Patent GB-438449-A (GB)
Title: Manufacture of unsymmetrical heptacarbocyanine dyestuffs
Filed: 1934-05-18
Abstract: Unsymmetric heptacarbocyanine dyes are prepared by condensing in the presence of an alkaline condensing agent, an intermediate product obtainable by condensation of equimolecular quantities of a quaternary ammonium salt of a heterocyclic nitrogen base containing a reactive methyl group and a pentamethine compound of the general formula <FORM:0438449/IV/1> (wherein R1 stands for an aryl residue, R2 for hydrogen or an alkyl or aralkyl group and X for an acid residue such as chlorine or bromine, and wherein one or more hydrogen atoms of the pentamethine chain may be replaced by an alkyl group or groups), with an equimolecular quantity of a quaternary ammonium salt of a heterocyclic base containing a reactive methyl group and different from the heterocyclic base from which the intermediate product is derived.  Suitable condensing agents are pyridine, piperidine, ethanolamines, alkylamines and sodium ethylate.  Suitable bases containing a reactive methyl group are the mono- and polynuclear thiazoles, selenazoles and 2- and 4-methyl quinolines. The intermediate products are prepared by condensing in the presence of an alkaline condensing agent (such as a primary, secondary or tertiary amine or sodium ethylate) equimolar proportions of a quaternary ammonium salt of a heterocyclic nitrogen base containing a reactive methyl group and of a e -phenylimido a -phenylamido-a  : g -pentadiene hydrohalide (cf. Specification 438,484); generally the quantity of condensing agent is at most equivalent to that of the base to be used, otherwise the formation of a symmetrical dyestuff is promoted.  In examples: (1) equimolar proportions of 2-methylbenzthiazole ethiodide and e -phenylimido-a -phenylamido-a  : g -pentadiene hydrobromide are condensed together in alcohol and presence of piperidine and the resulting intermediate condensed with (a) 2-methyl-b -naphthothiazole diethyl sulphate in alcohol and in presence of diethylamine, (b) 2.5.6-trimethylbenzselenazole ethiodide as in (a), (c) lepidine ethiodide as in (a), and (d) 2-methyltetrahydro-b -naphthiazole ethiodide as in (a); (2) 2-methylbenzselenazole ethiodide is condensed with e -phenylimido-a -phenylamino-a  : g -pentadiene hydrobromide (1 mol.) in alcohol and in the presence of piperidine and the resulting intermediate is condensed with 2.4-dimethylthiazole ethiodide in alcohol and in presence of diethylamine; (3) the intermediate obtained by condensing 2-methylbenzselenazole ethiodide with e -N-methylphenylimino-a -N-methylphenylamido - a  : g  - pentadiene hydrobromide in alcohol and in presence of triethanolamine, is condensed with lepidine ethiodide in alcohol and in presence of triethylamine; (4) the intermediate obtained by condensing 2-methyl-5-methoxybenzselenazole ethiodide with e  - N - methylphenylimino - a  - N - methylphenylamido - a  : g  - pentadiene hydrobromide as in (3) is condensed with 2-methyl-5-diethylaminobenzthiazole ethiodide in alcohol containing sodium alcoholate; (5) 2-methylbenzthiazole ethiodide is condensed with an equimolar proportion of e -phenylimido-a -phenylamido-g -methyl-a  : g -pentadiene hydrobromide in alcohol and in presence of piperidine and the resulting intermediate condensed with 2-methyl-a -naphthothiazole ethiodide in alcohol and in presence of diethylamine; (6) the intermediate obtained by condensing p-toluquinaldine ethiodide with e  - N - methylphenylimido - a  - N - methylphenylamido - a  : g  - pentadiene hydrobromide in acetic anhydride and in presence of sodium acetate, is condensed with 2-methylbenzthiazole ethiodide in alcohol containing sodium ethylate; (7) the intermediate obtained by condensing 2,5,6-trimethylbenzthiazole ethiodide with an equimolar proportion of e -N-methylphenylimido - a  - N - methylphenylamido - a : g -pentadiene hydrobromide in alcohol and in presence of triethanolamine is condensed with 2,4-dimethylthiazole ethiodide in alcohol and in presence of diethylamine; (8) the intermediate obtained by condensing 2 : 6-dimethyl-5 - ethoxybenzthiazole ethiodide with e  - N-methylphenylimido - a  - N - methylphenylamido-a  : g -pentadiene hydrobromide in alcohol and in presence of sodium ethylate, is condensed with 2-methylacenaphthenethiazole ethiodide in alcohol and in presence of diethylamine; (9) the intermediate obtained by condensing 2-methylbenzthiazole ethiodide with e -N-methylphenylimido - a  - N - methylphenylamido - a  : g -pentadiene hydrobromide in alcohol and in presence of monomethylamine, is condensed with 2 - methyl - 4,5 - naphthobenzthiazole - p-toluenesulphoethylate in alcohol and in presence of diethylamine.  The products are valuable photographic sensitizers for the infra-red portion of the spectrum (cf. Specification 438,450).  Specification 355,693 also is referred to. 2.5.6-Trimethylbenzselenazole ethiodide is prepared by treating diazotized 1-amino-2-nitro-4.5-dimethylbenzene with potassium selenocyanide, saponifying, reducing and air oxidizing the product to o,o<1>-diaminodiphenyldiselenide which is treated with zinc dust and acetic anhydride to give the thiazole from which the quaternary salt is derived by reaction with ethyl iodide.  e  - Phenylimido - a  - phenylamido - g  - methyl-a  : g -pentadiene hydrobromide is prepared by König's process from aniline, g -picoline and cyanogen bromide analogously to the unsubstituted compound.  The Specification as open to inspection under Sect. 91 relates in addition to the manufacture of the intermediate bodies as referred to above, such process also being effected in a medium of acetic anhydride, and comprises the following additional examples: (10) the intermediate obtained by condensing 2-methyl-5-diethylaminobenzthiazole ethiodide with a -(N-methylphenylamido) -e - (N-methylphenylimido)-a  : g -pentadiene hydrobromide in alcohol and in presence of triethanolamine, is condensed with lepidine ethiodide in alcohol and in presence of diethylamine, and similarly with 2.4-dimethylthiazole methiodide; (11) the intermediate of (4) above is condensed with 2-methyl-4-phenylthiazole methiodide in alcohol and in presence of trimethylamine; (12) the intermediate of (3) above is condensed with a -picoline ethiodide in pyridine; (13) the intermediate obtained by condensing 2,6-dimethyl-5-ethoxybenzthiazole ethiodide with e -phenylimido-a -phenylamido-a  : g -pentadiene hydrobromide in alcohol and in presence of piperidine, is condensed with 2.5.6 - trimethylbenzselenazole ethiodide in alcohol and in presence of triethanolamine; (14) the intermediate of (9) above is condensed with 2.4-dimethyl-5-carbethoxythiazole methiodide in alcohol and in presence of diethylamine, and similarly with 2-methyl-5.6-methylenedioxy-benzthiazole ethiodide; (15) the intermediate obtained by condensing lepidine methiodide with e  - (N - methylphenylimido) - a  - (N - methylphenylamido)-a  : g -pentadiene hydrobromide in alcohol and in presence of triethanolamine, is condensed with 2 - methyl - 6 - methoxybenzthiazole ethiodide in alcohol and in presence of trimethylamine; (16) the intermediate obtained by condensing quinaldine ethiodide with e -(N-methylphenylimido) - a  - (N - methylphenylamido-a  : g -pentadiene hydrobromide in alcohol and in presence of triethanolamine, is condensed with 2.4-dimethylthiazole methiodide in alcohol and in presence of diethylamine; (17) the intermediate obtained by condensing 2-methyl-5-ethoxybenzselenazole ethiodide with e -(N-methylphenylimido) - a  - (N - methylphenylamido) - a  : g  - pentadiene hydrobromide in alcohol and in presence of benzylamine, is condensed with 2-methyl-5-chloro-6-methoxybenzthiazole ethiodide in alcohol and in presence of trimethylamine.  This subject-matter does not appear in the Specification as accepted.