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Regarding Initial Ring Opening of Propylene Oxide in its Copolymerization with CO 2 Catalyzed by a Cobalt(III) Porphyrin Complex
Author(s) -
Xia Wei,
Vagin Sergei I.,
Rieger Bernhard
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201404147
Subject(s) - cobalt , propylene oxide , porphyrin , epoxide , propylene carbonate , onium , catalysis , chemistry , triphenylphosphine , polymer chemistry , bimetallic strip , copolymer , ring (chemistry) , tetraphenylporphyrin , cyclohexene oxide , photochemistry , inorganic chemistry , organic chemistry , ethylene oxide , ion , electrode , electrochemistry , polymer
Cobalt(III) tetraphenylporphyrin chloride (TPPCoCl) was experimentally proved to be an active catalyst for poly(propylene carbonate) production. It was chosen as a model catalyst in the present work to investigate the initiation step of propylene oxide (PO)/CO 2 copolymerization, which is supposed to be the ring opening of the epoxide. Ring‐opening intermediates ( 1 – 7 ) were detected by using 1 H NMR spectroscopy. A first‐order reaction in TPPCoCl was determined. A combination of monometallic and bimetallic ring‐opening pathways is proposed according to kinetics experiments. Addition of onium salts (e.g., bis(triphenylphosphine)iminium chloride, PPNCl) efficiently promoted the PO ring‐opening rate. The existence of axial ligand exchange in the cobalt porphyrin complex in the presence of onium salts was suggested by analyzing collected 1 H NMR spectra.