通过化学反应催化固定CO 2一直是合成化学的一项艰巨任务。本文介绍了一种设计,合成了一种环保,低成本,含锌金属的非均相改性胺类氧化石墨烯催化剂。催化剂的表征已通过拉曼光谱和FTIR光谱,AAS,XRD,TEM,SEM,EDX和N 2吸附脱附研究进行。发现该催化剂通过胺的N-甲酰化和氨基甲酸酯形成反应非常熟练地固定了CO 2。在1 bar CO 2下,存在聚甲基氢硅氧烷(PMHS)作为还原剂的情况下,芳族胺和脂肪族胺的N甲酰化反应可得到相应的甲酰化产物,收率很高压力和温和的温度。在我们合成的催化剂存在下,在无溶剂条件下,在相同的CO 2压力下,也可以在相同的CO 2压力下,由苯胺或其衍生物和烷基/芳基溴化物形成氨基甲酸酯,并具有良好的产品选择性。即使经过六个循环,催化剂仍可重复使用且高效。
Process for producing diphenylmethane dicarbamates
申请人:Asahi Kasei Kogyo Kabushiki Kaisha
公开号:EP0110732A2
公开(公告)日:1984-06-13
A process for producing a diphenylmethane dicarbamate by reacting a N-phenylcarbamate with a methylenating agent is disclosed. The process is carried out by condensing N-phenylcarbamate in two steps using a combination of two different types of acid catalysts. The catalysts exhibit a strong catalizing effect and yet can be radily separated from the reaction mixture. The process produces dineuclear diphenylmethane dicarbamates in high selectivity. The acid catalysts can be easily recovered from the reaction mixtures and put to another use.
Method for manufacture of diphenylmethane diisocyanates
申请人:Asahi Kasei Kogyo Kabushiki Kaisha
公开号:EP0123412A1
公开(公告)日:1984-10-31
Manufacture of a diphenylmethane diisocyanate for an N-phenylcarbamate is economically accomplished in high yield with high selectivity by a method which comprises (A) a process of methylenation forthe formation of a condensation product containing at least 80 mol% of a dinuclear diphenylmethane dicarbamate by the steps of 1) causing a methylenating agent to react upon at least 2 moles of an N-phenylcarbamate, based on 1 mole of the methylene group of said methylenating agent, in a liquid phase in the presence of an aqueous inorganic acid solution, 2) separating the resultant reaction mixture into the aqueous inorganic acid solution and an organic phase reaction mixture containing substantially none of said inorganic acid, and 3) subsequently treating said organic phase reaction mixture in the presence of an N-phenylcarbamate and a carboxylic acid having a pKa of not more than 4 in an aqueous solution at a temperature of25°C or a solid acid or an acid consisting of said two acids thereby converting a reaction intermediate possessing a methylene-amino bond and contained in said organic phase reaction mixture to a diphenylmethane dicarbamate, and (B) a process of thermal decomposition by the steps of allowing a mixture comprising 1 to 50% by weight of the condensation product obtained in said process of (A) and 99 to 50% by weight of a thermal decomposition solvent having a boiling point under atmospheric pressure in the range of 120 to 350%C and being inactive to isocyanates to flow down into a reactor maintained attemperatu res in the range of 180 to 380°C through the upper part thereof, causing said mixture to come into counterflow contact with a carrier introduced into said reactor upwardly via the lower part thereof thereby producing an organic hydroxyl compound, allowing said organic hydroxyl compound to be discharged from said reactor in the form of vapor in conjunction with said carrier through the upper part thereof, and withdrawing the resultant isocyanate solution from said reactor through the lower part thereof.
4,4′-Diphenylmethane dicarbamates are produced with high selectivity and in high yield by the one-stage condensation of a N-phenyl carbamate with a methylenating agent in presence of zinc halide as catalyst.