GB811692A - Improvements in or relating to chlorobenzimidazolone compounds - Google Patents

Abstract

The invention comprises compounds of the general formula: <FORM:0811692/IV (b)/1> wherein R is an ethyl or an allyl group and X and Y are hydrogen or chlorine atoms in the combination 5-chloro, 6-chloro- or 5,6-dichloro, and the manufacture thereof by (a) reacting at temperatures above 75 DEG C. a phenylenediamine compound of the formula: <FORM:0811692/IV (b)/2> with a carbonic acid derivative such as a dialkyl carbonate, an alkyl, aralkyl or aryl chloroformate, a urea, phosgene, an alkyl or aryl isocyanate or urethane or a dialkyliminocarbonate; (b) cyclizing a N-acyl phenylenediamine of the general formula: <FORM:0811692/IV (b)/3> wherein Z is an alkoxy, amino or substituted amino group, at elevated temperature in the presence of a basic condensation catalyst; and (c) subjecting a 1-isopropenyl-chlorobenzimidazolone of the general formula: <FORM:0811692/IV (b)/4> to acid hydrolysis in the presence of a solvent. Examples describe the preparation by process (a) of 6-chloro-1-ethylbenzimidazolone by reacting 5 - chloro - N1 - ethylphenylene - 1,2-diamine and ethyl carbonate in the presence of sodium methoxide, of 5 : 6-dichloro-1-ethylbenzimidazolone and of 1-allyl-6-chloro-, 5-chloro-, and -5,6-dichloro-benzimidazoles by reacting the corresponding diamines with urea in boiling 2-butoxyethanol; by process (b) of 5- and 6-chloro-1-ethylbenzimidazoles from 4- and 5 - chloro - N1 - carbethoxy - N1 - ethylphenylenediamines respectively, using sodium ethoxide as the basic condensation catalyst; and by process (c) of 1-allyl-5,6-dichlorobenzimidazolone by first reacting 4,5-dichlorophenylene-1,2-diamine with ethyl acetoacetate and then with sodium and 2-ethoxyethanol to give a reaction mixture containing 5,6-dichloro-1 - isopropenylbenzimidazolone, treating this with allyl bromide to give 3-allyl-5,6-dichloroisopropenylbenzimidazolone, and hydrolysing with concentrated hydrochloric acid. An example describes the preparation of 5,6-dichloro-1-ethylbenzimidazolone by reacting 4,5 - dichloro - N - ethyl - 2 - nitroaniline with butyl chloroformate, hydrogenating the product in the presence of a platinum oxide catalyst and then with sodium and 2-ethoxyethanol. 4 : 5 - Dichloro - and 5 - chloro - N1 - ethylphenylenediamines, 5 - chloro -, 4 - chloro - and 4 : 5 - dichloro - N1 - allylphenylenediamines are prepared by reducing 4 : 5-dichloro- and 5-chloro - 2 - nitro - N - ethylaniline, 5 - chloro -, 4 - chloro - and 4 : 5 - dichloro - 2 - nitro - N - allylanilines, respectively with iron in an aqueous acidic medium. 4 : 5 - Dichloro - and 5 - chloro - 2 - nitro - N - ethylanilines, and 4 : 5 - dichloro - 2 - nitro - N - allylaniline are prepared from 2 : 4 : 5-trichloro- and 2 : 4-dichloronitrobenzenes and ethyl- and allylamines. 5 - Chloro - N1 - carbethoxy - N1 - ethylphenylenediamine is prepared by reacting 5-chloro-N-ethyl-2-nitroaniline with ethylchloroformate and hydrogenating the resultant 5-chloro-2-nitro-N-carbethoxy-N-ethylaniline.