GB146870A - Manufacture of arseno-compounds of the pyrazolone series - Google Patents

Abstract

Products giving alkali salts having spirillocide properties are obtained by introducing acid salt-forming groups (-CH2COOH1 -CH2SO2H, -CH2SO3H, &c.) into the amino groups of arseno-di-(1-aryl -2 : 3-dialkyl-4-amino-5-pyrazolones). The introduction of alkylenesulphoxyl groups may be effected simultaneously with the formation of the arseno compound by treating a 4-nitroso- or 4-nitro-1-aryl-2 : 3-dialkyl-5-pyrazolone arsinic acid with aldehyde sulphoxylate. According to examples: 1-(phenyl-p-arsinic acid)-3-methyl-5-chlorpyrazole is prepared by reaction of diazotized 1-p-aminophenyl-3-methyl-5 -chlorpyrazole with an arsenite; this product is converted into 1- (phenyl-p-arsinic acid)-2 : 3 -dimethyl-5-pyrazolone by treatment with dimethyl sulphate followed by heating with sodium carbonate solution; 1-(phenyl-p-arsinic acid)-3-methyl-5-pyrazolone is prepared by reducing diazotized arsanilic acid by means of stannous chloride and hydrochloric acid to phenylthydrazine -p-arsinic acid and condensing this with acetoacetic ester; methylation of this product gives 1-(phenyl-p-arsinic acid)-2 : 3-dimethyl-5-pyrazolone; 4-nitroso-1-(phenyl-p-arsinic acid)-2 : 3-dimethyl-5-pyrazolone is obtained by treating the last-mentioned compound with sodium nitrite and sulphuric acid; reduction of this nitroso compound by hydrosulphite gives p-arseno - di - (1 - phenyl - 2 : 3-dimethyl-4-amino-5-pyrazolone); this product is converted into its mono- or di-glycine derivatives by reaction with bromacetic acid, or into its mono- or di-methylenesulphoxylic derivatives by treatment with formaldehydesulphoxylate.