Synthesis of cyclic carbonates

Abstract

A dimeric aluminium(salen) catalyst of formula I: wherein: Y-Q is CR C1 ═N or CR C1 R C2 —NR N1 , where R C1 , R C2 and R N1 are independently selected from H, halo, optionally substituted C 1-20 alkyl, optionally substituted C 5-20 aryl, ether and nitro; each of the substituents R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 , is independently selected from H, halo, optionally substituted C 1-20 alkyl, optionally substituted C 5-20 aryl, optionally substituted C 3-20 heterocyclyl, ether and nitro; X 1 and X 2 are independently either (i) a C 2-5 alkylene chain, which is optionally substituted by one or more groups selected from C 1-4 alkyl and C 5-7 aryl, or a C 1-3 bisoxyalkylene chain, which is optionally substituted by one or more groups selected from C 1-4 alkyl and C 5-7 aryl or (ii) represent a divalent group selected from C 5-7 arylene, C 5-7 cyclic alkylene and C 3-7 heterocyclylene, which may be optionally substituted; (i) (a) at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 is selected from L-A, where L is a single bond or a C 1-10 alkylene group and A is an ammonium group paired with a counterion selected from Cl, Br and I; and/or (b) at least one of X 1 and X 2 is a divalent C 3-7 heterocyclene group, containing a ring atom which is a quaternary nitrogen atom paired with a counterion selected from Cl, Br and I; and/or (c) at least one of X 1 and X 2 is a C 2-5 alkylene chain or a C 1-3 bisoxyalkylene chain, substituted by a group -Q-L-A, where Q is either —C(═O)—O—, —C(═O)—NH—, or a single bond; and/or (ii) (a) one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 is L-A′, where L is as defined above and A′ is a ammonium linking group bound to a solid support and paired with a counterion selected from Cl, Br and I; or (b) one of X 1 and X 2 is a divalent C 3-7 heterocyclene group, containing a ring atom which is a quaternary nitrogen forming part of an ammonium linking group bound to a solid support and paired with a counterion selected from Cl, Br and I; or (c) one of X 1 and X 2 is a C 2-5 alkylene chain or a C 1-3 bisoxyalkylene chain, substituted by a group -Q-L-A′.

1 . A dimeric aluminium(salen) catalyst of formula I: 
       
         
           
           
               
               
           
         
       
       wherein:
 Y-Q is CR C1 ═N or CR C1 R C2 —NR N1 , where R C1 , R C2  and R N1  are independently selected from H, halo, optionally substituted C 1-20  alkyl, optionally substituted C 5-20  aryl, ether and nitro; each of the substituents R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 , is independently selected from H, halo, optionally substituted C 1-20  alkyl, optionally substituted C 5-20  aryl, optionally substituted C 3-20  heterocyclyl, ether and nitro; 
 X 1  and X 2  are independently either (i) a C 2-5  alkylene chain, which is optionally substituted by one or more groups selected from C 1-4  alkyl and C 5-7  aryl, or a C 1-3  bisoxyalkylene chain, which is optionally substituted by one or more groups selected from C 1-4  alkyl and C 5-7  aryl or (ii) represent a divalent group selected from C 5-7  arylene, C 5-7  cyclic alkylene and C 3-7  heterocyclylene, which may be optionally substituted; 
 (i) (a) at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16  is selected from L-A, wherein L is a single bond or a C 1-10  alkylene group and A is an ammonium group paired with a counterion selected from Cl, Br and I; or
 (b) at least one of X 1  and X 2  is a divalent C 3-7  heterocyclene group, containing a ring atom which is a quaternary nitrogen atom paired with a counterion selected from Cl, Br and I; or 
 (c) at least one of X 1  and X 2  is a C 2-5  alkylene chain or a C 1-3  bisoxyalkylene chain, substituted by a group -Q-L-A, where Q is either —C(═O)—O—, —C(═O)—NH—, or a single bond; or 
 
 (ii) (a) one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16  is L-A′, wherein L is as defined above and A′ is a ammonium linking group bound to a solid support and paired with a counterion selected from Cl, Br and I; or
 (b) one of X 1  and X 2  is a divalent C 3-7  heterocyclene group, containing a ring atom which is a quaternary nitrogen forming part of an ammonium linking group bound to a solid support and paired with a counterion selected from Cl, Br and I; or 
 (c) one of X 1  and X 2  is a C 2-5  alkylene chain or a C 1-3  bisoxyalkylene chain, substituted by a group -Q-L-A′. 
 
 
     
     
         2 . A catalyst according to  claim 1 , wherein Y-Q is CR C1 ═N. 
     
     
         3 . A catalyst according to  claim 2 , wherein R C1  is selected from H and C 1-4  alkyl. 
     
     
         4 . A catalyst according to  claim 1 , wherein Y-Q is CR C1 R C2 —NR N1 , and R C1 , R C2  and R N1  are H. 
     
     
         5 . A catalyst according to  claim 1 , wherein R 4 ═R 8 ═R 12 ═R 16 ═H. 
     
     
         6 . A catalyst according to  claim 1 , wherein those of R 1 , R 2 , R 3 , R 5 , R 6 , R 7 , R 9 , R 10 , R 11 , R 13 , R 14 , R 15  and R 16  which do not comprise -L-A or L-A′ are independently selected from H, C 1-7  alkyl, ether and nitro. 
     
     
         7 . A catalyst according to  claim 1 , wherein L is an unsubstituted C 1-3  alkylene group. 
     
     
         8 . A catalyst according to  claim 1 , wherein (a) at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16  is selected from L-A; or (b) at least one of X 1  and X 2  is a divalent C 3-7  heterocyclene group, containing a ring atom which is a quaternary nitrogen atom paired with a counterion selected from Cl, Br and I; or (c) at least one of X 1  and X 2  is a C 2-5  alkylene chain or a C 1-3  bisoxyalkylene chain, substituted by a group -Q-L-A, where Q is either —C(═O)— or a single bond, is immobilized on a solid support, either by the use of steric effects or by electrostatic binding. 
     
     
         9 . A catalyst according to  claim 1 , wherein one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16  is selected from L-A′ and wherein A′ is selected from —NH(CH 3 )(CH 2 )—, —NH(CH(CH 3 ) 2 )(C(CH 3 ) 2 )—, —N(CH 3 ) 2 (CH 2 )—, —N(CH 2 CH 3 ) 2 (CH 2 CH 2 )—, and —NHPh(CH 2 )—. 
     
     
         10 . A catalyst according to  claim 1 , wherein X 1  or X 2  is substituted by -Q-L-A′ and is of formula: 
       
         
           
           
               
               
           
         
       
     
     
         11 . A catalyst according to  claim 1 , wherein X 1  or X 2  is a divalent C 3-7  heterocyclene group containing a ring atom which is a quaternary nitrogen forming part of an ammonium linking group, and is of formula: 
       
         
           
           
               
               
           
         
       
       where R N1  is selected from H, C 1-7  alkyl and C 5-20  aryl and where R N4  is a C 1-7  alkylene group. 
     
     
         12 . A catalyst according to  claim 1 , wherein X 1  and X 2  are independently selected from is —(CH 2 ) n — or —O—(CH 2 ) p —O—, and n is 2 or 3 and p is 1 or 2. 
     
     
         13 . A catalyst according to  claim 12 , wherein X 1  and X 2  are both —C 2 H 4 —. 
     
     
         14 . A catalyst according to  claim 1 , wherein X 1  and X 2  independently represent C 6  cyclic alkylene or benzylene. 
     
     
         15 . A catalyst according to  claim 1 , wherein X 1  and X 2  independently represent a divalent group selected from C 5-7  arylene, C 5-7  cyclic alkylene and C 3-7  heterocyclylene and is unsubstituted. 
     
     
         16 . A catalyst according to  claim 1 , wherein the ammonium counter group is Br − . 
     
     
         17 . A process for production of cyclic carbonates comprising contacting an epoxide with carbon dioxide in a presence of a dimeric aluminium(salen) catalyst according to  claim 1 . 
     
     
         18 . The process of  claim 17 , wherein the catalysed reaction is: 
       
         
           
           
               
               
           
         
       
       wherein R C3  and R C4  are independently selected from H, optionally substituted C 1-10  alkyl, optionally substituted C 3-20  heterocyclyl and optionally substituted C 5-20  aryl, or R C3  and R C4  form an optionally substituted linking group between the two carbon atoms to which they are respectively attached. 
     
     
         19 . The process according to  claim 18 , wherein R C4  is H. 
     
     
         20 . The process according to  claim 18 , wherein R C3  is selected from optionally substituted C 1-4  alkyl and optionally substituted C 5-7  aryl. 
     
     
         21 . The use of a dimeric aluminium (salen) catalyst according to  claim 1  for the production of cyclic carbonates from epoxides.