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Influence of the Boron Moiety and Water on Suzuki–Miyaura Catalyst‐Transfer Condensation Polymerization
Author(s) -
Kosaka Kentaro,
Ohta Yoshihiro,
Yokozawa Tsutomu
Publication year - 2015
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201400530
Subject(s) - moiety , catalysis , polymerization , polymer chemistry , condensation , boron , chain transfer , materials science , chemistry , chemical engineering , organic chemistry , radical polymerization , polymer , thermodynamics , physics , engineering
Although water promotes Suzuki–Miyaura coupling reaction, it also induces side reactions such as deboronation and dehalogenation. Therefore, Suzuki–Miyaura polymerization of triolborate halothiophene monomer 1 with t Bu 3 PPd( o ‐tolyl)Br ( 2 ) in dry tetrahydrofuran (THF) is investigated. However, the resultant poly(3‐hexylthiophene) (P3HT) shows a broad molecular weight distribution and uncontrolled polymer ends. Model reactions of a number of boron reagents 3 with 2,5‐dibromothiophene ( 4 ) in the presence or absence of water indicate that intramolecular transfer of the catalyst is hardly affected by the boron moiety of 3 , whereas it is hindered in the absence of water. Indeed, polymerization of 1 with 2 in H 2 O/THF affords P3HT with a narrower molecular weight distribution and controlled tolyl/H ends, as compared to the reaction in dry THF.