Chlorine Peroxidase Catalyzed Olefin Epoxidation Small Molecules

Small molecule epoxides are important organic synthesis intermediates, which can provide large space for the development of down-stream products, which are widely used in the preparation of fine chemicals and pharmaceutical production industry.Chloroperoxidase (CPO) has catalytic activity of peroxidase, catalase and cytochrome P450due to its unique active site structure, it is now considered as the most versatile enzyme in heme metalloproteinases. Halogenated activity is the most characteristic catalytic activity of CPO, while the most powerful catalytic function is epoxidation of olefins with H2O2as a source of oxygen. CPO has a wide range of suitable substrates and the most outstanding feature of it is the chiral recognition function. It can be applied to synthesis of epoxy compound with enantioselectivity.Therefore, in this paper, CPO was employed as catalyst due to its stereospecific selectivity to investigate epoxidation reaction of small molecule cycloolefins and short chain olefins with different substituents, and researched the effects of the structure of substrates and the solvent on the CPO enzyme-catalyzed olefin epoxidation, furthermore, it investigated the embedded CPO in the hydrogel systems. The main findings were as follows:(1) The epoxidation of cyclohexene is most easily to take place among cyclopentene, cyclohexene, cycloheptene, and the yield can reach44.5%; cyclopentene epoxidized product as a by-product with a yield of only10.2%, while the main product is2-cyclopentenone with a yield of15.6%; the main oxidation product of cycloheptene is cycloheptanone in16.3%yield.(2) The epoxidation of3-chloropropene, propylene alcohol, acrylonitrile,3-chloropropene under the condition of tert-butyl hydrogen peroxide oxidation generated in epichlorohydrin with a yield of41%; propylene alcohol under the condition of hydrogen peroxide oxidation generated2,3-epoxy-1-propanol with a yield of28%; epoxidized product of acrylonitrile was not detected.(3) The epoxidized products of3-bromopropene,4-bromo-1-butane and5-bromo-1-pentene were not detected, but the hydroxylation product of3-bromopropene was detected. With the growth of the carbon chain, electron withdrawing group had a great effect on the olefin epoxidation reaction, the longer the carbon chain, the more unfavorable to the occurrence of the epoxidation reaction, at the same time, it found that these three olefins were terminal olefins which can lead to suicide inactivation of CPO.(4) Cyclopentene was prepared for2-chloro cyclopentanol in CPO catalytic and H2O2oxidation, its influence factors (pH value, dosage of oxidant, enzyme dosage and reaction time) were optimized, but the yield of product was only11.63%, the product selectivity was83.56%. Because the substrate was hydrophobic and CPO was hydrophilic, the substrate and CPO can’t effectively contact, leading to the low yield of the product. Therefore, in this paper, we used solvent engineering effect by introducing tetrafluoroborate ionic liquids, polyhydroxy compounds, polysaccharides and surfactants to improve the yield of target product. Results showed that the introduction of the ionic liquid1-ethyl-3-methylimidazolium tetrafluoroborate concentration of5%(VILs/VBuffer) was the best result, the yield of2-chloro-cyclopentanol increased to56.46%.(5) As the free CPO was in poor stability under the extreme conditions such as high temperatures, strong acids, strong alkalis, organic solvents, and could not be reused, and severely restricted the industry applications of CPO. Therefore, the row material sodium alginate with the good biocompatibility was prepared for producing calcium alginate hydrogel as the carrier of chloroperoxidase, and studied the enzymatic properties and applications of encapsulated enzyme, by using CPO enzymatic oxidation degradation of decolorization of dye as the evaluation indexes of encapsulated enzyme activity and through the orthogonal experiment optimization of enzyme in the encapsulated process. Research results showed that the catalytic performance of encapsulated enzyme was improved significantly, expanded the application scope of encapsulated enzyme in the pH value, increased thermal and storage stability, and it can be reused5times. In addition, the study also found that the introduction of additives (polysaccharides and organic solvents) can not only improve the encapsulated rate of the enzyme, but also improve the catalytic performance of the entrapped enzyme.