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Titanium complexes bearing amine bis(phenolate) ligands: Synthesis, structure and catalysis in ring‐opening polymerization of lactide
Author(s) -
Wang Baolong,
Zhang Jianing,
Zhao Huanqin,
Huang He,
Zheng Junpei,
Wang Liying,
Sun Junmin,
Zhang Yongfeng,
Cao Zhenzhu
Publication year - 2017
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3688
Subject(s) - chemistry , ring opening polymerization , lactide , polymerization , monomer , crystal structure , catalysis , amine gas treating , stereochemistry , crystallography , medicinal chemistry , polymer chemistry , polymer , organic chemistry
Monomeric bis(isopropoxy) titanium complexes LTi(O i Pr) 2 (L = ─ OC 6 H 2 –4‐R 1 –6‐R 2 –2‐CH 2 N[(CH 2 ) 2 N(R 3 ) 2 ]CH 2 –4‐R 4 –6‐R 5 ‐C 6 H 2 O ─ , R 1 = R 2 = t Bu, R 3 = Et, R 4 = R 5 = Cl, (L 1 )Ti(O i Pr) 2 ; R 1 = R 2 = Me, R 3 = Et, R 4 = R 5 = Me, (L 2 )Ti(O i Pr) 2 ; R 1 = R 2 = t Bu, R 3 = Et, R 4 = OMe, R 5 = t Bu, (L 3 )Ti(O i Pr) 2 ; R 1 = R 4 = OMe, R 3 = Et, R 2 = R 5 = t Bu, (L 4 )Ti(O i Pr) 2 ; R 1 = R 2 = t Bu, R 3 = Me, R 4 = OMe, R 5 = t Bu, (L 5 )Ti(O i Pr) 2 ) supported by amine bis(phenolate) ligands were synthesized and characterized using NMR spectroscopy and elemental analysis. The solid‐state structure of (L 3 )Ti(O i Pr) 2 was determined using single‐crystal X‐ray diffraction. (L 1 –5 )Ti(O i Pr) 2 were all found to initiate the ring‐opening polymerization of l ‐lactide and rac ‐lactide in a controlled manner at 110–160°C. As shown by kinetic studies, (L 1 )Ti(O i Pr) 2 polymerized l ‐lactide faster than did (L 2 –5 )Ti(O i Pr) 2 . In addition, good number‐average molecular weight and narrow polydispersity index (1.00–1.71) of polymers were also obtained. The microstructure of the polymers and a possible mechanism of coordination–insertion of polymerization were evidenced by MALDI‐TOF and 1 H NMR spectra of the polylactides.