Patent GB-807460-A (GB)
Title: Merocyanine dyes and photographic silver halide emulsions containing them
IPC: C09B23/10
Filed: 1956-10-11
Abstract: Rhodanines having the general formula <FORM:0807460/IV (b)/1> wherein R4 is a pyridyl or quinolyl group, are prepared by cyclizing a carboxymethyl-dithiocarbamate of the formula R4NH-CS-SCH2COOH. Examples are given of the cyclization in acetic anhydride or by heating of dithiocarbamates of the above formula wherein R4 is 2-pyridyl, 6-methyl-2-pyridyl, 3-quinolyl, 3-pyridyl and 4-pyridyl. If an alkyl orthoacetate or orthopropionate is present during the cyclization, the group R5O-CR6=(wherein R5 is alkyl and R6 is methyl or ethyl) is substituted in the 5-position.  Thus, the N-(2-pyridyl) or N-(6-methyl-2-pyridyl) - carboxymethyl - dithiocarbamates are cyclized in acetic anhydride in the presence of ethyl orthoacetate to give 5-11-ethoxyethylidene - 3 - (2 - pyridyl) - rhodamine and 5 - 11-ethoxyethylidene - 3 - (6 - methyl - 2 - pyridyl) - rhodanine respectively.  Carboxymethyl-dithiocarbamates of the formula R4-NH-CS-SCH2COOH, wherein R4 is a pyridyl or quinolyl group, are obtained by condensing an alkali metal salt of chloroacetic acid with a compound R4NHCS2M, where M is alkali metal, ammonium or organic amine.  Examples are given of condensing sodium chloracetate with triethylammonium N-(2-pyridyl)-dithiocarbamate, or the corresponding N - (6 - methyl - 2 - pyridyl), N - (3 - quinolyl), N-(3-pyridyl) or N-(4-pyridyl) derivatives to give carboxymethyl N-(2-pyridyl)-dithiocarbamate, carboxymethyl N - (6 - methyl - 2 - pyridyl) - dithiocarbamate, carboxymethyl N - (3 - quinolyl) - dithiocarbamate, carboxymethyl N - (3 - pyridyl) - dithiocarbamate and carboxymethyl N - (4 - pyridyl) - dithiocarbamate respectively. Specifications 517,769, 544,647, [both in Group IV], 742,206, and 800,244 are referred to.ALSO:Merocyanine dyes are described having the general formula: <FORM:0807460/IV (c)/1> wherein R4 is a pyridyl or quinolyl group, R is an alkyl, allyl or substituted alkyl group, n is 0 or 1, d is 0, 1 or 2, Z completes a 5- or 6-membered heterocyclic nucleus and R1 is hydrogen, or when d is 1 it may be methyl, ethyl, methoxy, or ethoxy.  R4 may be 2-pyridyl, 3-pyridyl, 4-pyridyl, 6-methyl-2-pyridyl, 4 - methyl - 2 - pyridyl or 3 - quinolyl.  R may be methyl, ethyl, propyl, butyl, amyl, carboxymethyl, b -carboxyethyl, carbomethoxymethyl, carbethoxymethyl, b -hydroxyethyl, b -methoxyethyl or benzyl.  The dyes wherein d=0 are prepared by condensing a cyclammonium quaternary salt having a reactive alkylmercapto or arylmercapto group with the appropriate rhodanine derivative.  Those wherein d is 1 or 2 and R1 is hydrogen are prepared by condensing a quaternary salt of the formula: <FORM:0807460/IV (c)/2> wherein q is 1 or 2, X is an anion, R2 is an acyl group and R3 is an aryl group, with the rhodanine derivative, or by condensing a cyclammonium quaternary salt having a reactive a  - or g -methyl group with a rhodanine derivative of the general formula: <FORM:0807460/IV (c)/3> where p is 1 or 3 and the other symbols are as defined above.  The dyes wherein d is 1 and R4 is alkyl are prepared by condensing a rhodamine derivative of the formula: <FORM:0807460/IV (c)/4> where R5 and R6 are methyl or ethyl groups, with a cyclammonium quaternary compound having a reactive methyl group and those wherein d is 1 and R1 is alkoxy, by condensing a compound of formula (VII) wherein R6 is methyl with a cyclammonium quaternary compound having a reactive alkylmercapto or arylmercapto group.  In the examples, the preparations of dyes of Formula (I) are described wherein Z completes a benzoxazole, naphthoxazole, benzthiazole, naphthathiazole, thiazoline or 2-quinoline nucleus. Specifications 517,769, 544,647, [both in Group IV], 742,206 and 800,244 are referred to.