TY - JOUR
T1 - Photoreduction of phenacyl halides by NADH analogues. Origins of different mechanistic pathways
AU - Fukuzumi, Shunichi
AU - Mochizuki, Seiji
AU - Tanaka, Toshio
PY - 1989
Y1 - 1989
N2 - Photoreduction of phenacyl halides (PhCOCH2X) by an NADH analogue, 10-methyl-9-acridone (AcrH2) in acetonitrile (MeCN) under irradiation of light (λ > 320 nm) proceeds via the rate-determining photoinduced electron transfer from the singlet excited state of AcrH 2 to PhCOCH2X to give the radical ion pair (AcrH 2+. PhCOCH2X-.). The subsequent fast reaction is completed within the complex by proton transfer from AcrH 2+. to PhCOCH2X-., followed by electron transfer from AcrH. to PhĊ(OH)CH2X, yielding 10-methylacridinium ion (AcrH+) and acetophenone (PhCOCH 3). However, photoreduction of PhCOCH2X by another NADH analogue, 1-benzyl-1,4-dihydronicotinamide (BNAH), in MeCN under irradiation with visible light of λ > 360 nm proceeds by a different reaction pathway; electron-transfer radical chain reactions, in which the chain carrier radicals are produced by photoinduced electron transfer from the singlet excited state of BNAH to PhCOCH2X. The origins of these different mechanistic pathways dependent on the NADH analogues are discussed.
AB - Photoreduction of phenacyl halides (PhCOCH2X) by an NADH analogue, 10-methyl-9-acridone (AcrH2) in acetonitrile (MeCN) under irradiation of light (λ > 320 nm) proceeds via the rate-determining photoinduced electron transfer from the singlet excited state of AcrH 2 to PhCOCH2X to give the radical ion pair (AcrH 2+. PhCOCH2X-.). The subsequent fast reaction is completed within the complex by proton transfer from AcrH 2+. to PhCOCH2X-., followed by electron transfer from AcrH. to PhĊ(OH)CH2X, yielding 10-methylacridinium ion (AcrH+) and acetophenone (PhCOCH 3). However, photoreduction of PhCOCH2X by another NADH analogue, 1-benzyl-1,4-dihydronicotinamide (BNAH), in MeCN under irradiation with visible light of λ > 360 nm proceeds by a different reaction pathway; electron-transfer radical chain reactions, in which the chain carrier radicals are produced by photoinduced electron transfer from the singlet excited state of BNAH to PhCOCH2X. The origins of these different mechanistic pathways dependent on the NADH analogues are discussed.
UR - http://www.scopus.com/inward/record.url?scp=37049086113&partnerID=8YFLogxK
U2 - 10.1039/p29890001583
DO - 10.1039/p29890001583
M3 - Article
AN - SCOPUS:37049086113
SN - 1472-779X
SP - 1583
EP - 1589
JO - Journal of the Chemical Society. Perkin Transactions 2
JF - Journal of the Chemical Society. Perkin Transactions 2
IS - 10
ER -