Disulfonyl silver halide solvents substituted with piperazine at one sulfonyl group

Alkanes containing an intralinear sulfonyl group and an intralinear 1-piperazinylsulfonamido group separated by a single carbon substituted with at least one hydrogen atom are employed as silver halide solvents in photographic processes and compositions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to photography and, in particular, it is concerned 
with a new class of silver halide solvents and with photographic products, 
processes and compositions employing the same. 
2. Description of the Prior Art 
Photographic processing composition capable of forming water-soluble 
complex silver salts are known to be useful in many types of silver halide 
photography. To obtain a relatively stable image in an exposed and 
developed photosensitive silver halide emulsion, the silver halide 
remaining in the unexposed and undeveloped areas of the emulsion should be 
converted to a soluble silver complex that can be removed by washing or 
converted to a stable silver complex that will not "print-out" upon 
prolonged exposure to light. In conventional or "tray" development, it is 
customary to fix the developed silver halide emulsion by applying a 
solution of silver halide solvent, i.e., silver halide complexing agent 
which forms a water-soluble silver complex with the residual silver 
halide. The water-soluble silver comlex thus formed and excess silver 
halide solvent are then removed from the developed and fixed emulsion by 
washing with water. 
Silver halide solvents also have been employed in monobaths where a single 
processing compositions containing a silver halide developing agent in 
addition to the silver halide solvent is utilized for both developing and 
fixing an exposed photosensitive silver halide layer. Silver halide 
solvents also have been employed in diffusion transfer photographic 
processes. Such processes are now well known in the art; see for example, 
U.S. Pats. Nos. 2,543,181; 2,647,056; 2,983,606; etc. In processes of this 
type, an exposed silver halide emulsion is treated with a processing 
composition whereby the exposed silver halide emulsion is developed and an 
imagewise distribution of diffusible image-forming components is formed in 
the unexposed and undeveloped portions of the silver halide emulsion. This 
distribution of image-forming components is transferred by imbibition to 
an image-receiving stratum in superposed relationship with the silver 
halide emulsion to provide the desired transfer image. In diffusion 
transfer processes where a silver transfer image is formed, processing is 
effected in the presence of a silver halide solvent which forms a 
diffusible complex with the undeveloped silver halide. The soluble silver 
complex thus formed diffuses to the superposed image-receiving layer where 
the transferred silver ions are deposited as metallic silver to provide 
the silver transfer image. In preparing silver prints in this manner, the 
image-receiving element preferably includes a silver precipitating agent, 
for example, heavy metal sulfides and selenides as described in U.S. Pat. 
No. 2,698,237 of Edwin H. Land. 
Various compounds have been employed as silver halide solvents in the 
photographic processes described above. One of the most commonly employed 
is sodium thiosulfate. Other silver halide solvents that have been used 
include thiocyanates, such as potassium and sodium thiocyanate; and cyclic 
imides, such as barbituric acid and uracil. U.S. Pat. No. 3,769,014 
disclosed still another class of silver halide solvents, namely, 
1,1-bis-sulfonyl alkanes. 
The present invention is concerned with a new class of silver halide 
solvents comprising alkanes that contain both a sulfonyl group and a 
tertiary sulfonamido group. 
SUMMARY OF THE INVENTION 
It is, therefore, the primary object of the present invention to provide 
photographic products, processes and compositions employing a new class of 
silver halide solvents. 
Other objects of this invention will in part be obvious and will in part 
appear hereinafter. 
The invention accordingly comprises and processes involving the several 
steps and the relation and order of one or more of such steps with respect 
to each of the others, and the products and compositions possessing the 
features, properties and the relation of elements which are exemplified in 
the following detailed disclosure, and the scope of the application of 
which will be indicated in the claims. 
For a fuller understanding of the nature and objects of the invention, 
reference should be had to the following detailed description. 
DETAILED DESCRIPTION OF THE INVENTION 
According to the present invention, it has now been found that open-chain 
alkanes containing (a) an intralinear sulfonyl group and (b) an 
intralinear 1-piperazinyl sulfonamido group wherein said groups are 
separated by a single carbon, substituted with at least one hydrogen atom 
are useful for complexing silver ion, i.e., undeveloped silver halide in 
photographic processes. Compounds of this type found particularly useful 
in both conventional and diffusion transfer photography are those 
represented by the following formula: 
##STR1## 
wherein R.sup.1 is lower alkyl; R.sup.2 is hydrogen, lower alkyl or 
--CH.sub.2).sub.m S--R.sup.o wherein R.sup.o is lower alkyl and m is a 
whole number 2 to 5; and X represents the residue of a 1-piperazine, 
preferably 
##STR2## 
wherein A is a halide or sulfonate, R.sup.3 is hydrogen or lower alkyl and 
R.sup.4 and R.sup.5 each are lower alkyl. As used herein, the term "lower 
alkyl" is intended to mean alkyl groups containing one or four carbon 
atoms, for example, methyl, ethyl, propyl, isopropyl, s-butyl and n-butyl, 
which groups may be unsubstituted or substituted preferably in the omega 
position with, for example, --OH and --COOR wherein R is H or alkyl having 
1 to 4 carbon atoms. 
Typical of the compounds containing -OH and -COOR substituents are those 
represented by the following formula: 
##STR3## 
wherein R.sup.1 is alkyl having 1 to 4 carbon atoms; R.sup.2 is hydrogen, 
alkyl having 1 to 4 carbon atoms or --CH.sub.2).sub.m S--CH.sub.2).sub.n Y 
wherein m is a whole number 2 to 5, n is a whole number 1 to 4 and Y is 
hydrogen, --OH or --COOR wherein R is hydrogen or alkyl having 1 to 4 
carbon atoms; and X is 
##STR4## 
wherein A is a halide or sulfonate, R.sup.3 is hydrogen or 
--CH.sub.2).sub.n Y wherein n and Y have the same meaning given above, 
R.sup.4 is --CH.sub.2).sub.n Y wherein n and Y have the same meaning given 
above and R.sup.5 is alkyl having 1 to 4 carbon atoms. 
Specific examples of compounds useful as silver halide solvents in 
accordance with the present invention are those set out in the following 
formulas: 
##STR5## 
The silver halide solvents of the present invention are per se novel 
compounds and comprise the subject matter of copending U.S. Pat. 
application Ser. No. 681,583 of Richard B. Greenwald filed Apr. 29, 1976, 
now U.S. Pat. No. 4,009,167 which is a continuation-in-part of application 
Ser. No. 564,166 filed Apr. 1, 1975, now U.S. Pat. No. 3,976,647. For 
convenience, the specification of said applications are specifically 
incorporated herein. 
In preparing the non-quaternized compounds, the non-S-substituted compounds 
may be synthesized, for example, by reacting a sulfene with the selected 
piperazine in accordance with the procedure described by G. Opitz et al., 
Angew. Chem. internat. Edit., Vol. 5 (1966), p. 594-5. The compounds 
substituted with the --S-containing moiety may be prepared, for example, 
by reacting the non-S-substituted sulfonyl-sulfonamido alkanes with the 
chloro-substituted derivative of the selected R.sup.2 substituent, i.e., 
R.sup.o --S--(CH.sub.2).sub.m --Cl. The quaternized compounds may be 
synthesized by reacting the non-S-substituted or the S-substituted 
compounds usually as a tertiary amine, i.e., R.sup.3 is other than 
hydrogen, with an alkyl halide or sulfonate. 
As an example, the compound of the formula 
##STR6## 
was prepared as follows: 
A. A solution of triethylamine (31 g., 300 mmoles) in 200 mls of 
acetonitrile was chilled in dry ice/alcohol to about -50.degree. C. 
Methanesulfonylchloride (23 g., 200 mmoles) was added dropwise to the 
cooled solution over 10 minutes with stirring. Stirring was continued for 
20 minutes, and N-methylpiperazine (10 g., 100 mmoles) was added over 10 
minutes. The reaction mixture was allowed to stand for about 2 days at 
room temperature and then stripped on a rotovac. The residue was 
triturated with water and the title compound collected (15.3 g., melting 
range 195.degree.-198.degree. C.) 
The above compound was substituted with an S-containing moiety to give the 
compound: 
##STR7## 
B. The compound of Step (A) (5 g., 19.4 mmoles) was dissolved in 
N,N-dimethylformamide by heating to 60.degree. C. Sodium hydride (57% by 
weight dispersion in oil; 1 g.) was added to the solution and the mixture 
heated at about 70.degree. C. for 1.25 hours. The chloride, 
Cl--(CH.sub.2).sub.2 S(CH.sub.2).sub.2 CO.sub.2 C.sub.2 H.sub.5 (4.6 g., 
23.3 mmoles) was then added over 15 minutes and the reaction mixture 
heated to 100.degree. C. Heating at about 85.degree. C. was continued 
overnight and then the reaction mixture was heated at 105.degree. C. for 
about 2 hours. After cooling, the mixture was poured onto ice, and the 
filtrate decanted from a tacky gray solid. The remaining filtrate was 
stripped on a rotovac and the residue taken up in 50 mls. ethanol. A white 
solid (1.2 g.) was collected by filtration and the filtrate stripped to 
give a sticky white solid (4.8 g.) which was triturated briefly with 
ether. The title compound was separated from the white solid by 
chromatography using about 100 g. of silica gel which was eluted with 
chloroform, 2% methanol and 5% methanol in 200 ml fractions. Fraction 6 
contained about 1.4 g. of the title compound, essentially homogeneous by 
NMR (&gt; 95% purity, melting range 124.degree.-126.degree. C.) 
The compound of step (B) was converted to the corresponding 
carboxy-substituted compound 
##STR8## 
as follows: 
C. The compound of Step (B) (1.2 g., 2.9 mmoles) was dissolved in 25 mls. 
of 6N hydrochloric acid and heated at reflux for 2.5 hours. The solution 
was allowed to stand overnight at room temperature and then stripped on a 
rotovac yielding the title compound as a white powder (1.1 g., melting 
point about 100.degree. C.) 
The compound prepared in Step (A) was quaternized as follows to give the 
compound of the formula 
##STR9## 
D. The compound of Step (A) (1.25 g., 4.9 mmoles) was dissolved in 25 mls 
of acetonitrile by warming and the solution allowed to cool to room 
temperature. Methylfluorosulfonate (0.56 g., 4.9 mmoles) was added to the 
cooled solution and the reaction mixture was warmed briefly. A white solid 
separated, and after about 15 minutes when the reaction mixture had cooled 
to room temperature, the white solid was collected to give 1.4 g. of the 
title compound. 
In formulating photographic processing compositions utilizing the 
above-described compounds, the above-described compounds, the compounds 
may be used singly or in admixture with each other. The total amount 
employed may vary widely depending upon the particular photographic system 
and should be used, for example, in a quantity sufficient for fixing a 
developed negative in conventional "tray" processing or in a quantity 
sufficient to give a satisfactory transfer print in diffusion transfer 
processes under the particular processing conditions employed. 
Though the silver halide solvents of the present invention are broadly 
useful in a variety of photographic processes of the type in which 
water-soluble silver complexes are formed from the unreduced silver halide 
of a photoexposed and at least partially developed silver halide stratum, 
they find particular utility in diffusion transfer processes. A 
composition embodying the present invention specifically suitable for use 
in the production of transfer images comprises, in addition to the silver 
halide complexing agents of the above-described type, a suitable silver 
halide developing agent, preferably an organic developing agent. Examples 
of developing agents that may be employed include hydroquinone and 
substituted hydroquinones, such as tertiary butyl hydroquinone, 
2,5-dimethyl hydroquinone, methoxyhydroquinone, ethoxyhydroquinone, 
chlorohydroquinone; pyrogallol and catechols, such as catechol, 4-phenyl 
catechol and tertiary butyl catechol; aminophenols, such as 
2,4,6-triamino-orthocresol; 1,4-diaminobenzenes, such as 
p-phenylenediamine, 1,2,4-triaminobenzene and 
4-amino-2-methyl-N,N-diethylaniline; ascorbic acid and its derivatives, 
such as ascorbic acid, isoascorbic acid and 5,6-isopropylidene ascorbic 
acid and other enediols, such as tetramethyl reductic acid; and 
hydroxylamines, such as N,N-di-(2-ethoxyethyl)hydroxylamine and 
N,N-di-(2-methoxyethoxyethyl)hydroxylamine. 
In diffusion transfer processes, the processing composition, if it is to be 
applied to the emulsion by being spread thereon in a thin layer, also 
usually includes a viscosity-imparting reagent. The processing composition 
may comprise, for example, one or more silver halide solvents of the 
present invention; one or more conventional developing agents such as 
those enumerated above; an alkali, such as sodium hydroxide or potassium 
hydroxide; and a viscosity-imparting reagent, such as a high molecular 
weight polymer, e.g., sodium carboxymethyl cellulose or hydroxyethyl 
cellulose. 
In one such transfer process, the processing solution is applied in a 
uniformly thin layer between the superposed surfaces of a photoexposed 
photosensitive element and an image-receiving element, for example, by 
advancing the elements between a pair of pressure-applying rollers. The 
elements are maintained in superposed relation for a predetermined period, 
preferably for a duration of 15 to 120 seconds, during which exposed 
silver halide is reduced to silver and unreduced silver halide forms a 
water-soluble, complex salt which diffuses through the layer of solution 
to the image-receiving element, there to be reduced to an argental image. 
At the end of this period, the silver halide element is separated from the 
image-receiving element. Materials useful in such a transfer process are 
described in U.S. Pat. No. 2,543,181, issued in the name of Edwin H. Land 
on Feb. 27, 1951, and in numerous other patents. 
The photosensitive element may be any of those conventionally used in 
silver diffusion transfer processes and generally comprises a silver 
halide emulsion carried on a base, e.g., glass, paper or plastic film. The 
silver halide may be a silver chloride, iodide, bromide, iodobromide, 
chlorobromide, etc. The binder for the halide, though usually gelatin, may 
be a suitable polymer such as polyvinyl alcohol, polyvinyl pyrrolidone and 
their copolymers. 
The image-receiving element preferably includes certain materials, the 
presence of which, during the transfer process has a desirable effect on 
the amount and character of silver precipitated on the image-receiving 
element. Materials of this type are specifically described in U.S. Pats. 
Nos. 2,690,237 and 2,698,245, both issued in the name of Edwin H. Land on 
Dec. 28, 1954 and U.S. Pat. No. 3,671,241 of Edwin H. Land issued on June 
20, 1972. 
Separating of the silver halide element from the image-receiving element 
may be controlled so that the layer of processing composition is removed 
from the image-receiving element or the layer of processing composition is 
caused to remain in contact with the image-receiving element, e.g., to 
provide it with a protective coating. Techniques which enable such results 
to be accomplished as desired are described in U.S. Pat. No. 2,647,054 
issued to Edwin H. Land on July 28, 1953. In general, the processing 
reagents are selected so that traces remaining after the solidified 
processing layer has been separated from the silver image or which remain 
in said layer adhered as a protective coating on the silver image, as 
indicated above, are colorless or pale, so as not be appreciably affect 
the appearance of the image and to have little or no tendency to adversely 
react with the silver image. 
The silver halide solvents of the present invention also may be employed in 
diffusion transfer processes adapted to provide positive silver transfer 
images which may be viewed as positive transparencies without being 
separated from the developed negative silver image including such 
processes adapted for use in forming additive color projection positive 
images. Diffusion transfer processes of this type are described in U.S. 
Pat. No. 3,536,488 of Edwin H. Land and U.S. Pat. No. 3,615,428 of 
Lucretia J. Weed and in U.S. Pat. application Ser. No. 383,196 of Edwin H. 
Land filed July 27, 1973, now U.S. Pat. No. 3,894,871. The subject 
compounds also find utility as silver halide solvents in diffusion 
transfer processes utilizing the properties of the imagewise distribution 
of silver ions in the soluble silver complex made available in the 
undeveloped and partially developed areas of a silver halide emulsion to 
liberate a reagent, e.g., a dye in an imagewise fashion, as described in 
U.S. Pat. No. 3,719,489 of Ronald F. W. Cieciuch, Robert R. Luhowy, Frank 
A. Meneghini and Howard G. Rogers.

To illustrate the utility of the above-defined compounds as photographic 
silver halide solvents, a photosensitive silver halide emulsion on a 
support was exposed to a step wedge and processed by spreading a layer of 
processing composition approximately 1.2 mils. thick between the exposed 
emulsion and a superposed image-receiving element comprising a layer of 
regenerated cellulose containing colloidal palladium sulfide carried on a 
transparent support. The processing composition was prepared by adding a 
silver solvent of the present invention in a concentration of 5% by weight 
to the following formulation: 
______________________________________ 
Water 814.0 g. 
Potassium hydroxide 
(Aqueous 50% w/w solution) 
348.0 g. 
Hydroxyethyl cellulose 35.0 g. 
Zinc acetate 15.0 g 
Triethanolamine 5.6 g. 
Bis-N,N-methoxyethyl 
hydroxylamine 50.0 g. 
______________________________________ 
After an imbibition period of approximately 1 minute, the developed silver 
halide emulsion was separated from the image-receiving element, and the 
maximum and minimum transmission densities were measured for the positive 
image. 
The compounds added to the base formulation as silver halide solvents, and 
the density measurements for the positive image obtained with each of the 
compounds are set forth in the following table: 
TABLE 
______________________________________ 
Compound Density 
(Formula No.) Maximum Minimum 
______________________________________ 
(9) 2.32 0.26 
(10) 0.98 0.30 
(11) 1.70 0.09 
(12) 1.67 0.08 
______________________________________ 
Though other open-chain alkanes containing a sulfonyl group and a 
t-sulfonamido group are also useful as silver halide complexing agents, 
the compounds of the present invention have been found to give higher 
maximum densities than the corresponding compound with other heterocyclic 
groups in place of the 1-piperazinyl group. For example, the foregoing 
procedure was repeated using 
##STR10## 
The density measurements for the positive image obtained, i.e., D.sub.max 
/D.sub.min were 0.55/0.7, 0.08/0.02 and 0.49/0.06, respectively. 
It will be apparent that the relative proportions of the subject silver 
halide solvents and of the other ingredients of the processing 
compositions may be varied to suit the requirements of a given 
photographic system. Also, it is within the scope of this invention to 
modify the formulations set forth above by the substitution of alkalies, 
antifoggants and so forth other than those specifically mentioned. Where 
desirable, it is also contemplated to include in the processing 
compositions, other components as commonly used in the photographic art. 
Rather than being dissolved in the aqueous alkaline processing composition 
prior to application thereof to an exposed silver halide emulsion, it is 
also contemplated that the silver halide solvents of the present invention 
may be disposed prior to exposure in a layer or layers of the photographic 
film unit, e.g., by placing them behind a silver halide emulsion layer in 
the photosensitive element. In this instance, the processing composition 
containing the silver halide solvent is formed by application to the 
photosensitive element of an aqueous alkaline solution capable of 
solubilizing the silver halide solvent. In diffusion transfer processes, 
the subject silver halide solvents may be disposed in a layer or layers of 
the film unit but usually are contained in the processing composition. 
As noted above, in diffusion transfer film units the negative component 
comprising at least one photosensitive layer and the positive component 
comprising an image-receiving layer may be in separate sheet-like elements 
which are brought together during processing and thereafter either 
retained together as the final print or separated following image 
formation. 
Rather than the photosensitive layer and the image-receiving layer being in 
separate elements, they may be in the same element. In such a film unit, 
the image-receiving layer is coated on a support and the photosensitive 
layer is coated on the upper surface of the image-receiving layer. The 
liquid processing composition is applied between the combined 
negative-positive element and a second sheet-like element or spreading 
sheet which assists in spreading the liquid composition in a uniform layer 
adjacent the surface of the photosensitive layer. 
Still other film units are those where the negative and positive components 
together may comprise a unitary structure wherein the image-receiving 
layer carrying the transfer image is not separated from the developed 
photosensitive layer(s) after processing but both components are retained 
together as a permanent laminate. Such film units include those for 
providing positive silver transfer images which may be viewed as positive 
color transparencies, such as, those described in aforementioned U.S. Pat. 
No. 3,894,871. Film units of this type also include those adapted for 
forming a transfer image viewable by reflected rather than by transmitted 
light. In addition to the aforementioned photosensitive layer(s) and 
image-receiving layer, such film units include means for providing a 
reflecting layer between the image-receiving and photosensitive layer(s) 
in order to mask the developed photosensitive layer(s) and to provide a 
white background for viewing the transfer image. This reflecting layer may 
comprise a preformed layer of a reflecting agent included in the film unit 
or the reflecting agent may be provided subsequent to photoexposure, for 
example, by including the reflecting agent in the processing composition. 
In addition to these layers, the laminate usually includes dimensionally 
stable outer layers or supports, at least one of which is transparent so 
that the resulting transfer image may be viewed by reflection against the 
background provided by the light-reflecting layer. Integral 
negative-positive film units wherein the photosensitive and 
image-receiving layers are retained as a permanent laminate after 
processing are described, for example, in U.S. Pat. No. 3,415,644 issued 
Dec. 10, 1968 and U.S. Pat. No. 3,647,437 issued Mar. 7, 1972, both to 
Edwin H. Land and in U.S. Pat. No. 3,594,165 issued July 20, 1971 to 
Howard G. Rogers. 
It will be appreciated that in the formation of color transfer images, a 
dye image-providing material such as the compounds of aforementioned U.S. 
Pat. No. 3,719,489 may be associated with the photosensitive silver halide 
layer or layers of the negative component, and, usually, these and the 
other diffusion transfer film units described above are employed in 
conjunction with means, such as, a rupturable container containing the 
requisite processing composition and adapted upon application of pressure 
of applying its contents to develop the imagewise exposed film unit. 
As mentioned previously, the silver halide solvents of the present 
invention may be initially disposed in an alkali permeable, i.e., 
processing composition permeable layer or layers of the film unit, for 
example, in the negative component in a layer other than the 
photosensitive silver halide layer and usually in a layer behind the 
photosensitive layer(s), and/or in the image-receiving component in the 
image-receiving layer or in another layer thereof. Usually, however, the 
silver halide solvent is included in the aqueous alkaline processing 
composition. 
Since certain changes may be made in the above compositions and processes 
without departing from the scope of the invention herein involved, it is 
intended that all matter contained in the above description should be 
interpreted as illustrative and not in a limiting sense.