Trapping of photoenols from o-tolualdehydes in gas matrices. Dependence of photoenol formation on the nature of the carbonyl function
- 1 January 1984
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 10,p. 1623-1627
- https://doi.org/10.1039/p29840001623
Abstract
o-Methylbenzaldehyde (1) and o-methylacetophenone (2), matrix-isolated in Ar, N2, Xe, or carbon monoxide, were irradiated with u.v. light. In contrast to the ketone (2) which was unreactive, the benzaldehyde gave a photoenol in all gas matrices. Irradiation of 2,5- or 2,4-dimethylbenzaldehyde (9) and (10), respectively, also produced photoenols under the above conditions. In propan-2-ol under cryogenic conditions, o-methylacetophenone (2) can be photoisomerized to an enol, probably the consequence of stabilization of the Z-enol by hydrogen bonding. 5,8-Dimethyltetralone (11) does not give a photoenol in gas matrices, although it is reported to give one at 77 K in EPA.‡ It is proposed that cage effects in gas matrices can significantly alter rates of internal rotation and are determinants in the production of E-enols in this environment. I.r. spectral evidence for photoenols is presented for the first time.Keywords
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