取代

Direct competitions of intramolecular C - H insertions into benzylic C - H and 4-nitroor 4-methoxy substituted benzylic C - H of methyl 2-diazo-3-oxo-6-(4-substituted phenyl)-4-(2-phenylethyl)hexanoate 44a and 44b catalyzed by Rh-mediated carbenoid were alsoinvestigated, and the relative reactivities obtained by compound 44a or 44b were comparableto those obtained by indirect method.

此外，还研究了Rh催化分解下，对位硝基取代或甲氧基取代的4-(2-苯基乙基)-6-(4-取代苯基)-2-重氮基-3-氧代己酸甲酯44a、44b苯甲位C-H插入反应的相对速率，与化合物47a和47f得到的结果比较，数据平行。

The result shows that the best reaction conditions for synthesizing CMC with a high degree of substitution (1.68) are that the ratio of chitosan to sodium chloroacetate is 1:5, reaction temperature is 90℃, reaction time is 5h, and the amount of catalyst is 3%.

研究了投料比、反应温度、反应时间、催化剂等单因素对取代度的影响，合成高取代度的最佳反应条件为m：m=1：5、温度90℃、时间5h、催化剂量为3%，可制得取代度为1.68的羧甲基壳聚糖。

The factors affect on the degree of substitution of product, yield and apparent viscosity, such as the mol rates of EPTAC with -NH2, reaction temperature, reaction time and the content of water in system have been discussed in detail. FTIR spectrometer and UV spectrometer are used to characterize the structure of the derivative and it is proved that substitution reaction mainly occurs on the -N element .The particle size and morphology of chitosan and quantemary ammonium salt of chitosan are analysised by comparing photos of their scanning electron microscope. The degree of substitution of HACC is determined by acid -base conductometric titration. An error in current formula of DS has pointed out and a correct formula has presented.On the base of experience of above experiment, the reaction conditions of HACC were systematically investigated through orthogonal design, and then the best conditions are found. Water-solubility and dependence of pH are studied.

壳聚糖和环氧丙基三甲基氯化铵在异相条件下发生反应，通过单因素实验，制备了一系列不同性能的壳聚糖季铵盐，本文首次详细讨论了反应条件(反应摩尔比、反应时间、反应温度、水含量)对产率及产物性能的影响；用红外光谱和核磁共振对结构进行表征分析时，发现季铵盐阳离子基以N位上取代为主；通过电镜图片对壳聚糖和季铵盐衍生物外观形貌进行对比，采用酸碱电导滴定法测定产物的取代度，并对常用取代度公式做了修正。

The chapter two was focused on the samarium diiodide promoted organic reactions and their applications in organic synthesis, firstly, a new synthesis of highly substituted cyclopentadienes from a,β-alkynone promoted by samarium diiodide was investigated and the highly substituted cyclopentadienes were prepared in moderate to good yields under mild conditions. Secondly, the Michael addition and Michael-aldol tandem reaction of diorganyl diselenides or diorganyl disulfides with α,β-alkynones mediated by samarium diiodide were studied and a series of alkenylsulfides and alkenylselenides were prepared in good yields. Then the highly regioselecfive nucleophilic addition of the allylsamarium bromide to α,β-alkynones were explored. We found that the allylsamarium bromide reacts with α,β-alkynones to afford regiospecificly 1. 2-nucleophilic addition products in good yields under mild condition. At last we studied the coupling reaction of aryl halides promoted by NiCl〓/PPh〓/Sm〓.

第二章 研究了二碘化钐、金属钐促进的有机反应：1、二碘化钐促进下α，β-炔基酮的偶联环化反应，提供了一种制备多取代环戊二烯的新方法；2、二碘化钐促进下的二硫醚、二硒醚与α，β-炔基酮的Michael加成反应，为高产率地制备多取代的烯基硫或烯基硒化合物提供了方便可靠的新方法；3、二碘化钐促进下的二硫醚、二硒醚与α，β-炔基酮和醛、酮的Michael—aldol串联反应，提供了一种一锅法高产率地制备多取代的含硫的烯丙基醇或含硒的烯丙基醇类化合物的方便可靠的原子经济性的新方法；4、烯丙基溴化钐与α，β-炔基酮的高度区域选择性的1，2-亲核加成反应；5、NiCl〓/PPh〓/Sm〓促进的卤代芳烃的偶联反应-一种从各种卤代芳烃制备联苯类化合物的有效方法。

The positive charge transport properties of monosubstituted triphenylene are better than those of disubstituted and trisubstituted triphenylenes obviously.

在苯并菲上单取代的分子明显比其双取代、三取代的分子正电荷传输性质好。

The electronic effect of para substituents and both the steric and electronic effect of meta substituents in the substituted iodosobenzene were well linear correlated to the yields of cyclohexanol.

取代亚碘酰苯中对位取代基的电子效应和间位取代基的电子及立体效应对氧化产物环己醇的产率有良好线性相关性。

With it, simple, mechanistically significant and highly predictive QSAR models were developed. These QSARs successfully model and predict the short-term phytotoxicity of substituted phenols involved both polar narcosis and bio-reactivity, the growth inhibition toxicity to Saccharomyces cerevisiae of substituted nitrobenzenes with mixed mechanisms of toxic action based on electrophilicity and the growth inhibition toxicity to Saccharomyces cerevisiae of large set of substituted benzenes with complex molecular structures and multiple mechanisms of action.

应用响应曲面分析方法建立了形式简单、意义明确并且具有高度预测性的QSAR模型，成功地预测了具有多种毒性机制的取代苯酚对高等植物的短期生长抑制毒性、具有多种亲电反应性机制的取代硝基苯对酿酒酵母菌生长抑制的反应性毒性以及结构复杂、机制多样的78种取代苯衍生物对酿酒酵母菌生长抑制毒性。

The analytical results have shown that p ro ducts mainly consisted of some monosubstituted, disubstituted and a few trisub stituted naphthalenes. Except the low activity of HZSM-5 catalyst, all other z eolite catalysts have higher activity. HY and Hβ catalytic activities were the highest, and their naphthalene conversions attained to 79.12 and 55.79 percent respectively, but their selectivities for 2-isopropylnaphthalene, 2,6-diisopropylnaphthalene(2,6-DIPN) and 2,7-diisopropylnaphthalene ( 2,7-DIPN) were too low. ZM catalysts had good activity and much better selecti vity, especially for ZM4-3, of which its 2,6-DIPN/2,7-DIPN ratio was 2.97. Th er efore, some zeolite catalysts are recommended for shape selective isopropylat ion of coal tar naphthalene.

研究结果表明，煤焦油萘异丙基化产物主要由一取代萘、二取代萘以及少量三取代萘组成；除HZSM-5活性较低以外，其它催化剂均有较高的反应活性，其中HY和Hβ反应活性最高，萘转化率分别达75.15％和55.96％，但β位产物的选择性较差；ZM类催化剂既有一定的活性，又有较高的β选择性，是萘择形异丙基化反应理想的备选催化剂。

In the presence of catalytic rhodium acetate, ethyl 2-diazo-3-oxo-per fluoroalkanoates, reacted readily with nitriles to give a series of 5-fluoroalkyl substituted 1, 3oxazoles with high regio-selectivity through a metal carbenoid intermediate. The reactions of carbenoids with noncyclic vinyl ethers or cyclic vinyl ethers afforded dihydrofuroates in good to excellent yields. Interestingly, only vinyl C-H insertion compound was obtained concerning of the reaction of carbenoids with 2, 5dimethylfuran due to the steric hindrance of methyl group

醋酸铑分解2-重氮-3-氧代-全氟羧酸乙酯形成的金属卡宾作为1，3-偶极体，可以与一系列芳基或烷基取代的腈反应，高度区域选择性地生成一系列4-乙氧羰基-5-氟烷基取代的噁唑化合物；也可以与富电子的链状和环状的烯基醚反应，以优良的产率得到一系列氟烷基取代的二氢呋喃类化合物；而与2，5-二甲基呋喃的反应，由于甲基的位阻作用，只得到金属卡宾对呋喃3-位烯基碳氢键插入产物。

Coding and non-coding sequences are expected to have very different patterns of sequence changes because of the following characteristics of coding sequences: biased codon composition, higher conservation, absence of stop codons and frameshifts, higher fraction of synonymous than nonsynonymous substitutions, higher frequency of substitutions corresponding to changes of chemically similar amino acids, higher proportion of mutable contexts.

我们可以预期可转录的序列及不可转录的序列会有相当不同的序列改变特徵，因为可转录的序列有以下特色：偏颇的密码子组成，较高的保存度，有终止密码子和移码的出现，相较於异义取代有较高比例的同义取代，较高的频率出现化学结构相似的胺基酸取代，较高比例的可变之前后序列。

I'm strongly against the death penalty — it's an eye for an eye.

我不赞成死刑——这是以牙还牙的报复行为。

And to get you the support you need, we're enlisting all elements of our national power: our diplomacy and development, our economic might and our moral suasion, so that you and the rest of our military do not bear the burden of our security alone.

并给你们所须的支援，我们正徵召国家所有各种的力量：我们的外交及发展，我们的经济力量与道德劝说，所以你们与其他军人不须要孤独地负起国家安全的责任。