摘要
研究了水溶性钌－膦配合物催化肉桂醛选择加氢反应中，相转移剂和表面活性剂对反应转化率和选择性的影响，考察了表面活性剂ＣＴＡＢ（十六烷基三甲溴化铵）浓度以及影响两相界面性质的因素—水相和有机相体积比、有机溶剂的改变等的影响．结果表明，相转移剂可以促进反应进行，其中以季铵盐相转移剂最好；表面活性剂能够显著地加快反应，其中以阳离子表面活性剂的效果最佳，且分子中含有长链烷基者（如ＣＴＡＢ）效果更好，非离子和阴离子表面活性剂的效果较差；对于ＣＴＡＢ，其浓度的增加导致反应速度的明显加快，但ＣＴＡＢ浓度达到１．６５×１０－２ｍｏｌ／Ｌ之后，反应体系乳化严重，反应完成后，两相分离变得困难．而增加水相体积和加入适当的有机溶剂，有利于转化率和选择性的提高．
In the selective hydrogenation of cinnamaldehyde with water soluble ruthenium complexes in the biphasic catalytic system consisting of organic solvent and water, a marked influence of the biphasic interface nature was observed. The hydrogenation rate of cinnamaldehyde increased greatly with the addition of phase transfer agents and surfactants. The promotion by the cationic sufactants for the hydrogenation was much greater than that of phase transfer agent, anionic and non ionic surfactant. The effect of the concentration of CTAB(cetyltrimethylammonium bromide) on the hydrogenation rate was studied. The rate increased with the increase of CTAB concentration when the CTAB concentration was lower than 2.24×10 -3 mol/L, but the rate increased a little in the range of CTAB concentration from 2.24×10 -3 mol/L to 5.94×10 -3 mol/L. The rate increased pronouncedly again when the CTAB concentration increased further. However, the reaction system became an emulssion under higher CTAB concentration, and the seperation of organic phase from aqueous phase was difficult. The great promotion of CTAB cationic surfactant for the hydrogenation was caused by the interattraction between the cation of CTAB and anion of Ru complexes, which was favorable for the coordination of substrate with the Ru complexes located on the interface of the two phases. The conversion of cinnamaldehyde and the selectivity for cinnamic alcohol increased with increase of water volume, and the conversion was the highest when the volume of organic phase was equal to that of water. The best solvent for the selective hydrogenation of cinnamaldehyde was aromatics. The long chain normal alcohols were also suitable solvents.
出处
《分子催化》
EI
CAS
CSCD
1996年第5期351-356,共6页
Journal of Molecular Catalysis(China)
关键词
醛
表面活性剂
加氢反应
两相催化
Water soluble Ru phosphine complex, Cinnamaldehyde, Selective hydrogenation, Phase transfer agent, Surfactant
