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筆墨輕點(diǎn)

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[求助] 翻譯中文有機(jī)合成

To investigate the effects of solvent, the condensation reaction of benzaldehyde, dimedone, ethylacetoacetate, and ammonium acetate in various organic solvents at room temperature using 4.85 wt.% Ni0-nanoparticles as the catalyst was carried out. About 75% of the expectedproduct 4a was obtained when the solvent was ethanol. Obviously, thepolar solvents such as ethanol and acetonitrile [Table 2] were much better than non polar solvents. It was observed that in the presence ofsolvent the reaction takes more time to give high yields of product under similar ratio of the reactants. This may be due to the competitive adsorption of the solvent with the substrate molecule on the catalyst surface; hence reaction under solvent-free condition gives better yields in less time. The model reaction was carried out without any catalyst,but the product formation was in poor yield. Therefore, the catalyst plays an important role in the success of the reaction in terms of rate and yields of Hantzsch polyhydroquinoline derivatives. The reaction was also investigated with acid activated Mont. alone as catalyst and only a negligible amount of product formation was observed. Therefore, it is evident that supported Ni0 -nanoparticles are the active sites.

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1樓 2014-09-25 10:30:35

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筆墨輕點(diǎn): 金幣+25, 翻譯EPI+1, ★★★★★最佳答案 2014-09-25 20:20:29

為研究溶劑的作用，在室溫條件下用各種有機(jī)溶劑和4.85%（重量百分比）的Nio納米顆粒作為催化劑對苯甲醛，雙甲酮，乙酰乙酸乙酯和醋酸銨進(jìn)行了縮合反應(yīng)。當(dāng)用乙醇為溶劑時，可以獲得約75％的預(yù)期產(chǎn)物。顯然，極性溶劑如乙醇和乙腈[表2]均明顯優(yōu)于非極性溶劑。據(jù)觀察，在反應(yīng)物比例相似的條件下，有溶劑存在時反應(yīng)需要更多時間以得到高產(chǎn)物產(chǎn)率。這可能是由于溶劑與催化劑表面上底物分子的競爭吸附作用; 因此，無溶劑條件下反應(yīng)，在更短的反應(yīng)時間內(nèi)能夠得到更好的產(chǎn)率。在沒有任何催化劑存在的模型反應(yīng)，形成產(chǎn)物的產(chǎn)率低。因此，催化劑在合成Hantzsch多聚羥基喹啉衍生物的反應(yīng)中，不管在反應(yīng)速率還是產(chǎn)率方面的成功都發(fā)揮重要作用。同時還以酸活化蒙脫石為催化劑單獨(dú)使用，研究了反應(yīng)情況，結(jié)果產(chǎn)物產(chǎn)量可以忽略不計。顯而易見，支持的Nio納米顆粒是活性位點(diǎn)。

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2樓2014-09-25 13:13:22

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