Kinetics and Mechanism of Ethyl Acetate Production Using Eco-Benign Solid Catalyst

Esterification reaction generally refers to the formation of esters by the interaction of alcohols and carboxylic acids. Alternatively, it refers to as the process of formation of an ester by the reaction between an alkanol and an acid. It is a reversible process and does not proceed to any appreciable extent in the absence of catalysts or supercritical condition. This process is described as an acidcatalyzed equilibrium synthesis developed by Emil Fischer. It is the simplest pathway among several pathways used in synthesis of esters. When catalysed by a strong acid usuallytetraoxosulphate (VI) acid, the reaction is called Fisher esterification. This important process is one of the most organic reactions in chemical and allied industries visa vis its applications as intermediate in the synthesis of fine chemicals, drugs, perfumes, food preservatives, and also in the production of biodiesels via transesterification. It is widely applied from the preparation of highly specialized esters in the chemical laboratory to the production of millions of tons of commercial ester products. 

Esterification process can be carried out either as a batch or a continuous process. The batch procedure involves a single pot reactor that is filled with the acid and alcohol reactants. The acid catalyst is added and the water removed as the reactionproceeds. This method is most often used in the chemical laboratories, but in a few cases, it is used by industry to make large quantities of esters. Ethyl acetate is a colorless liquid with a characteristic smell.

Kinetics and Mechanism of Oxidation of Vanillin by Chromium(VI) in Sulfuric Acid Medium

Vanillin is a phenolic aldehyde, which is an organic compound including aldehyde, hydroxyl and ether. It is the primary component of the extract of the vanilla bean. Vanillin is a significant flavoring reagent in the industry of food and is widely used in the production of drugs. It has been also used as a chemical intermediate in the preparation of pharmaceuticals and other fine chemicals. Furthermore, it is used in the synthesis of perfume and as a catalyst in various polymerization reactions. When the hydroxyl group in vanillin molecule is protected, vanillin is oxidized to vanillic acid. Kinetics of oxidation of vanillin has been studied previously in alkaline solutions by different reagents, as hexacyanoferrate(III), diperiodatoargentate(III), bismuth(V), diperiodatonickelate(IV) and periodate catalyzed by ruthenium(III), and in acid media by cerium(IV).

Oxidation reactions are very important in nature and in organic synthesis. Among the most important oxidants is chromium(VI) which may play a significant role in the chemistry of vanillin in the environment due to the mutagenic and carcinogenic activity of chromium. Chromium exists in both trivalent, Cr(III), and hexavalent, Cr(VI), species in aqueous solutions and the two oxidation states are identified by various physical/chemical behavior and toxicity. 

Chromium(VI) compounds are very dangerous for biological systems, but those of chromium(III) are relatively non-toxic. Chromium(VI) is employed for oxidation of organic compounds and it is reduced to lower oxidation states [9]. The chemistry of Cr(V) and Cr(IV) as intermediate species which may be formed during reduction of chromium(VI) were attracted many researchers because of their involvement in the mechanism of Cr–induced cancers