Methods for the manufacture of acetals and ketals, and the acetals and ketals produced thereby

Abstract

A method for producing a product that comprises glycerol ketal of ethyl levulinate or propylene glycol ketal of ethyl levulinate comprises reacting either glycerol or propylene glycol with ethyl levulinate in the presence of a homogenous or heterogeneous catalyst system in a reactor system. The ethyl levulinate and either glycerol or propylene glycol are heated to remove water, polyol, and excess ethyl levulinate. The excess ethyl levulinate and polyol is recycled back to the reactor. The product is distilled in a specific fashion and optionally treated by means of a stabilizing agent or acid species removal bed, to obtain a composition comprising glycerol ketal of ethyl levulinate or propylene glycol ketal of ethyl levulinate wherein the composition comprises less than or equal to about 2 wt % contaminants.

1 . A method for the manufacture of a glycerol ketal of ethyl levulinate, the method comprising:
 contacting glycerol with ethyl levulinate and an acid catalyst in a reactor under reaction conditions to produce a product that comprises a glycerol ketal of ethyl levulinate;   fractionating the product under fractionation conditions to separate fractionated materials from the product until the product comprises less than 1000 parts per million of glycerol;   recycling the fractionated materials back to the reactor; and   distilling the product under distillation conditions wherein the resulting product comprises the glycerol ketal of ethyl levulinate and less than or equal to about 2 wt % contaminants; wherein the contaminants comprise one or more of glycerol, acid species, ethyl levulinate, water, or a high molecular weight byproduct having molecular weights that are at least 1.5 times greater than the molecular weight of the glycerol ketal of ethyl levulinate.   
     
     
         2 . The method of  claim 1 , wherein the reactor is a continuous multistage reactor comprising a first reactor, a second reactor and a third reactor, and the method comprises
 contacting the glycerol with the ethyl levulinate and the acid catalyst in the first reactor under a first set of reaction conditions to produce the product that comprises the glycerol ketal of ethyl levulinate:   continuously sending the product from the first reactor to the second reactor that is downstream of the first reactor and subjecting the product to a second set of reaction conditions; and   continuously sending the product from the second reactor to the third reactor that is downstream of the second reactor and subjecting the product to a third set of reaction condition.   
     
     
         3 . The method of  claim 1 , wherein the high molecular weight byproduct is one or more of dimers, trimers or oligomers produced by a reaction between one or more of the glycerol ketal of ethyl levulinate, ethyl levulinate, glycerol, and/or an aldol of the glycerol ketal of ethyl levulinate or produced by a reaction between the glycerol ketal of ethyl levulinate and itself 
     
     
         4 . The method of any of  claim 1 , wherein the product comprises less than 200 ppm water, less than 20 ppm acid, less than or equal to about 10,000 ppm of glycerol, less than or equal to about 0.25 wt % of dimers obtained from a reaction between monomers of the glycerol ketal of ethyl levulinate, less than or equal to about 0.25 wt % of dimers obtained from a reaction between the glycerol ketal of ethyl levulinate and an aldol of the glycerol ketal of ethyl levulinate, less than or equal to about 0.25 wt % of dimers obtained from a reaction between the glycerol ketal of ethyl levulinate and ethyl levulinate, less than or equal to about 0.1 wt % of trimers obtained from a reaction between the glycerol ketal of ethyl levulinate, ethyl levulinate and aldols of glycerol ketal of ethyl levulinate and less than or equal to about 0.10 wt % of trimers obtained from a reaction between the glycerol ketal of ethyl levulinate and ethyl levulinate, where the weight percents are based on the total weight of the composition. 
     
     
         5 . The method of  claim 1 , wherein the ethyl levulinate is added to the reactor system in a stoichiometric excess relative to the glycerol. 
     
     
         6 . The method of  claim 1 , wherein a molar ratio of ethyl levulinate to propylene glycol or glycerol is between about 5:1 to about 1:5. 
     
     
         7 . The method of  claim 1 , wherein the acid catalyst is camphor sulfonic acid. 
     
     
         8 . The method of  claim 1 , further comprising subjecting the product to an acid removal column to remove the acid prior to the fractionation. 
     
     
         9 . The method of  claim 1 , further comprising purging the distillation column to remove the high molecular weight species. 
     
     
         10 . The method of  claim 1 , where the reaction conditions comprise a temperature between about 50 and 150° C. 
     
     
         11 . The method of  claim 1 , where the reaction conditions comprise a pressure of between about 5 and 760 millimeters of mercury. 
     
     
         12 . The method of  claim 2 , wherein:
 the fractionated materials are separated from the product in a first distillation column and the glycerol ketal of ethyl levulinate is separated from the high molecular weight species in a second distillation column, wherein the first reactor, the second reactor, the third reactor, the first distillation column and the second distillation columns are in fluid communication with each other.   
     
     
         13 . The method of  claim 12 , wherein the first reactor, the second reactor, the third reactor, the first distillation column and the second distillation column are in series. 
     
     
         14 . The method of  claim 12 , wherein the first reactor, the second reactor, the third reactor, the first distillation column or the second distillation column are in parallel. 
     
     
         15 . The method of  claim 12 , where the first distillation column or the second distillation column is purged to remove substantially all acid species or the high molecular weight species. 
     
     
         16 . The method of  claim 1 , further comprising passing the product through a bed of inorganic base or buffer. 
     
     
         17 . The method of  claim 16 , where the base is a carbonate, an amine, a hydroxide, a phosphate or an oxide. 
     
     
         18 . The method of  claim 16 , where the buffer comprises a packed bed of inorganic salt. 
     
     
         19 . The method of  claim 16 , where the buffer comprises a solution of citric acid, sodium citrate, sodium carbonate, sodium bicarbonate, sodium phosphate, calcium phosphate, or a combination comprising at least one of the foregoing buffers. 
     
     
         20 . The method of  claim 1 , further comprising hydrogenating the product. 
     
     
         21 . The method of  claim 1 , wherein the catalyst is a heterogeneous catalyst. 
     
     
         22 . The method of any of  claim 1 , wherein the catalyst is a homogeneous catalyst. 
     
     
         23 . A composition comprising a ketal adduct having the structure (6): 
       
         
           
           
               
               
           
         
       
       where R 1 , R 2 , R 3 , and R 4  is independently a hydrogen, C1-12 alkyl, C3-6 cycloalkyl, C1-12 alkenyl, C6-12 aryl, C7-13 arylalkyl, or C7-13 alkylaryl, and b is 1-4, R 5  is a C1-12 alkyl, C3-6 cycloalkyl, C2-12 alkenyl, C2-12 alkynyl, C6-12 aryl, C7-13 arylalkyl, or C7-13 alkylaryl, each of which can optionally be substituted with one or more addition hydroxyl groups, R 6 , R 7 , R 10 , and R 11  is independently a hydrogen, C1-12 alkyl, C1-12 hydroxyalkylene, C1-12 alkyl substituted with up to six hydroxy groups, C3-6 cycloalkyl, C2-5 heterocycloalkyl, C1-12 alkenyl, C1-12 hydroxyalkenyl, C6-12 aryl, C7-13 arylalkyl, or C7-13 alkylaryl, each R 8  and R 9  is independently a hydrogen, hydroxyl, C1-12 alkyl, C1-12 hydroxyalkyl, C3-6 cycloalkyl, C1-12 alkenyl, C1-12 hydroxyalkenylene, C6-12 aryl, C7-13 arylalkyl, or C7-13 alkylaryl and c is 0-1 and wherein the composition comprises less than or equal to about 2 wt % contaminants; wherein the contaminants comprise one or more of glycerol, acid, ethyl levulinate, water, or a high molecular weight byproduct having molecular weights that are at least 1.1 times greater than the molecular weight of the ketal adduct. 
     
     
         24 . The composition of  claim 23 , wherein the ketal adduct has the structure (6a): 
       
         
           
           
               
               
           
         
       
       wherein R 1  is a C1-6 alkyl and R 9  is hydrogen or C1-4 alkyl. 
     
     
         25 . The composition of  claim 23 , wherein the ketal adduct has the structure (6b): 
       
         
           
           
               
               
           
         
       
       wherein R 1  is a C1-6 alkyl. 
     
     
         26 . The composition of  claim 23 , wherein the high molecular weight byproduct comprises dimers, trimers or oligomers produced by a reaction of one or more of a propylene glycol ketal of ethyl levulinate, propylene glycol and/or an aldol of a propylene glycol ketal of ethyl levulinate or produced by a reaction between a propylene glycol ketal of ethyl levulinate, propylene glycol and itself 
     
     
         27 . The composition of  claim 23 , wherein the composition comprises less than less than 200 ppm water, less than 20 ppm acid, less than or equal to about 10,000 ppm of glycerol, less than or equal to about 0. 25 wt % of dimers obtained from a reaction between monomers of the propylene glycol ketal of ethyl levulinate, less than or equal to about 0.25 wt % of dimers obtained from a reaction between the propylene glycol ketal of ethyl levulinate and an aldol of propylene glycol ketal of ethyl levulinate, less than or equal to about 0.25 wt % of dimers obtained from a reaction between the propylene glycol ketal of ethyl levulinate and ethyl levulinate, less than or equal to about 0.1 wt % of trimers obtained from a reaction between the propylene glycol ketal of ethyl levulinate, ethyl levulinate and aldols of propylene glycol ketal of ethyl levulinate and less than or equal to about 0.10 wt % of trimers obtained from a reaction between propylene glycol ketal of ethyl levulinate and ethyl levulinate, where the weight percents are based on the total weight of the composition. 
     
     
         28 . The composition of  claim 23  where the composition is color stable. 
     
     
         29 . The composition of  claim 23 , where the composition is hydrolytically stable. 
     
     
         30 . A formulation comprising the composition of  claim 23 . 
     
     
         31 . The formulation of  claim 30  wherein the formulation is a water-based formulation. 
     
     
         32 . The formulation of  claim 31 , further comprising a buffer. 
     
     
         33 . An article comprising the composition of  claim 23 .