| #-Pinene as one of the best important monoterpenes, which exists in turpentine oil, can be used as original material to produce a series of perfumes and medicine intermediates. In this paper, the photo-sensitized catalytic oxidation and mechanism of a-pinene were studied. Through a-pinene photosensitized catalytic oxidation, verbenol, verbenone, myrental, myrentol, 4-hydroxy-2,3-epioxypinane, 4-hydr-oxy-2,3-epioxypinane were produced from a-pinene. The reaction take place in a water-bathed reactor, in which photosensitizer, solvent and catalysts were poured in, oxygen as stirred gas and reactant, high pressure sodium light as irradiated source. Capillary column GC instrument, and GC-MS, IR, UV-Vis analyzed the products; 'HNMR also were used to identify their structure. The effects of. photo-sensitizer, solvent, catalyst were investigated.1. The comparison of photosensitizersHigh pressure sodium light used as irradiated source, methanol as solvent, several photosensitizers were considered, When #-pinene's concentration is 0.5mol-L-1, Rose Bengal as photosensitizer, the conversion is 81.77%, the main product is verbenone, and, its selectivity is 34.52%. While methylene blue was employed, the conversion and selectivity are 89.35%, 32.17% respectively. But for other photosensitizers have conversion were less than 40%, and the main products' selectivity even lower than 10%.The most possible mechanism of photo-sensitized oxidation of a-pinene may be described as through an allylic hydroperoxide process, then the intermediates can be reduced to alcohols, decomposed to ketones or aldehydes, and through a intermolecular oxidation to get the epioxypinanes.2. The catalytic effect in Rose Bengal as photosensitizerWhen the molar ratio of Rose Bengal and #-pinene with 1:150, theconversion of #-pinene was 83.41%, the selectivity of verbenone was 36.46%.The influence of several containing nitrogen heterocyclic com-pounds as catalysts were studied, and it was found out that 2,6-di-methylpyridine to get a better catalytic effect, the conversion of a-pinene and the selectivity of verbenone were 84.90%, 61.64% respectively, while the residues were 10.70%.When acetic anhydride and 2,6-dimethylpyridine used as composite with the molar ratio is 1:1,which get a good catalytic effect. At 300K, and 4hour reaction time, the conversion of #-pinene was up to 96.77%, while the selectivity of verbenone was 55.98%. The residues only 1.56%. 3.The catalytic effect in methylene blue as photosensitizerWhen methylene blue was used as photosensitizer, 2,6-dimethyl-pyridine was used as catalysts, the conversion of a-pinene was 93.93%, and the selectivity of verbenone and 4-hydroxy-2,3-epioxypinane were 37.20% and 27.53% respectively.When DMF as solvent, which had the conversion up to 99.21% and the selectivity of verbenol, verbenone, myrental were 20.61%, 53.07%, 18.84%. The residues only 3.01%.When amino acids were used as catalysts, L-phenylalanine had a better catalytic effect, the conversion was 97.40%, while the selectivity of verbenol, verbenone, and 4-hydroxy-2,3-epioxypinane were 11.45%, 41.76%, 23.62% respectively. 4. Comparison of several monoterpenesa-Pinene, P-pinene and carene were irradiated at the same conditions, #-pinene had the highest conversion and the main product was verbenone, P-pinene had a higher conversion and the main product was myrental, its selectivity up to 85.58%, while the conversion of carene was the lowest.
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