低温苯甲醇醇解法制备高活性锐钛矿型纳米晶TiO2光催化剂

 以TiCl4 为钛源,采用低温苯甲醇醇解法制备了不同粒径及晶相组成的大表面TiO2纳米晶,利用X射线衍射、热重-差热分析、透射电子显微镜、拉曼光谱、紫外-可见漫反射光谱和N2物理吸附等方法考察了焙烧温度和焙烧时间对其晶相组成、晶粒尺寸、比表面积及孔体积等微结构性质的影响,并以苯酚的光催化降解为模型反应评价了样品的光催化活性. 结果表明,未经任何热处理的TiO2样品即为锐钛矿晶相,控制焙烧温度及焙烧时间可进一步调控样品的粒径、比表面积、晶相结构及表面氧缺位浓度. 经400 ℃焙烧3 h制备的纳米晶TiO2具有最佳的光催化活性,其活性比商用Degussa P-25 TiO2更高.     

A new catalyst system for silyl ether synthesis

Phenyl substituted silanes are converted to silyl ethers by catalytic amounts of tetrachlorocopper(II) complexes at ambient temperature in high yields.     

A family of novel bifunctional organocatalysts:Highly enantioselective alcoholysis of meso cyclic anhydrides and its application for synthesis of the key intermediate of P2X7 receptor antagonists

A family of novel squaramides/sulfamides based on 1,2-alkamine was developed as chiral bifunctional catalysts to promote the asymmetric alcoholysis of meso cyclic anhydrides.The hemiesters were obtained in high yield with up to 93%ee.The usefulness of this methodology was demonstrated in the asymmetric synthesis of the key intermediate of P2X₇ receptor antagonists.     

甲基二乙氧基硅烷的合成

以MeSiHCl2和EtOH为原料，分别采用溶剂法、酸吸收剂法、气-液相反应法合成了MeSiH(OEt)2，结果表明：溶剂法效果较好，产物含量高达78％左右；其最佳合成条件为：用正己烷作溶剂，MeSiHCl2和EtOH的摩尔比为1：1.9，EtOH以一定的速度滴入MeSiHCl2溶液中，控制反应温度在33℃左右，反应时间2h。     

Tandem One-Pot Conversion of Aldehydes into Ethyl Esters

A facile one-pot synthesis of ethyl esters from aldehydes has been developed. This tandem process involves the formation of a nitrile intermediate obtained from the reaction of an aldehyde with hydroxylamine hydrochloride in dimethylsulfoxide (DMSO) at 100 °C and the subsequent reaction of the nitrile with ethanol and sulfuric acid at 130 °C. The resulting ethyl ester products were produced in good yields (65–90%) and high purity (>95%).

Lipases-Catalyzed Alcoholysis for the Preparation of Chiral 1-or 2- Hydroxyalkanephosphonates

Enzymatic alcoholysis has been developed for the preparation of some chiral 1-and 2-hydroxyalkanephosphonates with high optical purity.This method ensures the convenient access to the optically pure phosphocarnitine,phosphogabob and phosphomycin.     

硫酸氢季铵盐催化环氧化物和氮杂环丙烷的醇解反应

利用四丁基硫酸氢铵(TBAHS)和大孔树脂(D201型)支载的硫酸氢季铵盐(D201-HSO4), 分别催化环氧化合物或氮杂环丙烷与甲醇的开环反应, 以高产率得到β-甲氧基醇或β-甲氧基胺. 两种催化剂对该反应都很有效, 但大孔树脂支载的硫酸氢季铵盐(D201-HSO4)易于制备, 并可以重复使用.     

Development of a Chemical Methodology for the Preparation of Peptide Thioesters Applicable to Naturally Occurring Peptides Using a Sequential Quadruple Acyl Transfer System

Peptide thioesters are very useful in protein chemistry, and chemistry- and biochemistry-based protocols are used for the preparation of thioesters. Among such protocols, only a few biochemistry-based approaches have been use for naturally occurring peptide sequences. The development of chemistry-based protocols applicable to natural sequences remains a challenge, and the development of such methods would be a major contribution to protein science. Here, we describe the preparation of peptide thioesters using innovative methodology that features nickel(II)-mediated alcoholysis of a naturally occurring peptide sequence, followed by O−N and N−S acyl transfers. This protocol involves sequential quadruple acyl transfer, termed SQAT. Notably, the SQAT system consists of sequential chemical reactions that allow naturally occurring peptide sequences to be converted to thioesters without requiring an artificial chemical unit.     

乙酐的醇解反应和集团结构适应性

本文用集团结构适应性原理研究乙酐在CH_3OH、C_2H_5OH和n-C_3H_7OH等14种醇中的醇解反应机理,并对乙酐的醇解反应与醇的分子结构之间的关系进行了探讨.ROH的自身缔合作用不利于乙酐的醇解反应.     

Curing and Glass Transition of Epoxy Resins from Ester-Carboxylic Acid Derivatives of Mono- and Disaccharides,and Alcoholysis Lignin

Mono- and disaccharides (SAC) such as glucose (Glc), fructose (Frc) and sucrose (Suc), and also alcoholysis lignin (AL) were dissolved in ethylene glycol and each of the obtained mixtures was reacted with succinic anhydride to form a mixture of ester-carboxylic acid derivatives such as SAC-polyacid, SACPA, and AL-polyacid, ALPA. Ethylene glycol-polyacid (EGPA) was also prepared from ethylene glycol. Each of the obtained mixtures of ester carboxylic acid derivatives was reacted with ethylene glycol diglycidyl ether in the presence of a catalytic amount of dimethylbenzylamine to form ester-epoxy resins. The molar ratios of epoxy groups to carboxylic acid groups ([EPOXY]/[ACID] ratios, mol mol⁻¹) was maintained at 1.0. The contents of SACPA and ALPA in the mixtures of SACPA/EGPA, and ALPA/EGPA, respectively, were also varied from 0 to 100 %. The curing reaction of SucPA and ALPA was studied by differential scanning calorimetry (DSC). Activation energy of the curing reaction for the SucPA system was 80.5 kJ/mol. Thermal properties of epoxy resins were studied by DSC. Glass transition temperatures (T_g) decreased with increasing numbers of repeating units in ester chains between cross-linking points, suggesting that ester chain lengths between cross-linking points mainly affect the mobility of ester chains in epoxy resin networks.