740872-00-8Relevant academic research and scientific papers
Phototransposition reactions of methyl-substituted benzotrifluorides: Proof of the role of trifluoromethyl-substituted carbon
DeCosta, Dayal,Pincock, James
, p. 9484 - 9487 (2002)
Irradiation in acetonitrile of any one of the six isomers of dimethylbenzotrifluoride 8 resulted in efficient photoisomerization to the others. The dominant processes in these phototransposition reactions divides the isomers into two triads. The first consists of 8-2,6 (2,6-dimethylbenzotrifluoride), 8-2,3, and 8-3,4; the second consists of 8-3,5, 8-2,4, and 8-2,5. Moreover, irradiation of 2,6-dideuterio-4-methylbenzotrifluoride 5-d2 resulted in formation of 5,6-dideuterio-3-methylbenzotrifluoride 6-d2. These observations demonstrate that it is the trifluoromethyl-substituted carbon that is the migratory one in these reactions.
Phototransposition reactions of arylboronate esters in acetonitrile and 2,2,2-trifluoroethanol
Cameron,Pincock,Pincock,Thompson
, p. 4954 - 4960 (2007/10/03)
The phototransposition (para, meta, ortho) reactions of the arylboronate esters 4-, 3-, and 2-(4′,4′,5′,5′-tetramethyl-1′, 3′,2′-dioxaborolanyl)toluenes (1,2, and 3, respectively) in both acetonitrile and 2,2,2-trifluoroethanol (TFE) using 254 nm irradiation have been examined. The irradiations resulted in steady-state compositions of para (5%), meta (19%), and ortho (76%) isomers in acetonitrile starting from the ortho isomer and para (12%), meta (54%), and ortho (35%) isomers in TFE starting from the para isomer. Analysis of the 13C NMR spectrum of the product mixture obtained from the photochemistry of the para isomer selectively deuterated at C3 and C5 (1d2) revealed that the boron-substituted carbon is the active one in the phototransposition reactions in both acetonitrile and TFE. Similar results were observed for irradiations of 1 in cyclohexane. Fluorescence spectra, singlet-state lifetimes, and Stern-Volmer quenching of fluorescence with 2,3-dimethyl-1,3-butadiene indicated that the excited singlet states of these three isomers were spectroscopic minima and that the excited singlet state was the reactive one for 3 in acetonitrile.
