Diaryl carbonate and method for producing the same, and method for producing an aromatic polycarbonate resin

Abstract

wherein R1 represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, or an aryloxy group.

1 . A diaryl carbonate containing a compound of the following formula (I) in an amount of less than 1,000 ppm by mass: 
       
         
           
           
               
               
           
         
       
       wherein R 1  represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, or an aryloxy group. 
     
     
         2 . A method for producing the diaryl carbonate according to  claim 1 , the method comprising:
 a first step of reacting urea with an alkyl alcohol to yield a first reaction mixture containing a dialkyl carbonate;   a second step of reacting the dialkyl carbonate in the first reaction mixture with an aryl alcohol to yield a second reaction mixture containing an alkylaryl carbonate;   a third step of subjecting the alkylaryl carbonate in the second reaction mixture to disproportionation to yield a third reaction mixture containing a diaryl carbonate; and   a fourth step of purifying the third reaction mixture,   wherein the third reaction mixture further contains the compound of the formula (I) in an amount of 1,000 ppm by mass or more.   
     
     
         3 . The method according to  claim 2 , wherein the fourth step comprises a distillation step of, using a distillation column, obtaining the diaryl carbonate containing the compound of the formula (I) in an amount of less than 1,000 ppm by mass from the top of the column and obtaining a mixture having concentrated the compound of the formula (I) from the bottom of the column, wherein the distillation step is conducted under the following conditions (a) and (b):
 (a) that the pressure at the top of the distillation column is 0.01 to 10 kPa, and   (b) that the reflux ratio is 2 to 20.   
     
     
         4 . The method according to  claim 3 , which further comprises a fifth step of filtering off the compound of the formula (I) which is precipitated from the concentrated mixture at a temperature in the range of from 80 to 230° C. 
     
     
         5 . The method according to  claim 4 , which further comprises a recycling step (sixth step) of recovering the compound of the chemical formula (I) filtered off in the fifth step and bringing the filtrate back to the fourth step. 
     
     
         6 . The method according to  claim 2 , wherein the alkyl alcohol used in the first step is an alkyl alcohol having 3 to 6 carbon atoms. 
     
     
         7 . A method for producing an aromatic polycarbonate resin, the method comprising performing melt polycondensation in the presence of a transesterification catalyst using the diaryl carbonate according to  claim 1  and an aromatic dihydroxy compound. 
     
     
         8 . The method according to  claim 3 , wherein the alkyl alcohol used in the first step is an alkyl alcohol having 3 to 6 carbon atoms. 
     
     
         9 . The method according to  claim 4 , wherein the alkyl alcohol used in the first step is an alkyl alcohol having 3 to 6 carbon atoms. 
     
     
         10 . The method according to  claim 5 , wherein the alkyl alcohol used in the first step is an alkyl alcohol having 3 to 6 carbon atoms.