查询词典 enolate

The reaction process in methanol solvent can be deduced from the computational results with CPCM solvent model and the supermolecular handling, namely the reaction involves four steps in the methanol solvent. The nucleophilic addition of trimethylamine to acraldehyde generates an enolate. Nucleophilic attack of the enolate on the aldehyde forms the carbon-carbon bond, followed by the proton-transfer process and the further elimination generating the product and liberating the trimethylamine catalyst.

对于CH3OH对反应体系的影响，可以综合考虑CPCM溶剂模型及超分子模型下的研究结果，即CH3OH溶剂中反应按四步进行，催化剂三甲胺首先与丙烯醛发生亲核加成，生成的两性离子中间体与甲醛发生类似于Aldol的醛醇缩合，形成碳-碳键，之后发生分子内质子转移，最后经E1cb消除得到产物，并释放催化剂三甲胺。

The author and his colleagues have performed the experiment before the introduction of electro- philic aromatic substitution or enolate halogenation in lectures.

作者和他的团队在介绍亲电芳基取代或烯醇卤化的课程前已经进行了实验。

Understand keto-enol tautomerism, reactivity of enolate ions.

A5 E3J3 了解酮－烯醇互变异构性，烯醇离子的反应性。

Master the Keto-Enol tautomerism; reactions of enols:α-H substitution reactions;α-halogenation of aldehydes and ketones;α-bromination of carboxylic acids; acidity ofα-H atoms: enolate ion formation; reactivity of enolate ions; alkylation of enolate ions; mechanism of carbonyl condensation reactions;condensations of aldehydes and ketones: the Aldol reaction; dehydration of Aldol products; the Claisen condensation reaction; the Michael addition.

熟练掌握酮式－烯醇式互变异构；烯醇的反应：α-H的活性；醛酮的α卤代反应；羧酸的α-溴代反应；α-H的酸性：烯醇负离子的形成；烯醇负离子的反应；烯醇负离子的烃基化；羰基化合物的缩合反应机理；醛酮的缩合反应－Aldol缩合；Aldol缩合产物的脱水反应； Cleisen 酯缩合反应；麦克尔加成反应。

Extensive experimentation revealed several issues, along with several corresponding solutions:(1) given that lithium metal dissolves slowly in liquid ammonia, considerable time was required to generate the dissolved metal solution (ca. 1 h);(2) the t -BuOH must be freshly distilled prior to use 21 to diminish the formation of ketone 19 (Figure 2);(3) efficient capture of the lithium enolate ( 11 ) required the use of freshly distilled TMSCl and Et 3 N; and (4) the presence of residual thiophenol upon workup was found to inhibit the subsequent Sc 3 -promoted hydroxymethylation.

大量实验揭示若干问题，随着几个对策 1鉴于锂金属溶化慢慢液氨、需要相当多的时间创造了金属溶液溶解(约占1小时)；(2) T恤使操作必须事先用新鲜蒸馏水形成酮减少2119(图2)；有效捕获的锂烯醇(11)使用新鲜蒸馏水需氯和ET三氮；含有残余硫workup经发现抑制随后推选3-羟甲晋升。

Its mechanism is the use of anthraquinone in alkali conditions off proton surface forming 10 more stable carbon anion face, but because carbon anion and oxygen ion exist between testosterone and enolate type each other changes, cause reaction product complex, at least five, reaction selectivity, product yield, separation difficulties, and product purity is not high, therefore, using the type and quantity of alkali, phase transfer catalyst type, solvent, to optimize the selection process conditions so as to improve the yield target product.

其机理是利用蒽酮在碱存在的条件下脱去氢质子面形成10位较稳定的碳负离子面进行，但是因为碳负离子和氧负离子之间存在酮式和烯醇式的互变，导致反应复杂，产物至少有五种，反应选择性差，产物分离困难，产率低，且产品纯度不高，因此，利用对碱的种类和量的多少，相转移催化剂的种类，反应溶剂的选择，来优化反应工艺条件从而提高目标产物的产率。

To further extend the scope of this type Cannizzaro disproportionation reaction and the reactivity of enolate ligand in complex with aldehyde,we designed to synthesis new rare earth complexes containing arylamido and.enolate mixed ligands,studied their reactivity with aromatic aldehydes for the disproportionation reaction.

为了进一步探索这种歧化反应的应用范围及配合物中作为配体的乙烯醇基与醛的反应性，我们设计合成了含胺基、乙烯醇基混合配体的新型稀土配合物，并研究了其与芳香醛的反应。

Thirdly,in the view of some different results between the reaction of complexes(2)、(3)and[(Me_3Si)_2N]_3LnLi_3 with aromatic aldehydes, the reaction of 2 equiv of aromatic aldehydes with 1 equiv of lithium amide(1) catalyzed by the YCl_3 was subsequently studied,and better yields of the corresponding amides and alcohols can be isolated.These results indicated that the enolate ligand in complexes(2)、(3)may have impact on the Cannizzaro disproportionation reaction.

第三，鉴于上述配合物2、3和[(Me_3Si_2)2_N]_3LnLi_3与芳香醛反应结果上的一些差别，我们又以三氯化钇为催化剂，将两当量的芳香醛与一当量化合物1的锂盐直接进行反应，结果以较好的产率得到了相应的酰胺和醇，这说明配合物2、3中所含的乙烯醇基可能对此Cannizzaro-型歧化反应存在一定的影响。

Firstly,two novel rare earth complexes(CH_2=CHO)Ln~Ⅲ[2,6-_2PhNSiMe _3]_2Li_3Ln=Y(2,Yb(3)containing arylamido and enolate mixed ligands have been synthesized by treatment of 2 equiv of of 2,6-~iPr_2PhNHSiMe_3 with exces n-BuLi at -78℃in THF for 12h,followed by reaction with 1 equiv of LnCl_3at 80℃for 24h in one-pot.All the two compounds were characterized by spectroscopic methods,elemental analyses,and a single-crystal X-ray diffraction study.

首先，-78℃下，在两当量的2，6-~iPr_2PhNHSiMe_3(1)THF溶液中加入过量的n-BuLi，反应12小时，再加入一当量的LnCl_380℃下，反应24小时，一锅法合成了含胺基、乙烯醇基混合配体的新型稀土金属配合物(CH_2=CHO)Ln~Ⅲ[2，6-_2PhNSiMe_3]_2Li_3Ln=Y(2、Yb(3)，上述化合物结构经单晶X-ray衍射、光谱和元素分析表征，表明我们得到的是一类新型的三价稀土配合物。

Employing acetyl chloride as the electrophile afforded the β-acetoxyvinyl-γ-butyrolactone 3 as the product, which provided an experimental evidence to the mechanism involving the palladium enolate intermediate.

使用乙酰氮作为亲电试剂得到了β－乙酰氧基烯基－γ－丁丙酯3，这一结果为烯醇钯中间体的机理提供了一个实验证据。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。