环氧环己烷的电化学合成

环氧环己烷的电化学合成何俊翔＊周锦成（温州师范学院化学系温州３２５００３）关键词电化学环氧化，环氧环己烷，环己烯，钛基氧化物电极１９９６－１１－２２收稿，１９９７－０６－０５修回间接电解氧化合成环氧化合物的研究已有报道［１～４］．它们均在铂电极上完成...     

钙和钒离子对钒-溴过氧化物酶催化 H2O2 氧化环己烯反应的影响

 在溴化钾存在下, 大型海洋藻类珊瑚藻的钒-溴过氧化物酶 (V-BPO) 可在常温下催化 H₂O₂ 环氧化环己烯生成环氧环己烷. 通过用含 1.0 mmol/L 钒离子和 1.0 mmol/L 钙离子的缓冲溶液透析 V-BPO, 用恒流泵向反应体系中连续添加 H₂O₂, 并优化其它反应条件, 可提高该催化反应时空收率. 在优化的反应条件下, 产物环氧环己烷的时空收率为 4.79 g/(h•L), 对 H₂O₂ 的收率为 74%, 均比文献最高值提高了 78%.     

Mechanistic discussion of cationic crosslinking copolymerizations of 1,2‐epoxycyclohexane with diepoxide crosslinkers accompanied by intramolecular and intermolecular chain transfer reactions

Our previous mechanistic discussion of the free‐radical crosslinking monoallyl/diallyl copolymerizations was extended to the cationic crosslinking monoepoxide/diepoxide copolymerizations, typically including 1,2‐epoxycyclohexane (ECH) as a monoepoxide and bis[3,4‐epoxycyclohexylmethyl] adipate (BECHMA) as a diepoxide crosslinker. In the cationic polymerization, oligomer is usually obtained because of the occurrence of characteristic chain‐forming reactions. Therefore, cationic crosslinking monoepoxide/diepoxide copolymerizations could be in the category of the network formation through free‐radical crosslinking monoallyl/diallyl copolymerizations. Thus, the gelation behavior was discussed by comparing the actual gel points with the theoretical ones; the greatly delayed gelation from theory was observed. Then, the resulting network polymer precursors (NPPs) were characterized by SEC‐MALLS‐viscometry to clarify the cationic crosslinking ECH/BECHMA copolymerization mechanism. Notably, the correlation lines of molecular weight versus elution volume were specific for the NPPs obtained at a high conversion close to the gel point as compared with those obtained by the free‐radical crosslinking monoallyl/diallyl copolymerization. This may be ascribed to the occurrence of intramolecular and intermolecular chain transfer reactions characteristic of cationic polymerization; the chain transfer reactions involve the intramolecular and intermolecular nucleophilic attack of ether oxygen or terminal hydroxyl oxygen in the NPPs to a terminal growing cation that leads to the formation of not only the loop‐ but also the crosslink‐structures containing NPPs, providing fragile ultrahigh‐molecular‐weight NPP in the SEC columns. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

磷酸镍纳米管的合成及其催化环己烯环氧化反应性能

 在不添加有机模板剂的情况下, 通过尿素缓慢分解调节局部 pH 值, 水热法合成了具有均一孔道直径的磷酸镍纳米管材料 (NiPO-NTs). 采用 N2 吸附-脱附、吡啶吸附红外光谱和氨程序升温脱附对材料进行了表征, 并将其用于催化 H2O2 氧化的环己烯反应中, 考察了反应条件对环氧化反应性能的影响. 结果表明, NiPO-NTs 具有狭窄的孔径分布, 比表面积为 96.6 m2/g, 其表面酸中心以弱 Lewis 酸为主. 该反应中以乙腈为溶剂较为适宜, 高温和高 H2O2/环己烯摩尔比有利于提高环己烯转化率; 而低温和高 H2O2/环己烯摩尔比有利于提高环氧环己烷选择性. 在 60 oC, H2O2/环己烯摩尔比为 3, 反应 6 h 时, 环己烯转化率可达 50.6%, 环氧环己烷选择性为 72.1%.