Abstract
The system hydrogen peroxide/sodium bicarbonate/manganese sulfate was used for the first time to epoxidize cyclopentene. Effects of parameters such as type and amount of solvent, ratio of hydrogen peroxide and manganese sulfate to cyclopentene, presence of additives, and reaction time and temperature on the selectivity to cyclopentene oxide were evaluated. Gas chromatography was used to quantify residual cyclopentene and produced cyclopentene oxide using the internal standard method. Type and amount of solvent, addition method, and temperature were important factors to increase the selectivity to cyclopentene oxide. Unlike previous reports on epoxidation of different substrates, additives like sodium acetate and salicylic acid did not improve the selectivity to cyclopentene oxide. One time, single-step addition of hydrogen peroxide/sodium bicarbonate to the solution of cyclopentene/solvent/manganese sulfate produced more cyclopentene oxide than stepwise addition. The maximum selectivity obtained was 56%, possibly due to the high reactivity of cyclopentene that causes the formation of oxidation products different to cyclopentene oxide, which were not detected in the analyzed phase.
Highlights
Oxidation reactions are important in the petrochemical and fine chemicals industry, and in processes to clean the environment (Wang and Yang, 2015)
Epoxidation reactions have been performed under a wide variety of conditions such as methods developed by Sharpless, Katsuki-Jacobsen, and Shi (Fingerhut et al, 2015) for the enantioselective epoxidation of allylic alcohols or olefins
We report the epoxidation of CPE with sodium bicarbonate/hydrogen peroxide/ manganese (II), a less expensive and environmentally benign system, which has not been reported in the epoxidation of this substrate
Summary
Oxidation reactions are important in the petrochemical and fine chemicals industry, and in processes to clean the environment (Wang and Yang, 2015). Epoxidation reactions have been performed under a wide variety of conditions such as methods developed by Sharpless, Katsuki-Jacobsen, and Shi (Fingerhut et al, 2015) for the enantioselective epoxidation of allylic alcohols or olefins. In the Sharpless–Katsuki method, chiral epoxides of allylic alcohols could be obtained with a catalytic system that contained diethyltartrate, titanium tetraisopropoxide, and terbutylhydroperoxide as oxidant (Sharpless and Katsuki, 1980).Katsuki and Jacobsen used Mn III (salen) complexes as catalyst in epoxidation processes of olefins (Adam et al, 2000). The epoxidation system developed by Shi (Wang et al, 1997) was based on a fructosederived ketone as catalyst and peroxomonosulfate as oxidant. Tungstic acid and its derivatives, zeolites, hydrotalcites, polyoxometalates, manganese complexes, and its salts have been used as epoxidation catalysts (Lane and Burgess, 2003)
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