1269621-50-2Relevant articles and documents
Sulfonamide, phenolate, and directing ligand-free indium initiators for the ring-opening polymerization of rac-lactide
Blake, Matthew P.,Schwarz, Andrew D.,Mountford, Philip
, p. 1202 - 1214 (2011/05/05)
Reaction of In(CH2SiMe3)3 with H 2N2TsNpy or H2N 2TsNOMe gave the five-coordinate indium alkyls In(N2TsNpy)(CH2SiMe3) (14) and In(N2TsNOMe)(CH2SiMe 3) (15). The corresponding reaction with H2N 2TsNPh gave four-coordinate In(N 2TsNPh)(CH2SiMe3) (16). Reaction of H2N2TsNpy with In{N(SiMe3)2}3 gave the amide In(N 2TsNpy){N(SiMe3)2} (19). Reaction of Na2N2TsNpy with InCl3 in THF followed by LiOiPr gave the "ate" product In(N2TsNpy)(OiPr)Cl{Li(THF)} (21). The chloride complex In(N2TsNpy)Cl(py) (22) was also isolated. Reaction of In(CH2SiMe3) 3 with H2O2MeNpy gave the bis(phenolate)amine compound In(O2MeNpy) (CH2SiMe3) (23), and reaction with iPrOH or Me2NCH2CH2OH gave the mixed alkyl-alkoxides In(CH2SiMe3)2(OiPr) (17) and In(CH2SiMe3)2(OCH2CH 2NMe2) (18), which are dimeric in the solid state. The X-ray structures of 14, 15, 17-19, and 21 - 23 have been determined. The compounds were evaluated as initiators for the ring-opening polymerization of rac-lactide. With the alkyl and amide initiators, the Mn control was poor because of an unfavorable mismatch between initiation and propagation rates. The molecular weight control with the "ate" complex 21 was better, but the ROP was slow. The best-behaved initiator in terms of living ROP was In(CH2SiMe3)2(OiPr) (17). When used alone, In(CH2SiMe3)3 was a very poor initiator, but in the presence of BnNH2 amine-co-initiated immortal ROP occurred to give atactic amine-terminated PLA in a controlled manner. Use of InCl3 and Et3N in place of the indium alkyl gave a 4-fold increase in activity and a substantial increase in heterotacticity (P r = 0.85). Initial studies showed that BnNH2 and InCl 3 alone could also produce heterotactically enriched, amine-terminated PLA at room temperature, albeit very slowly. (H 2N2TsNpy = (2-NC5H 4)CH2N(CH2CH2NHTs)2; H2N2TsNOMe = MeOCH 2CH2N(CH2CH2NHTs)2; H2N2TsNPh = PhCH 2N(CH2CH2NHTs)2; H2O 2MeNpy = (2-NC5H4)CH 2N(CH2ArOH)2 (Ar = C6H 2Me2).)
