溶剂和酰基受体对α-氰基-3-苯氧基苄醇乙醇的酶促对映体选择性转酯化反应的影响

研究了在有机溶剂中固定化Alcaligenes sp.脂肪酶催化α-氰基-3-苯氧基苄醇乙酯的对映体选择性转酯化反应，考察了不同性质的溶剂和酰基受体对酶的催化活性和选择性以及对产物稳定性的影响．结果发现在弱极性溶剂如正己烷中酶具有较高的催化活性但产物e．e．％值低，而且容易分解；在四氢呋喃等溶剂中酶催化活性相对低，但产物e．e．％值高，也较为稳定；但反应时间太长，会导致产物分解及纯度下降；不同酰基受体对酶反应无显著影响，甲醇为最佳酰基受体，太多醇会导致反应速率下降；溶剂水含量大于2．0％时对酶活性和产物稳定性产生明显不利影响．在优化条件下，酶反应可得到（S）-α-氰基-3-苯氧基苄醇产率＞48％，纯度＞99％e．e．     

Influence of the Br?nsted and Lewis Acid Sites in Platinum/Solid Acid Catalysts on the Hydrogenation of Benzene and Toluene

The hydrogenation of benzene and toluene was investigated over US-SSY, -Al₂O₃, and Ha1-MCM-41 supported platinum catalysts. The acidity of catalyst supports was measured by IR spectra of pyridine adsorption. On the Brönsted acid supported catalyst, both the hexacyclic saturation product and the pentacyclic one, the hydroisomerization product, were observed, and these two products were revealed to be primary reaction products. The two products were proposed to be formed competitively on Brönsted acid sites with carbonium ions as the reaction intermediate. By contrast, no hydroisomerization product was found on Lewis acid supported catalysts. It was inferred that the electron-deficient reaction intermediate formed on Lewis acids could not undertake any skeletal isomerization process to give a pentacyclic saturation product.     

Mesoscopic simulation of the aggregation behavior of fluorinated surfactant in aqueous solution

The aggregation behavior of fluorinated surfactant in aqueous solution was investigated using dissipative particle dynamics (DPD) simulation method. Simulation results show that fluorinated surfactants behave mainly as their hydrocarbon analogues, having similar sequences of phases and aggregate structures, which are capable of building micelle, hexagonal phase and lamellar phase. But fluorinated surfactants also show interesting differences from hydrocarbon analogues, which can easily form hexagonal and lamellar structures with comparative little curvature. They can also form ellipsoid or rod-like micelles even in very low concentrations instead of spheroid ones. The dynamic aggregation behavior of fluorinated surfactants, as well as the comparison with hydrogenated ones, was also investigated.     

DIRECT DETERMINATION OF NEODYMIUM AND ERBIUM IN RARE EARTH MIXTURE BY DERIVATIVE SPECTROPHOTOMETRY

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol~(-1).cm~(-1) for Nd and 62.5 l.mol~(-1).cm~(-1) for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures.     

手性丙烯酸酯液晶原位光聚合反应

手性丙烯酸酯液晶原位光聚合反应何流，张树范，金顺子，漆宗能，王佛松（中国科学院化学研究所北京１０００８０）关键词手性丙烯酸酯，原位光聚合，双折射，近晶相手性侧链液晶高分子显示近晶Ｓ！相，具有铁电性，在光电功能材料和非线性光学材料方面有潜在的应用前景’...     

STUDY ON POLYSULFONE-POLYESTER BLOCK COPOLYMERS

Synthesis and characterization of a series of Polysulfone (PSF)-Polyester (PEs) block copolymers were studied.The degree of randomness (B) of these block eopolymers was calculated from the intensities of their proton signals in ~1H NMR spectra and lies in the region of 0相似文献   

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