Method for producing ditrimethylolpropane

Abstract

In the method of producing ditrimethylolpropane of the present invention, the distillation still residue obtained in the production of trimethylolpropane is subjected to crystallizing treatment while strictly regulating the amount of organic solvent to be used, the crystallization temperature and the crystallization time within the specific ranges. With the method of the present invention, a highly pure di-TMP is obtained only by a single operation of the crystallization.

What is claimed is:  
     
         1 . A method for producing ditrimethylolpropane represented by the following formula 1:  
       
         
           
           
               
               
           
         
         the method comprising:  
         a step of reacting n-butyl aldehyde and formaldehyde in the presence of a basic catalyst to obtain a reaction product solution;  
         a step of extracting the reaction production solution with an organic extractant to obtain an extract;  
         a step of distilling the extract to separate trimethylolpropane as a distillate and obtain a distillation still residue; and  
         a step of adding an organic solvent to the distillation still residue in an amount of 0.6 to 10 times a weight of the distillation still residue, and treating the distillation still residue at a crystallization temperature Y ° C. satisfying the following formula 3:  
         (30×ln( X )−92)≦ Y≦ 55  (3)  
         wherein X is a percent by weight concentration of ditrimethylolpropane in the distillation still residue before adding the organic solvent,  
         for 0.1 to 20 h, thereby crystallizing ditrimethylolpropane.  
       
     
     
         2 . The method according to  claim 1 , wherein the organic solvent is at least one compound selected from the group consisting of aliphatic ketones and aliphatic esters.  
     
     
         3 . The method according to  claim 2 , wherein the organic solvent is at least one compound selected from the group consisting of acetone, methyl ethyl ketone and ethyl acetate.