碱性反应

The match of the acidity and basicity is very important to obtain good reactivity and high yield in the bifunctional organocatalyst system.

在双功能催化的Aldol反应中，要获得高的反应活性和好的收率，催化剂的酸性基团和碱性基团的酸碱强弱匹配非常重要。

The present invention relates to the depolymering cyclization reaction of aromatic dithio ether polymer to prepare aromatic cyclic dithio ether compound under the presence of mercapto group containing compound and alkali matter.

本发明涉及利用芳香双硫醚聚合物的解聚成环反应来制备芳香双硫醚环状化合物的方法。该方法采用芳香双硫醚聚合物在含巯基的化合物和碱性物质存在的条件下发生解聚成环反应生成双硫醚环状化合物。

Cephalotaxine ester of 2-oxo-6-methylheptanoic acid was treated with lithium diisopropylamide and Me O-(1-methoxyisopropyl)glycolate to give a mixture of homoisoharringtonine and its stereoisomers with 56% yield. The four stereoisomers separated by TLC showed identical mass spectra and almost superimposed IR but with different 1H NMR spectra. The configuration of the 2'-C and 3'-C of the four isomers were postulated based upon their 1H NMR spectra as compared with the 1H NMR spectra of isoharringtonine and its stereoisomers.

2-氧代-6-甲基庚酰基三尖杉碱(3)与0-(1-甲氧基异丙基)羟基乙酸甲酯(4)在强碱性试剂二异丙胺锂存在下，起亲核加成反应，反应中间体5在室温用酸性丙酮水解，得到一种新的三尖杉酯类生物碱一一高异三尖杉酯碱(6c)及其立体异构体(6a、6b、6d)的混合物，产率56%、通过制备薄层层析分得这四个立体异构体，它们的1H NMR和异三尖杉酯碱及其立体异构体的1H NMR类似，推定了它们的绝对构型。

The reaction of the hexyl hexylphosphonite is studied with some nucleophilic reagent s in the basicity and tetrachoromethane, and the mechanism of the reaction is discussed.

研究了正己亚膦酸正己酯在碱性条件下以四氯化碳为溶剂，与各种亲核试剂的反应情况。并对其反应机理进行了探讨

The analytical method for sodium methyl mercaptide was established based on the reaction in quantity between methyl mercaptan and iodine at the base condition.

采用甲硫醇与碘在碱性条件下定量反应生成双硫醚的反应原理，建立了甲硫醇钠的定量分析方法。

Under basic conditions p-nitrotoluene was oxidized to p-nitrobenzoic acid with oxygen or air. The reaction parameters, such as reaction temperature, reaction time, substrate concentration were optimized and 75% of p-nitrobenzoic acid was obtained under proper conditions.

论文探讨了在碱性条件下，用空气／氧气氧化对硝基甲苯的反应，得出了温度、时间、底物浓度、催化剂用量等工艺参数对反应的影响，在较佳的工艺条件下，对硝基苯甲酸的收率可达到75％左右。

These two ores have contrasting mineral associations: anthothyllite + plagioclase + rutile + magnesiohornblende + alkline fledspar for red ore and anthothyllite + phlogopite + epsode + Rutile for black ore.

根据岩相学观察，认为红色金红石矿中存在如下方向的反应：镁角闪石+碱性长石→直闪石+／-斜长石+／-金云母，斜长石很可能只是过渡相，反应最终将形成直闪石+金云母。

Starting from piperonal, the initial total synthesis of CET involved BischlerNapieralski reaction, 3, 2-sigmatropic rearrangement, unusual Nazarov-type electrocyclization, and autoxidative dehydrogenation of desmethylcephalotaxine to desmethylcephalotaxinone etc.

第一条路线我们以胡椒醛为起始原料，经Bischler-Napieralski反应，[3，2]-σ重排，6-6环系到7-5环系的还原重排，Nazarov氧化环化；碱性条件下脱甲基三尖杉碱到脱甲基三尖杉酮碱的氧化脱氢等20步反应，完成了三尖杉碱的全合成。

With the characterization of NMR and IR, combining with the synthesis of active species and studies of their structures, it is suggested that the hydride [RuHCl(PPh3)3], being favorably formed in the acid media, exhibited higher activity in the reduction of the C=C bond, while the hydride [RuH4(PPh3)3], being preponderantly formed in the basic media, showed activity and higher selectivity towards the C=O reduction.

通过核磁、红外等表征手段，并结合可能催化活性配合物的合成和结构研究，推测了在非水介质中对C=C和C=O双键起到活化作用的催化剂活性物种和可能的选择加氢反应机理，即，催化剂[RuCl2(PPh3)3]在酸性环境下倾向于生成[RuHCl(PPh3)3]物种，该Ru-H物种对C=C双键加氢反应表现出较高的活性；而碱性环境下则易于生成[RuH4(PPh3)3]物种，该Ru-H物种对C=O双键加氢具有较高的催化活性。

The solvolysis activity can be inhibited remarkably if a small amount of base was added in the medium. And the activity can be enhanced if acid was added.

原料中加入碱性物质可以显著抑制TS-1催化环氧丙烷溶剂解反应的活性；原料中添加酸性物质可以增强TS-1催化环氧丙烷溶剂解反应的活性。

I think he's learned how to approach hitters....

Johhny Damon说，『他已是最好的了，再没有人能够比他做的更好，我想他的球技已经完全成熟了，而且他也已经学会了如何去对付和压迫各种打击者。。。。。。

In effect, an 18 foot King Cobra could actually look down onto the average human being.

际上，一个18尺眼镜蛇王其实可以俯视到的平均人。