Oxidative Cleavage of Methyl 9,10-Epoxystearate over WO3/MCM-41 for Methyl 9-Oxononanoate Production

At present, the utilization of grease has attracted more and more attention. This article presents a simple method that efficiently cleaves methyl oleate-derived methyl 9,10-epoxystearate (a) to give high yields of methyl 9-oxononanoate (d) with nonanal (c) as co-product. A WO3/MCM-41 catalyst is prepared via direct mixed-gel synthesis. The catalyst is tested in the oxidative cleavage of a to produce d which can be used as a polymer precursor or an important feedstock. The effects of WO3 loading, temperature, time, H2O2/a molar ratio, catalyst/a weight ratio, and t-BuOH/a weight ratio on the a conversion and d yield are examined using single-factor experiments. The optimal reaction conditions are determined by orthogonal experiments. The optimal WO3 loading, temperature, time, H2O2/a molar ratio, catalyst/a weight ratio, and t-BuOH/a weight ratio are 35%, 80 degrees C, 20min, 1.3, 0.04, and 0.5, respectively. Under these conditions, the a conversion and d yield reach 99.4 and 78.4%, respectively. In addition, the catalyst shows no significant decrease in activity after being reused three times. Moreover, the reaction mechanism is studied based on the product distribution over time.Practical Applications: Few studies on methyl 9,10-epoxystearate used as the raw material to give methyl 9-oxononanoate and nonanal are found. Because the ethylene oxide bond is more unstable than the carbon-carbon double bond, the oxidative cleavage of methyl 9,10-epoxystearate is easier than cleavage of methyl oleate that allows the oxidative cleavage to be done under milder conditions. Methyl 9-oxononanoate can be converted to a monomer of high-value polymers and is also an important feedstock in the production of chemicals. The co-product nonanal is a natural spice which can be used in the fragrance industry. The results show that the reaction time is short and methyl 9-oxononanoate yield is high under mild reaction conditions. The method in this study can also be widely used in other oxidative cleavage reactions of epoxides. Methyl 9,10-epoxystearate is used as the raw material to produce methyl 9-oxononanoate with nonanal as co-product using WO3/MCM-41 as catalyst and H2O2 as oxidant.