| Olefinic oxides,such as epoxides,ketones and aldehydes mainly prepared by oxidation of olefines,are important chemical intermediates, which are widely used in fine chemicals,polymer materials,organic synthesis,perfumer and medicament.Although many methods on the oxidation of olefines to their derivatives were reported,there are many problems concerning low yield,catalyst lost,harsh condition,and serious pollution.In order to improve the method of synthesizing olefinic oxides, we chosed molecular oxygen as the oxidant,and the research works below have been done:At first,the supported catalyst CMPS-Co(acac)2 has been synthesized by grafting reaction of chloromethylated polystyrene resin(CMPS) and acetylacetone cobalt(Ⅱ),and the two other catalysts Co(acac)2/SiIm and MoO2(acac)2/SiIm have been prepared by supporting Co(acac)2 and MoO2(acac)2 on silica gel modified with 3-chloropropyltrimethoxysilane and imidazole(SiIm).And the process conditions of supporting reaction were optimized.Under the optimum conditions,The cobalt content in CMPS-Co(acac)2 was 8.78%(grafting ratio 77.09%),cobalt content in Co(acac)2/SiIm was 3.84%(0.65 mmol/g),and the molybdenum content in MoO2(acac)2/SiIm was 6.43%(0.67 mmol/g) measured by ICP-AES.Then,the oxidation ofβ-ionone catalyzed by CMPS-Co(acac)2 has been performed,andβ-ionone was oxidized to 4-oxo-β-ionone as the main product,and the influence of a series of different conditions for the reaction was also investigated.In acetone,utilizing O2 as the oxidant, CMPS-Co(acac)2 as catalyst has been perfected:(1) To a solution ofβ-ionone(0.02 mol) in acetone(20 mL) in a three-necked flask equipped reflux condenser was added CMPS-Co(acac)2(2 mol%),the mixture was heated to 55℃and stirred for 6 h under 1 atm O2.The yield of 4-oxo-β-ionone and 5,6-epoxy-β-ionone were 33.7%and 25.6% respectively.(2) Other things being equal,the oxidation ofβ-ionone catalyzed by CMPS-Co(acac)2,Co(acac)2/SiIm and MoO2(acac)2/SiIm combined with 150 mol%butyraldehyde as reductant have also been studied.The results showed that the reaction conversion and selectivity were increased remarkably,the yield of 5,6-epoxy-β-ionone as the predominant product were 87.0%,81.9%and 84.4%respectively.On the basis of aerobic oxidation ofβ-ionone catalyzed by supported catalysts/butyraldehyde system,a series of cycloolefines such as cyclohexene,β-methylionone,α-ionone,andα-pinene were oxidized under the general conditions to give corresponding epoxides and allylic oxides. Generally speaking,the reaction conversion and selectivity had a big change,but the oxidation of cycloolefines in three catalyst systems were similar with horizontal comparison.Specifically,the reaction conversion and yield of epoxides for cyclohexene,β-methylionone,α-ionone, limonene andα-pinene were 78-96%and 81-91%,for example,under MoO2(acac)2/SiIm-butyraldehyde catalytic system,the the conversion of cyclohexene and the yield of 2-cyclohexene-1-one were 95.1%and 86.1%.But theβ-pinene and 1-phenyl cyclohexene were oxidized to give allylic oxides as the main products,in which the conversion ofβ-pinene and the selectivity ofβ-epoxypinane were 67.3%and 45.8%respectively; the conversion of 1-phenyl cyclohexene and the selectivity of 3-phenyl-2-cyclohexen-1-one were 47.8%and 55.1%respectively. |
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