78398-38-6Relevant academic research and scientific papers
Methoxy-substituted stilbenes, styrenes, and 1-arylpropenes: Photophysical properties and photoadditions of alcohols
Roberts, Jeffrey C.,Pincock, James A.
, p. 1480 - 1492 (2007/10/03)
The photochemistry of trans-stilbene and four methoxy-substituted stilbene derivatives has been investigated in a variety of solvents. The fluorescence of all five trans isomers was quenched by 2,2,2-trifluoroethanol (TFE). Upon irradiation of the five substrates in TFE, the products derived from photoaddition of the solvent were detected. Nuclear magnetic resonance spectroscopy of the products formed by irradiation in TFE-OD indicated that the proton and nucleophile are attached to two adjacent atoms of the original alkene double bond. Irradiation of the corresponding methoxy-substituted styrenes and trans-1-arylpropenes in TFE produced the analogous solvent adducts. The photoaddition of TFE proceeded with the general order of reactivity: styre > trans-1-arylpropenes > trans-stilbenes. Transient carbocation intermediates were observed following laser flash photolysis of the stilbenes in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). The results are consistent with a mechanism that involves photoprotonation of the substrates by TFE or HFIP, followed by nucleophilic trapping of short-lived carbocation intermediates. Compared to the other stilbene derivatives, trans-3,5-dimethoxystilbene displayed a large quantum yield of fluorescence and a low quantum yield of trans-cis isomerization in polar organic solvents. The unique photophysical properties of trans-3,5-dimethoxystilbene are attributed to formation of a highly polarized charge-transfer excited state (μe = 13.2 D).
STEREOCHEMISTRY OF PHOTOSOLVOLYSIS OF A CHIRAL, 18O-LABELED 1-ARYLETHYL ACETATE
Jaeger, David A.,Angelos, George H.
, p. 803 - 806 (2007/10/02)
The stereochemistry of photosolvolysis of (R)-(+)-1-(3,5-dimethoxyphenyl)ethyl acetate-ether-18O in methanol-water and 2,2,2-trifluoroethanol has been determined.An ion pair intermediate was detected in the latter solvent.
