Ethyl Z-methylmercapto-4-methyl-pyrimidine-5-carboxylate (m.p.53-54°)was synthesized by condensing ethyl ethoxymethylene-acetoacetate with S-methylpseudothiourea sulfate in ethanol in the presence of sodium ethylate.Its structure was substantitated through the conversion into its corresponding acid, 2-methylmercapto-4-methyl-pyrimidine-5-carboxylic acid, melting at 169-171°.The latter dissolved in dilute sodium bicarbonate solution and did not give iodoform test.This acid could be converted into its silver salt, which reacted with ethyl iodide to form the original ester.