Ying Chen,Wenchao Peng,Shaobin Wang,Fengbao Zhang,Guoliang Zhang,Xiaobin Fan
Gold nanoparticles supported on three metal oxides , TiO 2 , Al 2 O 3 and Fe 2 O 3 , were prepared by a modified precipitation-deposition method using urea as an additive. These catalysts were tested in chemoselective reduction of 4,4′-dinitrostilbene-2,2′-disulfonic acid to 4,4′-diaminostilbene-2,2′-disulfonic acid. Three reagents, hydrogen, carbon monoxide , and sodium formate, were employed as reductants . It was found that >94% of the nitrostilbene was transformed into the aminostilbene without the reduction of olefinic group. In addition, these catalysts exhibited stable performance after regeneration by calcination at 400 °C for 5 h. This clean approach provides a promising application for synthesis of amino substituted stilbene sulfonic acid on an industrial scale.
Kelong Ding,Ze-Nan Hu,Wenhui Zhang,Jiaxing Liang,Yiming Wang,Hong Li,Zejun Sun,Qionglin Liang,Hong-bin Sun
Chemoselective hydrogenation of nitrostyrene to aminostyrene still faces the trouble of low selectivity and poor activity. The bimetallic catalysts, which adjust the activity of noble metal nanoparticles through the doping of non-noble metals, are promising for selectively catalytic transfer hydrogenation (CTH). For another aspect, the hydrogen source also plays a vital role in selective CTH. Based on this, we prepared activity-inhibited bimetallic RhIn/ZIF-8 catalyst to study the catalytic performance towards different hydrogen sources (N 2 H 4 ·H 2 O, NaBH 4 , NH 3 ·BH 3 and H 2 ) and to explore the natural selectivity of these hydrogen sources. We found that the hydrazine hydrate was the most selective H-donor for the nitro group, while the H 2 had the highest natural selectivity to olefins . The H 2 produced from hydrazine hydrate is responsible for the formation of completely reduced products. The potential reduction by the intermediate imine did not occur to C C double bonds, this indicates controlling the decomposition of N 2 H 4 will enhance the selectivity of nitroarenes. Based on this, the reaction system with the catalyst bimetallic RhIn/ZIF-8 and N 2 H 4 ·H 2 O as the hydrogen source is established, which can fully reduce many nitrostyrenes with >98% selectivity to corresponding aminostyrenes.
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