.); a 
2-thio-2,4-imidazolidinedione (i.e., 2-thiohydantoin) nucleus (e.g., 
2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidinedione, 
3-(2-carboxyethyl)-2-thio-2,4-imidazolidinedione, 
3-phenyl-2-thio-2,4-imidazolidinedione, 
1,3-diethyl-2-thio-2,4-imidazolidinedione, 
1-ethyl-3-phenyl-2-thio-2,4-imidazolidinedione, 
1-ethyl-3-naphthyl-2-thio-2,4-imidazolidinedione, 
1,3-diphenyl-2-thio-2,4-imidazolidinedione, etc.); a 2-imidazolin-5-one 
nucleus. 
G.sub.2 represents a substituted or unsubstituted amino group (e.g., 
primary amino, anilino), or a substituted or unsubstituted aryl group 
(e.g., phenyl, naphthyl, dialkylaminophenyl, tolyl, chlorophenyl, 
nitrophenyl). 
According to the formulas 75-79, each J represents a substituted or 
unsubstituted methine group. Examples of substituents for the methine 
groups include alkyl (preferably of from 1 to 6 carbon atoms, e.g., 
methyl, ethyl, etc.) and aryl (e.g., phenyl). Additionally, substituents 
on the methine groups may form bridged linkages. 
W.sub.2 represents a counterion as necessary to balance the charge of the 
dye molecule. Such counterions include cations and anions for example 
sodium, potassium, triethylammonium, tetramethylguanidinium, 
diisopropylammonium and tetrabutylammonium, chloride, bromide, iodide, 
para-toluene sulfonate and the like. 
D.sub.1 and D.sub.2 are each independently substituted or unsubstituted 
aryl groups (preferably of 6 to 15 carbon atoms), or more preferably, 
substituted or unsubstituted alkyl groups (preferably of from 1 to 6 
carbon atoms). Examples of aryl include phenyl, tolyl, p-chlorophenyl, and 
p-methoxyphenyl. Examples of alkyl include methyl, ethyl, propyl, 
isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc., and substituted 
alkyl groups (preferably a substituted lower alkyl containing from 1 to 6 
carbon atoms), such as a hydroxyalkyl group, e.g., 2-hydroxyethyl, 
4-hydroxybutyl, etc., a carboxyalkyl group, e.g., 2-carboxyethyl, 
4-carboxybutyl, etc., a sulfoalkyl group, e.g., 2-sulfoethyl, 
3-sulfobutyl, 4-sulfobutyl, etc., a sulfatoalkyl group, etc., an 
acyloxyalkyl group, e.g., 2-acetoxyethyl, 3-acetoxypropyl, 
4-butyroxybutyl, etc., an alkoxycarbonlyalkyl group, e.g., 
2-methoxycarbonlyethyl, 4-ethoxycarbonylbutyl, etc., or an aralkyl group, 
e.g., benzyl, phenethyl, etc. The alkyl or aryl group may be substituted 
by one or more of the substituents on the above-described substituted 
alkyl groups. 
Particularly preferred dyes are: 
##STR93## 
The linking group L may be attached to the dye at one (or more) of the 
heteroatoms, at one (or more) of the aromatic or heterocyclic rings, or at 
one (or more) of the atoms of the polymethine chain, at one (or more) of 
the heteroatoms, at one (or more) of the aromatic or heterocyclic rings, 
or at one (or more) of the atoms of the polymethine chain. For simplicity, 
and because of the multiple possible attachment sites, the attachment of 
the L group is not specifically indicated in the generic structures. 
Specific illustrative structures of preferred Z-(L-X--H).sub.k compounds 
are provided below, but the present invention should not be construed as 
being limited thereto. 
##STR94## 
In another aspect of the present invention, the deprotonating donor 
compound X--H can be part of a molecule such that when the X--H moiety is 
conjugated with a group, Q, the resulting molecule contains the atoms 
necessary to form a chromophore consisting of an amidinium-ion, a 
carboxyl-ion or dipolar-amidic chromophoric system, represented by the 
formula. 
EQU Q-X--H 
In this formula, the X--H symbol represents a group which has a structure 
and properties which are identical to those described for the unattached 
X--H compounds described above. 
When the X--H group is connected in conjugation to the Q group, a 
chromophore results which consists of an amidinium-ion, a carboxyl-ion or 
dipolar-amidic chromophoric system that is generally found in cyanine, 
complex cyanine, hemicyanine, merocyanine, and complex merocyanine dyes as 
described in F. M. Hamer, The Cyanine Dyes and Related Compounds 
(Interscience Publishers, New York, 1964). 
Particularly preferred is Q as represented by the general formulae 88-91 
below: 
##STR95## 
As defined above for the Z group, in this formula: 
E.sub.1 represents the atoms necessary to form a substituted or 
unsubstituted hetero ring, 
each J independently represents a substituted or unsubstituted methine 
group, 
q is a positive integer of from 1 to 4, 
p represents 0 or 1, 
D.sub.1 represents a substituted or unsubstituted alkyl or a substituted or 
unsubstituted aryl, 
and, W.sub.2 is a counterion as necessary to balance the charge; 
##STR96## 
wherein G, J and q are defined above; 
##STR97## 
wherein D.sub.1, E.sub.1, E.sub.3, J, p, and q are as defined above; 
##STR98## 
wherein E.sub.3, J, G, and q, are as defined as above. 
In the above formulae, E.sub.1, E.sub.3 and G are the same as defined 
above. Especially desriable nuclei for E1 are benzothiazole nuclei, 
naphthanothiazole nuclei, benzoxazole nuclei, naphthoxazole nuclei and 
benzimidazole nuclei. Especially preferred nuclei for E.sub.3 are the 
rhodanine nucleus, 3-alkylrhodanine nucleus the 
3-alkyl-2-thioxazolidin-2,4-dione nucleus, the 3-alkyl-2-thiohydantoin 
nucleus, the 3-alkyl-2-thio-oxazolin-2,4-dione nucleus, the iso-rhodanine 
nucleus, the barbituric acid, and the 2-thiobarbituric acid nuclus. 
Specific illustrative structures of preferred Q-X--H compounds are provided 
below, but the present invention should not be construed as being limited 
thereto. 
##STR99## 
In another aspect of the present invention, the deprotonating donor 
compound X--H can be part of a molecule wherein the X--H moiety is 
connected to a group, A, which is a silver halide adsorptive group as 
described above. 
EQU A-(X--H).sub.k 
or 
EQU (A).sub.k -X--H 
These compounds are distinguished from the A-(L-X--H).sub.k and (A-L).sub.k 
-X--H compounds described in detail above in that the X--H moiety is not 
attached to the A moiety via a linking group, but is directly connected to 
the A moiety. Detailed descriptions of the A and X--H moiety are given 
above, with the following expections: (1) when A is a cyclic or an acyclic 
thioether, or their Se or Te analogues, in the structures set forth above 
for preferred thioethers and analogs, the parameter "a" should be equal to 
0; (2) preferred phosphine compounds are of the formula (R").sub.2 --P. 
The X--H moiety can be either a one-electron or a two-electron donor as 
described above. 
The connection of the X--H and A moieties may be at one (or more) of the 
heteroatoms, at one )or more) of the aromatic or heterocyclic rings on the 
X portion of the X--H. Specific examples which illustrate the way in which 
the two mioeties are connected are given below. The structures shown below 
are examples only and the present invention should not be construed as 
being limited thereto. 
##STR100## 
In another aspect of the present invention, the deprotonating donor 
compound X--H can be part of a molecule wherein the X--H moiety is 
connected to a group, Z, where Z is a light absorbing group as described 
above which includes, for example, cyanine dyes, complex cyanine dyes, 
merocyanine dyes, complex merocyanine dyes, homopolar cyanine dyes, styryl 
dyes, oxonol dyes, hemioxonol dyes, and hemicyanine dyes. 
EQU Z-(X--H).sub.k 
or 
EQU (Z).sub.k -X--H 
These compounds are distinguished from the Z-(L-X--H).sub.k and (Z-L).sub.k 
-X--H compounds described in detail above in that the X--H moiety is not 
attached to the Z moiety via a linking group, but is directly connected to 
the Z moiety. Detailed descriptions of the Z and X--H moiety are given 
above. The X--H moiety can be either a one-electron or a two-electron 
donor as described above. The connection of the X--H and A moieties may be 
at one (or more) of the heteroatoms, at one )or more) of the aromatic or 
heterocyclic rings on the X portion of the X--H. Specific examples which 
illustrate the way in which the two mioeties are connected are given 
below. The structures shown below are examples only and the present 
invention should not be construed as being limited thereto. 
##STR101## 
The deprotonating electron donors useful in this invention are vastly 
different from the silver halide adsorptive (one)-electron donating 
compounds described in U.S. Pat. No. 4,607,006. The electron donating 
moieties described therein, for example phenothiazine, phenoxazine, 
carbazole, dibenzophenothiazine, ferrocene, tris(2,2'-bipyridyl)ruthenium, 
or a triarylamine are well known for forming extremely stable, i.e., 
non-deprotonating, radical cations as noted in the following references: 
J. Heterocyclic Chem., vol. 12, 1975, pp 397-399, J. Org. Chem., vol 42, 
1977, pp 983-988, "The Encyclopedia of Electrochemistry of the Elements", 
Vol XIII, pp 25-33, A. J. Bard Editor, published by Marcel Dekker Inc., 
Advances in Physical Organic Chemistry, vol 20. pp 55-180, V. Gold Editor, 
1984, published by Academic Press, NY. Also, the electron donating 
adsorptive compounds of U.S. Pat. No. 4,607,006 donate only one electron 
per molecule upon oxidation. In a preferred embodiment of the present 
invention, the deprotonating electron donors are capable of donating two 
electrons. 
The deprotonating electron donors of the present invention also differ from 
other known photographically active compounds such as R-typing agents, 
nucleators, and stabilizers. Known R-typing agents, such as Sn complexes, 
thiourea dioxide, borohydride, ascorbic acid, and amine boranes are very 
strong reducing agents. These agents typically undergo multi-electron 
oxidations but have oxidation potentials more negative than 0 V vs SCE. 
For example the oxidation potential for SnCl.sub.2 is reported in CRC 
Handbook of Chemistry and Physics, 55th edition, CRC Press Inc., Cleveland 
Ohio 1975, pp D122 to be .about.-0.10 V and that for borohydride is 
reported in J. Electrochem. Soc., 1992, vol. 139, pp 2212-2217 to be -0.48 
V vs SCE. These redox characteristics allow for an uncontrolled reduction 
of silver halide when added to silver halide emulsions, and thus the 
obtained sensitivity improvements are very often accompanied by 
undesirable levels of fog. Conventional nucleator compounds such as 
hydrazines and hydrazides differ from the deprotonating electron donors 
described herein in that nucleators are usually added to photographic 
emulsions in an inactive form. Nucleators are transformed into 
photographaically active compounds only when activated in a strongly basic 
solution, such as a developer solution, wherein the nucleator compound 
undergoes a deprotonation or hydrolysis reaction to afford a strong 
reducing agent. In contrast, the X--H compounds of this invention do not 
deprotonate or undergo hydrolysis to give strong reducing agents under 
such basic conditions. 
Amines with carboxylic acid groups have previously been added to 
photographic emulsions, but have completely different functions or 
structures to the deprotonating electron donors of the present invention. 
The use of certain amino carboxylic acids to improve stability and 
sensitivity of photographic emuslions has been described in U.S. Pat. No. 
4,314,024. Only aliphatic amino carboxylic acids were described, however, 
which distinguishes these species from the deprotonating electron donors 
of the present invention which are mainly aromatic amine derivatives. The 
use of amino acids to prevent desensitization by chelating adventitious 
metals has been described in U.S. Pat. No. 4,514,492. The use of 
dihydropyridines to reduce desensitization is described in U.S. Pat. No. 
5,192,654. These compounds showed no sensitization effect in the absence 
of added dyes, which is exactly opposite to the behavior observed for the 
present deprotonating donor compounds. The use of dihydropyridines as 
nucleating agents has also been described in Japanese Patent Nos. 06208195 
A2, 010521426 A2 and 63034535. An aminophenol substituted with a 
carboxylic group has been used as an anti-foggant Japan Patent No. 
62011850 A2. No change in the intrinsic photographic sensitivity was 
observed with this compound. The use of carboxylate substituted anilino 
dyes which act as filter dyes and which do not influence the intrinsic 
sensitivity of the emulsion has been described in U.S. Pat. No. 4925782, 
Japanese Patent No. 03103846 A2, Japanese Patent No. 01042646 A2. 
Carboxylate substituted anilino dyes have been used as filter dyes in 
direct reversal films U.S. Pat. No. 4,756,995, and in Japanese Patent No. 
59154439 A2. 
The emulsion layer of the photographic element of the invention can 
comprise any one or more of the light sensitive layers of the photographic 
element. The photographic elements made in accordance with the present 
invention can be black and white elements, single color elements or 
multicolor elements. Multicolor elements contain dye image-forming units 
sensitive to each of the three primary regions of the spectrum. Each unit 
can be comprised of a single emulsion layer or of multiple emulsion layers 
sensitive to a given region of the spectrum. The layers of the element, 
including the layers of the image-forming units, can be arranged in 
various orders as known in the art. In an alternative format, the 
emulsions sensitive to each of the three primary regions of the spectrum 
can be disposed as a single segmented layer. 
A typical multicolor photographic element comprises a support bearing a 
cyan dye image-forming unit comprised of at least one red-sensitive silver 
halide emulsion layer having associated therewith at least one cyan 
dye-forming coupler, a magenta dye image-forming unit comprising at least 
one green-sensitive silver halide emulsion layer having associated 
therewith at least one magenta dye-forming coupler, and a yellow dye 
image-forming unit comprising at least one blue-sensitive silver halide 
emulsion layer having associated therewith at least one yellow dye-forming 
coupler. The element can contain additional layers, such as filter layers, 
interlayers, overcoat layers, subbing layers, and the like. All of these 
can be coated on a support which can be transparent or reflective (for 
example, a paper support). 
Photographic elements of the present invention may also usefully include a 
magnetic recording material as described in Research Disclosure, Item 
34390, November 1992, or a transparent magnetic recording layer such as a 
layer containing magnetic particles on the underside of a transparent 
support as in U.S. Pat. No. 4,279,945 and U.S. Pat. No. 4,302,523. The 
element typically will have a total thickness (excluding the support) of 
from 5 to 30 microns. While the order of the color sensitive layers can be 
varied, they will normally be red-sensitive, green-sensitive and 
blue-sensitive, in that order on a transparent support, (that is, blue 
sensitive furthest from the support) and the reverse order on a reflective 
support being typical. 
The present invention also contemplates the use of photographic elements of 
the present invention in what are often referred to as single use cameras 
(or "film with lens" units). These cameras are sold with film preloaded in 
them and the entire camera is returned to a processor with the exposed 
film remaining inside the camera. Such cameras may have glass or plastic 
lenses through which the photographic element is exposed. 
In the following discussion of suitable materials for use in elements of 
this invention, reference will be made to Research Disclosure, September 
1994, Number 365, Item 36544, which will be identified hereafter by the 
term "Research Disclosure I." The Sections hereafter referred to are 
Sections of the Research Disclosure I unless otherwise indicated. All 
Research Disclosures referenced are published by Kenneth Mason 
Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire 
P010 7DQ, ENGLAND. The foregoing references and all other references cited 
in this application, are incorporated herein by reference. 
The silver halide emulsions employed in the photographic elements of the 
present invention may be negative-working, such as surface-sensitive 
emulsions or unfogged internal latent image forming emulsions, or positive 
working emulsions of the internal latent image forming type (that are 
fogged during processing). Suitable emulsions and their preparation as 
well as methods of chemical and spectral sensitization are described in 
Sections I through V. Color materials and development modifiers are 
described in Sections V through XX. Vehicles which can be used in the 
photographic elements are described in Section II, and various additives 
such as brighteners, antifoggants, stabilizers, light absorbing and 
scattering materials, hardeners, coating aids, plasticizers, lubricants 
and matting agents are described, for example, in Sections VI through 
XIII. Manufacturing methods are described in all of the sections, layer 
arrangements particularly in Section XI, exposure alternatives in Section 
XVI, and processing methods and agents in Sections XIX and XX. 
With negative working silver halide a negative image can be formed. 
Optionally a positive (or reversal) image can be formed although a 
negative image is typically first formed. 
The photographic elements of the present invention may also use colored 
couplers (e.g. to adjust levels of interlayer correction) and masking 
couplers such as those described in EP 213 490; Japanese Published 
Application 58-172,647; U.S. Pat. No. 2,983,608; German Application DE 
2,706,117C; U.K. Patent 1,530,272; Japanese Application A-113935; U.S. 
Pat. No. 4,070,191 and German Application DE 2,643,965. The masking 
couplers may be shifted or blocked. 
The photographic elements may also contain materials that accelerate or 
otherwise modify the processing steps of bleaching or fixing to improve 
the quality of the image. Bleach accelerators described in EP 193 389; EP 
301 477; U.S. Pat. No. 4,163,669; U.S. Pat. No. 4,865,956; and U.S. Pat. 
No. 4,923,784 are particularly useful. Also contemplated is the use of 
nucleating agents, development accelerators or their precursors (UK Patent 
2,097,140; U.K. Patent 2,131,188); development inhibitors and their 
precursors (U.S. Pat. No. 5,460,932; U.S. Pat. No. 5,478,711); electron 
transfer agents (U.S. Pat. No. 4,859,578; U.S. Pat. No. 4,912,025); 
antifogging and anti color-mixing agents such as derivatives of 
hydroquinones, aminophenols, amines, gallic acid; catechol; ascorbic acid; 
hydrazides; sulfonamidophenols; and non color-forming couplers. 
The elements may also contain filter dye layers comprising colloidal silver 
sol or yellow and/or magenta filter dyes and/or antihalation dyes 
(particularly in an undercoat beneath all light sensitive layers or in the 
side of the support opposite that on which all light sensitive layers are 
located) either as oil-in-water dispersions, latex dispersions or as solid 
particle dispersions. Additionally, they may be used with "smearing" 
couplers (e.g. as described in U.S. Pat. No. 4,366,237; EP 096 570; U.S. 
Pat. No. 4,420,556; and U.S. Pat. No. 4,543,323.) Also, the couplers may 
be blocked or coated in protected form as described, for example, in 
Japanese Application 61/258,249 or U.S. Pat. No. 5,019,492. 
The photographic elements may further contain other image-modifying 
compounds such as "Development Inhibitor-Releasing" compounds (DIR's). 
Useful additional DIR's for elements of the present invention, are known 
in the art and examples are described in U.S. Pat. Nos. 3,137,578; 
3,148,022; 3,148,062; 3,227,554; 3,384,657; 3,379,529; 3,615,506; 
3,617,291; 3,620,746; 3,701,783; 3,733,201; 4,049,455; 4,095,984; 
4,126,459; 4,149,886; 4,150,228; 4,211,562; 4,248,962; 4,259,437; 
4,362,878; 4,409,323; 4,477,563; 4,782,012; 4,962,018; 4,500,634; 
4,579,816; 4,607,004; 4,618,571; 4,678,739; 4,746,600; 4,746,601; 
4,791,049; 4,857,447; 4,865,959; 4,880,342; 4,886,736; 4,937,179; 
4,946,767; 4,948,716; 4,952,485; 4,956,269; 4,959,299; 4,966,835; 
4,985,336 as well as in patent publications GB 1,560,240; GB 2,007,662; GB 
2,032,914; GB 2,099,167; DE 2,842,063, DE 2,937,127; DE 3,636,824; DE 
3,644,416 as well as the following European Patent Publications: 272,573; 
335,319; 336,411; 346,899; 362,870; 365,252; 365,346; 373,382; 376,212; 
377,463; 378,236; 384,670; 396,486; 401,612; 401,613. 
DIR compounds are also disclosed in "Developer-Inhibitor-Releasing (DIR) 
Couplers for Color Photography," C. R. Barr, J. R. Thirtle and P. W. 
Vittum in Photographic Science and Engineering, Vol. 13, p. 174 (1969), 
incorporated herein by reference. 
It is also contemplated that the concepts of the present invention may be 
employed to obtain reflection color prints as described in Research 
Disclosure, November 1979, Item 18716, available from Kenneth Mason 
Publications, Ltd, Dudley Annex, 12a North Street, Emsworth, Hampshire 
P0101 7DQ, England, incorporated herein by reference. The emulsions and 
materials to form elements of the present invention, may be coated on pH 
adjusted support as described in U.S. Pat. No. 4,917,994; with epoxy 
solvents (EP 0 164 961); with additional stabilizers (as described, for 
example, in U.S. Pat. No. 4,346,165; U.S. Pat. No. 4,540,653 and U.S. Pat. 
No. 4,906,559); with ballasted chelating agents such as those in U.S. Pat. 
No. 4,994,359 to reduce sensitivity to polyvalent cations such as calcium; 
and with stain reducing compounds such as described in U.S. Pat. No. 
5,068,171 and U.S. Pat. No. 5,096,805. Other compounds which may be useful 
in the elements of the invention are disclosed in Japanese Published 
Applications 83-09,959; 83-62,586; 90-072,629; 90-072,630; 90-072,632; 
90-072,633; 90-072,634; 90-077,822; 90-078,229; 90-078,230; 90-079,336; 
90-079,338; 90-079,690; 90-079,691; 90-080,487; 90-080,489; 90-080,490; 
90-080,491; 90-080,492; 90-080,494; 90-085,928; 90-086,669; 90-086,670; 
90-087,361; 90-087,362; 90-087,363; 90-087,364; 90-088,096; 90-088,097; 
90-093,662; 90-093,663; 90-093,664; 90-093,665; 90-093,666; 90-093,668; 
90-094,055; 90-094,056; 90-101,937; 90-103,409; 90-151,577. 
The silver halide used in the photographic elements may be silver 
iodobromide, silver bromide, silver chloride, silver chlorobromide, silver 
chloroiodobromide, and the like. 
The type of silver halide grains preferably include polymorphic, cubic, and 
octahedral. The grain size of the silver halide may have any distribution 
known to be useful in photographic compositions, and may be either 
polydipersed or monodispersed. 
Tabular grain silver halide emulsions may also be used. Tabular grains are 
those with two parallel major faces each clearly larger than any remaining 
grain face and tabular grain emulsions are those in which the tabular 
grains account for at least 30 percent, more typically at least 50 
percent, preferably &gt;70 percent and optimally &gt;90 percent of total grain 
projected area. The tabular grains can account for substantially all (&gt;97 
percent) of total grain projected area. The tabular grain emulsions can be 
high aspect ratio tabular grain emulsions--i.e., ECD/t&gt;8, where ECD is the 
diameter of a circle having an area equal to grain projected area and t is 
tabular grain thickness; intermediate aspect ratio tabular grain 
emulsions--i.e., ECD/t=5 to 8; or low aspect ratio tabular grain 
emulsions--i.e., ECD/t=2 to 5. The emulsions typically exhibit high 
tabularity (T), where T (i.e., ECD/t.sup.2)&gt;25 and ECD and t are both 
measured in micrometers (.mu.m). The tabular grains can be of any 
thickness compatible with achieving an aim average aspect ratio and/or 
average tabularity of the tabular grain emulsion. Preferably the tabular 
grains satisfying projected area requirements are those having thicknesses 
of &lt;0.3 .mu.m, thin (&lt;0.2 .mu.m) tabular grains being specifically 
preferred and ultra-thin (&lt;0.07 .mu.m) tabular grains being contemplated 
for maximum tabular grain performance enhancements. When the native blue 
absorption of iodohalide tabular grains is relied upon for blue speed, 
thicker tabular grains, typically up to 0.5 .mu.m in thickness, are 
contemplated. 
High iodide tabular grain emulsions are illustrated by House U.S. Pat. No. 
4,490,458, Maskasky U.S. Pat. No. 4,459,353 and Yagi et al EPO 0 410 410. 
Tabular grains formed of silver halide(s) that form a face centered cubic 
(rock salt type) crystal lattice structure can have either {100} or {111} 
major faces. Emulsions containing {111} major face tabular grains, 
including those with controlled grain dispersities, halide distributions, 
twin plane spacing, edge structures and grain dislocations as well as 
adsorbed {111} grain face stabilizers, are illustrated in those references 
cited in Research Disclosure I, Section I.B.(3) (page 503). 
The silver halide grains to be used in the invention may be prepared 
according to methods known in the art, such as those described in Research 
Disclosure I and James, The Theory of the Photographic Process. These 
include methods such as ammoniacal emulsion making, neutral or acidic 
emulsion making, and others known in the art. These methods generally 
involve mixing a water soluble silver salt with a water soluble halide 
salt in the presence of a protective colloid, and controlling the 
temperature, pAg, pH values, etc, at suitable values during formation of 
the silver halide by precipitation. 
In the course of grain precipitation one or more dopants (grain occlusions 
other than silver and halide) can be introduced to modify grain 
properties. For example, any of the various conventional dopants disclosed 
in Research Disclosure, Item 36544, Section I. Emulsion grains and their 
preparation, sub-section G. Grain modifying conditions and adjustments, 
paragraphs (3), (4) and (5), can be present in the emulsions of the 
invention. In addition it is specifically contemplated to dope the grains 
with transition metal hexacoordination complexes containing one or more 
organic ligands, as taught by Olm et al U.S. Pat. No. 5,360,712, the 
disclosure of which is here incorporated by reference. 
It is specifically contemplated to incorporate in the face centered cubic 
crystal lattice of the grains a dopant capable of increasing imaging speed 
by forming a shallow electron trap (hereinafter also referred to as a SET) 
as discussed in Research Discolosure Item 36736 published November 1994, 
here incorporated by reference. 
The SET dopants are effective at any location within the grains. Generally 
better results are obtained when the SET dopant is incorporated in the 
exterior 50 percent of the grain, based on silver. An optimum grain region 
for SET incorporation is that formed by silver ranging from 50 to 85 
percent of total silver forming the grains. The SET can be introduced all 
at once or run into the reaction vessel over a period of time while grain 
precipitation is continuing. Generally SET forming dopants are 
contemplated to be incorporated in concentrations of at least 
1.times.10.sup.-7 mole per silver mole up to their solubility limit, 
typically up to about 5.times.10.sup.-4 mole per silver mole. 
SET dopants are known to be effective to reduce reciprocity failure. In 
particular the use of iridium hexacoordination complexes or Ir.sup.+4 
complexes as SET dopants is advantageous. 
Iridium dopants that are ineffective to provide shallow electron traps 
(non-SET dopants) can also be incorporated into the grains of the silver 
halide grain emulsions to reduce reciprocity failure. To be effective for 
reciprocity improvement the Ir can be present at any location within the 
grain structure. A preferred location within the grain structure for Ir 
dopants to produce reciprocity improvement is in the region of the grains 
formed after the first 60 percent and before the final 1 percent (most 
preferably before the final 3 percent) of total silver forming the grains 
has been precipitated. The dopant can be introduced all at once or run 
into the reaction vessel over a period of time while grain precipitation 
is continuing. Generally reciprocity improving non-SET Ir dopants are 
contemplated to be incorporated at their lowest effective concentrations. 
The contrast of the photographic element can be further increased by doping 
the grains with a hexacoordination complex containing a nitrosyl or 
thionitrosyl ligand (NZ dopants) as disclosed in McDugle et al U.S. Pat. 
No. 4,933,272, the disclosure of which is here incorporated by reference. 
The contrast increasing dopants can be incorporated in the grain structure 
at any convenient location. However, if the NZ dopant is present at the 
surface of the grain, it can reduce the sensitivity of the grains. It is 
therefore preferred that the NZ dopants be located in the grain so that 
they are separated from the grain surface by at least 1 percent (most 
preferably at least 3 percent) of the total silver precipitated in forming 
the silver iodochloride grains. Preferred contrast enhancing 
concentrations of the NZ dopants range from 1.times.10.sup.-11 to 
4.times.10.sup.-8 mole per silver mole, with specifically preferred 
concentrations being in the range from 10.sup.-10 to 10.sup.-8 mole per 
silver mole. 
Although generally preferred concentration ranges for the various SET, 
non-SET Ir and NZ dopants have been set out above, it is recognized that 
specific optimum concentration ranges within these general ranges can be 
identified for specific applications by routine testing. It is 
specifically contemplated to employ the SET, non-SET Ir and NZ dopants 
singly or in combination. For example, grains containing a combination of 
an SET dopant and a non-SET Ir dopant are specifically contemplated. 
Similarly SET and NZ dopants can be employed in combination. Also NZ and 
Ir dopants that are not SET dopants can be employed in combination. 
Finally, the combination of a non-SET Ir dopant with a SET dopant and an 
NZ dopant. For this latter three-way combination of dopants it is 
generally most convenient in terms of precipitation to incorporate the NZ 
dopant first, followed by the SET dopant, with the non-SET Ir dopant 
incorporated last. 
The photographic elements of the present invention, as is typical, provide 
the silver halide in the form of an emulsion. Photographic emulsions 
generally include a vehicle for coating the emulsion as a layer of a 
photographic element. Useful vehicles include both naturally occurring 
substances such as proteins, protein derivatives, cellulose derivatives 
(e.g., cellulose esters), gelatin (e.g., alkali-treated gelatin such as 
cattle bone or hide gelatin, or acid treated gelatin such as pigskin 
gelatin), deionized gelatin, gelatin derivatives (e.g., acetylated 
gelatin, phthalated gelatin, and the like), and others as described in 
Research Disclosure I. Also useful as vehicles or vehicle extenders are 
hydrophilic water-permeable colloids. These include synthetic polymeric 
peptizers, carriers, and/or binders such as poly(vinyl alcohol), 
poly(vinyl lactams), acrylamide polymers, polyvinyl acetals, polymers of 
alkyl and sulfoalkyl acrylates and methacrylates, hydrolyzed polyvinyl 
acetates, polyamides, polyvinyl pyridine, methacrylamide copolymers, and 
the like, as described in Research Disclosure I. The vehicle can be 
present in the emulsion in any amount useful in photographic emulsions. 
The emulsion can also include any of the addenda known to be useful in 
photographic emulsions. 
The silver halide to be used in the invention may be advantageously 
subjected to chemical sensitization. Compounds and techniques useful for 
chemical sensitization of silver halide are known in the art and described 
in Research Disclosure I and the references cited therein. Compounds 
useful as chemical sensitizers, include, for example, active gelatin, 
sulfur, selenium, tellurium, gold, platinum, palladium, iridium, osmium, 
rhenium, phosphorous, or combinations thereof. Chemical sensitization is 
generally carried out at pAg levels of from 5 to 10, pH levels of from 4 
to 8, and temperatures of from 30 to 80.degree. C., as described in 
Research Disclosure I, Section IV (pages 510-511) and the references cited 
therein. 
The silver halide may be sensitized by sensitizing dyes by any method known 
in the art, such as described in Research Disclosure I. The dye may be 
added to an emulsion of the silver halide grains and a hydrophilic colloid 
at any time prior to (e.g., during or after chemical sensitization) or 
simultaneous with the coating of the emulsion on a photographic element. 
The dyes may, for example, be added as a solution in water or an alcohol. 
The dye/silver halide emulsion may be mixed with a dispersion of color 
image-forming coupler immediately before coating or in advance of coating 
(for example, 2 hours). 
Photographic elements of the present invention are preferably imagewise 
exposed using any of the known techniques, including those described in 
Research Disclosure I, section XVI. This typically involves exposure to 
light in the visible region of the spectrum, and typically such exposure 
is of a live image through a lens, although exposure can also be exposure 
to a stored image (such as a computer stored image) by means of light 
emitting devices (such as light emitting diodes, CRT and the like). 
Photographic elements comprising the composition of the invention can be 
processed in any of a number of well-known photographic processes 
utilizing any of a number of well-known processing compositions, 
described, for example, in Research Disclosure I, or in T. H. James, 
editor, The Theory of the Photographic Process, 4th Edition, Macmillan, 
New York, 1977. In the case of processing a negative working element, the 
element is treated with a color developer (that is one which will form the 
colored image dyes with the color couplers), and then with a oxidizer and 
a solvent to remove silver and silver halide. In the case of processing a 
reversal color element, the element is first treated with a black and 
white developer (that is, a developer which does not form colored dyes 
with the coupler compounds) followed by a treatment to fog silver halide 
(usually chemical fogging or light fogging), followed by treatment with a 
color developer. Preferred color developing agents are 
p-phenylenediamines. Especially preferred are: 
4-amino N,N-diethylaniline hydrochloride, 
4-amino-3-methyl-N,N-diethyl aniline hydrochloride, 
4-amino-3-methyl-N-ethyl-N-(.beta.-(methanesulfonamido) ethylaniline 
sesquisulfate hydrate, 
4-amino-3-methyl-N-ethyl-N-(.beta.-hydroxyethyl)aniline sulfate, 
4-amino-3-.beta.-(methanesulfonamido)ethyl-N,N-diethylaniline hydrochloride 
and 
4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine di-p-toluene sulfonic acid. 
Dye images can be formed or amplified by processes which employ in 
combination with a dye-image-generating reducing agent an inert transition 
metal-ion complex oxidizing agent, as illustrated by Bissonette U.S. Pat. 
Nos. 3,748,138, 3,826,652, 3,862,842 and 3,989,526 and Travis U.S. Pat. 
No. 3,765,891, and/or a peroxide oxidizing agent as illustrated by Matejec 
U.S. Pat. No. 3,674,490, Research Disclosure, Vol. 116, December, 1973, 
Item 11660, and Bissonette Research Disclosure, Vol. 148, August, 1976, 
Items 14836, 14846 and 14847. The photographic elements can be 
particularly adapted to form dye images by such processes as illustrated 
by Dunn et al U.S. Pat. No. 3,822,129, Bissonette U.S. Pat. Nos. 3,834,907 
and 3,902,905, Bissonette et al U.S. Pat. No. 3,847,619, Mowrey U.S. Pat. 
No. 3,904,413, Hirai et al U.S. Pat. No. 4,880,725, Iwano U.S. Pat. No. 
4,954,425, Marsden et al U.S. Pat. No. 4,983,504, Evans et al U.S. Pat. 
No. 5,246,822, Twist U.S. Pat. No. 5,324,624, Fyson EPO 0 487 616, 
Tannahill et al WO 90/13059, Marsden et al WO 90/13061, Grimsey et al WO 
91/16666, Fyson WO 91/17479, Marsden et al WO 92/01972. Tannahill WO 
92/05471, Henson WO 92/07299, Twist WO 93/01524 and WO 93/11460 and 
Wingender et al German OLS 4,211,460. 
Development is followed by bleach-fixing, to remove silver or silver 
halide, washing and drying. 
The deprotonating electron donors of the present invention can be included 
in a silver halide emulsion by direct dispersion in the emulsion, or they 
may be dissolved in a solvent such as water, methanol or ethanol for 
example, or in a mixture of such solvents, and the resulting solution can 
be added to the emulsion. The compounds of the present invention may also 
be added from solutions containing a base and/or surfactants, or may be 
incorporated into aqueous slurries or gelatin dispersions and then added 
to the emulsion. The deprotonating electron donor may be used as the sole 
sensitizer in the emulsion. However, in preferred embodiments of the 
invention a sensitizing dye is also added to the emulsion. The compounds 
can be added before, during or after the addition of the sensitizing dye. 
The amount of electron donor which is employed in this invention may range 
from as little as 1.times.10.sup.-8 mole per mole of silver in the 
emulsion to as much as about 0.1 mole per mole of silver, preferably from 
about 5.times.10.sup.-7 to about 0.05 mole per mole of silver. Where the 
oxidation potential, E.sub.ox1, of a two-electron donating X--H, or the 
X--H part of a two-electron donating compound, is relatively low it is 
more active, and relatively less agent need be employed. Conversely, when 
the oxidation potential of a two-electron donating X--H, or the X--H part 
of a two-electron donating compound is relatively high, a larger amount 
thereof, per mole of silver, is employed. For deprotonating one-electron 
donor compounds, larger amounts per mole of silver are usually employed 
For deprotonating one or two electron donor compounds linked to or 
containing an adsorbable moiety, the maximum amount of compound employed 
in this invention is lower, about 0.01 mole or less per mole of silver in 
an emulsion layer, preferably 0.001 mole per mole of silver or less. For 
deprotonating one or two electron donor compounds linked to or containing 
a sensitizing dye, the maximum amount of compound employed in this 
invention is also lower, about 2.times.10.sup.-3 mole or less per mole of 
silver in an emulsion layer, preferably 2.times.10.sup.-4 mole per mole of 
silver or less. 
Spectral sensitizing dyes can be used together with the deprotonating 
electron donor of this invention. Preferred sensitizing dyes that can be 
used are cyanine, merocyanine, styryl, hemicyanine, or complex cyanine 
dyes. Illustrative examples of such sensitizing dyes are the same as those 
given for the Z groups described above.. Where the deprotonating one or 
two electron donor compound is linked to or contains a sensitizing dye, 
the molar ratio of conventional spectral sensitizing dye to the 
deprotonating electron donor compound of the present invention, is 
typically from about 99.99:0.01 to about 50:50. The optimum ratio can be 
determined through an ordinary emulsion test. 
Various compounds may be added to the photographic material of the present 
invention for the purpose of lowering the fogging of the material during 
manufacture, storage, or processing. Typical antifoggants are discussed in 
Section VI of Research Disclosure I, for example tetraazaindenes, 
mercaptotetrazoles, polyhydroxybenzenes, combinations of a thiosulfonate 
and a sulfinate, and the like. 
For this invention, polyhydroxybenzene and hydroxyaminobenzene compounds 
(hereinafter "hydroxybenzene compounds") are preferred as they are 
effective for lowering fog without decreasing the emulsion sensitvity. 
Examples of hydroxybenzene compounds are: 
##STR102## 
In these formulae, V and V' each independently represent --H, --OH, a 
halogen atom, --OM (M is alkali metal ion), an alkyl group, a phenyl 
group, an amino group, a carbonyl group, a sulfone group, a sulfonated 
phenyl group, a sulfonated alkyl group, a sulfonated amino group, a 
carboxyphenyl group, a carboxyalkyl group, a carboxyamino group, a 
hydroxyphenyl group, a hydroxyalkyl group, an alkylether group, an 
alkylphenyl group, an alkylthioether group, or a phenylthioether group. 
More preferably, they each independently represent --H, --OH, --Cl, --Br, 
--COOH, --CH.sub.2 CH.sub.2 COOH, --CH.sub.3, --CH.sub.2 CH.sub.3, 
--C(CH.sub.3).sub.3, --OCH.sub.3, --CHO, --SO.sub.3 K, --SO.sub.3 Na, 
--SO.sub.3 H, --SCH.sub.3, or -phenyl. 
Especially preferred hydroxybenzene compounds follow: 
##STR103## 
Hydroxybenzene compounds may be added to the emulsion layers or any other 
layers constituting the photographic material of the present invention. 
The preferred amount added is from 1.times.10.sup.-3 to 1.times.10.sup.-1 
mol, and more preferred is 1.times.10.sup.-3 to 2.times.10.sup.-2 mol, per 
mol of silver halide. 
Laser Flash Photolysis Method 
(a) Oxidation Potential of Radical X.sup..cndot. 
The laser flash photolysis measurements were performed using a nanosecond 
pulsed excimer (Questek model 2620, 308 nm, ca. 20 ns, ca. 100 mJ) pumped 
dye laser (Lambda Physik model FL 3002). The laser dye was DPS 
(commercially available from Exciton Co.) in p-dioxane (410 nm, ca. 20 ns, 
ca. 10 mJ). The analyzing light source was a pulsed 150W xenon arc lamp 
(Osram XBO 150/W). The arc lamp power supply was a PRA model 302 and the 
pulser was a PRA model M-306. The pulser increased the light output by ca. 
100 fold, for a time period of ca. 2-3 ms. The analyzing light was 
focussed through a small aperture (ca. 1.5 mm) in a cell holder designed 
to hold 1 cm.sup.2 cuvettes. The laser and analyzing beams irradiated the 
cell from opposite directions and crossed at a narrow angle (ca. 
15.degree.). After leaving the cell, the analyzing light was collimated 
and focussed onto the slit (1 mm, 4 nm bandpass) of an ISA H-20 
monochromator. The light was detected using 5 dynodes of a Hamamatsu model 
R446 photomultiplier. The output of the photomultiplier tube was 
terminated into 50 ohm, and captured using a Tektronix DSA-602 digital 
oscilloscope. The entire experiment is controlled from a personal 
computer. 
The experiments were performed either in acetonitrile, or a mixture of 80% 
acetonitrile and 20% water. The first singlet excited state of a 
cyanoanthracene (A), which acted as the electron acceptor, was produced 
using the nanosecond laser pulse at 410 nm. Quenching of this excited 
state by electron transfer from the relatively high oxidation potential 
donor biphenyl (B), resulted in efficient formation of separated, "free", 
radical ions in solution, A.sup..cndot.- +B.sup..cndot.+. Secondary 
electron transfer then occurred between B.sup..cndot.+ and the lower 
oxidation potential electron donor X--H, to generate X--H.sup..cndot.+ in 
high yield. For the investigations of the oxidation potentials of the 
radicals X.sup..cndot., typically the cyanoanthrancene concentration was 
ca. 2.times.10.sup.-5 M to 10.sup.-4 M, the biphenyl concentration was ca. 
0.1 M. The concentration of the X--H donor was ca. 10.sup.-3 M. The rates 
of the electron transfer reactions are determined by the concentrations of 
the substrates. The concentrations used ensured that the A.sup..cndot.- 
and the X--H.sup..cndot.+ were generated within 100 ns of the laser pulse. 
The radical ions could be observed directly by means of their visible 
absorption spectra. The kinetics of the photogenerated radical ions were 
monitored by observation of the changes in optical density at the 
appropriate wavelengths. 
The reduction potential (E.sub.red) of 9,10-dicyanoanthracene (DCA) is 
-0.91 V. In a typical experiment, DCA is excited and the initial 
photoinduced electron transfer from the biphenyl to the DCA forms a 
DCA.sup..cndot.-, which is observed at its characteristic absorption 
maximum (.lambda..sub.obs =705 nm), within ca. 20 ns of the laser pulse. 
Rapid secondary electron transfer occurs from X--H to the biphenyl radical 
cation to generate X--H.sup..cndot.+, which deprotonates to give 
X.sup..cndot.. A growth in absorption is then observed at 705 nm with a 
time constant of ca. 1 microsecond, due to reduction of a second DCA by 
the X.sup..cndot.. The absorption signal with the microsecond growth time 
is equal to the size of the absorption signal formed within 20 ns. If 
reduction of two DCA was observed in such an experiment, this indicates 
that the oxidation potential of the X.sup..cndot. is more negative than 
-0.9 V. 
If the oxidation potential of X.sup..cndot. is not sufficiently negative to 
reduce DCA, an estimate of its oxidation potential was obtained by using 
other cyanoanthracenes as acceptors. Experiments were performed in an 
identical manner to that described above except that 
2,9,10-tricyanoanthracene (TriCA, E.sub.red -0.67 V, .lambda..sub.obs =710 
nm) or tetracyanoanthracene (TCA, E.sub.red -0.44 V, .lambda..sub.obs =715 
nm) were used as the electron acceptors. The oxidation potential of the 
X.sup..cndot. was taken to be more negative than -0.7 if reduction of two 
TriCA was observed, and more negative than -0.5 V if reduction of two TCA 
was observed. Occasionally the size of the signal from the second reduced 
acceptor was smaller than that of the first. This was taken to indicate 
that electron transfer from the X.sup..cndot. to the acceptor was barely 
exothermic, i.e. the oxidation potential of the radical was essentially 
the same as the reduction potential of the acceptor. 
To estimate the oxidation potentials of X.sup..cndot. with values less 
negative than -0.5 V, i.e. not low enough to reduce even 
tetracyanoanthracene, a slightly different approach was used. In the 
presence of low concentrations of an additional acceptor, A2, that has a 
less negative reduction potential than the primary acceptor, A (DCA, for 
example), secondary electron transfer from A.sup..cndot.- to A2 will take 
place. If the reduction potential of A2 is also less negative than the 
oxidation potential of the X.sup..cndot., then A2 will also be reduced by 
the radical, and the magnitude of the A2.sup..cndot.- absorption signal 
will be doubled. In this case, both the first and the second electron 
transfer reactions are diffusion controlled and occur at the same rate. 
Consequently, the second reduction cannot be time resolved from the first. 
Therefore, to determine whether two electron reduction actually takes 
place, the A2.sup..cndot.- signal size must be compared with an analogous 
system for which it is known that reduction of only a single A2 occurs. 
For example, a reactive X--H.sup..cndot.+ which might give a reducing 
X.sup..cndot. can be compared with a nonreactive X--H.sup..cndot.+. Useful 
secondary electron acceptors (A2) that have been used are 
chlorobenzoquinone (E.sub.red -0.34 V, .lambda..sub.obs =450 nm), 
2,5-dichlorobenzoquinone (E.sub.red -0.18 V, .lambda..sub.obs =455 nm) and 
2,3,5,6-tetrachlorobenzoquinone (E.sub.red 0.00 V, .lambda..sub.obs =460 
nm). 
(b) Deprotonation Rate Constant Determination 
The laser flash photolysis technique was also used to determine 
deprotonation rate constants for examples of the oxidized donors X--H. The 
radical cations of the X--H donors absorb in the visible region of the 
spectrum. Spectra of related compounds can be found in "Electron 
Absorption Spectra of Radical Ions" by T. Shida, Elsevier, New York, 1988. 
These absorptions were used to determine the kinetics of the deprotonation 
reactions of the radical cations of the X--H. Excitation of 
9,10-dicyanoanthracene (DCA) in the presence of biphenyl and the X--H 
donor, as described above, results in the formation of the 
DCA.sup..cndot.- and the X--H.sup..cndot.+. By using a concentration of 
X--H of ca. 10.sup.-2 M, the X--H.sup..cndot.+ can be formed within ca. 20 
ns of the laser pulse. With the monitoring wavelength set within an 
absorption band of the X--H.sup..cndot.+, a decay in absorbance as a 
function of time is observed due to the deprotonation reaction. The 
monitoring wavelengths used were somewhat different for the different 
donors, but were mostly around 470-530 nm. In general the DCA.sup..cndot.- 
also absorbed at the monitoring wavelengths, however, the signal due to 
the radical anion was generally much weaker than that due to the radical 
cation, and on the timescale of the experiment the A.sup..cndot.- did not 
decay, and so did not contribute to the observed kinetics. As the 
X--H.sup..cndot.+ decayed, the radical X.sup..cndot. was formed, which in 
most cases reacted with the cyanoanthracene to form a second 
A.sup..cndot.-. To make sure that this "grow-in" of absorbance due to 
A.sup..cndot.- did not interfere with the time-resolved decay 
measurements, the concentration of the cyanoanthracene was maintained 
below ca. 2.times.10.sup.-5 M. At this concentration the second reduction 
reaction occurred on a much slower timescale than the X--H.sup..cndot.+ 
decay. Alternatively, when the decay rate of the X--H.sup..cndot.+ was 
less than 10.sup.6 s.sup.-1, the solutions were purged with oxygen. Under 
these conditions the DCA.sup..cndot.- reacted with the oxygen to form 
O.sub.2.sup..cndot.- within 100 ns, so that its absorbance did not 
interfere with that of the X--H.sup..cndot.+ on the timescale of its 
decay. 
The experiments measuring the deprotonation rate constants were performed 
in acetonitrile with the addition of 20% water, so that all of the salts 
could be easily solubilized. Most experiments were performed at room 
temperature. In some cases the deprotonation rate was either too fast or 
too slow to be easily determined at room temperature. When this happened, 
the deprotonation rate constants were measured as a function of 
temperature, and the rate constant at room temperature determined by 
extrapolation. 
Synthesis of Representative X--H Compounds 
The following examples illustrate the synthesis of typical deprotonating 
electron donor compounds. Other compounds can also be synthesized by 
analogy using appropriately selected known starting materials. 
1. Preparation of Intermediate I1. 
##STR104## 
2,6-Dimethylaniline (60.6 g, 0.5 mol), ethyl 4-bromobutyrate (97.5 g, 0.5 
mol), triethylamine (50.5 g, 0.5 mol) and toluene (100 mL) were stirred at 
reflux for 16 h. The resulting salt was removed by filtration, and the 
filtrate concentrated in vacuo at 90 C. to an oil (112 g). The desired 
secondary aniline I1 was isolated by vacuum distillation (52.3 g, b.p. 
120-132 C. at 0.1 to 0.2 mm Hg). 
.sup.1 H NMR (300 MHz, CD.sub.3 Cl): 1.25 (t, 3H), 1.90 (m, 2H), 2.30 (s, 
6H), 2.40 (t, 2H), 3.00 (bt, 2H+NH), 4.15 (2H, q) 6.80 (1H, t), 6.95 (d, 
2H). 
.sup.13 C NMR (75 MHz, CD.sub.3 Cl): 14.15, 18.42, 26.26, 31.87, 47.63, 
60.27, 121.85, 128.72, 129.43, 145.86, 173.27. 
2. Preparation of Compound 57. 
I1 (4.7 g, 0.02 mol), sodium hydroxide (0.8 g, 0.02 mol), ethanol (20 mL) 
and water (20 mL) were stirred at reflux for 60 h. The mixture was 
concentrated in vacuo at 90 C. to a white paste. Acetonitrile (50 mL) was 
added to give the product 37 as a white solid. The solid was collected, 
washed with acetonitrile and dried in vacuo at 80 C. (4.35 g). 
.sup.1 H NMR (300 MHz, D.sub.2 O): 1.85 (2H, m,), 2.30 (s, t, 8H), 2.95 (t, 
2H), 4.80 (HOD), 6.95 (t, 1H), 7.05 (d, 2H). 
.sup.13 C NMR (75 MHz, D.sub.2 O): 11.97, 20.88, 29.56, 42.34, 117.28, 
123.31, 124.60, 139.14, 177.06. 
3. Preparation of Intermediate I2. 
##STR105## 
I1 (7.06 g, 0.03 mol), ethyl triflate (5.35 g, 0.03 mol), 
ethyldiisopropylamine (3.88 g, 0.03 mol) and butyronitrile (20 mL) were 
stirred at reflux for 16 h. The mixture was concentrated in vacuo at 90 C. 
Ligroin was added and the resulting salt was removed by filtration and 
discarded. The filtrate was concentrated in vacuo at 90 C. to give an oil 
(7.22 g). The pure tertiary aniline ester 12 (6.0 g) was isolated via 
flash chromatography (SiO.sub.2, 9 ligroin: 1 EtOAc). 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.00 (t, 3H), 1.23 (t, 3H), 1.74 
(quintet, 2H), 2.30 (s, t, 8H), 3.05 (m, 4H), 4.10 (q, 2H), 6.95 (m, 3H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 14.18, 14.57, 19.51, 25.13, 32.15, 
47.82, 53.09, 60.15, 124.92, 128.76, 137.92, 147.69, 173.59. 
4. Preparation of Compound 44. 
I2 (5.26 g, 0.02 mol), sodium hydroxide (0.8 g, 0.02 mol), ethanol (20 mL) 
and water (20 mL) were stirred at reflux for 16 h. The mixture was 
concentrated in vacuo at 90 C. to give a gummy solid. Acetonitrile was 
added to produce a crystalline solid which was collected and dried in 
vacuo at 80 C. (4.25 g). 
.sup.1 H NMR (300 MHz, D.sub.2 O): 0.90 (t, 3H), 1.65 (quintet, 2H), 2.20 
(t, 2H), 2.28 (s, 6H), 3.30 (m, 4H), 6.90 (m, 3H). 
.sup.13 C NMR (75 MHz, D.sub.2 O): 8.21, 13.59, 20.28, 29.94, 41.80, 47.86, 
119.39, 123.15, 132.41, 141.60, 177.43. 
5. Preparation of Intermediate I3. 
##STR106## 
A mixture of I1 (4.65 g, 0.02 mol), 1,3-diiodopropane (11.83 g, 0.04 mol) 
ethyldiisopropylamine (2.58 g, 0.02 mol) and acetonitrile (25 mL) were 
stirred at reflux for 16 h. The mixture was concentrated in vacuo at 95 C. 
to give an oil (18.35 g). Ligroin (100 mL) was added to the oil to 
precipitate a salt. The salt was removed by filtration and the filtrated 
concentrated in vacuo at 95 C. to give an oil (11.05 g). The pure 
iodopropylaniline derivative I3 (2.4 g) was isolated by flash 
chromatography (SiO.sub.2, 9 ligroin: 1 EtOAc). 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.25 (t, 3H), 1.75 (quintet, 2H), 1.95 
(quintet, 2H), 2.28 (t, 2H), 2.30 (s, 6H), 3.05 (m, 2H), 3.15 (m, 4H), 
4.10 (q, 2H), 7.00 (m, 3H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 4.17, 14.22, 19.56, 24.89, 32.04, 
33.30, 53.99, 54.60, 60.25, 125.30, 129.04, 137.55, 147.37, 173.36. 
6. Preparation of Intermediate I4. 
##STR107## 
I3 (2.4 g, 0.006 mol), 
N,N-dimethyl-N'-methyl-N'-(2-N"-methylaminoethyl)thiourea (1.05 g, 0.006 
mol, ethyldiisopropylamine (0.78 g, 0.006 mol) and dichloromethane (20 mL) 
were stirred at reflux for 16 h. The solvent was removed in vacuo at 50 C. 
The resulting oil was partitioned between water (pH 10) and ethyl ether. 
The crude compound was recovered from the ether extract. The pure compound 
(0.19 g) was obtained via flash chromatography (SiO2, 9 dichloromethane, 1 
methanol). 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.25 (t, 3H), 1.65 (m, 2H), 1.80 (m, 
2H), 2.30 (m, 11H), 2.45 (t, 2H), 2.70 (t, 2H), 3.00 (m, 13H), 3.75 (t, 
2H), 4.10 (q 2H), 6.95 (m 3H). 
.sup.13 C NMR (75 MHz): 14.16, 19.57, 24.81, 26.89, 32.01, 41.34, 41.93, 
43.13, 51.98, 52.06, 53.59, 54.62, 55.81, 60.15, 125.05, 128.90, 137.51, 
147.62, 173.40, 193.84. 
7. Preparation of Compound 68. 
I4 (0.19 g, 0.42 mmol), sodium hydroxide (0.017 g, 0.42 nmol), ethanol (10 
mL) and water (10 mL) were refluxed for 16 h. The solvents were removed in 
vacuo at 90 C. The residue was extracted with ethyl ether. The ether 
extract consisted mainly of the starting ester (50 mg). The ether 
insoluble portion (100 mg), soluble in methanol, contained the desired 
sodium salt/free acid. 
.sup.1 H NMR (300 MHz, CD.sub.3 Cl): 1.60 (m, 2H), 2.0 (m, 2H), 2.20 (m, 
11H), 2.35 (m, 2H), 2.60 (m, 2H), 3.0 (m, 13H), 3.70 (m, 2H), 5.0 (m 1H), 
6.90 (m, 3H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 19.84, 26.53, 27.37, 36.03, 41.42, 
42.16, 43.25, 51.88, 52.24, 54.60, 54.69, 55.91, 124.88, 128.89, 137.52, 
148.18, 182.35, 193.70 
8. Preparation of Intermediate I5. 
##STR108## 
A mixture of 2,6-dimethylaniline (24.24 g, 0.2 mol), ethyl 6-bromohexanoic 
acid (44.62, 0.2 mol), triethylamine (20.2 g, 0.2 mol) and toluene (100 
mL) were refluxed for 16 h. The resulting salt was filtered and discarded. 
The filtrate was concentrated in vacuo at 90 C to an oil. The oil was 
dissolved in ethyl ether and washed with 30% NaCl (100 mL), fresh water 
(100 mL) and dried with magnesium sulfate. The ether extract was 
concentrated under vacuum at 90 C to give an amber oil (42.3 g). The pure 
aniline ester I5 (23.8 g) was obtained via vacuum distillation (139-165 C 
at 0.04 mm Hg). 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.25 (t, 3H), 1.40 (m, 2H), 1.60 (m, 
4H), 2.25 (s, 6H), 2.30 (t, 2H), 2.95 (t, 2H +1H), 4.10 (q, 2H), 6.80 (t, 
1H), 6.95 (d, 2H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 14.13, 18.39, 24.76, 26.62, 30.79, 
34.14, 48.32, 60.06, 121.52, 128.67, 129.05, 146.19, 173.42. 
9. Preparation of Intermediate I6. 
##STR109## 
A mixture of I5 (12.14 g, 0.046 mol), 1,3-diiodopropane (27.22 g, 0.092 
mol), diisopropylethylamine (5.95 g, 0.046 mol) and acetonitrile (50 mL) 
were stirred at reflux for 16. The mixture was concentrated in vacuo at 95 
C to an oil. The oil was partitioned between ethyl ether and water (to pH 
7) and the ether layer was dried with magnesium sulfate and concentrated 
to an oil (23.6 g). Three flash chromatography purifications (SiO2, 9 
ligroin, 1 ethyl acetate) gave a fraction (2.2 g) that was rich in the 
desired 3-iodopropy aniline ester I6. 
10. Preparation of Compound 59. 
I5 (5.26 g, 0.02 mol), sodium hydroxide (0.02 mol), ethanol (20 mL) and 
water (20 mL) were stirred at reflux for 16 h. The mixture was 
concentrated in vacuo at 90 C to give an oily solid. Acetonitrile was 
added, and the crystalline solid was collected and dried in vacuo at 80 C 
(4.8 g). 
.sup.1 H NMR (300 MHz, D.sub.2 O): 1.30 (m, 2H), 1.50 (m, 4H), 2.30 (m, 
8H), 2.80 (t, 2H), 4.80 (s, 1H), 6.80 (m, 1H), 6.90 (d, 2H). 
.sup.3 C NMR (75 MHz, D.sub.2 O): 22.10, 30.10, 30.92, 33.83, 41.97, 52.71, 
127.11, 133.26, 134.34, 149.35, 187.88. 
11. Preparation of I7. 
##STR110## 
I6 (2.12 g, 5 mmol), thiomorpholine (0.52 g, 5 mmol), triethylamine (1.01 
g, 10 mmol) and tetrahydrofuran (20 mL) were stirred at 25 C for 16 h. The 
mixture was concentrated in vacuo at 25 C, combined with ethyl ether (20 
mL) and washed with 30% NaCl (2.times.5 mL). The ether layer was dried 
with magnesium sulfate and concentrated in vacuo at 50 C to an oil (1.7 
g). The pure thiomorpholino aniline ethyl ester I7 (350 mg) was obtained 
via flash chromatography. 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.25 (t, 3H), 1.30 (m, 2H), 1.45 (m, 
2H), 1.60 (m, 4H), 2.25 (m, 10H), 2.65 (s, 8H), 3.30 (q, 4H), 4.10 (q, 
2H), 6.95 (m, 3H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 14.26, 19.63, 24.97, 26.65, 26.99, 
28.02, 29.32, 34.40, 52.19, 54.23, 55.10, 57.28, 60.16, 124.89, 128.84, 
137.73, 148.08, 173.66. 
12. Preparation of Compound 67. 
A mixture of I7 (300 mg, 0.74 mmol), sodium hydroxide (30 mg, 0.74 mmol), 
ethanol (10 mL) and water (10 mL) were stirred at reflux for 16 h. The 
mixture was concentrated in vacuo at 90 C. The resulting mass (300 mg) was 
triturated with acetonitrile (3.times.20 mL), the solvent decanted and the 
remaining solid dried in vacuo at 90 C to give 210 mg. 
.sup.1 H NMR (300 MHz, D.sub.2 O): 1.20 (bs, 2H), 1.40 (bs, 2H), 1.50 (bs, 
4H), 2.10 (bs, 2H), 2.25 (bs, 8H), 2.50 (bs, 8H), 2.95 (bs, 4H), 4.75 
(HOD), 6.90 (bs, 3H). 
.sup.13 C NMR (75 MHz, D.sub.2 O): 22.36, 28.27, 28.95, 29.29, 29.52, 
29.84, 30.00, 31.91, 40.68, 54.63, 56.95, 57.07, 59.63, 127.69, 131.73, 
140.16, 150.87, 185.82. 
13. Preparation of I8. 
##STR111## 
A mixture of 2,6-dimethylaniline (6.06 g, 0.05 mol), 1,3-propane sultone 
(6.10 g, 0.05 mol) and acetonitrile (10 mL) were stirred at reflux for 16 
h. The resulting white solid was collected, washed with acetonitrile and 
dried in vacuo at 80 C. Yield: 9.6 g. 
.sup.1 H NMR (300 MHz, D.sub.2 O as K salt): 1.95 (quintet, 2H), 2.30 (s, 
6H), 2.90 (t, 2H), 3.05 (t, 2H), 6.90 (t, 1H), 7.05 (d, 2H). 
.sup.13 C NMR (75 MHz, D.sub.2 O as K salt): 20.17, 27.48, 49.02, 51.21, 
125.12, 131.36, 132.32, 147.08. 
14. Preparation of Intermediate I9. 
##STR112## 
I8 (2.43 g, 0.01 mol), triethylamine (2.02 g, 0.02 mol) and acetonitrile 
(20 mL) were combined to obtain solution. Ethyl triflate (2.02 g, 0.02 
mol) was added and the mixture refluxed for 16 h. The resulting salt was 
removed by filtration and discarded. The filtrate was concentrated in 
vacuo to an oil (7 g). The pure ethyl sulfonate tertiary aniline I9 (1.1 
g) was obtained via flash chromatography (SiO2, 1 ligroin, 1 EtOAc). 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.00 (t, 3H), 1.35 (t, 3H), 1.95 (m, 
2H), 2.30 (s, 6H), 3.10 (m, 6H), 4.20 (q, 2H), 7.00 (m, 3 H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 14.80, 16.20, 19.50, 23.82, 47.99, 
48.62, 51.86, 65.79, 125.10, 129.00, 137.54, 146.00. 
15. Preparation of Compound 54. 
I9 (1 g, 3.3 mmol), sodium hydroxide (0.14 g, 3.5 mmol), ethanol (10 mL) 
and water (10 mL) were stirred at reflux for 16 h. The solution was 
filtered to remove a slight haze, and the filtrate concentrated in vacuo 
at 90 C to yield the solid sodium sulfonate (0.8 g). 
.sup.1 H NMR (300 MHz, D.sub.2 O): 0.90 (t, 3H), 1.80 (m, 2H), 2.20 (s, 
6H), 2.85 (t, 2H), 3.05 (m, 4H), 7.0 (m, 3H). 
.sup.13 C NMR (75 MHz, D.sub.2 0): 19.00, 22.20, 29.95, 52.78, 54.86, 
57.70, 130.10, 134.20, 143.30, 152.77. 
16. Preparation of Intermediate I10. 
##STR113## 
2-Nitrocinnamic acid (predominantly trans, 20.85 g, 0.11 mol) in water (125 
mL) was converted to its potassium salt. The solution was hydrogenated (50 
psi initially) in the presence of 10% Pd/carbon (2 g). The mixture was 
filtered to remove the catalyst and the filtrate concentrated in vacuo at 
90 C to give a solid. The solid was stirred with acetonitrile, filtered 
and dried in vacuo at 90 C. Yield of white powder, 23 g. 
.sup.1 H NMR (300 Mhz, D.sub.2 O): 2.45 (t, 2H), 2.80 (t, 2H), 6.85 (m, 
2H), 7.15 (m, 2H). 
.sup.13 C NMR (75 Mhz, D.sub.2 O): 30.00, 40.00, 119.64, 122.58, 130.00, 
130.80, 132.06, 146.10, 184.39. 
17. Preparation of I11. 
##STR114## 
I10 (10 g, 0.05 mol), ethyl iodide (31.2 g, 0.20 mol), 
ethyldiisopropylamine (25.8 g, 0.20 mol) and DMF (50 mL) were stirred at 
25 C for 60 h. The resulting salt was removed by filtration and discarded. 
The filtrate was concentrated in vacuo at 90 C to give a solid. The solid 
was partitioned between water (100 mL, pH 10) and ethyl ether (100 mL). 
The water layer was extracted with additional ether (2.times.100 mL). The 
combined extracts were dried with magnesium sulfate and concentrated in 
vacuo to give an oil (11 g). The pure ethyl 
3-(2-N,N-diethylaminophenyl)propionate I11 was obtained via flash 
chromatography (7 g). 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.00 (t, 6H), 1.25 (t, 3H), 2.65 (m, 
2H), 2.95 (q, 4H), 3.05 (m, 2H), 4.15 (q, 2H), 7.00 (m, 1H), 7.15 (m, 3H). 
.sup.13 C NMR (75 MHz, CDCl.sub.3): 12.78, 14.27, 26.50, 35.00, 48.50, 
59.98, 123.07, 124.10, 126.75, 129.62, 138.00, 150.00, 173.50. 
18. Preparation of Compound 29. 
I11 (7 g, 28 mmol), sodium hydroxide (1.12 g, 28 mmol), ethanol (20 mL) and 
water (10 mL) were stirred at reflux for 16. The solution was concentrated 
in vacuo at 90 C. Acetonitrile was added to the resulting solid. The solid 
was collected and dried in vacuo at 90 C. Yield, 6 g. 
.sup.1 H NMR (300 MHz, D.sub.2 O): 1.90 (t, 6H), 2.45 (t, 2H), 2.95 (m, 
6H), 7.20 (m, 1H), 7.30 (m, 3H). 
.sup.13 C NMR (75 MHz, D.sub.2 O): 16.50, 32.42, 43.77, 54.86, 128.50, 
130.00, 132.00, 134.50, 144.66, 152.88, 187.66. 
19. Preparation of intermediates I12. 
Amino-phenylmercaptotetrazole (50.0 g, 0.258 mol) was stirred with 
triethylamine (38.2 mL, 0.274 mol) in 450 mL of dry acetonitrile at rt. 
After initial dissolution a white precipitate formed. Diethylcarbamyl 
chloride (35 mL, 0.274 mol) was dissolved in 50 mL of acetonitrile and 
added dropwise. The solution was then heated at reflux for 3 h. The 
solution was chilled in an ice bath and the precipitated triethylammonium 
chloride removed by filtration. The solution was concentrated at reduced 
pressure to yield an orange oil. This oil was filtered through a 250 g 
plug of silica gel using 2L of methylene chloride. The filtrate was 
concentrated at reduced pressure and 50 mL of methanol was added. The 
methanol solution was cooled to 0.degree. C. and a white solid formed. The 
solid was collected, washed with ether, and dried to yield 40.3 g of the 
blocked 3-aminophenyltetrazole intermediate I12. 
##STR115## 
20. Preparation of intermediates I13 and I14. 
A mixture of the intermediate I12 (3.35 g, 11.5 mmol), intermediate I3 
(4.63 g, 11.5 mmol), potassium bicarbonate (1.15 g, 11.5 mmol) and 
acetonitrile (20 mL) was stirred at reflux for 40 h. The mixture was 
filtered and the filtrate concentrated in vacuo at 60 C. The concentrate 
was stirred with ligroin to give an insoluble oil. The supernatant ligroin 
was discarded and the insoluble oil dissolved in 1:1 ethyl acetate/ligroin 
to precipitate more salts. The salts were removed by filtration and the 
filtrate concentrated in vacuo at 60.degree. C. to give an oil (7.5 g). 
The oil was subjected to flash chromatography (silica gel/1 ethyl acetate: 
1 ligroin) to give intermediate I13 (monoalkylated monoester) (3.4 g, 52%) 
and intermediate I14 dialkylated diester (1.0 g). 
##STR116## 
.sup.1 H NMR (300 MHz, CDCl3): 1.05-1.30 (m, 9H), 1.70-1.85 (m, 4H), 
2.25-2.30 (m, 8H), 3.00-3.20 (m, 6H), 3.30 (bq, 4H), 3.95 (bs, 1H), 4.10 
(m, 2H), 6.65 (m, 2H), 6.80 (m, 1H), 6.90-7.00 (m, 3H), 7.25 (t, 1H). 
.sup.13 C NMR (75 MHz, CDCl3): 12.90, 13.85, 14.20, 19.61, 24.75, 29.27, 
31.98, 41.93, 43.09, 43.29, 51.70, 53.82, 60.28, 108.75, 113.16, 114.43, 
125.29, 129.05, 129.74, 135.00, 137.59, 147.02, 147.43, 149.18, 159.25, 
173.44. 
##STR117## 
.sup.1 H NMR (300 MHz, CDCl.sub.3): 1.05-1.30 (m, 12 H), 1.65 (m, 4H), 1.75 
(m, 4H), 2.35 (m, 16H), 2.95-3.15 (m, 12H), 3.30 (q, 4H), 4.10 (q, 4H), 
6.48 (m, 1H), 6.55 (m, 1H), 6.70 (m, 1H), 6.95 (m, 6H), 7.18 (t, 1H). 
.sup.13 C NMR (75MHz, CDCl3): 12.91, 13.84, 14.20, 19.64, 24.55, 26.69, 
32.03, 43.13, 43.21, 49.00, 51.22, 53.87, 60.25, 108.28, 111.64, 113.15, 
125.21, 129.07, 129.72, 135.06, 137.45, 147.06, 147.16, 148.60, 159.30, 
173.35. 
21. Preparation of compound 111 
A mixture of intermediate I13 (1.21 g, 2.13 mmol), sodium hydroxide (0.17 
g, 4.26 mmol), ethanol (4 mL) and water (8 mL) was stirred at reflux for 
48 h, then at 25 C for 96 h. The reaction mixture was filtered to remove a 
small quantity of insolubles and the filtrate concentrated in vacuo at 
80.degree. C. The concentrate was dissolved in methanol and filtered again 
to remove a small quantity of insolubles. The methanol filtrate was 
subjected to flash chromatography (silica gel/methanol). The product 
containing fraction was concentrated in vacuo to give compound 111 sodium 
salt (1.0 g). 
.sup.1 H NMR (300 MHz, D20): 1.70 (bm, 4H), 2.19 (bt, 2H), 2.33 (bs, 6H), 
3.08 (bt, 2H), 3.20 (bs, 1H), 3.30 (bt, 2H), 3.40 (bt, 2H), 4.75 (HOD), 
6.65 (bd, 1H), 6.77 (bd, 1H), 6.87 (bd, 1H), 7.05 (bs, 3H), 7.30 (bt, 1H). 
Mass Spectrum: ES+ (441+), ES- (439-) were the most intense ions observed. 
22. Preparation of compound 112. 
A mixture of the intermediate I14 (0.85 g, 1 mmol), sodium hydroxide (0.12 
g, 3 mmol), ethanol (4 mL) and water (8 mL) was stirred at reflux for 60 
h. The reaction mixture was concentrated in vacuo to an oil. The oil was 
partitioned between ethyl ether and water. The ether layer was discarded 
and the water layer concentrated in vacuo at 50.degree. C. The concentrate 
was stirred with acetonitrile to give a gummy solid. The acetonitrile was 
decanted and the remaining gummy solid dissolved in methanol. The methanol 
was removed in vacuo to give compound 112 dicarboxylate salt (0.57 g). 
.sup.1 H NMR (300 MHz, D.sub.2 O): 1.42 (bm, 4H), 1.63 (bm, 4H), 2.12 (bt, 
4H), 2.16 (s, 12H), 2.90 (bm, 12H), 6.40 (bd, 1H), 6.55 (bs, 1H), 6.67 
(bd, 1H), 6.90 (bm, 6H), 7.13 (bt, 1H). 
.sup.13 C NMR (75 MHz, D.sub.2 O): 24.46, 30.61, 31.12, 40.74, 54.04, 
55.57, 59.17, 114.09, 117.10, 118.11, 130.38, 134.27, 135.06, 142.88, 
143.05, 152.23, 153.67, 170.82, 188.47.

The following examples illustrate the beneficial use of deprotonating 
electron donors in silver halide emulsions. 
EXAMPLE 1 
An AgBrI tabular silver halide emulsion (Emulsion T-1) was prepared 
containing 4.05% total I distributed such that the central portion of the 
emulsion grains contained 1.5% I and the perimeter area contained 
substantially higher I as described by Chang et. al., U.S. Pat. No. 
5,314,793. The emulsion grains had an average thickness of 0.112 .mu.m and 
average circular diameter of 1.25 .mu.m. Emulsion T-1 was precipitated 
using deionized gelatin. The emulsion was sulfur sensitized by adding 
1,3-dicarboxymethyl-1,3-dimethyl-2-thiourea at 40.degree. C.; the 
temperature was then raised to 60.degree. C. at a rate of 5.degree. C./3 
min and the emulsions held for 20 min before cooling to 40.degree. C. The 
amount of the sulfur sensitizing compound used was 8.5.times.10.sup.-6 
mole/mole Ag. The chemically sensitized emulsion was then used to prepare 
the experimental coating variations indicated in Example Table I. 
The deprotonating electron donating (DPED) sensitizer compounds were 
dissolved in water and added to the emulsion at the relative 
concentrations indicated in Example Table I. At the time of DPED 
sensitizer addition, the emulsion melts had a VAg of 85-90 mV and a pH of 
6.0. Additional water, gelatin, and surfactant were then added to the 
emulsion melts to give a final emulsion melt that contained 216 grams of 
gel per mole of silver. These emulsion melts were coated onto an acetate 
film base at 1.61 g/m.sup.2 of Ag with gelatin at 3.22 g/m.sup.2. The 
coatings were prepared with a protective overcoat which contained gelatin 
at 1.08 g/m.sup.2, coating surfactants, and a bisvinylsulfonylmethyl ether 
as a gelatin hardening agent. 
For photographic evaluation, each of the coating strips was exposed for 0.1 
sec to a 365 nm emission line of a Hg lamp filtered through a Kodak 
Wratten filter number 18A and a step wedge ranging in density from 0 to 4 
density units in 0.2 density steps. The exposed film strips were developed 
for 6 min in Kodak Rapid X-ray Developer (KRX). S.sub.365, relative 
sensitivity at 365 nm, was evaluated at a density of 0.15 units above fog. 
The data in Example Table I compare the photographic sensitivities for an 
undyed emulsion containing the deprotonating electron donating sensitizer 
compounds 4, 5, 6, and 7. For this exposure, relative sensitivity was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test no. 1). Improved 
sensitivity for the 365 nm exposure was shown for the examples which 
contained the deprotonating electron donating sensitizing agents and the 
sensitivity improvement increased as the compound concentration was 
increased. The data in Example Table I show that sensitivity increases up 
to a factor of 1.8 relative to the control could be obtained with these 
inventive compounds. These sensitivity increases were obtained without any 
increases in fog in this undyed, sulfur sensitized emulsion. 
EXAMPLE TABLE I 
______________________________________ 
Speed and fog results for DPED compounds on Emulsion T-1 
Amount of DPED 
Photographic 
Test Compound added Sensitivity 
No. Compound (10.sup.-3 mol/mol Ag) 
S.sub.365 
Fog Remarks 
______________________________________ 
1 none 0.00 100 0.045 control 
2 6 1.4 98 0.045 invention 
3 6 4.4 114 0.045 invention 
4 6 44 182 0.045 invention 
5 4 1.4 94 0.045 invention 
6 4 4.4 100 0.045 invention 
7 4 44 141 0.045 invention 
8 7 1.4 122 0.045 invention 
9 7 4.4 143 0.045 invention 
10 7 44 184 0.045 invention 
11 5 1.4 104 0.045 invention 
12 5 4.4 117 0.045 invention 
13 5 44 158 0.045 invention 
______________________________________ 
EXAMPLE 2 
The sulfur sensitized AgBrI tabular emulsion T-1 described in Example I was 
used to prepare the experimental coating variations listed in Example 
Table II. In this table, various deprotonating two-electron donors having 
a covalently attached base capable of abstracting the leaving hydrogen 
atom are compared to structurally related compounds that do not contain 
such a base. The inventive and comparison compounds were added to the 
emulsion, and coatings prepared and tested as described in Example 1. 
The compounds 4 and 6 in Example Table II are X--H compounds having one 
electron oxidation potentials E.sub.ox1 that are less positive than 1.4 V. 
Upon oxidation, these compounds undergo a reaction in which a proton on 
one of the two aliphatic carbons adjacent to the aniline nitrogen reacts 
with a covalently attached carboxylate base to give the radical 
X.sup..cndot. and the protonated base, and the radical X.sup..cndot. has 
an oxidation potential equal to or more negative than -0.7 V. For the 365 
nm exposure, the data of Example Table II illustrates that these 
deprotonating two-electron donor compounds 4 and 6 gave large sensitivity 
increases, of a factor of greater than 1.5. These sensitivity gains could 
be obtained with no increase in fog levels. In contrast, the comparison 
compound COMP 1, in which the covalently attached carboxylate base is 
situated in a position where it cannot abstract a proton from the carbon 
atoms adjacent to the aniline nitrogen, gave very little or no sensitivity 
increase. Likewise, the related compound COMP-2, which has no covalently 
attached base, also gave only very small sensitivity increases. 
EXAMPLE TABLE II 
______________________________________ 
Results for Inventive and Comparison Compounds on Emulsion T-1 
Amount of Photographic 
Test Compound added Sensitivity -- 
No. Compound (10.sup.-3 mol/mol Ag) 
S.sub.365 
Fog Remarks 
______________________________________ 
1 none 0.00 100 0.05 control 
2 COMP 1 14 110 0.05 comparison 
3 COMP 1 44 95 0.05 comparison 
4 COMP 2 14 105 0.05 comparison 
5 COMP 2 44 105 0.05 comparison 
6 6 44 155 0.05 invention 
7 4 44 151 0.05 invention 
______________________________________ 
##STR118## 
##STR119## 
EXAMPLE 3 
The sulfur sensitized AgBrI tabular emulsion T1 as described in Example 1 
was used to prepare coatings containing the deprotonating electrondonatin 
sensitizing agent compound 7 without sensitizing dye and in combination 
with blue spectral sensitizing dye DI, green spectral sensitizing dye DII 
or red spectral sensitizing dye DIII, as listed in Example Table III. The 
sensitizing dyes were added to the emulsion at 40.degree. C., followed by 
the deprotonating electron donating compound and the coatings were 
prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. Relative sensitivity for this exposure was set equal to 100 fo 
the control emulsion coating with no dye and no deprotonating electron 
donating sensitizer agent added (test no. 1). Additional testing was 
carried out to determine the response of the coatings described in Exampl 
Table III to a spectral exposure. Each of the coating strips was exposed 
for 0.1 sec on a wedge spectrographic instrument that covers the 
wavelength range from 400 to 750 nm. The instrument contains a tungsten 
light source and a step tablet ranging in density from 0 to 3 density 
units in 0.3 density steps. After developing exposed strips for 6 min in 
Kodak Rapid Xray Developer (KRX), speed was read at 10 nm wavelength 
intervals at a density of 0.3 above fog. Correction for the instrument's 
variation in spectral irradiance with wavelength was done with a computer 
and a plot of log sensitivity vs. wavelength was generated. The relative 
sensitivity S.sub..lambda. at the wavelength of maximum spectral 
sensitivity is reported in Example Table III. For this exposure, for each 
dye used, the relative sensitivity was set equal to 100 for the control 
coating with no deprotonating twoelectron donor compound added. 
The data in Example Table III compare the photographic sensitivities for 
combinations of the deprotonating electron donating sensitizer compound 7 
with the undyed or the blue, green or red dyed emulsion T1. For the undye 
or blue dyed emulsion, the addition of compound 7 increased the 
photographic sensitivity of the emulsion at 365 nm by a factor of 
approximately 1.5. The addition of green or red sensitizing dyes DII or 
DIII caused some sensitivity decrease for the 365 nm exposure relative to 
the undyed control (tests nos. 5 and 7) due to desensitization. Addition 
of compound 7 to these dyed coatings gave some improvement in this 
desensitization (test nos. 6 and 8). For the spectral sensitivity as 
measured with the WR2B exposure, addition of compound 7 to the blue 
sensitized emulsion gave a factor of 1.4 increase in spectral sensitivity 
For the green or red sensitized emulsion, the increase in spectral 
sensitivity on addition of compound 7 was smaller, about a factor of 1.1. 
The data in Example Table III show that this deprotonating electron 
donating compound is able to give sensitivity increases in both dyed and 
undyed emulsions and that the sensitivity increases are observed for 
exposures in the region of intrinsic silver halide absorption as well as 
in the region of dye absorption. All of these sensitivity increases were 
achieved with essentially no increase in fog. 
EXAMPLE TABLE III 
__________________________________________________________________________ 
Speed and Fog Results for DPED Compound 7 with Undyed and Dyed Emulsion 
T-1 
Amount of Amount of 
Photographic 
Test Compound added Sens Sens. Dye Sensitivity 
No. 
Compound 
(10.sup.-3 mol/mol Ag) 
Dye 
(10.sup.-3 mol/mol Ag) 
S.sub.365 
S.sub.ax 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 0 none 
0.00 100 
-- 0.04 
comparison 
2 7 4.4 none 0.00 155 -- 0.04 invention 
3 none 0 D-I 0.91 117 100 0.04 comparision 
4 7 4.4 D-I 0.91 166 135 0.05 invention 
5 none 0 D-II 0.86 78 100 0.07 comparison 
6 7 4.4 D-II 0.86 85 112 0.07 invention 
7 none 0 D-III 0.86 62 100 0.09 comparison 
8 7 4.4 D-III 0.86 69 105 0.09 invention 
__________________________________________________________________________ 
##STR120## 
- 
##STR121## 
##STR122## 
EXAMPLE 4 
An AgBrI tabular silver halide emulsion (Emulsion T2) was prepared 
containing 4.05% total I distributed such that the central portion of the 
emulsion grains contained 1.5% I and the perimeter area contained 
substantially higher I as described by Chang et. al., U.S. Pat. No. 
5,314,793. The emulsion grains had an average thickness of 0.103 .mu.m an 
average circular diameter of 1.25 .mu.m. Emulsion T2 was precipitated 
using deionized gelatin. The emulsion was sulfur sensitized by adding 
1,3-dicarboxymethyl1,3-dimethyl-2-thiourea at 40.degree. C.; the 
temperature was then raised to 60.degree. C. at a rate of 5.degree. C./3 
min and the emulsions held for 20 min before cooling to 40.degree. C. The 
amount of the sulfur sensitizing compound used was 8.5.times.10.sup.-6 
mole/mole Ag. This sulfur sensitized emulsion T2 was then used to prepare 
coatings containing various deprotonating electrondonating sensitizing 
agents in combination with blue spectral sensitizing dye DI or green 
spectral sensitizing dye DII as listed in Example Table IV. The 
sensitizing dyes were added to the emulsion at 40.degree. C., followed by 
the deprotonating electron donating compounds and the coatings were 
prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 8). 
The data in Example Table IV compare the sensitivity increases obtained 
when compounds 1, 4 or 43 are added to the blue or green dyed emulsion T2 
Compounds 1 and 4 are deprotonating electron donating sensitizers of 
general structure II with propionate groups attached to the aniline 
nitrogen and no substituents ortho to the aniline nitrogen. Compound 43 i 
a deprotonating electron donating sensitizer with a propionate group 
attached to the aniline nitrogen and with methyl groups in both positions 
ortho to the aniline nitrogen. The data in Example Table IV shows that al 
three compounds give good speed increases for the blue dyed emulsion, up 
to a factor of 1.6 to 1.7 increase in S.sub.365 at optimum concentration. 
For the green dyed emulsion, increases in speed with compounds 1 and 4 ar 
very small but a factor of 1.3 increase in S.sub.365 is obtained with 
compound 43. This result illustrates the particularly advantageous effect 
of ortho substitution on the phenyl ring of the aniline moiety in 
providing deprotonating electron donating sensitizers of general structur 
II that are useful with both blue and green dyed emulsions. 
EXAMPLE TABLE IV 
__________________________________________________________________________ 
Speed and Fog Results for Various Deprotonating 
Electron Donor Compounds with Emulsion T-2 
Amount of 
Compound Amount of 
added Type of Sens. Dye Photographic 
Test Com- (10.sup.-3 Sens. (10.sup.-3 Sensitivity 
No. pound 
mol/mol Ag) 
Dye mol/mol Ag) 
S.sub.365 
Fog Remarks 
__________________________________________________________________________ 
1 none 
0 D-I 0.91 100 
0.05 
comparison 
2 1 4.4 D-I 0.91 174 0.05 invention 
3 1 44 D-I 0.91 166 0.05 invention 
4 4 4.4 D-I 0.91 126 0.05 invention 
5 4 44 D-I 0.91 155 0.05 invention 
6 43 4.4 D-I 0.91 158 0.05 invention 
7 43 44 D-I 0.91 174 0.05 invention 
8 none 0 D-II 0.86 100 0.07 comparison 
9 1 4.4 D-II 0.86 98 0.07 invention 
10 1 44 D-II 0.86 105 0.07 invention 
11 4 4.4 D-II 0.86 100 0.07 invention 
12 4 44 D-II 0.86 98 0.07 invention 
13 43 4.4 D-II 0.86 129 0.07 invention 
14 43 44 D-II 0.86 122 0.09 invention 
__________________________________________________________________________ 
EXAMPLE 5 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I or green spectral sensitizing dye D-II, as listed in 
Example Table V. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 12). 
The data in Example Table V compare the sensitivity increases obtained when 
compounds 43, 44, 45, 46, or 47 are added to the blue or green dyed 
emulsion T-2. This series of deprotonating electron donating compounds 
X--H are all tertiary anilines with ortho dimethyl substituents on the 
phenyl ring of the aniline moiety. The only structural difference in the 
series is the length of the methylene chain between the aniline nitrogen 
and the carboxylate base, which varies from 2 methylene carbons in 
Compound 43 to 6 methylene carbons in Compound 47. Consequently, this 
series of compounds all have oxidation potentials E.sub.ox1 which are 
closely similar. However, the chain length variation causes large 
differences in the rate of the deprotonation reaction undergone by the 
oxidized form of X--H. The rate of this reaction decreases as chain length 
increases beyond 3 methylene carbons. The data in Example Table V show 
that, within this closely related structural series, the compounds with 
the fastest deprotonation rates are more active than the compounds with 
the slowest deprotonation rates in the sense that the more active 
compounds gave more speed at lower concentrations than the less active 
compounds. This can be seen by comparing, for example, the data for 
compound 44 with the data for compound 47. For the blue dyed emulsion, 
compound 44 gave a factor of 1.7 increase in sensitivity at a 
concentration of 4.4.times.10.sup.-3 mole/mole Ag while compound 47 gave 
only a factor of 1.3 increase (test no. 4 vs. test no. 10). For the green 
dyed emulsion, compound 44 gave a factor of 1.6 increase in sensitivity at 
a concentration of 4.4.times.10.sup.-3 mole/mole Ag while compound 47 gave 
a factor of only 1.1 increase at this concentration (test no. 15 vs. test 
no. 21). Nevertheless, Example Table V also shows that all the compounds 
in this series can give useful speed increases with the blue and the green 
dyed emulsion and that concentrations can be found where these speed 
increases occur with little or no fog increase. 
EXAMPLE TABLE V 
__________________________________________________________________________ 
Speed and Fog Results for Tertiary Aniline DPED Compounds with Emulsion 
T-2 
Amount of 
Comp'd Amount of Sens. 
added Dye Photographic 
Test E.sub.ox1 k.sub.dp E.sub.ox2 (10.sup.-3 Sens. (10.sup.-3 Sensitivi 
ty 
No. 
Compound 
(V) 
(s.sup.-1) 
(V) 
mol/mol Ag 
Dye 
mol/mol Ag) 
S.sub.365 
Fog 
Remarks 
__________________________________________________________________________ 
1 none -- -- -- 0 D-I 
0.91 100 
0.04 
comparison 
2 43 0.71 1.8 .times. 10.sup.6 &lt;-0.9 4.4 D-I 0.91 145 0.05 invention 
3 43 " " " 44 D-I 0.91 174 
0.08 invention 
4 44 0.67 .about.1 .times. 10.sup.8 &lt;-0.9 4.4 D-I 0.91 166 0.05 
invention 
5 44 " " " 44 D-I 0.91 176 0.09 invention 
6 45 0.69 1.3 .times. 10.sup.7 &lt;-0.9 4.4 D-I 0.91 151 0.05 invention 
7 45 " " " 44 D-I 0.91 174 
0.09 invention 
8 46 0.71 1.4 .times. 10.sup.6 &lt;-0.9 4.4 D-I 0.91 138 0.05 invention 
9 46 " " " 44 D-I 0.91 166 
0.08 invention 
10 47 0.75 2.3 .times. 10.sup.5 &lt;-0.9 4.4 D-I 0.91 126 0.03 invention 
11 47 " " " 44 D-I 0.91 151 
0.06 invention 
12 none -- -- -- 0 D-II 0.86 100 0.06 comparison 
13 43 0.71 1.8 .times. 10.sup.6 &lt;-0.9 4.4 D-II 0.86 117 0.08 invention 
14 43 " " " 44 D-II 0.86 135 
0.10 invention 
15 44 0.67 .about.1 .times. 10.sup.8 &lt;-0.9 4.4 D-II 0.86 157 0.09 
invention 
16 44 " " " 44 D-II 0.86 176 0.21 invention 
17 45 0.69 1.3 .times. 10.sup.7 &lt;-0.9 4.4 D-II 0.86 132 0.06 invention 
18 45 " " " 44 D-II 0.86 148 
0.13 invention 
19 46 0.71 1.4 .times. 10.sup.6 &lt;-0.9 4.4 D-II 0.86 112 0.06 invention 
20 46 " " " 44 D-II 0.86 117 
0.09 invention 
21 47 0.75 2.3 .times. 10.sup.5 &lt;-0.9 4.4 D-II 0.86 107 0.05 invention 
22 47 " " " 44 D-II 0.86 105 
0.07 invention 
__________________________________________________________________________ 
EXAMPLE 6 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I or green spectral sensitizing dye D-I, as listed in 
Example Table VI. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 10). 
The data in Example Table VI compare the sensitivity increases obtained 
when compounds 57, 58, 59, or 60 are added to the blue or green dyed 
emulsion T-2. This series of deprotonating electron donating compounds 
X--H are all secondary anilines with ortho dimethyl substituents on the 
phenyl ring of the aniline moiety. The only structural difference in the 
series is the length of the methylene chain between the aniline nitrogen 
and the carboxylate base, which varies from 3 methylene carbons in 
compound 57 to 6 methylene carbons in compound 60. The data in Example 
Table VI show that the activity of the compounds decreases as this 
methylene chain length increases. This can be seen by comparing, for 
example, the data for compound 57 with the data for compound 60. For the 
blue dyed emulsion, compound 57 gave a factor of 1.8 increase in 
sensitivity at a concentration of 44.times.10.sup.-3 mole/mole Ag while 
compound 60 gave only a factor of 1.2 increase (test no. 3 vs. test no. 
9). For the green dyed emulsion, compound 57 gave a factor of 1.1 increase 
in sensitivity at a concentration of 44.times.10.sup.-3 mole/mole Ag while 
compound 60 gave no increase in sensitivity at this concentration. In 
general, the data in Example Table VI show that all of the compounds in 
the series gave useful speed increases in this blue dyed tabular grain 
emulsion with little or no increase in fog. The data also show that the 
more active members of the series can give useful speed increases in the 
green dyed tabular emulsion as well. 
EXAMPLE TABLE VI 
__________________________________________________________________________ 
Speed and Fog Results for Secondary Aniline DPED 
Compounds with Emulsion T-2 
Amount of Amount of 
Compound Sensitizing 
added Dye Photographic 
Test (10.sup.-3 Sens. (10.sup.-3 Sensitivity 
No. Compound 
mol/mol Ag) 
Dye 
mol/mol Ag) 
S.sub.365 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 0 D-I 
0.91 100 
0.04 
comparison 
2 57 4.4 D-I 0.91 166 0.04 invention 
3 57 44 D-I 0.91 176 0.09 invention 
4 58 4.4 D-I 0.91 162 0.04 invention 
5 58 44 D-I 0.91 170 0.09 invention 
6 59 4.4 D-I 0.91 123 0.03 invention 
7 59 44 D-I 0.91 145 0.06 invention 
8 60 4.4 D-I 0.91 100 0.03 invention 
9 60 44 D-I 0.91 123 0.04 invention 
10 none 0 D-II 0.86 100 0.06 compaiison 
11 57 44 D-II 0.86 107 0.06 invention 
12 58 44 D-II 0.86 89 0.05 invention 
13 59 44 D-II 0.86 83 0.05 invention 
14 60 44 D-II 0.86 83 0.05 invention 
__________________________________________________________________________ 
EXAMPLE 7 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agent in combination with blue spectral 
sensitizing dye D-I or green spectral sensitizing dye D-II, as listed in 
Example Table VII. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 14). 
The data in Example Table VI compare the sensitivity increases obtained 
when compounds 9, 10, 11, 12, 37, or 38 are added to the blue or green 
dyed emulsion T-2. Compounds 9, 10, 11, and 12 in this series of 
deprotonating electron donating compounds X--H are all tertiary anilines 
with a 3 carbon methylene chain between the aniline nitrogen and the 
carboxylate base. The only structural difference in the series is the 
identity of the ortho substituent on the phenyl ring of the aniline 
moiety, which varies from methyl to tertiary butyl through the series. 
This variation causes some increase in the oxidation potential E.sub.ox1 
of the X--H compound as the number of carbons in the ortho substituent 
increases. Nevertheless, all these compounds give radicals X.sup..cndot. 
with oxidation potentials E.sub.ox2 that are more negative than -0.9 V. 
The data in Example Table VII show that all of these tertiary aniline 
compounds gave useful speed increases with the blue and green dyed 
emulsions and that these speed increases can be obtained with little or no 
increase in fog on this sulfur sensitized tabular emulsion. Compounds 37 
and 38 are deprotonating electron donating compounds X--H that are the 
secondary aniline analogs of compounds 11 and 12 respectively. These 
compounds give radicals X.sup..cndot. with oxidation potentials E.sub.ox2 
that are less negative than 0.45 V. The data in Example Table VII shows 
that these secondary aniline compounds give useful speed increases in the 
blue dyed emulsion with no increase in fog. In the green dyed emulsion, 
small speed increases can also be obtained with these secondary aniline 
compounds, but the concentration of the compound used needs to be 
carefully chosen. 
EXAMPLE TABLE VII 
__________________________________________________________________________ 
Speed and Fog Results for Various Tertiary and Secondary Aniline DPED 
Compounds with 
Emulsion T-2 
Amount of 
Compound Amount of 
added Sens. Dye Photographic 
Test E.sub.ox1 E.sub.ox2 (10.sup.-3 Sens. (10.sup.-3 Sensitivity 
No. 
Compd 
(V) 
(V) mol/mol Ag 
Dye 
mol/mol Ag 
S.sub.365 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 
-- -- 0 D-I 
0.91 100 
0.04 
comparison 
2 9 0.695 &lt;-0.9 4.4 D-I 0.91 162 0.05 invention 
3 9 " " 44 D-I 0.91 191 0.08 invention 
4 10 0.70 &lt;-0.9 4.4 D-I 0.91 166 0.05 invention 
5 10 " " 44 D-I 0.91 182 0.10 invention 
6 11 0.715 &lt;-0.9 4.4 D-I 0.91 129 0.04 invention 
7 11 " " 44 D-I 0.91 170 0.04 invention 
8 12 0.760 &lt;-0.9 4.4 D-I 0.91 132 0.05 invention 
9 12 " " 44 D-I 0.91 164 0.O5 invention 
10 37 0.625 &gt;-0.45 4.4 D-I 0.91 126 0.04 invention 
11 37 " " 44 D-I 0.91 135 0.04 invention 
12 38 0.625 &gt;-0.45 4.4 D-I 0.91 117 0.04 invention 
13 38 " " 44 D-I 0.91 138 0.04 invention 
14 none -- -- 0 D-II 0.86 100 0.08 comparison 
15 9 0.695 &lt;-0.9 4.4 D-II 0.86 122 0.08 invention 
16 9 " " 44 D-II 0.86 123 0.08 invention 
17 10 0.70 &lt;-0.9 4.4 D-II 0.86 1 10 0.08 invention 
18 10 " " 44 D-II 0.86 115 0.08 invention 
19 11 0.715 &lt;-0.9 4.4 D-II 0.86 132 0.07 invention 
20 11 " " 44 D-II 0.86 132 0.07 invention 
21 12 0.760 &lt;-0.9 4.4 D-II 0.86 117 0.07 invention 
22 12 " " 44 D-II 0.86 124 0.09 invention 
23 37 0.625 &gt;-0.45 44 D-II 0.86 55 0.06 invention 
24 38 0.625 &gt;-0.45 4.4 D-II 0.86 120 0.07 invention 
25 38 " " 44 D-II 0.86 87 0.06 invention 
__________________________________________________________________________ 
EXAMPLE 8 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I, green spectral sensitizing dye D-II, or red 
sensitizing dye D-III as listed in Example Table VIII. The sensitizing 
dyes were added to the emulsion at 40.degree. C., followed by the 
deprotonating electron donating compounds and the coatings were prepared 
as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1, 6 and 11). 
Additional testing was carried out to determine the response of the 
coatings described in Example Table VIII to a spectral exposure as 
described in Example 3. The relative sensitivity S.sub..lambda. at the 
wavelength of maximum spectral sensitivity for each coating is reported in 
Example Table VIII. For this exposure, for each dye used, the relative 
sensitivity was set equal to 100 for the control coating with no 
deprotonating two-electron donor compound added. 
The data in Example Table VIII compare the sensitivity increases obtained 
when compounds 9, 12, 44, or 46 are added to the blue, green or red dyed 
emulsion T-2. Compounds 9 and 12 are active and less active tertiary 
aniline deprotonating electron donor compounds from the series in Example 
VII. These compounds have a single ortho substituent on the phenyl ring of 
the aniline moiety. Compounds 44 and 46 are active and less active 
tertiary aniline deprotonating electron donor compounds from the series in 
Example V. These compounds have methyl substituents on both ortho 
positions of the phenyl ring of the aniline moiety. The data in Example 
Table VIII show that there is an activity advantage for the ortho dimethyl 
substituted compounds: the active ortho dimethyl substituted compound 44 
gave more speed at lower concentration than the active ortho methyl 
substituted compound 9. (Compare tests 4 vs. 2, 9 vs. 7, and 14 vs. 12.) 
Similarly, the less active ortho dimethyl substituted compound 46 gave 
more speed at lower concentration than the less active ortho t-butyl 
substituted compound 12. (Compare tests 5 vs. 3, 10 vs. 8, and 15 vs. 13). 
However, Example Table VIII also shows that all the four of these 
compounds can give useful speed increases with the blue, green, and red 
dyed emulsions. These speed increases were observed for exposures in the 
region of intrinsic silver halide absorption as well as in the region of 
dye absorption and can be obtained with little or no fog increase. 
EXAMPLE TABLE VIII 
__________________________________________________________________________ 
Speed and Fog Results for DPED Compounds with 
Blue, Green and Red Sensitizing Dyes on Emulsion T-2 
Amount of 
Compound Amount of 
added Sens. Dye Photographic 
Test (10.sup.-3 Sens. (10.sup.-3 Sensitiviyt 
No. Comp'd 
mol/mol Ag) 
Dye 
mol/mol Ag) 
S.sub.365 
S.sub.ax 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 
0 D-I 
0.91 100 100 
0.04 
comparison 
2 9 44 D-I 0.91 182 170 0.08 invention 
3 12 44 D-I 0.91 148 141 0.05 invention 
4 44 4.4 D-I 0.91 186 170 0.05 invention 
5 46 4.4 D-I 0.91 151 148 0.05 invention 
6 none 0 D-II 0.86 100 100 0.06 comparison 
7 9 44 D-II 0.86 112 112 0.06 invention 
8 12 44 D-II 0.86 107 107 0.07 invention 
9 44 4.4 D-II 0.86 151 148 0.08 invention 
10 46 4.4 D-II 0.86 115 117 0.07 invention 
11 none 0 D-III 0.86 100 100 0.09 comparison 
12 9 44 D-III 0.86 110 102 0.10 invention 
13 12 44 D-III 0.86 112 102 0.09 invention 
14 44 4.4 D-III 0.86 151 141 0.12 invention 
15 46 4.4 D-III 0.86 115 112 0.10 invention 
__________________________________________________________________________ 
EXAMPLE 9 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I, or green spectral sensitizing dye D-II as listed in 
Example Table IX. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 6). 
The data in Example Table IX compare the sensitivity increases obtained 
when compounds 13, 25, or 28 are added to the blue or green dyed emulsion 
T-2. Compounds 13 and 25 are tertiary aniline deprotonating electron donor 
compounds having a single ortho substituent on the phenyl ring of the 
aniline moiety. In contrast to the compound series examined in Example 7, 
this ortho substituent is not an alkyl group but rather a phenyl ring (in 
Compound 13) or a bromo substituent (in Compound 25). Compound 28 is a 
tertiary aniline deprotonating electron donor compound having a saturated 
fused ring structure attached to ortho and meta positions on the phenyl 
ring of the aniline moiety. The data in Example Table IX show that all 
three of these compounds gave useful speed increases with the blue and 
green dyed emulsions with little or no increase in fog. In this behavior, 
the compounds are similar to the analogous compounds from Example 7 with a 
single alkyl substituent in the ortho position of the aniline moiety. 
EXAMPLE TABLE IX 
__________________________________________________________________________ 
Speed and Fog Results for Various DPED Compounds with Emulsion T-2 
Amount of 
Compound Amount of 
added Sens. Dye Photographic 
Test (10.sup.-3 mol/mol Sens. (10.sup.-3 mol/mol Sensitivity 
No. Compound 
Ag) Dye 
Ag) S.sub.365 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 0 D-I 
0.91 100 
0.04 
comparison 
2 13 4.4 D-I 0.91 174 0.05 invention 
3 13 44 D-I 0.91 182 0.15 invention 
4 25 4.4 D-I 0.91 166 0.04 invention 
5 25 44 D-I 0.91 182 0.07 invention 
6 28 4.4 D-I 0.91 175 0.05 invention 
7 28 44 D-I 0.91 191 0.08 invention 
8 none 0 D-II 0.86 100 0.06 comparison 
9 13 4.4 D-II 0.86 117 0.07 invention 
10 13 44 D-II 0.86 112 0.11 invention 
11 25 4.4 D-II 0.86 129 0.08 invention 
12 25 44 D-II 0.86 132 0.08 invention 
13 28 4.4 D-II 0.86 118 0.07 invention 
14 28 44 D-II 0.86 110 0.08 invention 
__________________________________________________________________________ 
EXAMPLE 10 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing the deprotonating 
electron-donating sensitizing agent Compound 64 in combination with the 
blue spectral sensitizing dye D-I as listed in Example Table X. The 
sensitizing dye was added to the emulsion at 40.degree. C., followed by 
the deprotonating electron donating compound and the coatings were 
prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. Relative sensitivity for this exposure was set equal to 100 for 
the control dyed emulsion coating with no deprotonating electron donating 
sensitizer agent added (test no. 1). 
The data in Example Table X show the sensitivity increase that can be 
obtained when compound 64 is added to the blue dyed emulsion T-2. Compound 
64 is a deprotonating electron donor compound of general structure I. At 
the lower concentration studied (4.4.times.10.sup.-3 mole/mole Ag), a 
factor of 1.3 sensitivity increase is obtained with only a very small 
increase in fog. At the higher concentration examined (44.times.10.sup.-3 
mole/mole Ag), a moderate increase in fog and a slight loss of sensitivity 
is observed. The data illustrate the importance of choosing the 
appropriate concentration for obtaining an advantageous speed effect with 
this compound. 
EXAMPLE TABLE X 
__________________________________________________________________________ 
Speed and Fog Results for Compound 64 with 
Emulsion T-2 
Amount of 
Compound Amount of 
added Sens. Dye 
(10.sup.-3 (10.sup.-3 Photographic 
Test mol/mol Sens. mol/mol Sensitivity 
No. Compound 
Ag) Dye 
Ag) S.sub.365 
Fog Remarks 
__________________________________________________________________________ 
1 none 0 D-I 
0.91 100 0.04 
comparison 
2 64 4.4 D-I 0.91 129 0.07 invention 
3 64 44 D-I 0.91 91 0.21 invention 
__________________________________________________________________________ 
EXAMPLE 11 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I, or green spectral sensitizing dye D-II as listed in 
Example Table XI. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 8). 
The data in Example Table XI compare the sensitivity increases obtained 
when compounds 29 and 54 are added to the blue or green dyed emulsion T-2. 
Compound 29 is a tertiary aniline deprotonating electron donor compound 
having the carboxylate base attached via a methylene chain to an ortho 
position on the phenyl ring of the aniline moiety rather than attached to 
the aniline nitrogen via a methylene chain. In this position, the 
carboxylate base is still capable of abstracting a proton from one of the 
ethyl groups attached to the aniline nitrogen. The data in Example Table 
XI show that compound 29 gave good speed increases with both the blue and 
the green dyed emulsions, indicating that the carboxylate base in this 
position gives a photographically useful deprotonating electron donating 
compound. Compound 54 is an ortho substituted tertiary aniline 
deprotonating electron donor compound having a sulfonate moiety instead of 
a carboxylate group. The data in Example Table XI show that compound 54 
gives good speed increases with the blue and green dyed emulsions with 
little or no increase in fog. 
EXAMPLE TABLE XI 
__________________________________________________________________________ 
Speed and fog results on Emulsion T-2 for DPED compounds with 
variations in attached base characteristics 
Amount of 
Compound Amount of 
added Sens. Dye Photographic 
Test (10.sup.-3 mol/mol Sens. (10.sup.-3 mol/mol Sensitivity 
No. Compound 
Ag) Dye 
Ag) S.sub.365 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 0 D-I 
0.91 100 
0.04 
comparison 
2 29 4.4 D-I 0.91 191 0.04 invention 
3 29 44 D-I 0.91 195 0.07 invention 
4 54 4.4 D-I 0.91 132 0.04 invention 
5 54 44 D-I 0.91 155 0.07 invention 
6 none 0 D-I 0.86 100 0.06 comparison 
7 29 4.4 D-II 0.86 105 0.06 invention 
8 29 44 D-II 0.86 120 0.07 invention 
9 54 4.4 D-II 0.86 100 0.06 invention 
10 54 44 D-II 0.86 107 0.07 invention 
__________________________________________________________________________ 
EXAMPLE 12 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with the blue spectral 
sensitizing dye D-I as listed in Example Table XII. The sensitizing dye 
was added to the emulsion at 40.degree. C., followed by the deprotonating 
electron donating compounds and the coatings were prepared as described in 
Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. Relative sensitivity for this exposure was set equal to 100 for 
the control dyed emulsion coating with no deprotonating electron donating 
sensitizer agent added (test no. 1). 
The data in Example Table XII compare the sensitivity increases obtained 
when compounds 48, 49, 23, 61, 62, or 41 are added to the blue emulsion 
T-2. These compounds are tertiary and secondary aniline deprotonating 
electron donor compounds with both ortho and para substituents on the 
phenyl ring of the aniline moiety. The data in Example Table XII shows 
that all these compounds give large sensitivity increases in this blue 
dyed emulsion. However, the tertiary aniline compounds 48 and 49 and their 
corresponding secondary aniline compounds 61 and 62, which all have ortho 
dimethyl substituents on the phenyl ring of the aniline moiety, generally 
give a better overall combination of speed with low fog than the tertiary 
aniline compound 23 and its corresponding secondary aniline compound 41, 
which have only a single ortho methyl substituent on the phenyl ring of 
the aniline moiety. 
EXAMPLE TABLE XII 
__________________________________________________________________________ 
Speed and Fog Results on Emulsion T-2 for Various DPED 
Compounds having ortho and para Substituents 
Amount of 
Compound Amount of 
added Sens. Dye Photographic 
Test Com- (10.sup.-3 Sens. (10.sup.-3 Sensitivity 
No. pound 
mol/mol Ag) 
Dye 
mol/mol Ag) 
S.sub.365 
Fog Remarks 
__________________________________________________________________________ 
1 none 
0 D-I 
0.91 100 0.04 
comparison 
2 48 4.4 D-I 0.91 182 0.05 invention 
3 48 44 D-I 0.91 219 0.07 invention 
4 49 4.4 D-I 0.91 182 0.04 invention 
5 49 44 D-I 0.91 209 0.08 invention 
6 23 4.4 D-I 0.91 191 0.05 invention 
7 23 44 D-I 0.91 178 0.20 invention 
8 61 44 D-I 0.91 200 0.05 invention 
9 62 44 D-I 0.91 204 0.15 invention 
10 41 44 D-I 0.91 155 0.10 invention 
__________________________________________________________________________ 
EXAMPLE 13 
The AgBrI tabular silver halide emulsion T-2 as described in Example 4 was 
optimally chemically and spectrally sensitized by adding NaSCN, 
1.07.times.10.sup.-3 mole/mole Ag of the blue sensitizing dye D-I, 
Na.sub.3 Au(S.sub.2 O.sub.3).sub.2.2H.sub.2 O, Na.sub.2 S.sub.2 
O.sub.3.5H.sub.2 O, and a benzothiazolium finish modifier and then 
subjecting the emulsion to a heat cycle to 65.degree. C. The antifoggant 
and stabilizer tetraazaindene at a concentration of 1.75 gm/mole Ag was 
added to the emulsion melt after the chemical sensitization procedure. For 
some experimental variations, the hydroxybenzene compound, 
2,4-disulfocatechcol (HB3) at a concentration 13.times.10.sup.-3 mole/mole 
Ag was also added. Various deprotonating electron donating sensitizing 
agents as listed in Example Table XIII were added to the emulsion after 
the additions of HB3 and tetraazaindene. Coatings were then prepared as 
described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1, except that the exposure time used was 0.01 s. Relative 
sensitivity for this exposure was set equal to 100 for the control dyed 
emulsion coating with no deprotonating electron donating sensitizer agent 
added (test no. 1). 
Additional testing was carried out to determine the response of the 
coatings to a spectral exposure. The dyed coating strips were exposed for 
0.01 sec to a 3000 K color temperature tungsten lamp filtered to give an 
effective color temperature of 5500K and further filtered through a Kodak 
Wratten filter number 2B and a step wedge ranging in density from 0 to 4 
density units in 0.2 density steps. This filter passes only light of 
wavelengths longer than 400 nm, thus giving light absorbed mainly by the 
sensitizing dye. The exposed film strips were developed for 6 min in Kodak 
Rapid X-ray Developer (KRX). S.sub.WR2B, relative sensitivity for this 
Kodak Wratten filter 2B exposure, was evaluated at a density of 0.15 units 
above fog. The relative sensitivity for this spectral exposure was set 
equal to 100 for the control dyed coating with no deprotonating electron 
donating compound added (test no. 1). 
The data in Example Table XIII compare the sensitivity increases obtained 
when compounds 43, 44, 46, 56, 57, and 59 were added to the fully 
sensitized, blue-dyed emulsion T-2. Compound 43, 44, and 46 are tertiary 
aniline deprotonating electron donor compounds with ortho dimethyl 
substituents on the phenyl ring of the aniline moiety. Compounds 56, 57, 
and 59 are the secondary anilines corresponding to these compounds. The 
only structural difference in the series is the length of the methylene 
chain between the aniline nitrogen and the carboxylate base, which varies 
from 2 methylene carbons in compounds 43 and 56 to 5 methylene carbons in 
compounds 46 and 59. The data in Example Table XIII show that all of these 
compounds gave good speed increases with only very small fog increases on 
this optimally sensitized, blue-dyed tabular emulsion. The data also show 
that addition of HB3 to the coatings containing these deprotonating 
electron donating compounds is able to eliminate any small fog increases 
while maintaining the speed increases obtained with the compounds. 
EXAMPLE TABLE XIII 
__________________________________________________________________________ 
Speed and Fog Results for DPED Compounds with 
fully sensitized, blue-dyed emulsion T-2, black and white format 
Amount of 
Compound Amount of 
added HB-3 added Photographic 
Test Com- (10.sup.-3 (10.sup.-3 Sensitivity 
No. pound 
mol/mol Ag) 
mol/mol Ag) 
S.sub.365 
S.sub.WR2B 
Fog Remarks 
__________________________________________________________________________ 
1 none 
0.00 none 100 
100 0.05 
comparison 
2 none 0.00 13 115 115 0.06 comparison 
3 43 4.4 none 145 145 0.08 invention 
4 43 4.4 13 138 138 0.06 invention 
5 43 44 none 170 174 0.13 invention 
6 44 4.4 none 145 151 0.09 invention 
7 44 4.4 13 145 145 0.06 invention 
8 44 44 none 174 182 0.14 invention 
9 46 4.4 none 126 126 0.08 invention 
10 46 4.4 13 129 123 0.06 invention 
11 46 44 none 148 141 0.10 invention 
12 56 4.4 none 123 120 0.06 invention 
13 56 44 none 141 141 0.07 invention 
14 57 4.4 none 132 135 0.07 invention 
15 57 44 none 170 170 0.09 invenfion 
16 59 4.4 none 117 -- 0.06 invention 
17 59 44 none 135 135 0.06 invention 
__________________________________________________________________________ 
EXAMPLE 14 
A monodisperse AgBrI tabular silver halide emulsion T-3 containing 3.6% 
total I was prepared according to the procedures described in Fenton et 
al. U.S. Pat. No. 5,476,760 in a manner such that the central portion of 
the emulsion grains contained essentially no I and the I was concentrated 
around the grain perimeter but was higher at the edges than at the 
corners. The emulsion grains had an average thickness of 0.12 .mu.m and an 
average circular diameter of 2.7 .mu.m. This emulsion T-3 was optimally 
chemically and spectrally sensitized by adding NaSCN, 0.77.times.10.sup.-3 
mole/mole Ag of the green sensitizing dye D-II, 0.17.times.10.sup.-3 
mole/mole Ag of the green sensitizing dye D-IV, Na.sub.3 Au(S.sub.2 
O.sub.3).sub.2.2H.sub.2 O, Na.sub.2 S.sub.2 O.sub.3.5H.sub.2 O, and a 
benzothiazolium finish modifier and then subjecting the emulsion to a heat 
cycle to 65.degree. C. The antifoggant and stabilizer tetraazaindene at a 
concentration of 1.00 gm/mole Ag was added to the emulsion melt after the 
chemical sensitization procedure. For some experimental variations, the 
hydroxybenzene compound, 2,4-disulfocatechcol (HB3) at a concentration of 
13.times.10.sup.-3 mole/mole Ag was also added. Various deprotonating 
electron donating sensitizing agents as listed in Example Table XIV were 
added to the emulsion after the additions of HB3 and tetraazaindene. 
Coatings were then prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1, except that the exposure time used was 0.01 s. Relative 
sensitivity for this exposure was set equal to 100 for the control dyed 
emulsion coating with no deprotonating electron donating sensitizer agent 
added (test no. 1). Additional testing was carried out to determine the 
response of the coatings to a spectral exposure, as described in Example 
XIII. The relative sensitivity S.sub.WR2B for this spectral exposure was 
set equal to 100 for the control dyed coating with no deprotonating 
electron donating compound added (test no. 1). 
The data in Example Table XIV compare the sensitivity increases obtained 
when compounds 43, 44, 45, and 46 were added to the fully sensitized, 
green-dyed emulsion T-3. These compounds are tertiary aniline 
deprotonating electron donor compounds with ortho dimethyl substituents on 
the phenyl ring of the aniline moiety. The only structural difference in 
the series is the length of the methylene chain between the aniline 
nitrogen and the carboxylate base, which varies from 2 methylene carbons 
in compound 43 to 5 methylene carbons in compound 46. The data in Example 
Table XIV show that all of these compounds gave reasonable speed increases 
on this optimally sensitized, green-dyed tabular emulsion. However, in the 
absence of HB3, these speed increases are accompanied by significant fog 
increases. The data show that addition of HB3 to the coatings containing 
these deprotonating electron donating compounds is able to minimize these 
fog increases while maintaining the speed increases obtained with the 
compounds. 
EXAMPLE TABLE XIV 
__________________________________________________________________________ 
#STR123## 
- Speed and Fog Results for DPED Compounds with fully sensitized, 
green-dyed emulsion T-3, black and white format 
Amount of 
Amount of 
Photographic 
Test Compound added HB-3 added Sensitivity -- 
No. 
Compound 
(10.sup.-3 mol/mol Ag) 
(10.sup.-3 mol/mol Ag) 
S.sub.365 
S.sub.WR2B 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 0.00 none 100 
100 0.08 
comparison 
2 none 0.00 13 105 107 0.08 comparison 
3 43 4.4 none 110 129 0.38 invention 
4 43 4.4 13 114 122 0.09 invention 
5 43 14 none 132 129 0.43 invention 
6 43 44 13 120 132 0.12 invention 
7 44 4.4 none -- -- 1.09 invention 
8 44 4.4 13 132 135 0.35 invention 
9 44 14 none -- -- 0.95 invention 
10 45 4.4 13 123 126 0.13 invention 
11 45 44 13 126 138 0.21 invention 
12 46 4.4 none 105 115 0.40 invention 
13 46 4.4 13 115 116 0.09 invention 
14 46 14 none 120 126 0.33 invention 
15 46 44 13 117 120 0.12 invention 
__________________________________________________________________________ 
EXAMPLE 15 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I, or green spectral sensitizing dye D-II as listed in 
Example Table XV. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. For some 
experimental variations, the hydroxybenzene compound, 2,4-disulfocatechcol 
(HB3) at a concentration of 13.times.10.sup.-3 mole/mole Ag was also added 
before the addition of the DPED compounds. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent and no disulfocatechol added (test nos. 
1 and 7). 
The data in Example Table XV compare the sensitivity increases obtained 
when compounds 44 or 68 were added to the sulfur sensitized, dyed emulsion 
T-2. Compound 68 is an example of a deprotonating electron donating 
compound attached via a linking group to an adsorbable group (a thiourea 
in this case). Compound 44 is the analog of Compound 68 with no adsorbable 
group attached. The data in Example Table XV show that Compound 68 is able 
to give good speed increases at much lower concentration than Compound 44 
in both the blue and green dyed emulsions. These speed increases are 
obtained with little or no fog increase. The data also show that the 
addition of HB3 is able to minimize any small fog increases that are 
present without any adverse effect on the speed increases obtained. 
EXAMPLE TABLE XV 
__________________________________________________________________________ 
Speed and Fog Results for Adsorbable DPED Compound 68 on Emulsion T-2 
Amount of 
Amount of 
Amount of 
Compound Sens. Dye HB-3 added Photographic 
Test added (10.sup.-3 Sens. (10.sup.-3 (10.sup.3 Sensitivity 
No. 
Comp'd 
mol/molAg) 
Dye 
mol/molAg) 
mol/molAg) 
S.sub.365 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 
0.00 D-I 
0.91 none 100 
0.05 
comparison 
2 none 0.00 D-I 0.91 13 107 0.05 comparison 
3 44 4.4 D-I 0.91 none 200 0.07 invention 
4 68 0.014 D-I 0.91 none 178 0.06 invention 
5 68 0.14 D-I 0.91 none 224 0.13 invention 
6 68 0.14 D-I 0.91 13 224 0.07 invention 
7 none 0.00 D-II 0.86 none 100 0.08 comparison 
8 none 0.00 D-II 0.86 13 112 0.08 comparison 
9 44 4.4 D-II 0.86 none 158 0.09 invention 
10 68 0.0014 D-II 0.86 none 112 0.08 invention 
11 68 0.014 D-II 0.86 none 141 0.08 invention 
12 68 0.014 D-II 0.86 13 138 0.08 invention 
__________________________________________________________________________ 
EXAMPLE 16 
The optimally sensitized blue-dyed emulsion T-2 as described in Example 13 
and the optimally sensitized green-dyed emulsion T-3 as described in 
Example 14 were used to prepare color format coatings containing the 
adsorbable DPED Compound 68, as detailed in Example Table XVI. The mild 
hydroxybenzene compound, 2,4-disulfocatechcol (HB3) at a concentration of 
13.times.10.sup.-3 mole/mole Ag and the antifoggant and stabilizer 
tetraazaindene at a concentration of 1.75 gm/mole Ag (emulsion T-2) or 
1.00 gm/mole Ag (emulsion T-3) were added to the emulsion melt before the 
addition of Compound 68 to the melts at 40.degree. C. 
The melts were prepared for coating by adding additional water, deionized 
gelatin, and coating surfactants. Coatings were prepared by combining the 
emulsion melts with a melt containing deionized gelatin and an aqueous 
dispersion of the cyan-forming color coupler CC-1 and coating the 
resulting mixture on acetate support. The final coatings contained Ag at 
0.81 g/m.sup.2, coupler at 1.61 g/m.sup.2, and gelatin at 3.22 g/m.sup.2. 
The coatings were overcoated with a protective layer containing gelatin at 
1.08 g/m.sup.2, coating surfactants, and a bisvinylsulfonylmethyl ether as 
a gelatin hardening agent. The coating strips obtained were then tested 
using the 365 nm exposure and the Kodak Wratten 2B exposure described in 
Example 13. For each exposure, relative sensitivity was set equal to 100 
for the control emulsion coating with no deprotonating electron donating 
sensitizer agent added (test no. 1). 
The data in Example Table XVI show the sensitivity increases obtained when 
Compound 68 was added to the fully sensitized blue-dyed emulsion T-2 or 
the fully sensitized green-dyed emulsion T-3. Speed increases were largest 
for the blue-dyed emulsion T-2 but for both emulsions, concentrations of 
Compound 68 can be found that give useful speed increases with only small 
fog increases. The table also shows that the optimum concentration of 
Compound 46 was lower in the optimally sensitized green-dyed emulsion T-3 
than in the optimally sensitized blue-dyed emulsion T-2. 
EXAMPLE TABLE XVI 
__________________________________________________________________________ 
#STR124## 
- Speed and Fog Results for DPED Compound 68 on 
Fully Sensitized Emulsions T-2 and T-3, Color Format 
Amount of 
Photographic 
Test Sens. Compound 68 Sensitivity -- 
No. 
Emulsion 
Dye (10.sup.-3 mol/mol Ag) 
S.sub.365 
S.sub.WR2B 
Fog 
Remarks 
__________________________________________________________________________ 
1 T-2 D-I none 100 
100 0.08 
comparison 
2 T-2 D-I 0.014 135 126 0.11 invention 
3 T-2 D-I 0.045 151 151 0.13 invention 
4 T-2 D-I 0.14 166 182 0.21 invention 
5 T-3 D-II + D-IV none 100 100 0.09 comparison 
6 T-3 D-II + D-IV 0.00045 102 102 0.09 invention 
7 T-3 D-II + D-IV 0.0014 105 105 0.12 invention 
8 T-3 D-II + D-IV 0.0045 112 117 0.26 invention 
__________________________________________________________________________ 
EXAMPLE 17 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I, or green spectral sensitizing dye D-II as listed in 
Example Table XVII. The sensitizing dyes were added to the emulsion at 
40.degree. C., followed by the deprotonating electron donating compounds 
and the coatings were prepared as described in Example 1. For some 
experimental variations, the hydroxybenzene compound, 2,4-disulfocatechcol 
(HB3) at a concentration of 13.times.10.sup.-3 mole/mole Ag was also added 
before the addition of the DPED compounds. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. In addition, S.sub.WR2B, relative sensitivity for a spectral 
exposure was evaluated as described in example 13, except that the 
exposure time used was 0.1 s. For each dye and each exposure type, 
relative sensitivity for the exposure was set equal to 100 for the control 
emulsion coating with no deprotonating electron donating sensitizer agent 
and no disulfocatechol added (test nos. 1 and 8). 
The data in Example Table XVII compare the sensitivity increases obtained 
when compounds 46 or 67 were added to the sulfur sensitized, dyed emulsion 
T-2. Compound 67 is an example of a deprotonating electron donating 
compound attached via a linking group to an adsorbable group (a 
thiomorpholino moiety in this case). Compound 46 is the analog of Compound 
67 with no adsorbable group attached. The data in Example Table XVII show 
that Compound 67 is able to give good speed increases at much lower 
concentration than Compound 46 in both the blue and green dyed emulsions. 
These speed increases were obtained with little or no fog increase in the 
blue-dyed emulsion. In the green dyed emulsion, these speed increases were 
accompanied by significant increases in fog. However, the data in Example 
Table XVII show that a combination of proper choice of Compound 67 
concentration with use of the disulfocatechcol compound HB3 allows 
Compound 67 to give good speed increases with only small increases in fog. 
EXAMPLE TABLE XVII 
__________________________________________________________________________ 
Speed and Fog Results for Adsorbable DPED Compound 67 on Emulsion T-2 
Amount of 
Amount of 
Amount of 
Compound Sens. Dye HB-3 added Photographic 
Test added (10.sup.-3 Sens. (10.sup.-3 (10.sup.3 Sensitivity 
No. 
Comp'd 
mol/molAg) 
Dye 
mol/molAg) 
mol/molAg) 
S.sub.365 
S.sub.WR2B 
Fog 
Remarks 
__________________________________________________________________________ 
1 none 
0.00 D-I 
0.91 none 100 
100 0.05 
comparison 
2 none 0.00 D-I 0.91 13 112 110 0.04 comparison 
3 46 4.4 D-I 0.91 none 158 166 0.08 invention 
4 67 0.044 D-I 0.91 13 162 170 0.07 invention 
5 67 0.14 D-I 0.91 none 174 186 0.06 invention 
6 67 0.14 D-I 0.91 13 178 182 0.07 invention 
7 67 0.44 D-I 0.91 13 182 200 0.10 invention 
8 none 0.00 D-II 0.86 none 100 100 0.07 comparison 
9 none 0.00 D-II 0.86 13 102 100 0.07 comparison 
10 46 4.4 D-II 0.86 none 120 132 0.24 invention 
11 67 0.044 D-II 0.86 13 151 162 0.08 invention 
12 67 0.14 D-II 0.86 none -- -- 0.71 invention 
13 67 0.14 D-II 0.86 13 162 174 0.13 invention 
14 67 0.44 D-II 0.86 13 141 155 0.38 invention 
__________________________________________________________________________ 
EXAMPLE 18 
The optimally sensitized blue-dyed emulsion T-2 as described in Example 13 
was used to prepare color format coatings containing the adsorbable DPED 
Compound 67, as described in Example Table XVIII. The hydroxybenzene 
compound, 2,4-disulfocatechcol (HB3) at a concentration of 
13.times.10.sup.-3 mole/mole Ag and the antifoggant and stabilizer 
tetraazaindene at a concentration of 1.75 gm/mole Ag (emulsion T-2) were 
added to the emulsion melt before the addition of Compound 67 to the melts 
at 40.degree. C. The melts were then used to prepare color format coatings 
as described in Example 16. The coating strips obtained were then tested 
using the 365 nm exposure and the Kodak Wratten 2B exposure described in 
Example 13. For each exposure, relative sensitivity was set equal to 100 
for the control emulsion coating with no deprotonating electron donating 
sensitizer agent added (test no. 1). 
The data in Example Table XVIII indicate that useful sensitivity increases 
are obtained for both intrinsic and spectral exposures when Compound 67 
was added to this fully sensitized, blue-dyed emulsion. These sensitivity 
increases were accompanied by minor increases in fog. Since the best 
combination of speed and fog was observed at the lowest concentration of 
Compound 67, the data in the table indicate that the optimum concentration 
for Compound 67 this emulsion is probably lower than the lowest 
concentration studies in this example. 
EXAMPLE TABLE XVIII 
______________________________________ 
Speed and Fog Results for Compound 67 on Fully 
Sensitized Blue Dyed Emulsion 
T-2 in Color Format 
Amount of 
Compound 
67 
Test (10.sup.-3 mol/mol Photographic Sensitivity 
No. Ag) S.sub.365 
S.sub.WR2B 
Fog Remarks 
______________________________________ 
1 none 100 100 0.06 comparison 
2 0.44 143 138 0.11 invention 
3 1.4 140 135 0.12 invention 
4 4.4 140 129 0.14 invention 
______________________________________ 
EXAMPLE 19 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing various deprotonating 
electron-donating sensitizing agents in combination with blue spectral 
sensitizing dye D-I, or green spectral sensitizing dye D-II as Table XIX. 
The sensitizing dyes were added to the emulsion at 40.degree. C., followed 
by the deprotonating electron donating compounds and the coatings were 
prepared as described in Example 1. 
S.sub.365, relative sensitivity at 365 nm, was evaluated as described in 
Example 1. For each dye, relative sensitivity for this exposure was set 
equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test nos. 1 and 5). 
The data in Example Table XIX compare the sensitivity increases obtained 
when compounds 44 or 55 were added to the sulfur sensitized, dyed emulsion 
T-2. Compound 55 is an example of a deprotonating electron donating 
compound with two X--H moieties attached to each other via methylene chain 
linking the two aniline nitrogens. Compound 44 is the analog of Compound 
55 with only a single X--H moiety. In both compounds, the X--H moiety 
contains ortho dimethyl substituents on the phenyl ring of the aniline 
structure. The data in Example Table XIX show that Compound 55 is similar 
in activity to Compound 29. Both compounds gave good speed increases in 
the blue and green dyed emulsions with only very slight fog increases. 
EXAMPLE TABLE XIX 
__________________________________________________________________________ 
Speed and Fog Results for DPED Compounds on Emulsion T-2 
Amount of Amount of 
Compound Sens. Dye Photographic 
Test added (10.sup.-3 Sens. (10.sup.-3 Sensitivity 
No. Comp'd 
mol/molAg) 
Dye mol/molAg) 
S.sub.365 
Fog Remarks 
__________________________________________________________________________ 
1 none 0.00 D-I 0.91 100 0.05 
comparison 
2 44 4.4 D-I 0.91 200 0.07 invention 
3 55 2.2 D-I 0.91 195 0.06 invention 
4 55 22 D-I 0.91 191 0.07 invention 
5 none 0.00 D-II 0.86 100 0.08 comparison 
6 44 4.4 D-II 0.86 158 0.09 invention 
7 55 2.2 D-II 0.86 141 0.10 invention 
8 55 22 D-II 0.86 158 0.15 invention 
__________________________________________________________________________ 
EXAMPLE XX 
The sulfur sensitized AgBrI tabular emulsion T-2 as described in Example 4 
was used to prepare coatings containing the deprotonating 
electron-donating sensitizing agent compound 31 in combination with blue 
spectral sensitizing dye D-I or green spectral sensitizing dye D-II as 
listed in Example Table XX. The sensitizing dyes were added to the 
emulsion at 40.degree. C., followed by the deprotonating electron donating 
compound and the coatings were prepared as described in Example 1. 
S.sub.WR2B, relative sensitivity for a spectral exposure was evaluated as 
described in example 13, except that the exposure time used was 0.1 s. For 
each dye, relative sensitivity for the exposure was set equal to 100 for 
the control emulsion coating with no deprotonating electron donating 
sensitizer agent added (test nos. 1 and 4). 
Compound 31 is a deprotonating electron donating sensitizer with an aryl 
carboxylate base attached to the ortho position of the aniline nitrogen. 
This attachment is via a keto linkage, which causes the compound to absorb 
light in the blue region of the spectrum. The data in Example Table XX 
shows that at the lower concentration, Compound 31 gives a moderate 
spectral speed increase for the blue dyed emulsion but that at the higher 
concentration, loss of speed is seen owing to a filtering effect of the 
compound on the blue light reaching the emulsion. For the green dyed 
emulsion, the filtration effect is absent in the spectrally sensitized 
region and small speed gains are seen for spectral exposures at the larger 
compound concentration. These data indicate that the attached aryl 
carboxylate moiety in this ortho position gives a photographically useful 
deprotonating electron donating compound. 
EXAMPLE TABLE XX 
__________________________________________________________________________ 
Speed and Fog Results for DPED Compound 31 with Dyed Emulsion T-2 
Amount of Amount of 
Compound Sens. Dye Photographic 
Test Com- added (10 
.sup.-3 Sens (10.sup.-3 Sensitivity 
No. pound 
mol/molAg) 
Dye mol/molAg) 
S.sub.WR2B 
Fog Remarks 
__________________________________________________________________________ 
1 none 0 D-I 0.91 100 0.04 
comparison 
2 31 4.4 D-I 0.91 123 0.04 invention 
3 31 44 D-I 0.91 110 0.04 invention 
4 none 0 D-II 0.86 100 0.07 comparison 
5 31 4.4 D-II 0.86 100 0.07 invention 
6 31 44 D-II 0.86 112 0.07 invention 
__________________________________________________________________________ 
EXAMPLE 21 
The optimally sensitized blue-dyed emulsion T-2 as described in Example 13 
was used to prepare color format coatings containing the adsorbable DPED 
compounds 109, 111, 113, and 115, as detailed in Table XXI. The 
antifoggant 2,4-disulfocatechcol (HB3) at a concentration of 
13.times.10.sup.-3 mole/mole Ag and the antifoggant and stabilizer 
tetraazaindene at a concentration of 1.75 gm/mole Ag were added to the 
emulsion melt before the addition of the adsorbable DPED compounds to the 
melts at 40.degree. C. The melts were used to prepare color format 
coatings as described in Example 16. The coating strips obtained were then 
tested using the 365 nm exposure and the Kodak Wratten 2B exposure as 
described in Example 13. Development was for 31/4 minutes in Kodak C-41 
color developer. For each exposure, relative sensitivity was set equal to 
100 for the control emulsion coating with no deprotonating electron 
donating sensitizer agent added (test no. 1). 
The data in Example Table XXI show the sensitivity increases obtained when 
the adsorbable DPED compounds 109, 111, 113, and 115 were added to the 
fully sensitized blue dyed emulsion T-2. At the optimum compound 
concentrations, speed increases of up to 1.6.times. could be obtained with 
only small increases in fog. 
TABLE XXI 
______________________________________ 
Speed and Fog Results for Adsorbable DPED Compounds on Fully 
Sensitized Blue Dyed Emulsion T-2, Color Format 
Amount 
Compound Photographic 
Test Com- (10.sup.-3 Sensitivity 
No. pound mol/mol Ag) 
S.sub.365 
S.sub.WR2B 
Fog Remarks 
______________________________________ 
1 none none 100 100 0.06 comparison 
2 109 0.0045 145 141 0.08 invention 
3 109 0.014 158 158 0.09 invention 
4 111 0.014 148 145 0.09 invention 
5 111 0.045 162 162 0.13 invention 
6 113 0.045 145 145 0.12 invenfion 
7 113 0.14 145 141 0.38 invention 
8 115 0.045 141 138 0.13 invention 
9 115 0.14 145 145 0.37 invention 
______________________________________ 
EXAMPLE 22 
The optimally sensitized green-dyed emulsion T-3 as described in Example 14 
was used to prepare black and white format coatings containing the 
adsorbable DPED compounds 109, 110, 111, and 112, as detailed in Table 
XXII. The antifoggant 2,4-disulfocatechcol (HB3) at a concentration of 
13.times.10.sup.-3 mole/mole Ag and the antifoggant and stabilizer 
tetraazaindene at a concentration of 1.00 gm/mole Ag were added to the 
emulsion melt before the addition of the adsorbable DPED compounds to the 
melts at 40.degree. C. The melts were used to prepare black and white 
format coatings as described in Example 16. The coating strips obtained 
were then tested using the 365 nm exposure and the Kodak Wratten 2B 
exposure as described in Example 13. Development was for 6 min in Kodak 
Rapid X-ray Developer (KRX). For each exposure, relative sensitivity was 
set equal to 100 for the control emulsion coating with no deprotonating 
electron donating sensitizer agent added (test no. 1). 
The data in Example Table XXII show the sensitivity increases obtained when 
the adsorbable DPED compounds 109, 110, 111, and 112 were added to the 
fully sensitized green-dyed emulsion T-3. At the optimum compound 
concentrations, speed increases of up to 1.2.times. could be obtained with 
only small increases in fog. 
TABLE XXII 
______________________________________ 
Speed and Fog Results for Adsorbable DPED Compounds on Fully 
Sensitized Green Dyed Emulsion T-3, Black and White Format 
Amount 
Compound Photographic 
Test Com- (10.sup.-3 Sensitivity 
No. pound mol/mol Ag) 
S.sub.365 
S.sub.WR2B 
Fog Remarks 
______________________________________ 
1 none 100 100 0.09 comparison 
2 109 0.45 123 115 0.12 invention 
3 109 1.4 141 141 0.24 invention 
4 110 0.23 107 112 0.10 invention 
5 110 0.7 112 117 0.15 invention 
6 110 2.3 129 132 0.24 invention 
7 111 1.4 107 110 0.10 invention 
8 111 4.5 117 120 0.16 invention 
9 111 14 132 145 0.30 invention 
10 112 0.7 100 105 0.10 invention 
11 112 2.3 102 107 0.11 invention 
12 112 7 107 110 0.13 invention 
______________________________________ 
EXAMPLE 23 
The sulfur sensitized AgBrI tabular emulsion T-1 described in Example 1 was 
used to prepare the black and white format coatings containing the DPED 
compound INV 32 in combination with a blue spectral sensitizing dye D-I or 
green spectral sensitizing dye D-II. The sensitizing dyes were added to 
the emulsion at 40 C, followed by the DPED and the coatings were prepared 
as described in Example 1. The coating strips were then tested using the 
365 nm exposure and the Kodak Wratten 2B exposure as described in example 
13. 
TABLE XXIII 
______________________________________ 
Amount of INV 32 
Test Sensitizing added Photographic Sensitivity 
No. Dye (10.sup.-3 mol/mol Ag) 
Fog S.sub.365 
S.sub.WR2B 
______________________________________ 
1 D-I 0 0.04 100 100 
2 D-I 4.4 0.04 110 110 
3 D-I 44 0.04 148 145 
4 D-II 0 0.07 100 100 
5 D-II 1.4 0.08 110 110 
6 D-II 14 0.09 112 110 
______________________________________ 
The data of Table XIII show the DPED compound INV 32, which contains the 
covalently attached basic moiety N--O, provides sensitivity increases on 
the AgBrI emulsions containing either the blue or green spectral 
sensitizing dye. At the optimum compound concentration, speed increases up 
to 1.4.times. could be obtained with little or no increase in fog. 
The invention has been described in detail with particular reference to 
preferred embodiments, but it will be understood that variations and 
modifications can be effected within the spirit and scope of the 
invention.