GB722795A - - Google Patents

Abstract

722,795. Hydroxyaminobenzoic acid esters. RHEINPREUSSEN AKT.-GES. FUR BERGBAU UND CHEMIE, [formerly STEINKOHLENBERGWERK RHEINPREUSSEN]. Oct. 23, 1950 [Oct. 22, 1949; July 31, 1950], No. 25817/50. Class 2 (3). The invention comprises esters of hydroxyaminobenzoic acids in which the alcohol residue has the general formula -R.NR 1 R 2 , where R is a saturated aliphatic hydrocarbon radical containing not more than 6 carbon atoms, one of R 1 and R 2 is hydrogen and the other an alkyl, aryl, aralkyl or alkaryl radical containing not more than 8 carbon atoms, or R 1 and R 2 are each an alkyl, aryl, aralkyl or alkaryl radical containing not more than 8 carbon atoms, or -NR 1 R 2 is a nitrogen-containing heterocyclic ring; but excluding the dimethylamino-, diethylamino-, dipropylamino- and piperidinoethyl esters of 2-hydroxy-4-aminobenzoic acid. The esters may be prepared by esterification of the acid with the amino alcohol in the presence of a concentrated inorganic or an aryl sulphonic acid, the amount used being sufficient to prevent undue decomposition of the hydroxy aminobenzoic acid. Alternatively, the amino alcohol may be replaced by a halogenated alcohol and the halogen-containing ester subsequently reacted with a primary or secondary amine. In other processes, a salt of a hydroxyaminobenzoic acid is reacted with a halogenated amine, and an alkyl ester of the hydroxyaminobenzoic acid is reacted with an N-substituted aminoalcohol in an ester-exchange process. In examples, (1) 2-hydroxy-3-aminobenzoic acid is esterified by means of #-diethylaminoethanol in the presence of substantial amounts of concentrated sulphuric acid; (2) 2-hydroxy-3- aminobenzoic acid is similarly esterified with ethylene chlorohydrin and the #-chloroethyl ester formed heated with diethylamine in benzene under pressure; and (3) 2-hydroxy-5- aminobenzoic acid is reacted with 1-chloro-2- diethylaminoethane in the presence of sodium and isopropanol. Specifications 588,032, 722,885 and 722,886 are referred to.