Pyroglutamic Acid Esters With Improved Biodegradility

Abstract

The invention relates to compounds of formula (1) in which is a C 2 - to C 4 -alkylene group; x is from 1 to 100; R′ is an aliphatic, cycloaliphatic or aromatic radical which contains at least one structural unit of the formula 2, and y is from 1 to 100. The invention also relates to the use of these compounds in quantities of 0.01 to 2% by weight for preventing the formation of gas hydrates in aqueous phases that are connected to a gaseous, liquid or solid organic phase.

1 . A pyroglutamic acid ester compound of the formula 1 
       
         
           
           
               
               
           
         
       
       in which
 A is a C 2 - to C 4 -alkylene group 
 x is from 1 to 100 
 R′ is an aliphatic, cycloaliphatic or aromatic radical which contains at least one structural unit of the formula 2 
 
       
         
           
           
               
               
           
         
       
       and
 y is from 0 to 100, 
 
       with the proviso that compounds in which R′ is the structural unit of the formula 2, x is one and y is zero or one are excluded. 
     
     
         2 . The compound as claimed in  claim 1 , in which R′ is derived from the group consisting of ethylene glycol, propylene glycol, glycerol, diglycerol, triglycerol, tetraglycerol, polyglycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, sorbitan, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol. 
     
     
         3 . The compound as claimed in  claim 1 , wherein the pyroglutamic ester is prepared by using L-glutamic acid in enantiomerically pure form. 
     
     
         4 . The compound as claimed in  claim 1 , wherein the pyroglutamic ester comprises a glutamic ester. 
     
     
         5 . The compound as claimed in  claim 1 , wherein x and y are each independently from 2 to 80. 
     
     
         6 . The compound as claimed in  claim 1 , wherein R′ is an organic radical of the formula 3 
       
         
           
           
               
               
           
         
       
       in which n is 1-100 and R is an aliphatic, cycloaliphatic or aromatic radical which may contain heteroatoms and bears at least (n+1) active hydrogen atoms which can be substituted by alkoxylation. 
     
     
         7 . The compound as claimed in  claim 1 , wherein A represents ethylene radicals, propylene radicals or mixtures of ethylene and propylene radicals. 
     
     
         8 . A method for inhibiting formation of a gas hydrate in a gas stream comprising water and an alkane or a mixture of alkanes, said method comprising adding to the stream a pyroglutamic acid ester compound of the formula 1 
       
         
           
           
               
               
           
         
       
       in which
 A is a C 2 - to C 4 -alkylene group 
 x is from 1 to 100 
 R′ is an aliphatic, cycloaliphatic or aromatic radical which contains at least one structural unit of the formula 2 
 
       
         
           
           
               
               
           
         
       
       and
 y is from 0 to 100. 
 
     
     
         9 . The method of  claim 8 , in which R′ is derived from a compound selected from the group consisting of ethylene glycol, propylene glycol, glycerol, diglycerol, triglycerol, tetraglycerol, polyglycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, sorbitan, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol. 
     
     
         10 . The method of  claim 8 , wherein the pyroglutamic acid ester is prepared by using L-glutamic acid in enantiomerically pure form. 
     
     
         11 . The method of  claim 8 , wherein the pyroglutamic acid ester comprises a glutamic ester. 
     
     
         12 . The method of  claim 8 , wherein x and y are each independently from 2 to 80. 
     
     
         13 . The method of  claim 8 , wherein R′ is an organic radical of the formula 3 
       
         
           
           
               
               
           
         
       
       in which n is 1-100 and R is an aliphatic, cycloaliphatic or aromatic radical which may contain heteroatoms and bears at least (n+1) active hydrogen atoms which can be substituted by alkoxylation. 
     
     
         14 . The method of  claim 8 , wherein A is an ethylene radical or a propylene radical or a mixture of ethylene and propylene radicals.