2-(2,5-二甲氧基苯基)硝基乙烯液-液催化加氢制备2,5-二甲氧基苯基乙胺

研究了在液-液两相(水/有机物)催化体系中,以RuCl3-TPPTS(三-间磺酸钠-三苯基膦)为催化剂前体,2-(2,5-二甲氧基苯基)硝基乙烯加氢制备2,5-二甲氧基苯基乙胺的反应性能。结果表明,当Ru的浓度为3mmol/L、n(TPPTS)/n(Ru)=6、H2分压4.0MPa、反应温度90℃时,延长反应时间,不仅能进一步提高底物转化率,且可以获得纯度较高的C　C加氢与—NO2完全加氢的目标产物,此条件下无苯环加氢副产物生成。

Preparation of 2,5-Dimethoxyphenethylamine by Liquid-Liquid Catalyst Hydrogenation of 2-(2,5-Dimethoxyphenyl) Nitroethene

2-(2,5-Dimethoxyphenyl)nitroethene and its hydrogenation product are widely used in fine chemical synthesis.Catalytic performances of RuCl_3-TPPTS(P(C_6H_4SO_3Na)_3)as catalyst precursor for selective hydrogenation of both CC and -NO_2 groups in 2-(2,5-dimethoxyphenyl) nitroethene had been studied in biphasic catalytic system (aqueous/organic phase).After a long reaction time of about 20 h,conversion rose substantially and the selectivity for hydrogenation of both CC and -NO_2 groups increased.Reaction conditions were:c(Ru)=3 mmol/L,TPPTS/Ru mole ratio=6,p_(H_2)=4.0 MPa and 90 ℃.Hydrogenation of aromatic ring was not found (or did not occur).Addition of a surfactant (cetyltrimethylammonium bromide,CTAB) to the system obviously decreased the hydrogenation activity as well as the selectivity for hydrogenation of both CC and -NO_2 groups although,in general,presence of the surfactant (CTAB) was known to increase hydrogenation activity.Steric hindrance of the surfactant micells formed might possibly decrease the solubility of 2-(2,5-dimethoxyphenyl)nitroethene in biphasic catalytic system.Under the best reaction conditions,the conversion of substrate reached 95.0%.It was easy to separate the hydrogenation product from the catalyst after the reaction .