12771-59-4Relevant articles and documents
A steady-state and picosecond pump-probe investigation of the photophysics of an acyl and a Bis(acyl)phosphine oxide
Jockusch, Steffen,Koptyug, Igor V.,McGarry, Peter F.,Sluggett, Gregory W.,Turro, Nicholas J.,Watkins, Diana M.
, p. 11495 - 11501 (1997)
The photophysics (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (1) and bis(2,6-dimethoxybenzoyl)4,4-trimethylpentylphosphine oxide (4) have been investigated by phosphorescence, and low time resolved electron spin resonance. Both 1 and 4 undergo a-cleavage to produce benzoyl and phosphorous centered radicals. The photochemistry of 1 and 4 has been investigated by nanosecond laser flash photolysis, picosecond pump probe spectroscopy, and study-state photolysis. The singlet states of 1 and 4 an the phosphorous radicals produced by α-cleavage were characterized directly by time resolved absorption spectroscopy. The triplet states of 1 and 4 were characterized indirectly by quenching with 1-phenylnaphthalene as a selective triplet quencher. The use of 1-phenylnaphtlhalene indicates that α-cleavage occurs mainly from the triplet states of 1 and 4. However, the observed rate of formation of phosphorous centered radicals derived from picosecond investigations is experimentally indistinguishable from the rate of disappearance of the singlet states of 1 and 4. The results are compatible with mechanisms for which the rate of intersystem crossing of the S1 states of 1 and 4 limits the observed rate of α-cleavage, because the rate of α- cleavage is of the same order or faster than the rate of intersystem crossing. This relatively uncommon situation appears to have an analogy in the well investigated photochemistry of dibenzyl ketone.
PULSE RADIOLYSIS STUDIES OF ENERGY TRANSFER REACTIONS FROM BENZENE EXCIMER TO PHOSPHINE OXIDES
Sumiyoshi, Takashi,Katayama, Meiseki,Schnabel, Wolfram
, p. 1647 - 1650 (1985)
Acylphosphine oxides were tested as a new class of singlet indicators and the diphenyl phosphonyl radical was detected as a result of singlet energy transfer from benzene excimers to 2,4,6-trimethylbenzoyldiphenylphosphine oxide.
Redox-Neutral P(O)-N Coupling between P(O)-H Compounds and Azides via Dual Copper and Photoredox Catalysis
Wu, Yanan,Chen, Ken,Ge, Xia,Ma, Panpan,Xu, Zhiyuan,Lu, Hongjian,Li, Guigen
supporting information, p. 6143 - 6149 (2020/07/30)
We report a redox-neutral P(O)-N coupling reaction of P(O)-H compounds with azides via photoredox and copper catalysis, providing new access to useful phosphinamides, phosphonamides, and phosphoramides. This transformation tolerates a wide range of nucleophilic functionalities including alcohol and amine nucleophiles, which makes up for the deficiency of classical nitrogen nucleophilic substitution reactions. As a demonstration of the broad potential applications of this new methodology, late-stage functionalization of a diverse array of azido-bearing natural products and drug molecules, a preliminary asymmetric reaction, and a continuous visible-light photoflow process have been developed.
Probing the reactivity of photoinitiators for free radical polymerization: Time-resolved infrared spectroscopic study of benzoyl radicals
Colley, Christopher S.,Grills, David C.,Besley, Nicholas A.,Jockusch, Steffen,Matousek, Pavel,Parker, Anthony W.,Towrie, Michael,Turro, Nicholas J.,Gill, Peter M. W.,George, Michael W.
, p. 14952 - 14958 (2007/10/03)
A series of substituted benzoyl radicals has been generated by laser flash photolysis of α-hydroxy ketones, α-amino ketones, and acyl and bis(acyl)phosphine oxides, all of which are used commercially as photoinitiators in free radical polymerizations. The benzoyl radicals have been studied by fast time-resolved infrared spectroscopy. The absolute rate constants for their reaction with n-butylacrylate, thiophenol, bromotrichloromethane and oxygen were measured in acetonitrile solution. The rate constants of benzoyl radical addition to n-butylacrylate range from 1.3 x 105 to 5.5 x 105 M-1 s-1 and are about 2 orders of magnitude lower than for the n-butylacrylate addition to the counterradicals that are produced by α-cleavage of the investigated ketones. Density functional theoretical calculations have been performed in order to rationalize the observed reactivities of the initiating radicals. Calculations of the phosphorus-centered radicals generated by photolysis of an acyl and bis(acyl)phosphine oxide suggest that P atom Mulliken spin populations are an indicator of the relative reactivities of the phosphorus-centered radicals. The α-cleavage of (2,4,6-trimethylbenzoyl)phosphine oxide was studied by picosecond pump-probe and nanosecond step-scan time-resolved infrared spectroscopy. The results support a mechanism in which the α-cleavage occurs from the triplet excited state that has a lifetime less than or equal to the singlet excited state.
