US EPA

1192778 

Journal Article 

Selective N-alkylation of aniline with methanol over gamma-alumina 

Ko, AN; Yang, CL; Zhu, WD; Lin, HE 

1996 

1 

Applied Catalysis A: General
ISSN: 0926-860X
EISSN: 1873-3875 

134 

1 

53-66 

10.1016/0926-860x(95)00209-x 

WOS:A1996TQ31100005 

http://://WOS:A1996TQ31100005
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The alkylation of aniline with methanol over γ-alumina was studied in a fixed-bed, integral-flow reactor at atmospheric pressure and 300-425°C. N-methylation is the predominant reaction with a selectivity higher than 98 mol-% over this temperature range. Increasing reaction temperature and methanol/aniline molar ratio enhances the selectivity of N,N-dimethylaniline. Consecutive methylation of aniline produces N-methylaniline and N,N-dimethylaniline; the corresponding apparent activation energies are 62.7 ± 2.1 and 48.3 ± 2.9 kJ mol-1. N-methylaniline reacts faster than aniline due to the electron donating effect of its methyl group on the nitrogen atom, that facilitates the alkylation with methanol. Based on the FT-IR results and those reported in the literature, it is proposed that both aniline and methanol are adsorbed undissociatively on the Lewis acid-base dual sites of γ-alumina. The electrophilic attack of the methyl group of methanol on the nitrogen atom of aniline or N-methylaniline yields N-methylaniline and N,N-dimethylaniline, respectively. 

activation energy; alkylation; aniline; gamma-alumina; methanol; methylation; N-methylaniline