HPW and supported HPW catalyzed condensation of aromatic aldehydes with aniline: Synthesis of DATPM derivatives

The mesoporous Si-MCM-41 was synthesized by hydrothermal method and various wt.% (20 and 30 wt.%) of HPW were loaded on Si-MCM-41 by wet impregnation method. The synthesized Si-MCM-41 and HPW-loaded catalysts were characterized by XRD, BET surface area, FF-IR, TEM and TGA-DTG techniques. The catalytic activity of the catalyst was tested over the condensation reaction of aniline with various aromatic aldehydes at refluxing temperature under liquid-phase condition, which yields highly commercial product namely diamino triphenyl rnethanes (DATPMs). The effects of various parameters like catalyst, mole ratio. solvents and substituent effect on the formation of DATPMs were optimized. The catalytic activity of the catalysts showed the following order: H3PW12O40 center dot nH(2)O > H3PMo12O40 center dot nH(2)O > H4SiW12O40 center dot nH(2)O > 20 wt.% HPW/MCM-41 > 30 wt.% HPW/MCM-41 > HM (12) > H beta (8) > HY (4) > HZSM-5 (15) > Al-MCM-41 (25). The results showed that mole ratio of 4:1 (aniline:aldehyde) gave higher yield than the other mole ratios. Acetonitrile and ethyl acetate shows better activity especially in the supported materials than toluene was used as a solvent. The product thus obtained was analyzed by H-1 NMR, FT-IR techniques. (C) 2007 Published by Elsevier B.V.