查询词典 first-order reaction

This work, concentrated on the asymmetric allylation of aldehydes controlled by different chiral auxiliaries prepared from rotational pure tartaric acid, can be divided into three parts.The first part aims to review the developments of chiral drugs and asymmetric synthesis, from which derived the present research topic backgrounds and works.Synthesis and applications of allylation from aldehydes are the second part of the thesis. By optimizing the reaction conditions, such as solvents, temperature, time and chiral auxiliaries like N,N\'-dibenzyl tartamide, N,N\'-p-dimethylphenyl tartamide, N,N\'-o-dimethylphenyl tartamide, N,N\'-o-dichlorophenyl tartamide, N,N\'-a-dinaphyl tartamide, N,N\'-dicyclohexyl tartamide and N,N\'-diphenyl tartamide, ideal experimenttal conditions are obtained according to HPLC monitoring, as well as the auxiliaries\' recoveries experiments. Starting from benzaldehyde and 3-bromopropaldehyde, N,N\'-dibenzyl tartamide is considered the best auxiliary in this reaction.

本文介绍了醛的不对称烯丙基化反应，以光学纯酒石酸为原料，研究了不同构型手性配体在醛的烯丙基化反应中的立体选择性，全文共分三部分十个章节：第一部分对当前手性药物和手性技术进行了概述，并由此展开了本文的研究背景和任务；第二部分为有机合成部分，对醛的不对称烯丙基化反应进行了深入探讨，以苯甲醛为原料对反应条件进行优化，在优化的反应条件下对制备的七种可回收手性酰胺配体(N-苄基酒石酸二酰胺、N-对甲苯基酒石酸二酰胺、N-邻甲苯基酒石酸二酰胺、N-邻氯苯基酒石酸二酰胺、N-a-萘基酒石酸二酰胺、N-环己基酒石酸二酰胺和N-苯基酒石酸二酰胺)进行筛选，优化配体回收实验条件，最终确定出N-苄基酒石酸二酰胺在苯甲醛的不对称烯丙基化反应中具有较大优越性，结晶回收的手性配体光学纯度保持不变。

The first asymmetric total synthesis of coumarinolignoids Daphneticin and it's enantiomer was accomplished starting from 7-hydroxycoumarin and 3, 4, 5-trimethoxybenzaldehyde, in which Sharpless asymmetric dihydroxy reaction was used to construct chiral center, and Mitsunobu reaction was used to obtain desired configuration.

并以7-羟基香豆素和3，4，5-三甲氧基苯甲醛为起始原料，用Sharpless不对称双羟化反应构筑手性中心，用Mitsunobu偶联反应作为关键步骤，合成了手性的香豆素木脂素Daphneticin及其异构体。

Single-component samarium diiodide catalyst system was first used with polymerization of acrylonitrile. Adding of hexamethylphosphoramide could greatly improve reaction activity of the catalyst system. AN/Sm12 and l{IVIPA1 Sm12 molar ratios, reaction time and temperature were mainly investigated with yields and molecular weights of resultant PAN.

研究发现HMPA的加入可以极大地提高催化活性；考察了单体与催化剂(SmI2)的摩尔比例、第二组分与催化剂(SmI2)的摩尔比例、反应温度、反应时间等因素对相应聚合物的产率和分子量的影响，通过对聚合物的红外和核磁的分析，提出了&单电子转移-双阴离子引发&机理。

The epoxide-terminated oligomer having ether mesogenic unit wassynthesized for the first time by reacting the diphenol with epichlorohydrin. Theepoxy equivalent increased as the elongation of reaction time or the decrease of theinitial ratio of diphenol and epichlorohydrin, but effect of the reaction time wassmaller than that of the initial ratio.

首次采用直接环氧化的方法合成了含酯类液晶基元的环氧结构预聚物，环氧化反应中反应配比和反应时间会影响产物的环氧当量；缩小反应配比或延长反应时间会使产物的环氧当量增大，反应时间对产物环氧当量的影响较小。5。

The function process of this kind of additives is that the additives discomposing reaction can occur before the electrolytes do at the first charge-discharge cycle, forming a fine SEI film, and avoiding or decreasing the discomposing reaction of electrolytes.

在首次充电过程中，添加剂首先发生还原分解反应，形成一层良好的SEI膜，从而避免和减少电解液的还原分解。

These concrete worksare the following:1, a new heterogonous SHS model had been proposed, which first included all the relativematerials characters, such as reactants particle sizes, changeable heat-conductivity and massdiffusion during SHS and so on, and its chemical reaction characters, initial combustion status.This new model made a more precise prediction about the SHS combustion way and itsTechnological characters possible.2, with the heterogonous SHS model, lots of combustion way had been imitated by changesystems relative factors and the rule of the combustion way change had also been studied,chemical reaction in these systems was controlled by a single mechanism.

在该模型中，首次将体系的微观不均匀特性、体系的基本物性及燃烧过程中的化学反应机理与整体燃烧动力学行为联系在一起，从而为更加准确地预测和控制SHS体系的燃烧行为，优化SHS的工艺过程奠定了理论基础。2、采用非均质燃烧模型，通过对相关参数的改变，模拟SHS燃烧过程中的各种燃烧行为，并研究了燃烧行为变化的规律。

During preparation, mercapto ethanol isooctanoate, alkyl or ester tin chloride and organic solvent are first heated and refluxed while adding catalyst; organic layer is then obtained through separating liquid and decompression distilled; and through further steps, the compound is obtained. The synthesis process of the present invention is simple, and has conversion rate higher than 95 %, normal pressure and low reaction temperature, low power consumption and less pollution, and the prepared compound has high reaction activity and low toxicity.

制备时，将异辛酸巯基乙醇酯、烷基或酯基氯化锡和有机溶剂加热回流，同时加入催化剂，然后通过分液，保留有机层，再对有机层进行减压蒸等步骤制得所述化合物；本发明合成工艺简单，转化率大于95％，反应在常压条件下，反应温度低，从而降低了能耗，减少了污染，所制备的化合物具有反应活性高和毒性小的特点，使用安全。

Calcining seed of rutile titanium dioxide was prepared at low temperature using metatitanic acid as raw material through alkaline hydrolysis, hydrolysis reaction, first washing, neutralization reaction, second washing and acid dissolution. These kinds of seed were added in the salt treatment, and the influences of calcining seed and calcination temperatures on the content of rutile TiO2 pigment were examined systemically.

以偏钛酸为原料，经碱解反应、水解反应、一次洗涤、中和反应、二次洗涤、酸溶反应，低温下制备了高活性金红石型TiO2锻烧晶种，并将其用于盐处理过程，考察了晶种添加量和锻烧温度对TiO2晶型转化的影响。

Calcining seed of rutile titanium dioxide was prepared at low temperature using metatitanic acid as raw material through alkaline hydrolysis,hydrolysis reaction,first washing,neutralization reaction,second washing and acid dissolution.

以偏钛酸为原料，经碱解反应、水解反应、一次洗涤、中和反应、二次洗涤、酸溶反应，低温下制备了高活性金红石型TiO2煅烧晶种，并将其用于盐处理过程，考察了晶种添加量和煅烧温度对TiO2晶型转化的影响。

Methylol polyacrylamide was first formed by the reaction of PAm with F in basic medium, then the cationic polyacrylamide was formed by the further reaction of PAm·M with D.

合成反应通过两步进行，先使PAm与F反应，生成羟甲基化产物PAm·M，然后在酸性条件下使PAm·M与D反应，制得PAm·MG。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。