Esterification of dicarboxylic acids to diesters over Mn+-montmoril lonite clay catalysts

Esterification of dicarboxylic acids with various alcohols and phenols in presence of metal exchanged montmorillonite clay catalyst (Mn+-mont; Mnþ ¼ Al3þ, Fe3+, Cr3+, Zn2+, Mn2+, and Ni2+) is studied. Among the catalysts used, Al3+-mont was found to be the most effective, as it gave good to excellent yields of esters under mild reaction conditions. The heterogeneous catalyst presented here can be regenerated and reused. All these features indicate the high potential of the reaction as ‘‘green chemistry’’ process

Direct esterification of carboxylic acids with <i style="">p</i>-cresol catalysed by acid activated Indian bentonite

1950-1953Acid activated Indian bentonite (AAIB) catalyst is used for the first time to esterify various carboxylic acids with p-cresol in average to excellent yields. Optimisation studies have been carried out for p-cresyl stearate synthesis. The catalyst is recoverable and recyclable

A facile synthesis of fatty acid esters of <i>p</i>-cresol catalysed by acid activated Indian bentonite

565-568p-Tolyl esters of some long chain fatty acids having commercial applications are synthesized using acid activated Indian bentonite as catalyst. Experimental conditions have been optimised to get the best yields. The effects of the molar ratio and reaction time have been investigated. The rate constant (κ), the equilibrium constant (K) and the standard Gibbs free energy (ΔGo) are calculated. The spent catalyst on regeneration [by washing and heating to 110oC ] shows the same activity, and is found to be reusable several times

Synthesis of <i style="">p</i>-tolyl stearate catalyzed by acid activated Indian bentonite

316-321Synthesis of p-tolyl stearate, catalyzed by acid activated Indian bentonite (AAIB) is reported. The esterification of stearic acid (SA) and p-cresol (p-C) gave p-tolyl stearate in high yield using acid activated Indian bentonite as the catalyst. White montmorillonite exchanged with Al3+ and treated with HCl gave 49 and 51% of the ester respectively after 12 h. Use of p-toluenesulphonic acid as catalyst gave 82% yield of the ester after 12 h in toluene. When the reaction was conducted in toluene and o-xylene with Indian bentonite treated with H2SO4 the yields were 89 and 97% (molar ratio, SA:p-C = 1:4) respectively after 12 h. Effects of molar ratio, amount of the catalyst, solvent, reaction time and catalyst activation temperature on the yield of p-tolyl stearate and reusability of the clay catalyst are investigated