Studies On The Synthesis And Process Of Pinene Epoxide And Strawberriff By Selective Oxidation

Oxidation reaction is one of the important organic reactions. Most of the oxidation products are very important fine chemical intermediates. Such as2,3-epoxypinane,2,10-epoxypinane and strawberriff are fragrance intermediates or food flavors. In this paper,5,7-dibrominated Q.MnⅢ complex was used to catalyze the epoxidation of a-pinene and β-pinene with30%aqueous solution of hydrogen peroxide.This catalysis system has the following advantages:The use of inexpensive catalyst and oxidant, green water-acetone solvent conditions, high utilization of H2O2, good yield of final products, easily isolating the products, and good repeatability of catalyst. Therefore, this catalysis system has certain value for developing pinene epoxide industry to some extent. In addition, air is an inexhaustible source of natural oxidant. Also, we have tried to explore the air oxidation of2-methyl-2-pentanal to strawberrif upon catalysis by various effective catalysts. So far we have done a series of exploratory works on the selective oxidation of2-methyl-2-pentanal, which possesses guiding significance for synthesizing strawberriff with air as oxidant. Our works are summarized in details as follows:1)5,7-dibrominated complex (Q3MnⅢ) has been prepared and characterized by IR, UV-Vis spectrocopy, TG-DSC and the titration of Mn ion content. And the epoxidation of α-pinene and β-pinene with30%hydrogen peroxide were used to check the catalytic performance of Q3MnⅢ. The results indicated when1mol%Q3MnⅢ catalyst with n(substrate):n(H2O2)=1:1.75was used to catalyze both the epoxidations in water-acetone solvent at10℃, providing α-pinene conversion of96%with2,3-epoxypinane selectivity of81%and β-pinene conversion of99%and2,10-epoxypinane selectivity of69%.2) A lot of works have been focused on isolating products, reusing the catalyst and solvent. It turns out that the catalyst is easily recovered by leaching and reused up to six times. Eventually, an optimal scheme of isolating products together with recycling of the catalyst and solvent was developed after fully considerating various factors.3) A sequence of inexpensive inorganic and organometallic compounds was used to catalyze the air oxidation of2-methyl-2-pentanal to strawberriff. The results revealed that cobalt(Ⅱ) acetylacetonate was an excellent catalyst for this oxidation reaction. When this reaction was carried out with0.1mol%cobalt(Ⅱ) acetylacetonate in isopropyl alcohol at25℃,2-methyl-2-pentanal conversion of31%, strawberriff selectivity of60%and strawberriff yield of19%were obtained.