GB707590A - 4-thioureido-2-hydroxybenzoic acids - Google Patents

Abstract

The invention comprises 4-thioureido-2-hydroxybenzoic acids and their alkali salts of the formula <FORM:0707590/IV (b)/1> in which R1 is hydrogen or an organic radical and R2 is hydrogen or a lower alkyl radical. They may be prepared by reacting 4-amino-2-hydroxybenzoic acid with thiocyanates; by converting 4-amino-2-hydroxybenzoic acid to ammonium dithiocarbamate by reaction with carbon disulphide and ammonia, and then splitting off hydrogen sulphide with lead oxide, lead carbonate or mercury salts; by converting 4-amino-2-hydroxybenzoic acid into the 3-hydroxy-4-carboxyphenylcyanamide by means of cyanogen chloride or bromide, and then adding hydrogen sulphide; by reacting the isothiocyanate (obtained from 4-amino-2-hydroxybenzoic acid by the process of Specification 707,589) with ammonia or primary or secondary amines or di- or polyamines, including amino-alcohols, amino-carboxylic and sulphonic acids, and hydrazines; by reacting 4-amino-2-hydroxybenzoic acid with isothiocyanates; or by the reaction of phosgene or carbon disulphide with an alkaline solution of 4-amino-2-hydroxybenzoic acid. Examples are given of the preparation of (1) 4-thioureido-2-hydroxybenzoic acid from 3-hydroxy-4-carboxyphenyl isothiocyanate and ammonia; (2) N-methyl-N1-(3-hydroxy - 4 - carboxyphenyl) - thiourea from 3 - hydroxy - 4 - carboxyphenyl isothiocyanate and methylamine; (3) N-methyl-N-(b -sulphoethyl) - N1 - (3 - hydroxy - 4 - carboxyphenyl)-thiourea sodium salt from methyltaurine and 3-hydroxy - 4 - carboxyphenyl isothiocyanate; (4) N - allylamino - N1(3 - hydroxy - 4 - carboxyphenyl)-thiourea from allyl isothiocyanate and 4-amino-2-hydroxybenzoic acid; (5) N-methyl-N-carboxymethyl - N1 - (3 - hydroxy - 4-carboxyphenyl)-thiourea from methylaminoacetic acid and 3-hydroxy-4-carboxyphenyl isothiocyanate; (6) N-(1-methyl-4-diethylaminobutyl) - N1 - (3 - hydroxy - 4 - carboxyphenyl)-thiourea sodium salt from 3-hydroxy-4-carboxyphenyl isothiocyanate and 2 - amino - 5 - diethylamino - pentane; (7) 1 - phenyl - 4 - (31-hydroxy - 41 - carboxyphenyl) - thiosemicarbazide from 3-hydroxy-4-carboxyphenyl isothiocyanate and phenylhydrazine; (8) N,N1-bis(3-hydroxy - 4 - carboxy - phenyl) - thiourea from 3 - hydroxy - 4 - carboxyphenyl isothiocyanate and 4 - amino - 2 - hydroxybenzoic acid; (9) N - (4 - methyl - pyrimidyl - 2) - N1(3 - hydroxy-4 - carboxyphenyl) - thiourea from 3 - hydroxy-4 - carboxyphenyl isothiocyanate and 4-methyl - 2 - aminopyrimidine; and (10) 4-thioureido - 2 - hydroxybenzoic acid from 3-hydroxy - 4 - carboxyphenylcyanamide and sodium hydrosulphide. Compounds are also specified in which the group -NR1R2 in the general formula is phenylamino, piperidino, 4-carboxyphenylamino, (pyridyl-2)-amino, (thiazolyl - 2) - amino, hydrazino, ethyleneimino - (tetramethylenesulphone - 3) - amino, and carbethoxy-hydrazino.