@article {7244,
	title = {PROTOTROPIC CONTROL OF ORGANIC-PHOTOCHEMISTRY - HYDROGEN-BONDING EFFECTS ON THE DI-PI-METHANE PHOTOREARRANGEMENT},
	journal = {Journal of Organic Chemistry},
	volume = {57},
	number = {1},
	year = {1992},
	note = {ISI Document Delivery No.: GY184Times Cited: 6Cited Reference Count: 54},
	month = {Jan},
	pages = {241-247},
	type = {Article},
	abstract = {The IR and UV spectra as well as the photochemistry of the isopropyl monoester of dibenzobarrelene dicarboxylic acid 2 were analyzed in detail in several media. A correlation was found between the photochemical results and the spectroscopically detected hydrogen-bonded structures of 2. An equilibrium between dimeric (2-HD) and intramolecularly hydrogen bonded (2-HI) structures was detected by IR spectroscopy in nonpolar solvents having weak hydrogen-bond-accepting capabilities. The ratio of the two regioisomeric dibenzosemibullvalene products 3 and 4 formed in the di-pi-methane photorearrangement of 2 was found to correlate with such an equilibrium, and it was concluded that intramolecular (2-HI) and dimeric (2-HD) hydrogen-bonded structures display significantly different photochemical reactivity. The infrared spectra and the photoproduct ratio in polar solvents possessing hydrogen-bond-accepting capabilities (e.g., acetonitrile), on the other hand, turned out to be concentration independent. High regioselectivity was found in the solid state where the dimer 2-HD is the only species, leading to 4 as the major product. In contrast, 3 was obtained preferentially in aqueous sodium bicarbonate solutions where 2 exists as the carboxylate anion. Supporting evidence regarding the different hydrogen bonding arrangements in 2 was found in the solvent effects on its UV spectra.},
	keywords = {ABSORPTION, DIBENZOBARRELENES, EXCITED-STATE, LASER EXCITATION FLUORESCENCE, METHYL SALICYLATE, ORTHO-HYDROXYBENZALDEHYDE, PHOTOISOMERIZATION, REARRANGEMENTS, SOLID-STATE, STATE PROTON-TRANSFER},
	isbn = {0022-3263},
	url = {<Go to ISI>://A1992GY18400043},
	author = {Garciagaribay, M. A. and Scheffer, J. R. and Watson, D. G.}
}
