Spectroscopy and photochemistry at low temperature. Part 2.—Hydrogen bonding and photochemical addition to the benzene ring
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Transactions of the Faraday Society
- Vol. 65, 390-407
- https://doi.org/10.1039/tf9696500390
Abstract
Perturbations in the near u.-v. absorption spectra of benzene and its derivatives are induced by CHCl3 and other halogenated protic solutes in hydrocarbon solution, at temperatures below 200°K; they have been ascribed to H-bonding with the aromatic ring. Two stages of association have been distinguished, and ascribed to specifically oriented complexes involving one, and two molecules of the non-aromatic solute. Thermodynamic parameters for the benzene + CHCl3 association at 77°K, have been evaluated, and the structure of the complex compared with that of pyridine and CHCl3 at 77°K. Association modified the low-temperature photochemistry of benzene and its alkyl derivatives, and substituted polyene adducts are produced with perchloro-alkanes. With substituted ethylenes, the photochemical reaction producing octatetraenes in fluid solution, is suppressed in a rigid solvent medium or by association. The two types of reaction are compared, and possible mechanisms discussed.Keywords
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