GB669061A - Preparation of an ester of 4-aminosalicylic acid with increased tuberculostatic effec - Google Patents

Abstract

The n-propyl ester of p-aminosalicylic acid, which has tuberculostatic properties, is manufactured by reacting p-amino- or p-nitrosalicylic acid or one of their esterifiable derivatives with propyl alcohol or a reactive derivative thereof (advantageously in an anhydrous solvent and in the presence of dehydrating agents, acid-binding agents, condensing agents or esterification catalysts), and, when starting from p-nitrosalicylic acid, subsequently reducing the nitro group to an amino group. In an example, dry hydrogen chloride is passed into a heated solution of p-nitrosalicylic acid in propyl alcohol, and the resulting ester is reduced with hydrogen in ethyl acetate solution in the presence of Raney nickel. The Specification as open to inspection under Sect. 91 comprises also the manufacture of other esters from acids of the general formula <FORM:0669061/IV (b)/1> (wherein R1 represents a free or substituted hydroxy group, a halogen atom, an amino, acyl, alkyl, aryl or aralkyl-amino group or a group convertible thereto, and R2 represents an amino, acylamino, alkylamino or arylamino group or a group convertible thereto), or functional derivatives of such acids suitable for the formation of esters, and aliphatic or carbocyclic compounds having more than two carbon atoms in the molecule and containing a primary, secondary or tertiary hydroxy group, or reactive derivatives thereof. Additional examples describe the preparation of p-aminosalicylic acid phenyl and n-butyl esters, and reference is also made to 2-chloro-4-aminobenzoic acid allyl, lauryl, benzyl and guaiacyl esters. Further hydroxy compounds specified are dodecyl and myricyl alcohols and menthol. This subject-matter does not appear in the Specification as accepted. Reference has been directed by the Comptroller to Specification 670,490.