20140316100 | METHOD FOR PREPARING POLYMETHYLENE POLYPHENYL POLYCARBAMATE - A method for preparing polymethylene polyphenyl polycarbamate is provided, which is carried out through the condensation of phenylcarbamate with a methylating reagent under the catalyzation of a phase transfer acid catalyst. The method comprises: dissolving phenylcarbamate in a water-immiscible organic solvent to form a solution A; formulating an aqueous acid catalyst solution to fibrin a solution B; forming a reaction system comprising an organic phase and an aqueous phase by firstly adding a methylating reagent to the solution B and then mixing the solution A and the solution B or by adding the methylating reagent at the same time of mixing the solution A and the solution B or after mixing the solution A and the solution B; reacting the reaction system under stirring at a reaction temperature of 30° C. to 200° C. and a reaction pressure of 0.05 MPa to 5 MPa; and separating a polymethylene polyphenyl polycarbamate product mixture by allowing the organic phase and the aqueous phase to stand still and stratify. The method can realize the high selectivity and yield of the product and is easy to separate the product. | 10-23-2014 |