1215088-38-2Relevant articles and documents
Sulfonamide-supported aluminum catalysts for the ring-opening polymerization of rac-lactide
Schwarz, Andrew D.,Chu, Zengyong,Mountford, Philip
, p. 1246 - 1260 (2010/05/01)
The synthesis, structures, and ring-opening polymerization (ROP) capability of a wide range of sulfonamide-supported aluminum alkyl and alkoxide complexes are reported. The synthesis of the new protio-ligands PhCH2N(CH 2CH2NHSO2R)2 (R = ToI (15, H 2N2TsNph) or Me (16, H 2N2MsNph)) is described. These and the previously reported 1,2-C6H10(NHSO2R) 2 (R = Tol (11, H2CyN2Ts) or Mes (12, H2CyN2so2Mes)) and RCH 2N(CH2CH2NHSO2TOl)2 (R = MeOCH2 (13, H2N2TSNOMe) or 2-NC5H4 (14, H2N2 TsNpy)) reacted with AlEt3 to form Al(CyN 2Ts)Et(THF) (17), Al(CyN2SO2Mes) Et(THF) (18), and Al(N2TsNR)Et (R = Ph (19), OMe (20), or py (21)), respectively. Subsequent reaction of these ethyl complexes with R'OH (R' = 1Pr or Bn) resulted in protonolysis of the sulfonamide supporting ligands to yield a mixture of products including Al(OR')3- In contrast, reaction of Al(OR')Et2 (R' = 1Pr, Bn, CH2CH2NH2, or CH2CH 2NMe2) with various protio-ligands formed the sulfonamide-supported alkoxides Al(N2TsN py)(OR') (R' = 1Pr (22) or Bn (23)), Al(N2 MsNph)(OR') (R' = Pr (26) or Bn (27)), Al(N 2TsNR)(OCH2CH2NH 2) (R = Ph (29), OMe (30), or py (31)), Al(CyN2 Ts)(OCH2CH2NMe2) (32), and Al(N 2TsNph)(OCH2CH2NMe 2) (33). Unexpectedly, reaction OfAl(OTr)Et2 with H 2N2TsNOMe led to O-demethylation of the sulfonamide ligand. Reaction of AlMe2Cl with H2N 2TsNph gave [Al(NTs 2Nph)Cl]2 (28). X-ray diffraction studies revealed four- or five-coordinate C.v-symmetric structures for 17-21, a five-coordinate C2-symmetric sulfonamide-bridged dimer for 28, and a five-coordinate C,-symmetric monomer for 30 stabilized by intramolecular hydrogen bonding between the sulfonyl oxygens and the amine protons. Compounds 19, 21, 22-27, and 29-33 are all catalysts for the ROP of rac-lactide, with the alkoxide compounds 22-27 and 32 giving well-defined molecular weights and molecular weight distributions. These compounds were also active in the melt at 130 °C, giving atactic poly(rac-lactide) with moderate to narrow PDIs and extremely good control of Mn and high activity in the case of 23.
