Umsetzungen von Monomethylthalliumdiacetat mit Aminen/Reactions of Monomethylthallium Diacetate and Amines

Abstract

Abstract Decomposition of MeTl(OAc)2 (Me = CH3, HO Ac = CH3COOH) in methanol in the presence of amines, like 2-, 3- and 4-picoline, benzylamines, dimethylaniline causes mainly N-methylation; the concurring O-methylation of acetate, giving MeOAc, is only of minor importance. The rate of N-methylation increases in the series 2-picoline ≤ pyridine < 3- picoline < 4-picoline ≤ dimethylaniline ≤ dimethylbenzylamine. Picolinic acid and MeTl(OAc)2 (molar ratio 1:1) react to give 25% N-methylpicolinic acid and 75% MeOAc; when the molar ratio was at least 2:1, a 1:1 mixture of N-methylpicolinic acid and the methylester of picolinic acid was produced. These results and rate changes in different solvents are explained by assuming MeT10Ac+ being the active methylthallium electrophile.