两相催化体系中烯烃氢甲酰化的高区域选择性

采用水溶性铑膦配合物催化剂在两相(水/有机物)体系中进行长链烯烃氢甲酰化反应合成高碳醛,具有反应条件缓和、催化剂与产物容易分离的优点,而且用水作溶剂既便宜、又安全,有利于环境保护,因此引起国内外化学家重视,进行了大量研究1,2].

HIGHLY REGIOSELECTIVE HYDROFORMYLATION OF OLEFIN CATALYZED BY RHODIUM-TPPTS IN TWO-PHASE CATALYTIC SYSTEM

The effects of different surfactants (cationic, anionic and nonionic) on 1 dodecene hydroformylation catalyzed by water soluble rhodium TPPTS P( m C 6H 4SO 3Na) 3] complex in two phase catalytic system were studied. The results showed that the cationic surfactant efficiently increased the reaction rate, owing to the solubilization of olefin in micelle and owing to the electrostatic interaction between the positive micelle and the negative catalytic active intermediates, HRh(CO) x P( m C 6H 4SO 3) 3] n 3n- , which favored the coordination with olefin. The nonionic surfactant, which has only the solubilization for olefin, just increased slightly the rate. However, the anionic surfactant inhibited the reaction owing to the electrostatic repulsion between the negative micelle and the catalytic active intermediates. When the benzene sulfonated salt substituted by hydrophobic group was added, the molar ratio of normal aldehyde to iso aldehyde increased dramatically from 6 5 to 22 3 for 1 dodecene hydroformylation in the presence of cetyltrimethylammonium bromide (CTAB). This may be attributed to the formation of tighter micelle caused by the insertion of the substituted benzene sulfonate into the palisade layer, which favored the formation of normal aldehyde with lower steric hindrance. The fact that the addition of substituted benzene sulfonate could not improve the regioselectivity for normal aldehyde in the presence of benzyltetradecyldimethylammoniun chloride (BDAC) supported the above hypothesis, because BDAC has larger cationic head and favors the formation of iso aldehyde than CTAB, therefore, the combination of the proper additives could attain highly regioselective hydroformylation in two phase catalytic system.