Ionic liquid and method for dissolving cellulose using the same

Abstract

The present invention provides an ionic liquid represented by the following chemical formula (I): [(CH 3 ) 3 N(CH 2 ) 2 OH] + [NH 2 -L-COO] −   (I) where L is —(CH 2 ) 2 — or —(CH 2 ) 3 —. The present invention also provides an ionic liquid composition containing an ionic liquid; and water. The ionic liquid is represented by the above chemical formula (I). A molar ratio of [(CH 3 ) 3 N(CH 2 ) 2 OH] + to [NH 2 -L-COO] − is not less than 0.86 and not more than 1.12. A weight ratio of the water to the ionic liquid composition is not more than 4.7%. The present invention provides an ionic liquid capable of dissolving cellulose without an cellulose-degrading enzyme (namely, an enzyme capable of hydrolyzing cellulose).

1 . An ionic liquid represented by the following chemical formula (I):
   [(CH 3 ) 3 N(CH 2 ) 2 OH] + [NH 2 -L-COO] −   (I)
   where L is —(CH 2 ) 2 — or —(CH 2 ) 3 —.   
     
     
         2 . An ionic liquid composition, containing:
 an ionic liquid; and   water,   wherein   the ionic liquid is represented by the following chemical formula (I):
   [(CH 3 ) 3 N(CH 2 ) 2 OH] + [NH 2 -L-COO] −   (I)
 
 where L is —(CH 2 ) 2 — or —(CH 2 ) 3 —; 
   a molar ratio of [(CH 3 ) 3 N(CH 2 ) 2 OH] +  to [NH 2 -L-COO] −  is not less than 0.86 and not more than 1.12; and   a weight ratio of the water to the ionic liquid composition is not more than 4.7%.   
     
     
         3 . The ionic liquid composition according to  claim 2 , wherein
 the ionic liquid composition does not contain an enzyme capable of hydrolyzing cellulose.   
     
     
         4 . The ionic liquid composition according to  claim 2 , wherein
 the molar ratio of [(CH 3 ) 3 N(CH 2 ) 2 OH] +  to [NH 2 -L-COO] −  is not less than 0.89 and not more than 1.10.   
     
     
         5 . The ionic liquid composition according to  claim 2 , wherein
 the weight ratio of the water to the ionic liquid composition is not less than 1.6%.   
     
     
         6 . The ionic liquid composition according to  claim 2 , further containing:
 an aprotic polar solvent.   
     
     
         7 . The ionic liquid composition according to  claim 6 , wherein
 the aprotic polar solvent is dimethyl sulfoxide.   
     
     
         8 . The ionic liquid composition according to  claim 7 , wherein
 a weight ratio of the dimethyl sulfoxide to the ionic liquid is not more than 309%.   
     
     
         9 . A method for dissolving cellulose, the method comprising:
 (a) adding cellulose to an ionic liquid composition;   wherein   the ionic liquid composition contains an ionic liquid and water;   the ionic liquid is represented by the following chemical formula (I):
   [(CH 3 ) 3 N(CH 2 ) 2 OH] + [NH 2 -L-COO] −   (I)
 
 where L is —(CH 2 ) 2 — or —(CH 2 ) 3 —; 
   a molar ratio of [(CH 3 ) 3 N(CH 2 ) 2 OH] +  to [NH 2 -L-COO] −  is not less than 0.86 and not more than 1.12; and   a weight ratio of the water to the ionic liquid composition is not more than 4.7%.   
     
     
         10 . The method according to  claim 9 , wherein
 the ionic liquid composition does not contain an enzyme capable of hydrolyzing cellulose.   
     
     
         11 . The method according to  claim 9 , wherein
 the molar ratio of [(CH 3 ) 3 N(CH 2 ) 2 OH] +  to [NH 2 -L-COO] −  is not less than 0.89 and not more than 1.10.   
     
     
         12 . The method according to  claim 9 , wherein
 the weight ratio of the water to the ionic liquid composition is not less than 1.6%.   
     
     
         13 . The method according to  claim 9 , further comprising:
 (b1) heating the ionic liquid composition to which the cellulose has been added to dissolve the cellulose in the ionic liquid composition, after the step (a).   
     
     
         14 . The method according to  claim 9 , further comprising:
 (b2) leaving the ionic liquid composition to which the cellulose has been added at rest to dissolve the cellulose in the ionic liquid composition, after the step (a).   
     
     
         15 . The method according to  claim 9 , further comprising:
 (b3) stirring the ionic liquid composition to which the cellulose has been added to dissolve the cellulose in the ionic liquid composition, after the step (a).   
     
     
         16 . The method according to  claim 9 , wherein
 the ionic liquid composition further contains an aprotic polar solvent.   
     
     
         17 . The method according to  claim 16 , wherein
 the aprotic polar solvent is dimethyl sulfoxide.   
     
     
         18 . The method according to  claim 17 , wherein
 a weight ratio of the dimethyl sulfoxide to the ionic liquid is not more than 309%.   
     
     
         19 . A method for fabricating a cellulose film; the method comprising:
 (a) adding cellulose to an ionic liquid composition to prepare a cellulose solution;   (b) applying the cellulose solution on a surface of a substrate to form a film on the surface;   (c) removing the ionic liquid composition from the film using a solvent; and   (d) removing the solvent from the film,   wherein   the ionic liquid composition contains an ionic liquid and water;   the ionic liquid is represented by the following chemical formula (I):
   [(CH 3 ) 3 N(CH 2 ) 2 OH] + [NH 2 -L-COO] −   (I)
 
 where L is —(CH 2 ) 2 — or —(CH 2 ) 3 —; 
   a molar ratio of [(CH 3 ) 3 N(CH 2 ) 2 OH] +  to [NH 2 -L-COO] −  is not less than 0.86 and not more than 1.12; and   a weight ratio of the water to the ionic liquid composition is not more than 4.7%.