Epoxidation of olefinic double bonds is of considerable importance in a variety of industries. Epoxides are raw materials for a wide variety of chemicals such as glycols, alcohols, carbonyl compounds, alkanolamines, and polymers such as polyesters, polyurethanes, and epoxy resins. Epoxidation of styrene with aqueous H2O2 was carried out by using synergism of heteropoly acids and phase-transfer catalysis in a biphasic system under the so-called Ishii−Venturello chemistry. The kinetics of epoxidation of styrene to styrene oxide was studied. Styrene was converted quantitatively to styrene oxide with 100% selectivity of the converted styrene in ethylene dichloride as the solvent at 50 °C. The effects of various parameters were studied on the rate of reaction. Dodecatungstophosphoric acid (DTPA) and cetyldimethylbenzylammonium chloride (CDMBAC) were found to be the best heteropoly acid (HPA) and PTC combination, respectively, for the epoxidation. The reaction mechanism is very complex. At higher temperatures, there is a slight degradation of hydrogen peroxide as well as some thermal oligomerisation of styrene. The kinetic equation is complex due to the nature of the epoxidising species. The reaction can be represented by a pseudo-first-order kinetics where the order in styrene concentration is unity. An apparent activation energy of 7.26 kcal/mol was found.

Sulfated zirconia (S−ZrO2) is a well-known solid superacid used as a catalyst in various reactions of commercial importance such as isomerization, Friedel−Crafts alkylation and acylation, nitration, cracking, esterification, etc. S−ZrO2, per se, is not a shape-selective catalyst. The selectivity toward the formation of the desired product can be greatly enhanced by eclectically designing a shape-selective catalyst by a synergistic combination between S−ZrO2 and carbon molecular sieves (CMS). The paper presents the novelty of the combination of S−ZrO2 and CMS, designated as UDCaT-2, as a shape-selective catalyst in the cyclization of citronellal to isopulegol which has industrial value. UDCaT-2 was found to be the best catalyst, among others, for the selective cyclization of citronellal to isopulegol wherein the shape selectivity can be tailored by proper pretreatment. The conversion and selectivity were found to be the maximum at 95 °C. The formation of isopulegol was found to be dependent on the average pore size of the carbon molecular sieve barrier encompassing S−ZrO2. A detailed kinetic study of the reaction showed that it followed a Langmuir−Hinshelwood−Hougen−Watson type of mechanism whereby citronellal was found to be weakly adsorbed on the catalytic surface sites. The reaction was found to follow first-order kinetics for the disappearance of citronellal.

Although phase-transfer catalysis (PTC) is a mature discipline, several intricacies of PTC in reactions of industrial importance are not understood or properly modeled. For instance, the effect of the nature and number of phases on the intensification of rates and selectivities has not been investigated in detail. This study deals with the efficacy of the so-called omega phase, which is a small quantity of aqueous phase in a solid reactant-organic liquid reaction involving PTC, in intensification of the rates of the cyanide displacement reaction on p-chlorobenzyl chloride, with special emphasis on the kinetic and modeling aspects. As the reaction proceeds, the process converts itself from a S(reagent)-L(ω)-L(org) into a L(ω)-L(org) PTC system. This paper gives a complete theoretical and experimental analysis of the role of the ω-phase in enhancing the rates of the reaction and the importance of the L(ω)-L(org) PTC system with a phase ratio divergent from that of the normal L(aq)-L(org) PTC system.