酯化作用

This paper is focused on the preparation, characterization of metal clusters and theircatalytic performance in the enantioselective as well as stereoselective hydrogenations. It iscomposed of the five parts as follows: Chapter 1 A review was given on the two most studied enantioselective systems—Ni/TA and Pt/cinchona system, including some recent progress.

本论文研究了铂、铱纳米金属簇在α-酮酯、α-二酮不对称氢化中的催化性能及金属离子在α-二酮立体选择性氢化中的修饰作用，主要分为以下几部分：第一章对多相不对称催化体系一Ni／TA和Pt／cinchona及其一些最新进展作了较系统的评述；同时简要介绍了纳米金属簇的特性及其在催化中的一些应用。

In the asymmetric hydrogenation of ethyl pyruvate catalyzed by 0 5% Rh/PVP TiO 2, the chiral modifier cinchonidine not only induces the enantioselectivity, but also accelerates the reaction rate greatly.

研究了辛可尼定作手性修饰剂修饰的负载型纳米铑簇合物催化剂(0 5 %Rh/PVP TiO2 )催化丙酮酸乙酯不对称氢化反应，在该反应中手性修饰剂辛可尼定不仅具有对产物生成的手性诱导作用，而且对反应具有明显加速作用；在优化反应条件后，反应的TOF和对映选择性分别可以达到 5 8 0min-1和

Secondly,a mixture of acetone and methyl formate was added into the methanol solution of sodium methoxide to prepare sodium formyl acetone by Claisen reaction.

以金属钠为原料，甲醇为溶剂，先制成甲醇钠的饱和甲醇溶液，再滴加丙酮和甲酸甲酯进行Claisen酯缩合制得丁酮烯醇钠，最后在强酸作用下与甲醇进行缩醛化反应合成了4，4-二甲氧基-2-丁酮，过程总收率达到73.1%，纯度98.7%。

It had been made clear that the carboxylic ester rare earth salt can promote the gelation acting of PVC.

研究表明羧酸酯稀土有促进PVC凝胶化的作用。

The influence of reed produced allelopathy material eathyl-2-methyl acetoacetate on respiration action, photosynthesis action and antioxidant enzymes system of Microcystis aeroginosa were studied.

研究了芦苇产生的化感物质2-甲基乙酰乙酸乙酯对铜绿微囊藻呼吸作用、光合作用和抗氧化酶体系的影响。

In this dissertation, I will represent my studies on the nitration of Chalcone derivatives, reaction of epoxide ketone, and the aromatization of 3,5-disubstitued 2-isoxazolines with nitric oxide.

本文主要研究了：(1)NO与查尔酮及其衍生物的硝化反应，反应以较高的产率得到了a-硝基化合物；(2)NO对环氧酮的开环反应，反应生成了顺式羟基硝酸酯；(3)3，5-二取代的-2-异恶唑啉在NO作用下可以发生芳环化反应，生成了对应的2-异恶唑化合物。

Aging mechanism of wood-plastic composite was: light and heat break down the long molecular chains of wood flour and plastic; the free radicals reacted with the oxygen, which generated carbonyl groups, hydroperoxides and so on; the free radicals also had cross linking reaction, which generated alkoxy; Water destroyed the interface of wood flour and plastic, hydrolyzed ester additives, extracted the small molecule additives and degradation products; Microorganism degraded cellulose, semicellulose, lignin and ester additives; degradation product from different component accelerated the aging, which could be exampled by the fact that HCl from degradation of PVC accelerated the hydrolyzation of cellulose and semicellulose.

木塑复合材料的老化机理为：光和热引发木塑复合材料中木质组分和塑料组分大分子链断裂，产生的自由基与氧气作用，发生链支化反应生成羰基、氢过氧化物等，发生交联反应生成烷氧基等；水分破坏木-塑界面、水解酯类添加剂、抽提小分子添加剂和降解产物；微生物分解纤维素、半纤维素、木素和酯类添加剂；木塑复合材料中各组分的降解产物相互促进老化，PVC降解产生的HCl溶于水，促进了纤维素和半纤维素的水解。

Some useful fluorine-containing intermedi-ates were synthesized by the reaction of activated methylenecompounds or silyl enol ether with 2,2-dihydropolyfluoro-alkanoates or 2-hydropolyfluoroalk-2-enoates in the presenceof different bases.

进一步研究表明，在氢化钠的作用下，苯乙腈，苄基苯基甲酮也可以与2-氢多氟-2-烯酸乙酯发生亲核加成反应，苄基苯基甲酮的加成中间体经多聚磷酸环化，得到了间位氟烷基取代的α-萘酚衍生物。

Besides, n-butyl and sec-butyl tosylate that are difficult for oxidative addition can react with phenylmagnesium bromide to form corresponding cross-coupling products. Primary alkyl halide which contains β-hydrogen and is relatively hard to undergo the reaction , n-butyl chloride for instance, can react with aryl Grignard reagents in the presence of NiB alloy as well.

此外，难以进行氧化加成的对甲苯磺酸正丁酯和对甲苯磺酸仲丁酯可以与苯基溴化镁作用生成相应的交叉偶联产物；反应相对困难的含β-H的伯卤烷，如：正氯丁烷也可以在NiB催化下与芳基格氏试剂发生偶联。

These novel reagents were treated with base to produce polystyrene-supported a-seleno carbanions, which reacted with alkyl halides, followed by stereospecific selenoxide syn-elimination to give 2i-vinylphosphonates and is-vinylsulfones respectively.

它们在碱的作用下形成α—硒基碳负离子，然后与卤代烃发生烷基化反应，烷基化后的树脂可以通过温和条件下的氧化消除以良好产率和较高纯度分别合成了烯基磷酸酯和烯基砜。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。