Patent GB-501803-A (GB)
Title: Manufacture of methine dyestuffs
IPC: C09B23/12
Filed: 1937-08-30
Abstract: 501,803. Dyes. I. G. FARBENINDUSTRIE AKT.-GES. Aug. 30, 1937, No. 23690. Convention date, Sept. 8, 1936. [Class 2 (iii)] [Also in Group XX] Cyanine and styryl dyes are made by condensing a quaternary salt of a 2-alkyltetrahydrobenzthiazole or selenazole with itself or with an N-alkylated nitrogenous heterocyclic base or a quaternary salt thereof containing linked to the hetero nucleus in the alpha- or gammaposition to a hetero nitrogen atom either directly or through a methine or polymethine chain a reactive atom or group of the kinds hereinafter referred to which is eliminated in the formation of the methine chain of the dyestuff or with another nitrogenous base containing a reactive aldehyde group or other reactive group capable of reacting as an aldehyde group in the presence of a condensing agent. The reactive atoms or groups referred to are hydrogen, aldehyde, anilino and the bivalent groups, mentioned in Specification 423,792. 2: 2<1>-Cyanines are made by condensing with a derivative of a heterocyclic nitrogen base having a reactive bivalent group in the alphaposition as described in Specification 423,792 or with quaternary salts of heterocyclic nitrogen bases substituted by iodine in alpha-position to the nitrogen. 2: 4<1>-Cyanines are made by condensing with quaternary ammonium salts of the quinoline series, using an alkaline condensing agent. Carbocyanines are made by condensing with an orthoformic ester or orthofatty carboxylic esters, diphenylformamidine, an ester of an arylated thioimidic acid (Specification 412,309), a substituted acid amide (Specification 439,359), or #-aldehydes of N- alkylated heterocyclic nitrogen bases. Using orthoformic ester in presence of acetic anhydride a tricyclic dyestuff of the neocyanine type is obtained. Pentacarbocyanines are made by condensing with #-ethoxyacrolein acetal or alpha-phenylamino-#-phenyliminopropene hydrohalide (Specification 434,234). Heptacarbocyanines are made by condensing with alphaphenylamino-alpha-phenylimino-alpha : gamma-pentadiene hydrohalide (Specification 438,449) or with dinitrophenylpyridinium halide. Styryl dyes are made by condensing with a dialkylaminobenzaldehyde. In examples (1) and (2) 2- methyltetrahydrobenzthiazole ethyl iodide and 2-methyltetrahydro-benzselenazole methyl iodide are condensed with ethyl ortho-formate and acetic anhydride to give neocyanines, (3), (4) 2-methyltetrahydrobenzthiazole methyl iodide. is condensed with ethyl orthoacetate or ethyl orthopropionate in pyridine, (5), (8), (10), (11), (14), (16), (17) 2-methyltetrahydrobenzthiazole ethyl iodide is condensed with N-methyl-2-methylenebenzthiazole-#-aldehyde, in acetic anhydride, with #-ethoxyacroleinacetal in pyridine, with alpha-N-methylphenylimido-#-N-methylphenylimido-alpha : gamma-pentadiene hydrobromide in pyridine, with N-methylphenylimidohexamethine-2-benzthiazole ethyliodide in diethylamine, with N-ethyl-7-methoxythioquinoline ethyl iodide in alcohol, with ptoluquinoline ethyl iodide in alcoholic sodium ethylate and with p-dimethylaminobenzaldehyde, (6), (7), (12) 2-ethyltetrahydrobenzthiazole methyl iodide is condensed with N- ethyl - 2 - methylenebenzthiazole - w - aldehyde in acetic anhydride, with 1:3:3-trimethyl-5- methoxyindolenine- 2 - methylene - # - aldehyde in acetic anhydride and with N-methyl-alphathiobenzthiazolone methyl iodide in alcohol, (9), (15), 2-methyltetrahydrobenzselenazolemethyl iodide is condensed with #-phenyliminotetramethine - 5 - methoxybenzselenazole ethyl iodide or with N-ethyl-p-tolu-alpha-thioquinolone ethyl iodide, (13) 2-methyltetrahydrobenzthiazole dimethyl sulphate is condensed with N-ethyl-p-tolu-alpha-thioquinolone ethyl iodide. The dyestuffs are sensitizers for silver halide emulsions. Specification 497,659 also is referred to. The Specification as open to inspection under Sect. 91 comprises the condensation of a quaternary salt of a 2-alkyltetrahydrobenzthiazole or -selenazole with itself, or with another quaternary salt of a heterocyclic base containing nitrogen and having a reactive methylene or methyl group, in such a manner, known per se, that the ring systems are joined by one or more methine groups. This subjectmatter does not appear in the Specification as accepted.