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N-Methylation of amines and nitroarenes with methanol using heterogeneous platinum catalysts
- Jamil, Md.A.R., Touchy, Abeda S., Rashed, Md. Nurnobi, Ting, Kah Wei, Siddiki, S.M.A. Hakim, Toyao, Takashi, Maeno, Zen, Shimizu, Ken-ichi
- Journal of catalysis 2019 v.371 pp. 47-56
- aromatic amines, catalysts, density functional theory, hydrogen, methanol, nanoparticles, platinum
- We report herein the selective N-methylation of amines and nitroarenes with methanol under basic conditions using carbon-supported Pt nanoparticles (Pt/C) as a heterogeneous catalyst. This method is widely applicable to four types of N-methylation reactions: (1) N,N-dimethylation of aliphatic amines under N2, (2) N-monomethylation of aliphatic amines under 40 bar H2, (3) N-monomethylation of aromatic amines under N2, and (4) tandem synthesis of N-methyl anilines from nitroarenes and methanol under 2 bar H2. All these reactions under the same catalytic system showed high yields of the corresponding methylamines for a wide range of substrates, high turnover number (TON), and good catalyst reusability. Mechanistic studies suggested that the reaction proceeded via a borrowing hydrogen methodology. Kinetic results combined with density functional theory (DFT) calculations revealed that the high performance of Pt/C was ascribed to the moderate metal–hydrogen bond strength of Pt.