Patent GB-424559-A (GB)
Title: Improvements in or relating to the production of compounds of the cyanine type
IPC: C09B23/04
Filed: 1933-05-18
Abstract: Cyanine compounds are prepared by reacting a heterocyclic nitrogen base having a thioether group in the a - or g - position to the nitrogen, with an alkyl salt and with a quaternary ammonium salt of a heterocyclic nitrogen compound having a reactive methyl group.  Thus the a - or lambdamercaptan of a heterocyclic nitrogen base is first alkylated or aralkylated to form the thioether and this is then converted to the quaternary salt and reacted with the quaternary ammonium salt of a heterocyclic nitrogen compound having a reactive methyl group.  A neutral solvent such as alcohol and an acid-binding agent such as sodium acetate is advantageously employed in such process, or the solvent may also be an acid-binding agent (pyridine). Alternatively a mixture of a heterocyclic nitrogen base having a reactive methyl group, a heterocyclic nitrogen base having a reactive thioether group in the a - or g - position to the nitrogen atom and the salt required to form the quaternary salts of these bases, is heated together, if necessary in the presence of a solvent and an acid-binding agent (pyridine may act in both capacities).  Thioethers may be prepared by alkylation of the mercapto bodies derived from thiazoles, thiazolines, oxazoles, oxazolines, selenazoles, selenazolines, quinolines, indolenines, and pyridines and they may contain substituents such as hydroxy, alkoxy, halogen alkyl, aryl, aralkyl, amino or substituted amino; they are converted to quaternary ammonium salts by heating with an alkyl salt and these may be condensed with quaternary ammonium salts of the foregoing heterocyclic bases having a reactive methyl substituent in a - or g -position to the nitrogen atom.  The cheapness of production, good yields and the purity of the products are mentioned as advantages of the process.  In examples: (1) 1-methylmercaptobenzthiazole ethiodide is condensed with quinaldine ethochloride to give 1<1>.2-diethyl-thiopseudocyanine iodide, 2-methyl-b -naphthoxazole ethiodide to give 2.2<1>-diethyl-3<1>.4<1>-thiobenzoxacyanine iodide, 2.3.3-trimethylindolenine methiodide to give 2-ethyl-1<1>.3<1>.3<1>-trimethylthioindocyanine iodide, 1-methylbenzthiazole ethochloride to give 2.2<1>-diethylthiocyanine iodide, 2.4-dimethylquinoline methiodide to give 1.4-dimethyl-2<1>-ethylthiopseudocyanine iodide, lepidine methiodide to give 2-ethyl-1<1>-methylthioisocyanine iodide, a -picoline ethiodide to give 1.2<1>-dimethylpyridothiopseudocyanine iodide, 1-methyl-5.6-benzbenzthiazole ethiodide to give 2.2<1>-diethyl-5.6-benzthiocyanine iodide, 6-ethoxyquinaldine ethiodide to give 2.1<1>-diethyl-6<1>-ethoxythiopseudocyanine iodide, 6-dimethylamino-2-methylquinoline ethiodide to give 2.1<1>-diethyl-6<1>-dimethylaminothiopseudocyanine iodide, p-toluquinaldine ethiodide giving 2.1<1>.6<1>-trimethylthiopseudocyanine iodide, and 1-methylbenzoxazole methiodide to give 2-ethyl-2<1>-methylthiooxacyanine iodide; (2) 1-methylmercaptobenzthiazole ethyl p-toluenesulphonate is condensed with 1 - methyl - 4.5 - dimethoxybenzthiazole - ethyl - p - toluenesulphonate to give 2.2<1> - diethyl - 4.5 - dimethoxythiocyanine - p - toluenesulphonate; this is converted to the bromide by adding ammonium bromide; (3) 1 - methylmercaptobenzthiazole, 1 - methyl - a -naphthoxazole and ethyl-p-toluenesulphonate are condensed together in alcohol and in presence of sodium acetate and potassium iodide added to precipitate out 2.2<1>-diethyl-5<1>-6<1>-benzthiooxacyanine iodide; by similar condensations of ethyl-p-toluenesulphonate with the following pairs of reactants the dyes specified in brackets are obtained: 1-methylmercaptobenzthiazole and 1-methyl-a -naphthathiazole (2.2<1> - diethyl - 5.6 - benzthiocyanine iodide), or 1-methyl-4.5-dioxymethylenebenzthiazole (2.2<1> - diethyl - 4.5 - dioxymethylene thiocyanine bromide), or 1-methyl-4-dimethylaminobenzthiazole (2.2<1>-diethyl-4-dimethylaminothiocyanine iodide), 1-ethylmercapto-4.5-dimethoxybenzthiazole and a -picoline (2.1<1>-diethyl-4.5-dimethoxythiopyridopseudocyanine iodide), 1-methylmercapto-4.5-dimethoxybenzthiazole and quinaldine (2.1<1>-diethyl-4.5-dimethoxythiopseudocyanine - p - toluenesulphonate, precipitation with potassium iodide being omitted), 1-methylmercapto-4.5-dioxymethylenebenzthiazole and a -picoline (2.1<1>-diethyl - 4<1>.5<1> - dioxymethylenethiopyridopseudocyanine iodide), 1-methylmercaptobenzoxazole and quinaldine (2.1<1>-diethyloxapseudocyanine), or 1.4.5-trimethylbenzoxazole (2.2<1>-diethyl - 4.5 - dimethyloxacyanine iodide), or 1 - methylbenzthiazole (2.2<1> - diethylthiooxacyanine iodide), or 1-methyl-a -naphthoxazole (2.2<1> - diethyl - 5.6 - benzoxacyanine iodide), or 1 - methyl - a  - naphthathiazole (2.2<1> - diethyl - 5.6-benzthiooxacyanine iodide), or 1-methylbenzoxazole (2.2<1>-diethyloxacyanine iodide), or 2 - methyl - b  - naphthathiazole (2.2<1>-diethyl-3.4-benzthiooxacyanine - p - toluenesulphonate, and thence by means of potassium iodide, the corresponding iodide), 1-methyl-4-dimethylaminobenzthiazole (2.2<1> - diethyl - 4 - dimethylaminothiooxacyanine iodide), or 2-methyl-4.5-diphenyloxazole, or 1.3.3-trimethylmethyleneindole (1.3.3-trimethyl-2<1>-ethylindoxacyanine iodide), 1-methylmercapto-4.5-dimethylbenz--oxazole and 1.4.5-trimethylbenzoxazole (2.2<1> diethyl - 4.5.4<1>.5<1> - tetramethyloxacyanine iodide), or quinaldine (2.1<1>-diethyl-4.5-dimethyloxapseudocyanine iodide), or 2.3.3-trimethylindolenine (1.3.3.4<1>.5<1> - pentamethyl - 2<1> - ethylindoxacyanine iodide), or 2-methyl-b -naphthoxazole (2.2<1>-diethyl-3.4-benzo-4<1>.5<1>-dimethyl oxacyanine iodide), or 2-methyl-b -naphthathiazole (2.2<1> - diethyl - 3.4 - benzthio - 4<1>.5<1\h  > - dimethyloxacyanine - p - toluenesulphonate, the precipitation with potassium iodide being omitted), or 2.4-dimethylthiazole (2.2<1>-diethyl-4.4<1>.5<1> - trimethylthiazolocyanine iodide), 1-methylmercapto - 5 - methylbenzoxazole and quinaldine (2.1<1>-diethyl-5-methyloxapseudocyanine iodide), or 2-methyl-b -naphthathiazole (2.2<1>-diethyl-3.4-benzthio-5<1>-methyloxacyanine-p -toluenesulphonate, the precipitation with potassium iodide being omitted), or 1.5-dimethylbenzoxazole (2.2<1> - diethyl - 5.5<1> - dimethyloxa - cyanine iodide), or 1.3.3-trimethylmethyleneindole (1.3.3.5<1> - tetramethyl - 2<1> - ethylindoxa - cyanine iodide), 2-methylmercapto-b -naphth-oxazole and 2-methyl-b -naphthoxazole (2.2<1>-diethyl-3.4.3<1>.4<1>-dibenzoxacyanine iodide), or quinaldine (2 - 1<1> - diethyl - 3.4 - benzoxapseudo - cyanine iodide), or lepidine (2.1<1>-diethyl-3.4-benzoxaisocyanine iodide), or 1.3.3-trimethyl-methylene indole (1.3.3-trimethyl-2<1>-ethyl-3.4-indobenzoxacyanine iodide). Samples have been furnished under Sect. 2 (5) of dyes prepared (a) by condensing 4-methylmercaptoquinaldine, 1-methylbenzthiazole and ethyl-p-toluenesulphonate together in pyridine followed by treatment with potassium iodide, (b) by condensing 4 - methylmercaptoquinaldine, 1 - methylbenzoxazole and methyl - p - toluenesulphonate together in pyridine followed by treatment with potassium bromide, and (c) by the action of one molar proportion of alcoholic sodium ethylate on two molar proportions of 4-methylmercaptoquinaldine methiodide.  Some of the dyes are of use in sensitizing silver halide emulsions and for this purpose they may be incorporated in the emulsion before or after it is applied to the film or plate.  Sensitizing data of a number of the dyes specified in examples are given.  Indolenine thioethers are prepared by reacting 2-chlorindolenine with alcoholic potassium hydrogen sulphide followed by alkylation. Oxazoline thioethers are prepared analogously.