Synthesis of calix[4]arene alkylamine derivatives as new phase-transfer catalysts for esterification reaction

This study reports the synthesis of calix4]arene-based phase-transfer catalysts derived from the reaction of 5,17-di-tert-butyl-25,27,26,28-tetrahydroxycalix4]arene with N-ethylpiperazine, diallylamine or 4-benzylpiperidine. The catalytic efficiency of the calix4]arenes alkylamine derivatives was evaluated by carrying out the ester-forming reaction of alkali metal carboxylates (sodium butyrate or sodium caprylate) with p-nitrobenzyl bromide. It has been observed that the ester-forming reaction of alkali metal carboxylates with p-nitrobenzyl bromide, using the N-ethylpiperazine amine derivative of calix4]arene as a phase-transfer catalyst in dichloromethane at 25 °C, provided the best yields.