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1694295 
Journal Article 
Selective mono-N-methylation of primary aromatic amines by dimethyl carbonate over faujasite X- and Y-type zeolites 
Selva, M; Bomben, A; Tundo, P 
1997 
Journal of the Chemical Society, Perkin Transactions 1
ISSN: 1472-7781
EISSN: 1364-5463 
7 
1041-1045 
WOS:A1997WU66400012 
The reaction of dimethyl carbonate (DMC) with different primary aromatic amines has been investigated under batch conditions (autoclave) in the presence of Y- and X-type zeolites. Operating at 120-150 degrees C, highly selective mono-N-methylations are observed for anilines even when they are deactivated by either electronic effects or steric hindrance (G-C6H4NH2, G = p-NO2, p-CN, o-CO2CH3 and 2,6-dimethylaniline); typical selectivities for the formation of the corresponding mono-N-methyl derivatives [ArNH(CH3)] are in the range 92-98%, at a substrate conversion of 72-93%. A synergic effect between the reactivity of DMC (acting both as a methylating and as a reversible methoxycarbonylating agent) and the dual acid-base properties of zeolites is considered to be responsible for the unusually high selectivity observed; accordingly, a reaction mechanism is discussed, involving carbamates (ArNHCO2CH3) and N-methyl-carbamates [ArN(CH3)CO2CH3] as intermediates. The reaction is an example of a synthesis with low environmental impact: it couples the use of a non-toxic methylating agent (DMC, in place of the highly toxic methyl halides or dimethyl sulfate) with eco-friendly catalysts (zeolites) in a waste-free process.