Process for the production of 2-equivalent yellow couplers

A one-stage process for the production of a 2-equivalent acylacetamide yellow coupler, in which one hydrogen atom of the .alpha.-methylene group of the acyl acetamide coupler molecule is substituted by a group which is attached through an oxygen or nitrogen atom and which can be split off during chromogenic development with an oxidized color developer containing a primary aromatic amino group, which process is carried out by reacting PA1 A 4-equivalent acylacetamide yellow coupler with PA1 A compound containing an aromatic hydroxyl group or an --NH-- group in a heterocyclic ring PA1 In the presence of a halogen, or an agent which releases halogen, and PA1 A basic condensation agent PA1 In a substantially aprotic solvent.

This invention relates to a new method of producing 2-equivalent yellow 
couplers. 
In color photographic materials, open-chain keto methylene compounds, 
preferably acyl acetamides and, in particular, acyl acetanilides, are 
known to be yellow-forming color couplers (cf. the book by Mees and James 
entitled "The Theory of the Photographic Process", 3rd Edition 1966, pages 
388 to 389). 
The above-mentioned yellow color couplers may be used in the form of 
so-called 4-equivalent yellow couplers, in which case they require about 4 
equivalents of developed silver halide for the chromogenic development of 
1 mole of yellow image dye, or in the form of 2-equivalent yellow 
couplers, in which case they usually only require 2 equivalents of 
developed silver halide for the chromogenic development of 1 mole of 
yellow image dye. In contrast to the 4-equivalent couplers, the 
2-equivalent couplers contain in the coupling position a radical which can 
be split off during chromogenic development. 
The advantages of 2-equivalent color couplers in photography are known. 
Since they require less silver halide for development, the photographic 
layers used with them can be thinner, which not only saves silver but also 
increases photographic sharpness and resolving capacity. 
In practice, compounds of the type which, in the coupling position, contain 
a spittable group attached through oxygen or nitrogen to the carbon atom 
of the activated methylene group of the acyl acetamide yellow coupler 
molecule, have proved to be effective 2-equivalent yellow couplers. 
Hitherto, couplers of this kind have been produced from the corresponding 
4-equivalent couplers in a two-stage reaction, in the first stage of which 
the 4-equivalent coupler is reacted with a halogenating agent to form the 
.alpha.-halogen acyl acetamide coupler, and in the second stage the 
halogen atom from the coupling position of the .alpha.-halogen acyl 
acetamide yellow coupler is exchanged by a substitution reaction with the 
corresponding oxygen- or nitrogen-containing group. 
Offenlegungsschrift No. 2,263,587 and U.S. Pat. Nos. 2,728,658 and 
3,730,722 describe the production of .alpha.-bromacyl acetamide yellow 
couplers. Unfortunately, the brominated coupler compounds obtained by the 
known processes are very difficult to purify because they generally have 
low melting points and because the number and quantity of secondary 
products formed is relatively large, especially in cases where the 
reaction is carried out with N-bromosuccinimide. 
The method for producing an .alpha.-chloroacyl acetamide yellow coupler 
compound described in Offenlegungsschrift No. 2,263,587 and in U.S. Pat. 
No. 2,728,658 also has its disadvantages because the sulfuryl chloride 
used for the reaction and its byproducts produced on reaction, which 
by-products consist essentially of H.sub.2 SO.sub.4, SO.sub.2 and HCl, are 
difficult to remove and in addition relatively long times are required for 
the reaction and for working up. 
As already mentioned, the .alpha.-halogen compounds obtained by the methods 
mentioned above first have to be carefully purified and are then reacted 
in a second reaction to form the corresponding 2-equivalent couplers, as 
described in Offenlegungsschrift No. 2,329,587; in U.S. Pat. Nos. 
3,644,498 and 3,730,722 and British Pat. Nos. 1,331,179; 1,402,511 and 
1,351,142. According to these publications, phenols or heterocyclic 
compounds are reacted with the .alpha.-halogen couplers in an aprotic 
solvent, for example acetonitrile, in the presence of a basic condensation 
agent to form the 2-equivalent couplers which contain the spittable 
radical attached through oxygen or nitrogen in the coupling position. 
Generally, these methods are accompanied by undesirable side reactions, 
depending both upon the type of base used and upon the reaction 
temperature, higher reaction temperatures generally promoting the 
formation of byproducts. 
It is accordingly, an object of the present invention to provide a new 
method which enables the required yellow coupler compounds to be simply 
obtained by a one-stage process. 
According to the present invention a process is provided for the production 
of 2-equivalent acyl acetamide yellow coupler, which process comprises 
reacting a 4-equivalent acyl acetamide yellow coupler compound the 
.alpha.-methylene group of which is unsubstituted, with a compound 
containing the desired aromatic hydroxyl group or an --NH--group in a 
heterocyclic ring, and conducting the reaction in the presence of a 
halogen or an agent capable of liberating a halogen, as well as a basic 
condensation agent, the reaction being carried out in a substantially 
aprotic solvent. The required 2-equivalent yellow coupler is formed in a 
one-stage reaction accompanied by the elimination of hydrogen halide, the 
NH--or OH--group-containing compound supplying the splittable group. This 
splittable group splits off during chromogenic development, by reaction 
with the oxidation product of the primary aromatic amine used as color 
developer. 
By comparison with the two-stage reaction methods of known processes, the 
process according to the present invention gives purer products quickly in 
a one-stage process. 
The OH-- and NH--containing compounds reacted in accordance with the 
present invention are essentially of the type which contain aromatic 
hydroxyl groups, or are cyclic compounds in which the abovementioned 
NH-group forms part of a heterocyclic ring. 
The hydrogen atom in these OH-- or NH--groups to be reacted in accordance 
with the present invention is sufficiently acid in order, when catalyzed 
with bases in the presence of halogen or halogen-releasing agents, to 
effect the desired substitution on the .alpha.-methylene group of acyl 
acetamide compounds in a one-stage process. 
In general, the reaction according to the present invention is carried out 
by initially introducing the acyl acetamide compound and the OH-- or 
NH--group-containing compound together with a base into a substantially 
aprotic solvent and slowly adding an equimolar quantity of a halogen or of 
a halogen-releasing compound at a temperature of preferably from 
-20.degree. C. to 100.degree. C. and more especially at a temperature of 
from 0.degree. C. 20.degree. C. However, it is of course also possible, if 
desired, to change the order in which the acyl acetamide compound and base 
are added, whereby alternatively the base or the acylacetamide compound is 
added slowly and the halogen or the halogen-releasing compound is 
introduced initially together with the remaining reactants. 
Halogens suitable for use in the process according to the invention are, in 
particular, bromine or iodine. Examples of halogen or halogen-releasing 
agents suitable for use in accordance with the invention are Br.sub.2, 
I.sub.2 and mixtures of halides with oxidizing agents which are capable of 
releasing the halogens from the halides, such as KI and H.sub.2 O.sub.2 or 
KI and Br.sub.2. 
In cases where molecular halogen is used, a minimum equimolar quantity of 
the halogen, based on the quantity of acyl acetamide compound used, is 
employed for the reaction according to the invention. In cases where 
mixtures of halides and oxidizing agents which are capable of liberating 
the halogen are used, a minimum of an euimolar quantity of the oxidizing 
agent is required, based on the acyl acetamide compound used. The quantity 
of halide used may be smaller because in the presence of oxidizing agents 
the halide, even in small traces, initiates the reaction according to the 
invention and is reformed again. More oxidizing agent in the reaction 
mixture then liberates new halogen. 
Examples of aromatic hydroxyl-group-containing compounds are, in 
particular, phenols substituted by acyl, carbamyl or sulfamyl radicals in 
para-position to the phenolic hydroxyl group, the acyl groups optionally 
being derived from monoesters of carbonic acid and from aromatic or 
aliphatic sulfonic acids or carboxylic acids, such as 4-carbamyl phenol, 
4-(N-alkyl-aralkyl- or aryl-, mono- or disubstituted sulfamyl)-phenol, 
4-acetyl phenol or 4-(4-hydroxyphenyl sulfonyl -phenol and the like. 
Examples of --NH--group-containing heterocyclic compounds are saturated, 
partially saturated or aromatic heterocyclic compounds which may be 
5-membered or 6-membered and which may contain a --CO-, 
##STR1## 
adjacent the nitrogen atom. The heterocyclic groups of such compounds may 
be monocyclic or may contain fused rings. Preferred compounds are 
5-membered or 6-membered cyclic amides or acid imides of carboxylic acids 
and/or sulphonic acids, or 5-or 6-membered heterocyclic rings having at 
least one nitrogen atom and a 
##STR2## 
or --CO-- group adjacent the nitrogen atom and which may have a benzene 
ring fused thereto. 
Compounds particularly suitable for the reaction according to the invention 
are phenolic compounds and heterocyclic compounds of the type which are 
not themselves halogenated by the halogenating agent apart from at the 
point of attachment to the coupler molecule. Accordingly, preferred 
heterocyclic compounds are those of which the reactivity with halogenating 
agents is reduced to such an extent, by selecting suitable substituents 
such as --CO-- groups or electrophilic radicals, that halogenation of the 
nucleus is not possible. 
Examples of phenols or --NH--group-containing heterocyclic compounds 
suitable for use in accordance with the invention are described in French 
Patent Specification No. 1,411,384; in Offenlegungsschrift Nos. 2,433,812; 
2,329,587; 2,363,675; 2,441,779 and 2,442,703; U.S. Pat. No. 3,730,722 and 
British Pat. Nos. 1,331,179; 1,386,151 and 1,351,424; 1,402,511. 
Some examples of compounds suitable as splittable groups are given in Table 
I below: 
##STR3## 
According to the present invention, substitution on the .alpha.-C-atom of 
the acyl acetamide compounds by the compounds containing phenolic 
OH-groups or by the acid-NH-containing heterocycles, is highly selective 
so that very few byproducts are formed, high yields are obtained and the 
reaction time can be greatly reduced by comparison with conventional 
methods. The isolated reaction products have a high degree of purity. 
Accordingly, the invention provides a method of producing 
.alpha.-substituted-.alpha.-acyl acetamides by reacting an .alpha.-acyl 
acetamide, corresponding in particular to the following formula: 
##STR4## 
in which R.sub.1, R.sub.2 and R.sub.3 represent groups which are normally 
used for acyl acetamide yellow couplers, with an --NH-- or 
OH-group-containing compound in the presence of a halogen or 
halogen-releasing agent and a basic condensation agent in a substantially 
aprotic solvent. 
Examples of R.sub.2, R.sub.2 and R.sub.3 are groups which are generally 
known in acyl acetamide yellow couplers, such as for example color 
couplers of the type described in U.S. Pat. Nos. 3,056,675; 3,369,899, 
3,393,040; 3,393,041; 3,409,439; 3,619,190; 3,645,742; 3,660,095 and 
3,725,072; in Belgian Patent Specification No. 717,841 and in 
Offenlegungsschrift Nos. 2,002,378; 2,114,576; 2,114,577 and 2,114,578. 
In particular R.sub.1, R.sub.2 R.sub.3 may represent one of the following 
groups: 
R.sub.1 a straight-chain or branched alkyl group having in particular 1 to 
18 carbon atoms, preferably a pivaloyl group, or an optionally substituted 
phenyl group which may contain on or more subsitutuents, such as alkyl, 
alkoxy, aralkyl, aryl, aroxy, sulfo, carboxy, halogen, acyl, acyloxy, 
acylamino, amino, carbamyl or sulfamyl which may in turn be substituted by 
alkyl, aryl, aralkyl or heterocyclic radicals; R.sub.2 hydrogen or an 
alkyl group having 1 to 5 carbon atoms, for example methyl; and 
R.sub.3 --an alkyl group having 1 to 18 carbon atoms, a heterocyclic group, 
such as 2 -thiazolyl or preferably an aryl group, such as a phenyl group 
which may be substituted by one or more of the substituents mentioned in 
reference to R.sub.1. 
Where one of the radicals R.sub.1 and R.sub.3 represents or contains alkyl, 
the radicals in question are alkyl radicals having 1 to 18 carbon atoms. 
Where one of the radicals R.sub.1 and R.sub.3 represents or contains acyl, 
the radicals in question are acyl radicals which may be derived from 
aliphatic or aromatic monoesters of carbonic acid or from aliphatic or 
aromatic carboxylic or sulfonic acids. 
The 2-equivalent yellow couplers produced in accordance with the invention 
are, of course, preferably derived from known color couplers which have 
excellent properties in regard to the light absorption characteristics and 
stability levels of the dyes produced from them during photographic color 
development. 
It is particularly preferred to use pivaloyl acetanolides and benozyl 
acetanilides with 1 to 3 substituents of the kind defined above in the 
anilide moiety, preferably in the 2-, 4- and 5-position, for the reaction 
according to the present invention. 
The reaction according to the invention is carried out while the reactants 
are stirred in a suitable aprotic solvent at temperature of from -20 to 
100.degree. C. and preferably at a temperature below room temperature. 
Reaction temperatures of from -5.degree. C. to +20.degree. C. have proved 
to be particularly suitable, depending upon the bases and couplers and the 
OH- or NH-containing compounds used. 
The solvents used for the process according to the invention are 
substantially aprotic solvents such as toluene, benzene, ether and the 
like, or preferably polar aprotic solvents such as hexamethyl phosphoric 
acid triamide, dimethyl formamide, acetonitrile, acetone, ethyl acetate or 
mixtures thereof. 
The quantity of solvent used is not critical and is governed by the 
solubility of the reactants in the solvent. 
The OH- or NH-containing compound is generally used in at least equimolar 
quantities based on the acyl acetamide compounds. In general, an addition 
of from 1 to 3 moles of the OH-group- or NH-group-containing compound, 
preferably from 1.3 to 1.8 moles, based on 1 mole of the acyl acetamide 
compound used, has proved to be suitable for the reaction according to the 
invention. 
Suitable basic condensation gents are substantially anydrous alkali metal 
hydroxides or alkali metal alcoholates, such as solid powdered sodium 
hydroxide or sodium methylate or potassium-tert-butylate. It is also 
possible to use alkali metal hydrides, such as sodium hydride, or tertiary 
manines, in particular aliphatic amines such as triethyl amine and 
N,N,N',N'-tetramethyl guanidine, as basic condensation agents. 
Such bases are generally used in more than two times the molar quantity, 
relative to the acyl acetamide compound. Quantities of from 2 to 6 moles, 
preferably from 3 to 4 moles, of base per mole of acyl acetamide compound 
have proved to be suitable. 
The process according to the invention is described by way of example in 
the following: 
1 mole of an acyl acetamide coupler and 1.5 moles of a quinazolineone was 
dissolved with 3 moles of sodium methylate in 100 ml of hexamethyl 
phosphoric acid triamide. The solution is then cooled to 0.degree. C. 
followed by the gradual dropwise addition, with stirring, of 1 mole o 
bromine. 
On completion of the addition, the reaction mixture is stirred for another 
30 minutes without further cooling. 
The reaction mixture is then poured onto a mixture of ice/HCl and the 
resulting deposit is filtered under suction and washed. The reaction 
product is then taken up in ethyl acetate, neutralized with sodium 
hydrogen carbonate and dried with sodium sulfate. After the drying agent 
has been filtered off under suction and the ethyl acetate has been removed 
in vacuo, the product obtained is recrystallized from a solvent such as 
toluene or methanol. 
The yellow coupler produced in accordance with the invention may be 
isolated from the reaction medium not only in the manner described above, 
but also in any other conventional manner as by pouring the reaction 
mixture into water, acetic acid or dilute sulfuric acid and purifying the 
reaction product obtained in the usual way by recrystallisation. 
Examples of 2-equivalent coupler compounds produced in accordance with the 
invention are given in Table II below: 
##STR5##

The process according to the invention is further illustrated by the 
following few special Examples: 
Production of Compound 1: 
a. 6.16 g of 2-methoxy-5-(2',4'-di-t-amylphenoxy)butyramido-p-methoxy 
benzoyl acetanilide, 2.0 g of quinazolinone and 1.62 g of sodium methylate 
were dissolved in 100 ml of hexamethyl phosphoric acid triamide and the 
resulting solution was cooled to 0.degree. C. 1.6 g of bromine were then 
slowly added dropwise to this mixture at 0.degree. C. The mixture was then 
stirred for 30 minutes without further cooling. 
The reaction mixture was worked up in known manner. Recrystallization from 
toluene left 6.3 g of compound No. 1. Yield: 83%: mp 135 - 137.degree. C. 
b. The same reaction was carried out in acetone instead of in hexamethyl 
phosphoric acid traimide. Working up in the same way as in a. produced 6.0 
g of compound No. 1 in a yield 78.5%. 
c. The same reaction was carried out in toluene instead of in hexamethyl 
phosphoric acid triamide. Working up in the same way as in a. produced 6.1 
g of compound No. 1 in a yield 80.0%. 
d. The same reaction was carried out in triethyl amine instead o in 
hexamethyl phosphoric acid triamide and with 1.2 g of NaOH instead of 
sodium methylate. Working up in the usual way gave 5.7 g of compound No. 1 
in a yield 75%. 
Production of compound 6: 
18.5 g of 2-methoxy-5-(2', 4'-di-t-amylphenoxy)butyramido-p-methoxy benzoyl 
acetanilide and 15 g of 4-hydroxy-4'benzyloxy phenyl ssslfonyl benzene 
were dissolved with 4.5 g of sodium methylate in 200 ml of hexamethyl 
phosphoric acid triamide and the resulting solution was cooled to 
0.degree. C. A solution of 7.6 g of iodine in 50 ml of hexamethyl 
phosphoric acid triamide was then added dropwise with stirring to this 
reaction mixture. On completion of the addition, the reaction temperature 
was increased to room temperature, after which the reaction mixture was 
worked up in the usual way. The crude product was purified by dissolution 
in and crystallization from acetonitrile. Yield: 22.6 g of compound No. 6 
(79%), mp 188-190.degree. C. 
Production of compound 9: 
27.6 g of 2-hexadecyloxy-5-methylaminosulfonyl pivaloyl acetanilide, 13.5 g 
of 5 chloroquinazoline and 6 g of powdered NaOH were dissolved in 300 cc 
of acetonitrile. A solution of 8.0 g of bromine in 30 cc of acetonitrile 
was added dropwise to the resulting solution at +5.degree. C. On 
completion of the addition, the reaction mixture was heated to room 
temperature. It was then filtered and the filtrate was concentrated by 
evaporation and subsequently worked up in the usual way. 
The crude product obtained was dissolved in and crystallized from methanol. 
Yield: 29.7 g of compound No. 9 or 81%. 
Production of compound 10: 
22.4 g of 2-hexadecyloxy-5-dimethyl aminosulfonyl pivaloyl acetanilide, 9.0 
g of benztriazinone and 7.5 g of sodium methylate were dissolved in 250 ml 
of hexamethyl phosphoric acid triamide. A solution of 6.4 g of bromine in 
50 ml of dimethyl formamide was added dropwise to the resulting solution 
at 0.degree. C. On completion of the addition, the reaction mixture was 
heated to room temperature and subsequently worked up in the usual way. 
The crude product was twice dissolved in and allowed to crystallize from 
alcohol. Yield: 23 g of compound No. 10 (83%), mp 100-102.degree. C.