Patent GB-645288-A (GB)
Title: Process for the preparation of thioketones and carbocyanine dyes
IPC: C07D277/84
Filed: 1948-02-24
Abstract: A mixture of a thioketone and an anhydromeso-substituted carbocyanine hydroxide is prepared by condensing a cyclammonium carboxyalkyl quaternary salt of the general formula <FORM:0645288/IV (b)/1> wherein R represents a carboxyalkyl group, X an anion, R1 H or a methyl group, and Z the non-metallic atoms to complete a benzthiazole, benzselenazole, or a -naphthathiazole nucleus, with an ester of a dithiocarboxylic acid of the general formula <FORM:0645288/IV (b)/2> wherein R2 represents a hydrocarbon radical and R4 an alcohol radical.  R may represent carboxymethyl, a - or b -carboxyethyl, g -carboxypropyl, or a  : g -dicarboxypropyl, X may represent chloride, bromide, iodide, perchlorate, acetate, propionate, or thiocyanate, and the dithiocarboxylic ester may be methyl, ethyl, or butyl dithioacetate, methyl or ethyl dithiopropionate, methyl, ethyl, or benzyl dithiobenzoate, or methyl dithiocyclohexanecarboxylate.  A mixture of 3-b -carboxyethyl-2-thioacetylmethylenebenzthiazoline and anhydro-3 : 31 - di - b  - carboxyethyl - 9 - methylthiacarbocyanine hydroxide is prepared by refluxing together 2-methylbenzthiazole b -carboxyethiodide, methyl dithioacetate, triethylamine, and pyridine. The cooled mixture is poured into dilute acetic acid, and the thioketone obtained by extracting the solid product with hot methyl alcohol and crystallising.  The insoluble residue of dye remaining is dissolved in hot methyl alcohol containing triethylamine, and the dye precipitated by adding acetic acid.  Mixtures of 3-b -carboxyethyl-2-thiopropionylmethylenebenzthiazoline and anhydro-3:31-di - b  - carboxyethyl - 9 - ethylthiacarbocyanine hydroxide, of 3 - b  - carboxyethyl - 5 - chloro - 2-thiopropionylmethylenebenzthiazoline and anhydro - 5 : 51 - dichloro - 3 : 31 - di - b  - carboxyethyl - 9 - ethylthiacarbocyanine hydroxide, of 3 - b  - carboxyethyl - 2 - thioacetylmethylenebenzselenazoline and anhydro - 3 : 31 p  - di - b -carboxyethyl - 9 - methylselenacarbocyanine hydroxide, and of 3 - b - carboxyethyl - I - 2 - thioacetylmethylene - a  - naphthathiazoline and anhydro - 3 : 31 - di - b  - carboxyethyl - 9 - methyl - 6 : 7 : 61 : 71 - dibenzthiacarbocyanine hydroxide are similarly prepared and separated. 3-b -Carboxyethyl-5-chloro-2-thioacetylmethylenebenzthiazoline is similarly prepared and separated, the dye bye-product not being worked up.  Alkylmercapto compounds of the general formula <FORM:0645288/IV (b)/3> wherein R3 represents an alkyl, allyl, benzyl, or b -ethoxyethyl group and X1 an anion (including a benzenesulphonate, acetate, propionate, or thiocyanate) are prepared by reacting the thioketones with alkyl esters.  2 - (2 - Methylmercaptopropenyl) - benzthiazole b  - carboxyetho - p - toluenesulphonate is prepared by heating together 3-b -carboxyethyl-2 - thioacetylmethylenebenzthiazoline and methyl p-toluenesulphonate. 2-(2-Methylmercapto - 1 - butenyl) - benzthiazole b  - carboxyetho-p - toluenesulphonate, 5 - chloro - 2 - (2 - methylmercapto - 1 - butenyl) - benzthiazole b  - carboxyetho - p - toluenesulphonate, and 2 - chloro - 2-(2 - methylmercaptopropenyl) - benzthiazole b -carboxyetho-p-toluenesulphonate are similarly prepared. Specifications 585,666 and 599,712 are referred to.ALSO:A mixture of a thioketone and an anhydromeso-substituted carbocyanine hydroxide is prepared by condensing a cyclammonium carboxyalkyl quaternary salt of the general formula <FORM:0645288/IV (c)/1> wherein R represents a carboxyalkyl group, X an anion, R1 H or a methyl group, and Z the non-metallic atoms to complete a benzthiazole, benzselenazole, or a -naphthathiazole nucleus, with an ester of a dithiocarboxylic acid of the general formula <FORM:0645288/IV (c)/2> wherein R2 represents a hydrocarbon radical and R4 an alcohol radical.  R may represent carboxymethyl, a - or b -carboxyethyl, g -carboxypropyl, or a  : g -dicarboxypropyl, X may represent chloride, bromide, iodide, perchlorate, acetate, propionate, or thiocyanate, and the dithiocarboxylic ester may be methyl, ethyl, or butyl dithioacetate, methyl or ethyl dithiopropionate, methyl, ethyl, or benzyl dithiobenzoate, or methyl dithiocyclohexanecarboxylate.  A mixture of 3-b -Carboxyethyl-2-thioacetylmethylenebenzthiazoline and anhydro-3 : 31-di - b  - carboxyethyl - 9 - methylthiacarbocyanine hydroxide is prepared by refluxing together 2-methylbenzthiazole b -carboxyethiodide, methyl dithioacetate, triethylamine, and pyridine. The cooled mixture is poured into dilute acetic acid, and the thioketone obtained by extracting the solid product with hot methyl alcohol and crystallizing.  The insoluble residue of dye remaining is dissolved in hot methyl alcohol containing triethylamine, and the dye precipitated by adding acetic acid.  Mixtures of 3 - b  - carboxyethyl - 2 - thiopropionylmethylenebenzthiazoline and anhydro - 3 : 31 - di - b  - carboxyethyl - 2 - ethylthiacarbocyanine hydroxide, of 3 - b  - carboxyethyl - 5 - chloro - 2 - thiopropionylmethylenebenzthiazoline and anhydro - 5 : 51 - dichloro - 3 : 31 - di - b  - carboxyethyl - 9 - ethylthiacarbocyanine hydroxide, of 3 - b  - carboxyethyl - 2 - thioacetylmethylenebenzselenazoline and anhydro - 3 : 31 - di - b  - carboxyethyl - 9 - methylselenacarbocyanine hydroxide, and of 3 - b - carboxyethyl - 2 - thioacetylmethylene - a  - naphthathiazoline and anhydro - 3 : 31 - di - b  - carboxyethyl - 9 - methyl - 6 : 7 : 61 : 71 - dibenzthiacarbo cyanine hydroxide are similarly prepared and separated.  Specifications 585,666 and 599,712 are referred to.