碳化钨在对硝基苯酚电还原过程中的电催化行为

以碳化钨(WC)粉末为电催化材料制成了碳化钨粉末微电极(WC-PME). 采用循环伏安和线性扫描等方法研究了酸性溶液中对硝基苯酚(PNP)在WC-PME上的电还原行为. 研究表明, 在相同测试条件下, PNP在WC-PME上电还原的电位比Cu-Hg微电极正得多；WC-PME对氢具有较强的吸附能力, 有利于有机物的电还原反应. PNP在WC-PME上和Pt微电极上的还原电位相近, 但在WC-PME上的峰电流比在Pt微电极上高5倍多, 这主要与WC粉末的结构形貌有关.     

二-(1-甲基-1-七氟异丙基)五氟丙基过氧化二碳酸酯的合成

报道了一个可能的自由基前体——二-(1-甲基-1-七氟异丙基)五氟丙基过氧化二碳酸酯(1)的合成方法及其特性. 以全氟2-甲基-3-戊酮(2)为原料, 与甲基碘化镁反应后所得到的醇再与光气进行氯甲酰化反应, 随后与过氧化钠的过氧化反应后, 以17%的总产率首次合成了目标化合物.     

4-吡唑基-2-芳氧基嘧啶类化合物的合成及除草活性

以2,4-二氯嘧啶为起始原料, 利用两个氯原子的活性差异, 经4-吡唑基-2-氯嘧啶合成了一系列4-吡唑基-2-芳氧基嘧啶类化合物, 通过¹H NMR和元素分析对所合成的化合物进行了结构表征. 初步生物活性测定结果表明, 所合成的化合物都表现出一定的除草活性. 当嘧啶环2位的氯原子被芳氧基取代后, 化合物的除草活性均有不同程度的提高, 例如5c和4a相比, 100 μg•mL^－1时化合物对油菜的抑制率由15.7%提高到85.4%, 对稗草的抑制率由原来的11.6%提高到84.0%.     

Unexpected epimerization and stereochemistry revision of IMDA adducts from sorbate-related 1,3,8-nonatrienes

Intramolecular Diels-Alder (IMDA) reaction of two sorbate-related 1,3,8-nonatrienes has been investigated in MeCN at 180 °C for 1.5 h under controlled microwave heating. On checking the crude product mixture before purification, partial epimerization of the major adduct was found during the reaction. After column chromatographic purification over silica gel, only two cis adducts were obtained and their structures have been thoroughly established by X-ray crystallographic analysis. It is concluded that the putative major trans adduct predicted by the IMDA reaction mechanism undergoes facile epimerization at high temperature or in the presence of silica gel. Structural revision on the adducts has been made.     

Steady State Approximation on Constant-Stepsized Computer Simulation

Constant-stepsized computer simulation of chemical reactions gives unreasonable results when the accepted stepsize exceeds a limit. The maximum permitted stepsize is found as the lifetime of the most reactive intermediate in the mechanism from mathematical derivations on simple reaction models. Steady state approximation on this reactive intermediate may relieve this limitation and save computer's computation time. This approximation method has been satisfactorily applied to the simulation of the thermal decomposition of methane.     

Clean preparation of S-thiocarbamates with in situ generated hydroxide in 2-methyltetrahydrofuran

A simple and clean protocol for the synthesis of various alkyl and (hetero)aryl S-thiocarbamates was established. The usage of in situ generated hydroxide as both an oxygen source and hydrogen source as well as biomass-derived 2-methyltetrahydrofuran as a green reaction medium, the avoidance of phosphorus-containing reductant, and the generation of harmless water and nitrogen as the side-products have given the present method atom-economy and environmental friendliness.     

One-pot regioselective annulation toward 3,4-dihydro-3-oxo-2H-1,4-benzoxazine scaffolds under controlled microwave heating

An efficient and general synthesis of 2-alkyl-3,4-dihydro-3-oxo-2H-1,4-benzoxazines under controlled microwave heating has been established. It consists of a microwave-assisted reductive N-arylmethylation of substituted 2-aminophenols with aromatic aldehydes followed by a one-pot base-mediated regioselective O-alkylation of the N-arylmethyl-2-aminophenols with 2-bromoalkanoates to give the acyclic intermediates, which cyclize spontaneously to furnish the benzoxazine scaffolds in good to excellent yields. It was found that microwave heating over 180 °C was necessary for ring closure of the acyclic intermediates possessing an electron-withdrawing group.     

Mg-Zn-Al三金属类水滑石的合成及其复合氧化物的催化性能

水滑石（[Mg_６Al_２（OH）_(１６)[CO_３·４H_２O）是一种类似于水镁石结构的层状阴离子黏土，其骨架为阳离子，层间为阴离子。如改变骨架中的金属阳离子或在层间引入不同的阴离子，就可形成各种新组成的类水滑石。水滑石对有机分子反应具有较高的催化活性和选择性，且可以作为复合氧化物催化剂的前体，应用广泛。它作为碱催化剂，可用于醇醛缩合；作为氧化还原催化剂，用于水煤气转化、NO的还原、甲烷氧化反应等犤１，２犦。作为一种具有特殊结构的化合物，各种双金属组分的水滑石或类水滑石的合成、性质与应用已受到广泛的重视犤３…     

片呐醇电合成的研究

以铝合金为电极在酸性条件下电合成片呐醇, 探讨了电压、反应时间等对产率的影响. 最佳反应条件为: 电解电压为12 V, 反应时间60～80 min, 甲醇和盐酸(36%)用量各5 mL, 片呐醇的产率可达31%～81%.