查询词典 Lewis acid

Being combining with products distribution in styrene oxidation, we propose the styrene epoxidation carry out with Ti metallacyclo intermediates, And at the same time Ti-ZSM-5 have properties both catalytic epoxidation and acid-catalysis, namely the skeletal Ti can catalyze styrene epoxidation to styrene oxide and the skeletal Ti and Al can provide Lewis acid site to cause the rearrangement of styrene oxide to phenylacetaldehyde rapidly, the solvolysis to glycols and the cleavage of C=C double bond. Ti-ZSM-5 can also provide Bronsted acid site simultaneously, which is also catalytic center for the solvolysis to glycols.

同时结合Ti-ZSM-5催化选择性氧化苯乙烯反应的产物分布结果，提出苯乙烯环氧化反应可能是通过金属有机环机理进行；Ti-ZSM-5同时具有催化环氧化和酸催化两种功能，其骨架钛可催化苯乙烯环氧化生成环氧苯乙烷，而骨架钛和骨架铝等可提供Lewis酸位使环氧苯乙烷迅速发生重排生成苯乙醛从而使其成为反应的主要产物，同时还可发生加成以及碳碳键的裂解等副反应：Ti-ZSM-5也提供Bronsted酸位，它也是生成加成产物的活性中心。

To be different from the already chloromethylation catalyst, it has a certain amount of moisture wet, which will not produce huge amounts of doughtic cancerogenic chloromethyl methyl ether during and after the reaction.4,4\'-bisbiphenyl, 1,4-bisbenzene, 1,4-bis(chloro- methyl)-2,5-dimethylbenzene, 1,5-bis-2,4-dimethylbenzene, 4-(chlor- omethyl)-1,2-dimethylbenzene, 1,2-bis-4,5-dimethylbenzene, 5,8-bis-1,2,3,4-tetrahydronaphthalene, 3,3\',5-tris-4,4\'-bisbiphenyl and 3,3\', 5,5\'-tetrakis-4,4\'-bisbiphenyl were synth- esized by using this new catalyst. Results indicated that when the reaction temperature was 55～60℃, the reaction time was 12h, the catalyst which consists of the concentration of 80%H_2SO_4, HAc and Lewis acid, the amount of Lewis acid 0.15 mol(nLewis:nbiphenyl=1.5:1), yield of biphenyl chloromethylation product 4,4\'-bis(chrolomethylbiphenyl can reach a maximum 85%.

采用这种催化体系完成了4，4′-二氯甲基联苯、对二氯甲基苯、1，4-二氯甲基-2，5-二甲基苯、1，5-二氯甲基-2，4-二甲基苯、4-氯甲基-1，2-二甲基苯、1，2-二氯甲基-4，5-二甲基苯、5，8-二氯甲基-四氢萘、3，3'，5-三氯甲基-4，4'-二甲基苯和3，3'，5，5'-四氯甲基-4，4'-二甲基苯的合成，结果表明：在反应条件为：反应温度55～60℃，反应时间12h，选择80%H_2SO_4、冰醋酸和Lewis酸为催化剂，反应最佳反应Lewis酸用量是0.15mol(和原料比为1.5：1)，反应效果最好，联苯氯甲基化产物(4，4′-二氯甲基联苯)收率为85%；在反应条件为：反应温度70℃，反应时间8h，80%H_2SO_4、冰醋酸和Lewis酸为催化剂，反应最佳反应Lewis酸用量是0.1mol(和原料比为1：1)时，反应效果最好，苯的氯甲基化产物收(来源：ABd0C论文eded网www.abclunwen.com)率为75%；在反应条件为：在反应条件为：反应温度40℃，反应时间10h，60%H_2SO_4和Lewis酸为催化剂，反应最佳反应Lewis酸用量是0.1mol(和原料比为1：1)时，反应效果最好，对二甲苯氯甲基化产物(1，4-二氯甲基-2，5-二甲基苯)收率为78.5%；在反应条件为：反应温度35℃，反应时间10h，60%H_2SO_4、冰醋酸和Lewis酸为催化剂，反应最佳反应Lewis酸用量是0.1mol(和原料比为1：1)时，反应效果最好，间二甲苯氯甲基化产物(1，5-二氯甲基-2，4-二甲基苯)收率为81.5%。

Rate enhancement in ligand-free palladium catalyzed Suzuki reaction by Lewis acid promoters;2. Metoprolol was synthesized with isopropylamine and 4-(2-methoxyethyl)phenyl glycidyl by different Lewis acid .

Lewis酸催化对甲氧乙基苯基缩水甘油醚与异丙胺的反应得到美托洛尔，考察不同的催化剂、反应温度、反应时间对反应的影响。

When using urea-hydroperoxide as oxygent, just the trimethylphosphine adsorbed on the Lewis acid sites in TS-1 zeolite was oxidized. It further confirmed that the hydroperoxo-titanium species formed by the interaction between the titanium in Lewis acid sites and urea-hydroperoxide are the active oxidation center, and the titanium in the framework as Lewis acid sites enhances the oxidation ability of hydroperoxide. 3. Phenylacetaldehyde and benzaldehyde are found to be the major products in the catalytic oxidation of styrene over TS-1 zeolite, and styrene epoxide is not as speculated detected.

当以过氧化氢尿素为氧化剂时，室温条件下吸附在TS-1分子筛Lewis酸性位的三甲基膦即能被氧化，由此进一步证明，TS-1分子筛中由Lewis酸性位的骨架钛与过氧化氢相互作用形成的过氧化钛物种是三甲基膦氧化反应的活性中心，骨架钛作为Lewis酸中心提高了过氧化氢的氧化能力。

Different from the Lewis acidity nature of SO4(superscript 2-)/ZrO2/MCM-41, SO4(superscript 2-)/TiO2 and S2O8(superscript 2-)/TiO2 behave mainly Brnsted acidities. The strongest Brnsted acid sites are formed on SO4(superscript 2-)/TiO2 promoted with H2SO4, while Lewis acid sites on S2O8(superscript 2-)/TiO2 are even stronger than those on SO4(superscript 2-)/ZrO2/MCM-41, and the former which are generated when persulfate solution is used as sulfating agent.

与SO4(上标 2-)/ZrO2/MCM-41主要表现为Lewis酸性不同，SO4(上标 2-)/TiO2和S2O8(上标 2-)/TiO2主要以Brnsted酸性为主，其中采用硫酸为促进剂制备的SO4(上标 2-)/TiO2具有最强的Brnsted酸性，而采用过硫酸根作为促进剂则使S2O8(上标 2-)/TiO2产生较SO4(上标 2-)/ZrO2/MCM-41更强的Lewis酸中心。

We postulate that this is a Lewis base activating Lewis acid reaction.

我们仔细研究了Lewis碱的变化对反应的影响，并根据实验结果提出了Lewis碱活化Lewis酸的反应机理。

Because substituted anilines have Lewis acid or Lewis base group, extractions with complexing agent was conducted.

由于取代苯胺都具有Lewis酸性或Lewis碱性官能团，采用相应的络合剂进行了络合萃取的研究。

It was found that Lewis acid-metal is a preferable catalyst system for the polymeri- zation of aromatic nitriles, and the polymerization rate is as about 10 times fast as Lewis acid alone.

结果表明以含质子化合物或水与Lewis酸组成的体系并不是有效的催化体系，不适用于催化芳香族腈进行聚合。

The acidity of Lewis acid sites and the basicity of Lewis base sites influence the intensity between water, 1,2-dichloropropane and catalyst. The specific area of catalyst influences the capacity of adsorption.

催化剂Lewis酸位和Lewis碱位的酸碱强度直接影响水、1，2－二氯丙烷与催化剂的作用强度，而催化剂的表面积直接影响吸附量。

In addition, in-situ infrared spectroscopy provides the information about the nature of the surface acid and base sites. For example, Lewis acid and base sites on metal oxides are coordinatively unsaturated metal cations and oxygen anions, respectively, while Brinsted acid and base sites are the hydroxyl groups on the surface.

结合原位红外光谱，还能够详细地了解表面酸碱中心的性质：金属氧化物表面的Lewis酸中心和碱中心分别是表面配位不饱和的金属离子和氧负离子， Brinsted酸中心和碱中心则是金属氧化物表面的羟基。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。