Mechanism of Formation of Organic Carbonates from Aliphatic Alcohols and Carbon Dioxide under Mild Conditions Promoted by Carbodiimides. DFT Calculation and Experimental Study
作者:Michele Aresta、Angela Dibenedetto、Elisabetta Fracchiolla、Potenzo Giannoccaro、Carlo Pastore、Imre Pápai、Gábor Schubert
DOI:10.1021/jo050392y
日期:2005.8.1
into a carbamate and a secondary amine, while in the presence of CO2, the dialkyl carbonate, (RO)2CO, is formed together with urea [CyHN−CO−NHCy]. The reaction has been tested with various aliphatic alcohols such as methanol, ethanol, and allyl alcohol. It results in being a convenient route to the synthesis of diallyl carbonate, in particular. O-Methyl-N,N‘-dicyclohexyl isourea also reacts with phenol
二环己基(CYN Ç NCY,DCC)促进在温度低至310 K和CO的中等压力容易形成从脂族醇与二氧化碳有机碳酸酯2(0.1兆帕)以可接受的速率。DCC的转化率是定量的,在330 K下,该反应对碳酸盐的选择性很高。升高温度可提高转化率,但会降低选择性。一项详细的研究使我们能够分离或鉴定在有或没有二氧化碳的情况下,醇与DCC反应形成的中间体。第一步是将醇添加到异丙苯中(已知反应)并形成O-烷基异脲[RHNC(OR')NR],其可以通过H键与第二个醇分子相互作用(到目前为止尚未描述过该反应)。这样的加合物可以通过NMR检测。在醇中,不存在CO 2时,会转化为氨基甲酸酯和仲胺,而在存在CO 2时,碳酸二烷基酯(RO)2 CO与尿素[CyHN-CO-NHCy]一起形成。已经用各种脂族醇如甲醇,乙醇和烯丙醇测试了该反应。尤其是,这是合成碳酸二烯丙酯的便利途径。O-甲基-N,N'-二环己基异脲也可在CO