Evidence for singlet state β cleavage in the photoreaction of α-(2,6-dimethoxyphenoxy)-acetophenone inferred from time-resolved CIDNP spectroscopy
Publikation: Beiträge in Zeitschriften › Zeitschriftenaufsätze › Forschung › begutachtet
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in: Journal of Photochemistry and Photobiology, A: Chemistry, Jahrgang 52, Nr. 3, 01.06.1990, S. 439-450.
Publikation: Beiträge in Zeitschriften › Zeitschriftenaufsätze › Forschung › begutachtet
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TY - JOUR
T1 - Evidence for singlet state β cleavage in the photoreaction of α-(2,6-dimethoxyphenoxy)-acetophenone inferred from time-resolved CIDNP spectroscopy
AU - Palm, W. U.
AU - Dreeskamp, Herbert
PY - 1990/6/1
Y1 - 1990/6/1
N2 - The photochemistry of α-(2,6-dimethoxyphenoxy)-acetophenone (1) was studied using CIDNP spectroscopy; an XeCl excimer laser (308 nm) and a 250 MHz 1H nuclear magnetic resonance (NMR) spectrometer were employed. The results are compared with the photoreactions of α-hydroxyacetophenone (2) and α-methoxyacetophenone (3). The CIDNP spectra of 1 can be interpreted as a result of a β cleavage from the singlet state. With time-resolved CIDNP spectroscopy it is possible to detect the enol of acetophenone in a second reaction path and to observe the tautomerization to acetophenone. Evidence is presented that this reaction path starts with the photoreduction of 1 from the triplet state. Compound 2 shows α cleavage from the triplet state and no β cleavage. As expected no CIDNP spectra are observed from 3 which is known to react via a Norrish type II mechanism.
AB - The photochemistry of α-(2,6-dimethoxyphenoxy)-acetophenone (1) was studied using CIDNP spectroscopy; an XeCl excimer laser (308 nm) and a 250 MHz 1H nuclear magnetic resonance (NMR) spectrometer were employed. The results are compared with the photoreactions of α-hydroxyacetophenone (2) and α-methoxyacetophenone (3). The CIDNP spectra of 1 can be interpreted as a result of a β cleavage from the singlet state. With time-resolved CIDNP spectroscopy it is possible to detect the enol of acetophenone in a second reaction path and to observe the tautomerization to acetophenone. Evidence is presented that this reaction path starts with the photoreduction of 1 from the triplet state. Compound 2 shows α cleavage from the triplet state and no β cleavage. As expected no CIDNP spectra are observed from 3 which is known to react via a Norrish type II mechanism.
KW - Chemistry
UR - http://www.scopus.com/inward/record.url?scp=0000049828&partnerID=8YFLogxK
U2 - 10.1016/1010-6030(90)85021-N
DO - 10.1016/1010-6030(90)85021-N
M3 - Journal articles
AN - SCOPUS:0000049828
VL - 52
SP - 439
EP - 450
JO - Journal of Photochemistry and Photobiology, A: Chemistry
JF - Journal of Photochemistry and Photobiology, A: Chemistry
SN - 1010-6030
IS - 3
ER -