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用不同分子量的聚乙二醇(PEG)及其单醚类化合物,作为相转移催化剂(PTC),研究了由硝基氯苯(Ⅰ)合成硝基苯烷醚的反应动力学和机理。结果表明,在一定浓度的催化剂存在下,合成反应遵循假一级动力学关系:-d[Ⅰ]=k[Ⅰ],反应活化能为E_2=71.43 kJ/mol,求得了该反应的活化参数△H~≠、△G~≠和△S~≠,并与季铵盐作为PTC的反应结果做了比较。在本反应体系中,PEG和相应的单醚类PTC,其催化活性大体一致,主要取决于分子链中的有效(?)CH_2CH_1O(?)单元数。此外,还初步研究了反应机理,认为相转移催化反应过程中形成一反应中间体络合物[PEG-Na]~+OH~-。
The kinetics and mechanism of the synthesis of nitrophenyl ethers from nitrochlorobenzene (Ⅰ) were studied by using different molecular weight polyethylene glycol (PEG) and its monoethers as phase transfer catalyst (PTC). The results showed that under the presence of a certain concentration of catalyst, the synthetic reaction followed the pseudo first order kinetics: -d [Ⅰ] = k [Ⅰ] and the activation energy was E_2 = 71.43 kJ / mol. The activation parameters △ H ~ ≠, △ G ~ ≠ and △ S ~ ≠, and with quaternary ammonium salt as a PTC reaction results were compared. In the present reaction system, the catalytic activity of PEG and the corresponding monoether PTC is almost the same, mainly depending on the number of available CH 2 CH 1 O (?) Units in the molecular chain. In addition, the reaction mechanism was also studied preliminarily, and it was considered that a reaction intermediate complex [PEG-Na] ~ + OH ~ - was formed during the phase transfer catalysis reaction.