Study On Catalytic Oxidation Of Pinene By Vanadium Pentoxide

Catalytic oxidation of monoterpenes has important economic value,so it is necessary to explore these reactions in depth.In this paper,the reaction of two typical monoterpenes,alpha-pinene and beta-pinene,under the catalytic oxidation of hydrogen peroxide by vanadium pentoxide was studied.Vanadium pentoxide is a common catalyst with good catalytic performance,so it has been widely used in catalytic reaction for a long time.The research mainly focuses on the following aspects.(1)Vanadium pentoxide was used to catalyze the oxidation of alpha pinene and beta pinene by hydrogen peroxide.The effects of temperature,time,kinds and dosage of solvents,amount of catalyst,ratio of pinene to hydrogen peroxide on the conversion and selectivity of products were investigated.The results showed that the conversion and selectivity of the reaction reached 90.0% and 47.4% respectively after 4 hours in acetone solvent at 20?.The conversion of the reaction decreased slightly after adding a small amount of acetic acid,but the selectivity of the main product,pinencephalon hydrate,increased to 54.1%.This also indicates that hydration pinencephalon,the main product,is easier to produce in weak acid environment.The utilization rate of hydrogen peroxide was also investigated by the residual amount of hydrogen peroxide after titration reaction.It was found that hydrogen peroxide was used at room temperature.Generally speaking,this reaction has the characteristics of simple operation,low energy consumption and high reactivity.(2)Alpha-pinene is easy to oxidize,and the products after oxidation are more and difficult to separate.No separation work has been carried out in many studies.In this paper,steam vacuum distillation,extraction and column chromatography were used to separate the products.After many attempts,fewer kinds of mixed products were obtained.The products were characterized by gas chromatography-mass spectrometry,and the structure of the products was determined by comparative analysis.(3)The mechanism of vanadium pentoxide catalyzing the oxidation of alpha-pinene by hydrogen peroxide is still mature,and it is also the difficulty of the research work.The research mainly starts from two aspects.One is to try to explore the mechanism of the reaction by characterizing the structure changes of the catalyst before and after the reaction and the composition of the reaction solution.First,according to the characterization results,the possibility of vanadium oxypyruvate formation was proposed,and the catalyst vanadium oxypyruvate was further synthesized.The catalytic performance of vanadium oxypyruvate was investigated by catalytic oxidation of alpha pinene.The results showed that vanadium oxypyruvate had good catalytic effect at room temperature,and the product distribution was consistent with that of vanadium pentoxide.All the substances were hydrated pinnacles.