Patent GB-753648-A (GB)
Title: Rhodanine compounds, processes for producing them and photographic emulsions containing them
IPC: C09B23/10
Filed: 1954-09-17
Abstract: Compounds of the general formula: <FORM:0753648/IV(a)/1> wherein R is methyl or alkoxy and R1 is alkyl, substituted alkyl or alkenyl are prepared by heating together a compound of the general formula CH3.CO.CO.R with a compound of the general formula: <FORM:0753648/IV(a)/2> in the presence of zinc chloride under substantially anhydrous conditions.  5-(Butan-3-on-2-ylidene) - 3 - carbethoxyethyl - 2 - thiothiazolid-4-one is prepared by heating together 3-carbethoxymethylrhodanine, diacetyl, powdered anhydrous zinc chloride, and dioxane.  5-(Butan - 3 - on - 2 - ylidene) - 3 - carboxymethyl-2 - thiothiazolid - 4 - one, 5 - (Butan - 3 - on - 2-ylidene) - 3 - carbo n - butoxymethyl - 2 - thiothiazolid-4-one, methyl a -(3-carbomethoxymethyl-4 - keto - 2 - thiothiazolid - 5 - ylidene) - propionate, ethyl a -(3-carbethoxymethyl-4-keto-2-thiothiazolid - 5 - ylidene) - propionate, n - butyl a -(3 - carbo - n - butoxymethyl - 4 - keto - 2 - thiothiazolid - 5 - ylidene) - propionate, and methyl a  - (3 - ethyl - 4 - keto - 2 - thiothiazolid - 5 - ylidene)-propionate are similarly prepared.ALSO:Merocyanine dyes of the general formula I <FORM:0753648/IV(c)/1> wherein R is methyl or alkoxy, R1 and R2 are alkyl, substituted alkyl or alkenyl, n and d each are 0 and 1, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, are prepared by condensing compounds of the general formula II <FORM:0753648/IV(c)/2> wherein X represents an acid radical and D an alkylthio, arylthio, or b -aminovinyl (e.g. b -acylarylaminovinyl) group, with compounds of the general formula III <FORM:0753648/IV(c)/3> e.g. with heating and in the presence of a diluent and a strongly basic condensing agent.  3-Carbethoxymethyl - 5 - [1 - (3 - ethylbenzthiazolin - 2 - ylidene) - hex - 2 - en - 5 - on - 4 - ylidene] - 2 - thiothiazolid -4- one is prepared by heating together 2-b -acetanilidovinylbenzthiazole ethiodide, 5-(butan - 3 - on - 2 - ylidene)-3-carbethoxyethyl - 2 - thiothiazolid - 4 - one, ethanol, and thiethylamine 3 - Carbethoxymethyl - 5 - [1 - 3 - ethylbenzthiazolin - 2 - ylidene) - butan - 3 - on - 2 - ylidene] - 2 - thiothiazo - lid - 4 - one, 3 - carbethoxymethyl - 5 - [1-(3 - methylthiazolidin - 2 - ylidene) - butan - 3 - on - 2 - ylidene] - 2 - thiothiazolid - 4 - one, and 3-carbomethoxymethyl - 5 - [1-carbomethoxy - 2 - (3-methylthiazolidin - 2 - ylidene) - ethylidene] - 2 - thiothiazolid - 4 - one are similarly prepared. Merocyanine dyes of the general formula IV <FORM:0753648/IV(c)/4> wherein L represents a substituted or unsubstituted methine group and R6 an alkyl, substituted alkyl or alkenyl group are prepared by condensing a compound of the general formula V <FORM:0753648/IV(c)/5> wherein R7 is alkyl and X, an acid radical, with compounds of the general formula III.  Compounds of the general formula V are prepared by heating together with an alkyl ester R7-X1 compounds of the general formula <FORM:0753648/IV(c)/6> 2 - [2 - (3 - Carbethoxymethyl - 4 - keto - 2 - thiothiazolidin - 5 - ylidene) - butan - 3 - on - 1 - ylidene] - 3 - ethyl - 5 - (3 - ethylbenzoxazolin - 2 - ylidene - ethylidene) - thiazolid - 4 - one is prepared by fusing together 3 - ethyl - 5 - (3 - ethylbenzoxazolin - 2 - ylidene - ethylidene) - 2 - thiothiazolid - 4 - one and methyl p-toluenesulphonate, adding 5-(butan - 3 - on - 2 - ylidene) - 3 - carbethoxy ethyl - 2 - thiothiazolid - 4 - one, ethanol and triethylamine, and refluxing.  3 - Allyl - 2 - [2 - (3 - carbethoxymethyl - 4 - keto - 2 - thiothiazolidin - 5 - ylidene) - butan - 3 - on - 1 - ylidene] - 5 - [1 - (3 - ethylbenzthiazolin-2 - ylidene) - but - 2 - ylidene] - thiazolid - 4 - one is similarly prepared.