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Liquid Crystalline Solvents as Mechanistic Probes. IV. The Influence of Ordered Media on the Norrish Type II Photoprocesses in α‐Diketones
Author(s) -
Nerbonne Jeanne M.,
Weiss Richard G.
Publication year - 1979
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197900041
Subject(s) - chemistry , quantum yield , diastereomer , solvent , octane , hexane , yield (engineering) , lability , photochemistry , liquid crystalline , organic chemistry , thermodynamics , phase (matter) , physics , quantum mechanics , fluorescence
Abstract The Norrish II photoreactions of octane‐4,5‐dione ( 1 ) and 1,6‐diphenylhexane‐3,4‐dione ( 2 ) have been investigated at several temperatures and in isotropic and ordered (liquid crystalline) media. The sole photoproducts detected in all solvents are 1/1 diastereomeric mixtures of α‐hydroxycyclobutanones. The quantum yields for disappearance of 1 and 2 tend to decrease as the temperature increases in all media investigated. Whereas the quantum yield ratio for disappearance of 1 in cholesteric mesophases and hexane is greater than one, the ratio for disappearance of 2 is less than one. Possible explanations for these observations, based upon the influence of solvent order on solute conformational lability, are advanced.