A number of β-dialkylaminoethyl esters of 2,5-disubstituted pyrimidine-4-carboxylic acids have been synthesized and characterized as their hydrochlorides and in some cases as their methobromide and methiodide salts. Mucochloric acid has been condensed withS-methylisothiouronium sulphate to give 2-methylthio-5-chloropyrimidine-4-carboxylic acid, and the corresponding 5-bromo- acid has been converted to the 5-amino-acid.