info:eu-repo/semantics/article
Direct synthesis of N-methylurethanes from primary amines with dimethyl carbonate
Fecha
2005-10Registro en:
Tundo, Pietro; Bressanello, Salimo; Loris, Alessandro; Sathicq, Angel Gabriel; Direct synthesis of N-methylurethanes from primary amines with dimethyl carbonate; Int Union Pure Applied Chemistry; Pure and Applied Chemistry; 77; 10; 10-2005; 1719-1725
0033-4545
1365-3075
CONICET Digital
CONICET
Autor
Tundo, Pietro
Bressanello, Salimo
Loris, Alessandro
Sathicq, Angel Gabriel
Resumen
The mechanism of the reaction between amines with dimethyl carbonate (DMC)
has been investigated. Whereas in the absence of bases, they give methylation and carboxymethylation reactions without selectivity (BAl2 and BAc2 mechanisms, respectively), in the presence of bases, the BAc2 mechanism prevails. The carbamate already formed reacts further with DMC via the BAl2 mechanism to give the corresponding N-methyl derivative. Such pronounced double selectivity has been explained in terms of Pearson’s Hard–Soft Acid-Base (HSAB) theory. Accordingly, N-methylcarbamates have been prepared from primary aliphatic and aromatic amines, either at reflux temperature of DMC (90 °C) or at 230 °C in autoclave. The reaction can be carried out in one step or through the isolation of the carbamate and the subsequent methylation reaction with DMC. This method is the direct synthesis, in high yield and selectivity, of secondary N-methylamines from the corresponding primary amines.