Patent GB-598985-A (GB)
Title: Improvements in or relating to the manufacture of azo dyestuffs
IPC: C09B39/00
Filed: 1945-07-13
Abstract: Compounds of the general formula <FORM:0598985/IV/1> and <FORM:0598985/IV/2> (where R is an alkyl, isocyclic or heterocyclic group containing no solubilizing group and X is an alkyl, alkoxy or alkylthio, and in which the benzene nuclei may contain other nonsolubilizing groups) are made by condensing an ester of an acylacetic acid with an aminobenzothiazole containing in the 2-position an alkyl, alkoxy or alkylthio group.  The products may be coupled with diazo or tetrazo compounds to form azo dyestuffs either in substance or on the fibre.  The amino-2-alkylbenzothiazoles may be prepared: (a) by the action of sulphur chloride on aminoacylanilides; (b) by nitration of 2-alkylbenzothiazoles, followed by reduction, or (c) by condensation of alkali disulphides with the compounds <FORM:0598985/IV/3> to obtain the disulphides <FORM:0598985/IV/4> followed by reduction to the corresponding o-aminothiophenol, oxidation to give the disulphide <FORM:0598985/IV/5> acylation and reduction to the thiophenol, and finally cyclisation and hydrolysis to give the required amino-2-alkylbenzothiazole. Amino-2-alkoxybenzothiazoles are prepared by: (a) alkylation of nitro-2-oxybenzothiazole, followed by reduction, or (b) condensation of an acyl-o-aminothiophenol with phosgene or urea to form the compound <FORM:0598985/IV/6> followed by alkylation of the oxy group and hydrolysis of the acyl group.  Amino-2-alkyl-thiobenzothiazoles are prepared by: (1) alkylation of the 2-mercaptobenzothiazole, followed by nitration and reduction, or (b) conversion of the compounds <FORM:0598985/IV/7> by means of sodium polysulphide and carbon disulphide to the salt of 2-mercapto-benzothiazole followed by alkylation, and hydrolysis of the acyl group.  The following examples are given:-(1) 2-Methylbenzothiazole is nitrated, reduced, and heated with acetylacetic ester to give 6-acetoacetylamino-2-methylbenzothiazole; the benzoylacetyl derivative is obtained similarly; (2) 1-Methyl-2-acetylamino-4-chloro-5-nitrobenzene is reacted with an aqueous solution of sodium disulphide and the disulphide formed is reduced and reacted with urea to form 5-methyl-6-acetylaminobenzothiazolone which is finally methylated with dimethyl sulphate.  The product is then hydrolyzed to give 6-amino-5-methyl-2-methoxybenzothiazole, which is condensed with acetylacetic ester or terephthaloylacetic ester.  The corresponding ethoxylated compound may be prepared in similar manner: (3) 5 - chloro - 6 - amino - 2 - methoxy-benzothiazole and the corresponding ethoxylated compound are prepared as in (2); (4) 5 - methoxy - 6 - amino - 2 - methoxybenzothiazole and its acylacylated derivatives are prepared by the subsequent operations of (2) starting from 2,21-dinitro-4,41-dimethoxy-5,51-diacetylamino-1, 11-diphenyl disulphide; (5) 2,21 - diamino - 4,41 - dimethyl - 5,51 - diacetylamino-1,11-diphenyl disulphide is acetylated and reduced with stannous chloride, and the 6-amino-2,5-dimethylbenzothiazole reacted with acetoacetic ester or terephthaloylacetic ester; 6 - amino - 5 - methoxy - 2 - methylbenzothiazole is obtained in a similar manner.; (6) 2,21 - diamino - 4,41 - dichloro - 5,51 - di acetylamino-1,11-diphenyl disulphide is acetylated, reduced and hydrolyzed to give 6-amino-5-chloro-2-methylbenzothiazole, which is then converted to the acetoacetyl or terephthaloylacetyl derivative; (7) 6-amino-2-methoxybenzothiazole and then its acetoacetyl derivative is prepared by reduction of the corresponding nitro compound; (8) 6-nitro-2-ethoxybenzothiazole is reduced and converted to the acetoacetyl derivative; (9) 2-mercaptobenzothiozole is methylated with dimethyl sulphate and the 2-methylthiobenzothiazole nitrated, reduced and converted to the acetoacetyl derivative of 6-amino-2-methylthiobenzothiazole; the corresponding ethylthiobenzothiazole compounds are obtained by using diethyl sulphate instead of dimethyl sulphate; (10) 2,5-dichloro-4-nitroacetanilide is treated with sodium disulphide and carbon disulphide to give 5-chloro-6-acetylamino-2-mercaptobenzothiazole, which is methylated and treated with acetylacetic ester to give 5-chloro-6-acetoacetylamino-2-methylthiobenzothiazole; the corresponding 2-ethylthio compound is formed similarly; (11) 2 - methoxy - 4 - nitro - 5 - chloroacetanilide is treated with sodium disulphide and carbon disulphide and the 5-methoxy-6-acetylamino-2-mercaptobenzothiazole is methylated, hydrolyzed and converted by means of acetylacetic ester to 6-acetoacetylamino-5-methoxy-2-methylthiobenzothiazole; the corresponding 2-ethylthio compound is obtained similarly; (12) 6 - acetoacetylamino - 5 - methyl - 2 - methylthiobenzothiazole and 6-acetoacetylamino-5-methyl-2-ethylthiobenzothiazole are obtained as in (11); (13) 6-amino-2-methylthiobenzothiazole is condensed with terephthaloylacetic ester in chloroform; in a similar manner the following are prepared: terephthaloyl-bis-(6-amino-2-ethylthiobenzothiazole), terephthaloylbis - (5 - chloro - 6 - amino - 2 - ethylthiobenzothiazole), terephthaloyl - bis - (5 - methoxy - 6 - amino - 2 - ethylthiobenzothiazole), terephthaloyl - bis - (5 - methoxy - 6 - amino - 2 - methylthiobenzothiazole), terephthaloyl-bis-(5-methyl - 6 - amino - 2 - ethylthiobenzothiazole) and terephthaloyl - bis - (5-methyl - 6 - amino - 2 - methylthiobenzothiazole; (14) bleached cotton is immersed in a dispersion containing the terephthaloylacetyl derivative of 2,5-dimethoxy-6-aminobenzothiazole and developed in diazonium chlorozincate of 2,5-dichloroaniline followed by boiling in sodium hydrosulphite; a similar result is obtained using the terephthaloylacetyl derivative of 6-amino-5-methoxy - 2 - methylthiobenzothiazole; (15) cotton is printed with a paste containing 6-acetoacetylamino - 2,5 - dimethoxybenzothiazole and the diazoamino derivative prepared from 4-chloro-o-toluidine and sarcosine, and steamed in acid vapour; (16) cotton is printed with a paste containing 5-chloro-6-acetoacetylamino-2-methoxybenzothiazole and a diazoamino compound or nitrosamine, several of which are specified, and then steamed in acid vapour; (17) cotton is printed with a paste containing 6 - acetoacetylamino - 2 - methylthiobenzothiazole and the diazoamino derivavative of p-chloro-o-aminoanisole and sarcosine, and steamed in acid vapour; (18) cotton is printed with a paste containing 5 - methyl - 6 - acetoacetylamino - 2 - methylthiobenzothiazole and a diazoamino compound, several of which are specified, and steamed in acid vapour; (19) cotton is treated in a bath containing terephthaloyl-bis-(5-methoxy-6-amino-2-ethylthiobenzothiazole), developed with diazotized o-nitroaniline, and boiled with hydrosulphite; similarly there may be used terephthaloyl - bis - (6 - acetylamino - 2 - methylthiobenzothiazole) and diazotized 2,5-dichloroaniline; (20) a yellow pigment is obtained by coupling diazotized m-nitro-p-toluidine with 6 - acetoacetylamino - 2 - methoxybenzothiazole (21) a yellow chromable dyestuff is obtained from diazotized 2-amino-3-naphthoic acid and 6 - acetoacetylamino - 5 - methyl - 2 - methoxybenzothiazole.  The Specification as open to inspection under Sect. 91 includes also the subject-matter of Specification 598,986.  This subject-matter does not appear in the Specification as accepted.