Cyclobutanetetracarboxylate compound and preparation method thereof

Abstract

The invention provides a cyclobutanetetracarboxylate compound of general formula (I) and a preparation method thereof: in which R and R 1 are as defined in the specification.

1 . A cyclobutanetetracarboxylate compound of general formula (I):  
     
       
         
         
             
             
         
       
     
     in which: 
 R can be the same or R is different from each other and independently represents hydrogen or a halogen or a monovalent organic radical;  
 and R 1  is a C 1 -C 4  alkyl.  
 
   
   
       2 . The cyclobutanetetracarboxylate compound of  claim 1 , wherein said monovalent organic radical is a straight-chained, branched, or cyclic C 1 -C 4  alkyl.  
   
   
       3 . The cyclobutanetetracarboxylate compound of  claim 1 , wherein said monovalent organic radical is methyl, ethyl, propyl, isopropyl, butyl, or isobutyl.  
   
   
       4 . A process for the preparation of the cyclobutanetetracarboxylate compound as defined in  claim 1 , comprising: 
 (a) conducting an esterification reaction of a diacid compound of general formula (II)                          (in which R is as defined hereinbefore) with an alcohol of general formula (III)      R 1 —OH  Formula (III)    in the presence of an acidic solvent to obtain a precursor compound of general formula (IV)                          (b) conducting a cyclization reaction by irradiating the precursor compound of general formula (IV) with an energy ray to obtain the cyclobutanetetracarboxylate compound of general formula (I).    
   
   
       5 . The process of  claim 4  wherein the alcohol of general formula (III) is methanol, ethanol, propanol, or isopropanol.  
   
   
       6 . The process of  claim 4  wherein the reaction of step (a) is conducted at a temperature from 60 to 110° C.  
   
   
       7 . The process of  claim 4  wherein the reaction of step (a) is conducted for 2 to 20 hours.  
   
   
       8 . The process of  claim 4  wherein the energy ray used in step (b) is a light source having a wavelength of from 200 to 600 nm.  
   
   
       9 . The process of  claim 4  wherein the energy ray used in step (b) is an ultraviolet light.  
   
   
       10 . The process of  claim 4  wherein the reaction of step (b) is conducted for 30 minutes to 30 hours.  
   
   
       11 . The process of  claim 4  wherein the reaction of step (b) is conducted in the presence of a solvent.  
   
   
       12 . The process of  claim 11  wherein the solvent is ethyl acetate, acetone, water, or methanol, or a mixture thereof.