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[求助]
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1 Introduction
The allylic oxidation of olefin into a, b-unsaturated alco-hols and ketone is an important transformation in natural product synthesis [1]. In particular, the oxidation products of cyclohexene (CHE) and their derivatives, viz. 2-cyclo-hexene-1-one (2-CHON), 1-metylcyclohex-1-en-3-one, etc., are important in organic synthesis owing to the pres-ence of a highly reactive carbonyl group, which is utilized in cycloaddition reaction [2]. Moreover, the products of allylic oxidation of CHE are important intermediates for the synthesis of medication, pesticide, and insect phero-mone [3]. Whitomore et al. synthesized 2-CHON by the oxidation of CHE using chromic anhydride as oxidation in acetic acid solution [4]. However, the separation of reac-tants and products from the reaction mixture was difficult and the yields were low by using this method. The process may also cause severe environmental pollution. Several homogenous and heterogeneous contained manganese, copper, iridium, iron and cobalt complexes catalysts were employed in the allylic oxidation of CHE [5–11]. But most of the cited work suffered from the drawback more or less. For example, the conversion was low and some reactions need organic solvents and special oxidants, such as, tert-butylhydroperoxide, and chloroperoxybenzoic. Some reactions were carried out using molecular oxygen as oxidant at high pressure. Particularly, some homogeneous medium has several disadvantages owing to the typical problems of separation of products from the catalyst. Sakthivel et al. overcame the typical drawback of homogeneous catalysis by using chromium containing mesoporous molecular sieves as catalyst for the oxidation of CHE to 2-CHON [12]. However, the conversion of CHE was also low and peroxide was used as oxidant. Interest-ingly, Sridhar and co-workers studied the effect of various kinetic parameters on the uncatalyzed oxidation of cyclo-hexene with molecular oxygen [13].
A few resinates, such as calcium, zinc, and manganese resinate, were synthesized and found these kind resinates wide application as dryers for paints and varnishes and as constituents of printing inks. But the catalytic properties of these materials have not been explored so far. Therefore, in this work cobalt resinate was synthesized and used as an efficient catalyst for the oxidation of CHE for the first time.
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