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1.前言 硝基苯在pd、Rh和Ru配合物催化剂作用下,在乙醇介质中可以直接还原羰基化为苯氨基甲酸乙酯。在最佳的反应条件下,硝基苯转化率和苯氨基甲酸乙酯选择性可达到或接近100％。但是,由于相对于底物的贵金属催化剂用量较大,且均相配合物催化剂难于回收再生使用,阻碍了羰基化法在工业上的应用。 本文在原有工作的基础上,对PdCl_2-邻菲咯啉(phen)催化剂体系加以改进。发现添加Ce(SO_4)_2和V_2O_5作为助催化剂,能明显提高Pd(Ⅱ)-phen催化剂的活性;在[ArNO_2]/[Pd]摩尔比值高达7000的条件下,硝基苯的转化率可达100％,苯氨基甲酸乙酯
1. Introduction nitrobenzene pd, Rh and Ru complex catalyst, ethanol in the medium can be directly reduced carbonylation into phenyl carbamate. Under optimal reaction conditions, nitrobenzene conversion and phenylisocyanate selectivity can be achieved at or near 100%. However, due to the large amount of precious metal catalyst relative to the substrate and the difficulty of homogenous complex catalysts being recycled for use, the carbonylation process has been hampered in the industry. Based on the previous work, the PdCl_2-phenanthroline (phen) catalyst system is improved. It was found that the addition of Ce (SO 4) 2 and V 2 O 5 as cocatalysts can significantly increase the activity of Pd (Ⅱ) -phen catalyst. Under the condition of [ArNO 2] / [Pd] molar ratio up to 7000, 100%, phenyl carbamate