Methods for producing alkyl hydroxyalkanoates

Abstract

Methods and systems for producing alkyl hydroxyalkanoates from hydroxycarboxylic acid recovery bottoms. The methods generally comprise the steps of obtaining a hydroxycarboxylic acid recovery bottom, adding a mono-alcohol to the hydroxycarboxylic acid recovery bottom to obtain a first mixture, heating the first mixture, optionally in the presence of a catalyst to form a reaction product, distilling the reaction product, and recovering an alkyl hydroxyalkanoate fraction.

1 . A method for producing an alkyl 3-hydroxypropionate, comprising:
 a) obtaining a 3-hydroxypropionate containing composition, comprising:
 (i) at least 40 percent by weight 3-hydroxypropionate equivalents; 
 (ii) greater than 0 and less than 45 percent by weight free 3-hydroxypropionate; 
 (iii) at least 1 percent by weight saccharide equivalents; and 
 (iv) less than 5 percent by weight water; 
   b) mixing a mono-alcohol in a molar ratio of from about 1.1 to 1.0 to about 10.0 to 1.0 of mono-alcohol to 3-hydroxypropionate equivalents present in the 3-hydroxypropionate containing composition to obtain a first mixture;   c) heating the first mixture to form a reaction product;   d) distilling the reaction product and recovering an alkyl 3-hydroxypropioniate fraction comprising:
 (i) at least 90 percent by weight alkyl 3-hydroxypropioniate; 
 (ii) less than 1 percent by weight 3-hydroxypropionic acid; 
 (iii) less than 1 percent by weight water; and 
 (iv) less than 0.5 percent by weight saccharide equivalents. 
   
     
     
         2 . The method of  claim 1 , wherein step (d) further comprises separating the reaction product into a first fraction enriched in mono-alcohol and water, and a second fraction enriched in alkyl 3-hydroxypropioniate, wherein the alkyl 3-hydroxypropioniate is recovered from the second fraction. 
     
     
         3 . The method of  claim 1 , wherein step (d) comprises:
 a first step to provide a first fraction enriched in water and mono-alcohol and a second fraction enriched in the alkyl 3-hydroxypropioniate and the saccharide equivalents; and   a second step to fractionate the second fraction into a saccharide equivalents enriched fraction, and an alkyl 3-hydroxypropioniate enriched fraction.   
     
     
         4 . The method of  claim 1 , wherein step (d) comprises:
 a first step to provide a first fraction enriched in water, mono-alcohol, and alkyl 3-hydroxypropioniate and a second fraction enriched in saccharide equivalents; and   a second step to fractionate the first fraction into a water and a mono-alcohol enriched fraction and an alkyl 3-hydroxypropioniate fraction.   
     
     
         5 . The method of  claim 1 , wherein the first mixture is heated to a temperature of from about 50° C. to about 300° C. 
     
     
         6 . The method of  claim 1 , wherein the first mixture is heated to a temperature of from about 50° C. to about 200° C. 
     
     
         7 . The method of  claim 1 , wherein the pressure in step (c) ranges from 1 atm to 100 atm. 
     
     
         8 . The method of  claim 1 , wherein the pressure in step (c) ranges from 10 atm to 50 atm. 
     
     
         9 . The method of  claim 1 , wherein the 3-hydroxypropioniate containing composition comprises at least 2 percent by weight saccharide equivalents. 
     
     
         10 . The method of  claim 1 , wherein the 3-hydroxypropioniate containing composition comprises at least 3 percent by weight saccharide equivalents. 
     
     
         11 . The method of  claim 1 , wherein the 3-hydroxypropioniate containing composition comprises at least 5 percent by weight saccharide equivalents. 
     
     
         12 . The method of  claim 1 , wherein the 3-hydroxypropioniate containing composition comprises less than 3 percent by weight water. 
     
     
         13 . The method of  claim 1 , wherein the 3-hydroxypropioniate containing composition comprises less than 2 percent by weight water. 
     
     
         14 . The method of  claim 1 , wherein the 3-hydroxypropioniate containing composition comprises less than 1 percent by weight water. 
     
     
         15 . The method of  claim 1 , wherein a pressure below atmospheric pressure is utilized during step (d) to recover the alkyl 3-hydroxypropioniate. 
     
     
         16 . The method of  claim 1 , wherein a pressure from about 0.1 torr to about 750 torr is utilized during step (d). 
     
     
         17 . The method of  claim 1 , wherein a pressure from about 0.1 torr to about 250 torr is utilized during step (d). 
     
     
         18 . The method of  claim 1 , wherein the mono-alcohol comprises a C1 to C6 mono-alcohol. 
     
     
         19 . The method of  claim 1 , wherein the mono-alcohol is selected from the group consisting of methanol, ethanol, propanol, butanol, and mixtures thereof. 
     
     
         20 . The method of  claim 1 , wherein the mono-alcohol comprises ethanol.