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Effect of Lewis base coordination on boryl radical reactivity: investigation using laser flash photolysis and kinetic ESR
Author(s) -
Lalevée Jacques,
Blanchard Nicolas,
Chany AnneCaroline,
Tehfe MohamadAli,
Allonas Xavier,
Fouassier JeanPierre
Publication year - 2009
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1549
Subject(s) - chemistry , flash photolysis , triethylamine , photochemistry , ketyl , reactivity (psychology) , borane , radical , bond dissociation energy , homolysis , reaction rate constant , medicinal chemistry , dissociation (chemistry) , organic chemistry , benzophenone , kinetics , catalysis , medicine , physics , alternative medicine , pathology , quantum mechanics
The effect of Lewis base coordination on boryl radical reactivity (L→BH 2 •where L is triethylamine, 2‐picoline, 4‐dimethylaminopyridine, quinoline and diphenyl phosphine) is examined. Direct detection of the different boryl radicals, their transient absorption spectra, their interaction with double or triple bonds, oxygen, oxidizing agent, alkyl halides and their hydrogen lability have been studied using laser flash photolysis (LFP), kinetic ESR (KESR), ESR spin trapping and MO calculations. For example, a strong decrease of both the bond dissociation energy (BDE)(BH) (33.8 kcal mol −1 ) and the addition rate constant to MA (1300 10 5 to >10 5 M −1 s −1 ) was noted when going from the triethylamine borane to the quinoline borane complex, in line with the spin delocalization (1.04 vs. 0.19). These structures are also proposed as new highly efficient co‐initiators for the acrylate photopolymerization. Copyright © 2009 John Wiley & Sons, Ltd.