Azo compounds useful in a photographic dye diffusion transfer process

Novel azo compounds and their preparation are provided. These compounds have the general formula ##STR1## wherein X is N or CR.sub.4 where R.sub.4 is a hydrogen atom or an optionally substituted alkyl or aryl group, Y is S.sup..sym., N.sup..sym. R.sub.5, O.sup..sym. or N where R.sub.5 is an optionally substituted alkyl or aryl group, R.sub.1 is an optionally substituted alkyl or aryl group, R.sub.1 is a substituted aromatic or heterocyclic group containing a ballasting group, R.sub.2 and R.sub.3 are each hydrogen or alkyl groups having 1 to 4 carbon atoms, or R.sub.2 and R.sub.3 together with the nitrogen atom complete a heterocyclic ring, or one of R.sub.2 or R.sub.3 can be hydrogen and the other of R.sub.2 or R.sub.3 can be aryl. There may be further substitution in either of the benz rings and these rings may be benzannelated. These azo compounds are useful in the photographic field especially in the photographic dye diffusion transfer process for the production of photographic images.

This invention relates to novel azo compounds and their preparation. 
According to the present invention there are provided azo compounds of the 
general formula 
##STR2## 
where X is N or CR.sub.4 where R.sub.4 is a hydrogen atom or an optionally 
substituted alkyl or aryl group, Y is S.sup..sym., N.sup..sym. R.sub.5, 
O.sup..sym. or N where R.sub.5 is a substituted aromatic or heterocyclic 
group containing a ballasting group, R.sub.2 and R.sub.3 are each hydrogen 
atoms or alkyl groups having 1 to 4 carbon atoms, or R.sub.2 and R.sub.3 
together with the nitrogen atom complete a heterocyclic ring, or one of 
R.sub.2 or R.sub.3 can be hydrogen and the other of R.sub.2 or R.sub.3 can 
be aryl, and T.sub.1 and T.sub.2 represent hydrogen, substituents or form 
a benzannelated ring. 
Examples of such substituents are alkyl of 1 to 4 carbon atoms and 
particularly methyl, amino groups and halogen atoms (fluorine, chlorine, 
bromine). 
Preferably the group R.sub.1 comprises a heterocyclic or preferably an 
aromatic ring containing a hydroxy or dialkylamino group with each alkyl 
of 1 to 18 carbon atoms ortho or para to the azo link as well as a 
ballasting group. 
Preferably R.sub.4 is hydrogen, alkyl of 1 to 4 carbon atoms, phenyl or 
phenyl substituted by alkyl of 1 to 4 carbon atoms, halogen, hydroxy or 
carboxyl. 
Preferably R.sub.5 has the meaning of R.sub.4 except hydrogen. R.sub.2 and 
R.sub.3 are each hydrogen or alkyl of 1 to 4 carbon atoms, or R.sub.2 and 
R.sub.3 together with the nitrogen atom complete a 5- or 6-membered 
heterocyclic ring, or one of R.sub.2 or R.sub.3 can be hydrogen and the 
other can be phenyl, and T.sub.1 and T.sub.2 represent hydrogen, alkyl of 
1 to 4 carbon atoms, especially methyl, or they constitute an annelated 
benzene ring. 
Preferred azo compounds of formula (1) are azo compounds of the general 
formula 
##STR3## 
where X is N or CR.sub.4 where R.sub.4 is a hydrogen atom or an optionally 
substituted alkyl or aryl group, Y is S.sup..sym., N.sup..sym. R.sub.5, 
O.sup..sym. or N where R.sub.5 is an optionally substituted alkyl or aryl 
group, R.sub.1 is a substituted aromatic or heterocyclic group containing 
a ballasting group, R.sub.2 and R.sub.3 are each hydrogen atoms or alkyl 
groups having 1 to 4 carbon atoms. 
It is to be understood that there may be further substitution in either of 
the benz rings in the compound of formula (2) and in particular these 
rings may be benzannelated or have an alkyl substituent in particular 
methyl. 
A particularly useful group R.sub.1 in formulae (1) or (2) is the group of 
the formula 
##STR4## 
where R.sub.6 is either an alkyl group containing at least 10 carbon atoms 
or a group containing such an alkyl group or is an aryl ballasting group. 
An example of an aryl ballasting group is the group of formula 
##STR5## 
Another useful group R.sub.1 is the group of the formula 
##STR6## 
wherein R.sub.7 and R.sub.8 are both alkyl groups having together at least 
12 carbon atoms. 
Compounds of formula (1) may be prepared by diazotising a compound of 
formula 
##STR7## 
to yield the diazo compound of formula 
##STR8## 
and then coupling the diazo compound of formula (7) with a coupler of the 
formula R.sub.1.sup..crclbar. A.sup..sym. in alkaline conditions where X, 
Y, R.sub.1, R.sub.2, R.sub.3, T.sub.1 and T.sub.2 have the meanings 
assigned to them above, Z.sup..crclbar. is an anion and A.sup..sym. is a 
cation. 
The general formula (6) covers several well known classes of dyes; 
compounds of formula (1) wherein X is N and Y is N.sup..sym. R.sub.5 are 
azo-phenazine compounds. 
Particularly useful azo-phenazine compounds of formula (1) are 
azo-phenazines of formula 
##STR9## 
where R.sub.1 has the meaning assigned to it above and T.sub.1 and T.sub.2 
are hydrogen atoms or substituents and in particular methyl groups and 
T.sub.3 is a phenyl or alkyl group, e.g. of 1 to 4 carbon atoms, and 
Z.sup..sym. is an anion. Sometimes the dyes exist in the zwitterionic 
form, especially if R.sub.1 is the group of formula (3). Preferably 
T.sub.3 is a phenyl group. Preferably Z is a fluoroborate ion. When the 
azo link is cleaved a diffusible magenta phenazine dye is released. 
An example of such an azo-phenazine compound is the compound of formula 
##STR10## 
Another example of such an azo-phenazine compound is the compound of 
formula 
##STR11## 
Compounds of formula (1) wherein X is N and Y is O.sup..sym. are 
azo-oxazine compounds. 
Particularly useful azo-oxazine compounds of formula (1) are azo-oxazine 
compounds of formula 
##STR12## 
where R.sub.1 and Z have the meanings assigned to them above. 
When the azo linkage is cleaved a diffusible blue or bluish oxazine dye is 
released. 
An example of such an azo-oxazine compound is the compound of formula 
##STR13## 
where B is the group: 
##STR14## 
Compounds of formula (1) wherein X is N and Y is S.sup..sym. are 
azo-thiazine compounds of formula 
##STR15## 
where T.sub.1, T.sub.2, Z.sup..crclbar., R.sub.1, R.sub.2 and R.sub.3 have 
the meanings assigned to them above. 
When the azo-linkage is cleaved a diffusible blue to magenta thiazine dye 
is released. 
Preferably R.sub.2, R.sub.3 and T.sub.2 are each methyl groups. 
An example of such an azo-thiazine compound is the compound of formula 
##STR16## 
where B has the meaning assigned to it above. 
Compounds of formula (1) wherein X is CR.sub.4 and Y is N.sup..sym. R.sub.5 
are azo-acridine compounds of formula 
##STR17## 
where R.sub.1, R.sub.4, R.sub.5 and Z have the meanings assigned to them 
above. 
When the azo linkage is cleaved a yellow diffusible acridine dye is 
released. 
Preferably R.sub.4 is hydrogen and R.sub.5 is methyl. 
An example of such an azo-acridine compound is the compound of formula 
##STR18## 
where B and Z have the meanings assigned to them above. 
Other useful azo-acridine compounds of formula (1), when X is CR.sub.4 and 
Y is N, are azo-acridine compounds of formula 
##STR19## 
where R.sub.1, T.sub.1, T.sub.2, R.sub.2, R.sub.3 and R.sub.4 have the 
meanings assigned to them above. 
When the azo linkage is cleaved a diffusible yellow acridine dye is 
released. 
Preferably T.sub.1 and T.sub.2 are each methyl and R.sub.2, R.sub.3 and 
R.sub.4 are hydrogen. 
An example of such an azo-acridine compound is the compound of formula 
##STR20## 
where B has the meaning assigned to it above. 
Compounds of formula (1) wherein X is CR.sub.4 and Y is O.sup..sym. are 
azo-pyrylium compounds (or azo-oxanthracene compounds). 
Particularly suitable azo-pyrylium compounds of formula (1) are 
azo-pyrylium compounds of formula 
##STR21## 
where R.sub.1, R.sub.2, Z.sup..crclbar. and R.sub.3 have the meanings 
assigned to them above and R.sub.8 is a substituent or hydrogen. Examples 
of substituents which R.sub.8 can represent are --COOH, alkyl, e.g. of 1 
to 4 carbon atoms, and halogen, e.g. chlorine or bromine. 
Preferably R.sub.8 is --COOH and such compounds are in fact derivatives of 
rhodamine. 
Preferably R.sub.2 and R.sub.3 are hydrogen. 
When the azo linkage is cleaved a yellow-magenta diffusible azo-pyrylium 
dye is released. 
An example of such an azo-pyrylium dye which is an azo-rhodamine is the 
compound of formula 
##STR22## 
where B is Z.sup..crclbar. have the meanings assigned to them above. 
The azo compounds of formulae (1) and (2) are of use in a photographic 
process wherein photographic material which comprises a certain class of 
azo compounds which includes the azo compounds of formulae (1) and (2) is 
treated with a reducing agent which breaks the azo link and a dye is 
liberated which is mordanted in a receiving layer, so forming a dye image. 
Thus the compounds of formula (1) and (2) comprise a diffusible dye moiety 
linked by an azo linkage to a group which comprises a ballasting group. 
The object of the ballasting group is to render the azo compounds 
substantive to the layer in the photographic material in which they are 
coated.

The following Examples will serve to illustrate the invention. 
EXAMPLE 1 
1-hydroxy-4[3-(7-amino-5-phenyl-5,10-phenazonia)azo]-2-naphth-4-(2-[2,4-dit 
ertamylphenoxy)n-butylamide]tetrafluoroborate (or zwitterion) 
Phenosafranine (0.33 g) was dissolved by heating in 2-methoxyethanol (20 
ml), cooled to 40.degree. C. and 42% tetrafluoroboric acid (1.6 ml) added 
and the mixture cooled to 5.degree. C. A solution of sodium nitrite (0.1 
g) in water was added and the mixture stirred at 5.degree. C. for 1 hour. 
A solution of 1-hydroxy-2-naphth-4-(2-ditertamylphenoxy)-n-butylamide 
(0.33 g) in 2-methoxyethanol (7 ml) was added followed by dropwise 
addition of sodium acetate (1.25 g) in a solution of 2-methoxy ethanol 
(8.5 ml) and water (1.5 ml). The resultant dyestuff separated from 
solution. The mixture was poured into water (200 ml) and the solid 
collected. It was recrystallised from 2-methoxy ethanol yielding almost 
black needles, m.p. 252.degree. C. Analysis indicated that the dyestuff 
was without anion. It is described by formula (10). 
EXAMPLE 2 
4-[3-(7-amino-5-phenyl-5,10-phenazonia)azo] -N-n-octadecyl-N-methylaniline 
tetrafluoroborate 
Phenosafranine (0.33 g) was diazotised as described above, then a solution 
of N-n-octadecyl-N-methylaniline (0.2 g) in 2-methoxy ethanol (7.0 ml) 
added at 5.degree. C. Sodium acetate (2 g approx) in aqueous 2-methoxy 
ethanol was added dropwise. The mixture was poured into water (200 ml) and 
the solid collected, which was washed and dried, m.p. 
190.degree.-2.degree. C. Thin layer chromatography (SiO.sub.2 gel/glass/5 
CHCl.sub.3 /1 CH.sub.3 OH) showed presence of a single blue-black spot. 
The dyestuff is described by formula (9). 
EXAMPLE 3 
1-hydroxy-4-[3-(7-amino-5-phenyl-5,10-phenazonia)azo]-2-naphth[3-(2,4-diter 
tamylphenoxy) n-propylamide]zwitterion 
This dye was prepared as described for Example 1 except the coupler used 
was 1-hydroxy-2-naphth-[3-(2,4-ditertamylphenoxy) n-propylamide]. 
The dye separated as blue-black needles from 2-methoxy ethanol, m.p. 
275.degree. C. Analysis indicated that it was without anion. 
EXAMPLE 4 
1-hydroxy-4-[3-(7-amino-5-phenyl-5,10-phenazonia)azo]-2-naphth-[5-(2,4-dite 
rtamylphenoxy acetylamino)-2-chloroanilide]zwitterion 
This dye was prepared as described for Example 1 except that the coupler 
used was 1-hydroxy-2-naphth-[5-(2,4-ditertamylphenoxy 
acetylamino)-2-chloroanilide]. It is recrystallised from 2-methoxy ethanol 
and has a m.p. of 275.degree. C. 
EXAMPLE 5 
1-hydroxy-4-[3-(6-amino-10-methyl-acridinio)azo]-2-naphth-[4-(2,4-ditertamy 
lphenoxy)n-butylamide]tetrafluoroborate or zwitterion 
This dye was prepared by the method described in Example 1, except the 
phenosafranine (0.33 g) was replaced by acriflavine (0.28 g). Purple black 
crystals, m.p. 213.degree. C. Thin layer chromatography showed a purple 
spot. The dyestuff corresponds to formula (16). 
EXAMPLE 6 
1-hydroxy-4-[3-(6-amino-2,7-dimethyl-acridinyl)azo]-2-naphth-[4-(2,4-ditert 
amylphenoxy)n-butylamide] 
The dye was prepared according to the method of Example 1, except that the 
phenosafranine (0.33 g) was replaced by Acridine yellow (0.28 g). Purple 
black crystals, m.p. 165.degree. C. Thin layer chromatography showed a 
single purple spot. The dyestuff corresponds to formula (18). 
EXAMPLE 7 
1-hydroxy-4-[3-(7-dimethylamino-2-methyl-phenothiazonia)azo]-2-naphth-[4-(2 
,4-ditertamylphenoxy)n-butylamide]-chloride or zwitterion 
The dye was prepared according to the method described in Example 1, except 
that the phenosafranine (0.33 g) was replaced by Toluidine blue (0.3 g). 
The product is isolated as blue-black crystals, m.p. 90.degree.-5.degree. 
C. The dyestuff is described by formula (14). 
EXAMPLE 8 
1-hydroxy-4-[3-(7-amino-8,9-benz-phenoxazonia)azo]-2-naphth-[4-(2,4-diterta 
mylphenoxy)n-butylamide]tetrafluoroborate or zwitterion 
This oxazine dye was prepared by the method described in Example 1, except 
that phenosafranine (0.33 g) was replaced by Cresyl violet acetate (0.35 
g). The product was blue-black crystals, m.p. 230.degree.-5.degree. C. 
Thin layer chromatography (SiO.sub.2 gel/glass/5 CHCl.sub.3 /1 (CH.sub.3 
OH) showed the presence of a single blue spot. The dyestuff is described 
by formula (12). 
EXAMPLE 9 
1-hydroxy-4[3-(7-amino-9-[2-hydroxycarbonylphenyl]-10-oxonia 
anthracenyl)azo]-2-naphth-[4-(2,4-ditertamylphenoxy)n-butylamide]tetrafluo 
roborate or zwitterion 
This dye was made by using the method described in Example 1, except 
phenosafranine (0.33 g) was replaced by Rhodamine 110 (0.36 g). The 
compound is a red-brown solid, laving a melting point of 135.degree. C. 
and corresponding to formula (20).