Patent GB-1417586-A (GB)
Title: Oxichromic compounds containing a reduced azomethine groups
IPC: G03C7/305
Filed: 1972-12-08
Abstract: 1417586 Oxichromic compounds containing a reduced azomethine group EASTMAN KODAK CO 8 Dec 1972 [10 Dec 1971 (3)] 56694/72 Heading C2C [Also in Divisions G2 and C4] The invention comprises compounds of the formula wherein D is an aromatic nucleus polysubstituted with OH groups, substituted OH groups hydrolysable by alkaline substances, amine groups or alkylamine groups and (OC) is an oxichromic moiety comprising a reduced azomethine linkage and is represented by the formula wherein (COUP) is a colour coupler radical which is bonded at its coupling position to the N atom, Ar is a substituted or unsubstituted arylene group, X is an amino or hydroxy group each of which may be substituted in such a manner that it hydrolyses in alkaline solution and R<SP>2</SP> is H or a substituent which prevents oxidation of the N atom with the formation of a double bond between "COUP" and "N" and which hydrolyses in alkaline solution. An embodiment of the invention comprises stabilized oxichromic compounds of the formulµ R<SP>2</SP> R<SP>2</SP> (PYC)N-Ar-OR<SP>1</SP> and (KMC)-N-Ar-OR<SP>1</SP> wherein (PYC) is a pyrazolone or pyrazolotriazole colour coupler moiety wherein the N atom in the formula is attached to (PYC) in the coupling (4) position and (KMC) is an openchain ketomethylene colour coupler moiety which couples at the C atom forming the methylene moiety and the N atom in the formula is attached to (KMC) in the coupling position, R<SP>1</SP> is a carbonyl-containing group which forms an ester group with the adjacent oxygen atom. Stabilized oxichromic developers of the formula wherein (OC) is an oxichromie moiety containing a stabilized reduced azomethine linkage, may be obtained by (1) condensing a silver halide developer having masking groups on said polysubstituted aromatic nucleus with a photographic colour coupler in order to link the developer to the coupler by an insulating linkage (this is a group which does not contribute a colour-producing group to the dye formed upon chromogenic oxidation but interrupts any system of conjugation or resonance extending from the azomethine group to the developing group), (2) reacting said condensed colour coupler with an aromatic primary amine to form an azomethine linkage at the coupling position of said colour coupler, (3) reducing the azomethine linkage to an amine linkage, (4) acylating said reduced azomethine linkage with at least a 3-molar excess of an acylating agent in a polar solvent under acidic or weakly basic conditions to form a N-aeyl group, and (5) hydrogenolysing the masking groups on said polysubstituted aromatic nucleus. The invention also comprises the preparation of stabilized reduced azomethines of the formula wherein "COUP" is a colour coupler bonded at the coupling position to the N atom, Ar is a C 6 -C 20  arylene group, X is OH, NH 2  or alkylamino and R<SP>2</SP> is -COR<SP>4</SP> wherein R<SP>4</SP> is alkyl or aryl each of which may be halogen substituted by acylating a compound of the formula by a method as defined in step (4) above. Other embodiments are described in which the process steps described above are conducted in a different order. The oxichromic compounds are useful in colour photography. A compound of the formula is obtained by condensing homogentisie acid with benzyl chloroformate in the presence of sodium dithionite. The corresponding acid chloride is obtained by treatment with SOCl 2  in DMF. The acid chloride of the formula is obtained in an analogous manner. A compound of the formula is obtained by condensing the acid chloride of compound 1A above with an amine of the formula in acetic acid containing potassium acetate. A compound of the formula and a compound of the formula wherein R is PhCH 2 OCO, are also obtained by condensing the said acid chloride with 1-phenyl- 3 - (m - aminobenzamido) - 5 - pyrazolone or an amine of the formula respectively. A compound of the formula is obtained by reduction with H 2  over Raneyniekel of the corresponding nitro compound which is itself obtained by acylation of a compound of the formula  with trifluoro-acetic anhydride in THF. A compound of the formula is obtained by condensing the acid chloride of Formula 8D with 1-phenyl-3-(m-aminobenzamido)-5-pyrazolone with the aid of N,N- dimethylaniline in dry acetone. The corresponding 4,4-dibromopyrazolone is obtained by treating the above compound with Br 2  in acetic acid.