Methylation of aniline over a mildly acidic siliconaluminium phosphate
catalyst (SAPO-11) with medium pores is reported. The selectivity of
N-methylates products is about 90%. By comparison with results obtaine
d from SAPO-5 with large pores and with amorphous aluminium phosphate,
molecular sieves with medium pores prevent the formation of bulky iso
mers and better resist formation of coke. The ortho isomer is most abu
ndant among toluidine isomers. Some ortho isomers may result from the
rearrangement of N-methylaniline.