Acid-Catalyzed Reactions in the Liquid Phase

Heteropolyacids are more active catalysts for various reactions in solution than conventional inorganic and organic acids, and they are used as industrial catalysts for several liquid-phase reactions (6, 12). Important characteristics accounting for the high catalytic activities are the acid strength, softness of the heteropolyanion, catalyst concentration, and nature of the solvent (6, 7, 9, 116, 160, 161). 

Rate constants (per mole of protons) for decomposition of isobutyl propionate as a function of Hu values of ll XW 2O40 (acetonitrile solutions). (From Ref. 63.) 

The concentration of the heteropolyacid is sometimes critical. Excellent performance was demonstrated for the hydration of butenes when heteropolyacids were used in a highly concentrated solution (163). As shown in Fig. 24, the rate increases remarkably with an increase in the concentration of 

TOSHIO OKAJHARA, NORITAKA MIZUNO, AND MAKOTO MISONO 

C6H5OCH3 + CHjCOCI ---- C H4OCH3(COCHj) H4SiMo,304o Reflux 

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Izumi, Y, Urabe, K., Onaka, M. 1997. Development of catalyst materials for acid-catalyzed reactions in the liquid phase. Catalysis Today 35(1-2) 183-188. 

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