Using heavy atom rare gas matrix to control the reactivity of 4-methoxybenzaldehyde: A comparison with benzaldehyde
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra (Portugal)
- Institute of Physics, Polish Academy of Sciences, Warsaw (Poland)
Different patterns of photochemical behavior were observed for 4-methoxybenzaldehyde (p-anisaldehyde) isolated in xenon and in argon matrices. Monomers of the compound isolated in solid Xe decarbonylate upon middle ultraviolet irradiation, yielding methoxybenzene (anisole), and CO. On the other hand, p-anisaldehyde isolated in an Ar matrix and subjected to identical irradiation, predominantly isomerizes to the closed-ring isomeric ketene (4-methoxycyclohexa-2,4-dien-1-ylidene) methanone. Experimental detection of a closed-ring ketene photoproduct, generated from an aromatic aldehyde, constitutes a rare observation. The difference between the patterns of photochemical transformations of p-anisaldehyde isolated in argon and xenon environments can be attributed to the external heavy-atom effect, where xenon enhances the rate of intersystem crossing from the singlet to the triplet manifold in which decarbonylation (via p-methoxybenzoyl radical) takes place. The parent compound, benzaldehyde, decarbonylates (to benzene + CO) when subjected to middle ultraviolet irradiation in both argon and xenon matrices. This demonstrates the role of the methoxy p-anisaldehyde substituent in activation of the reaction channel leading to the formation of the ketene photoproduct.
- OSTI ID:
- 22047198
- Journal Information:
- Journal of Chemical Physics, Vol. 136, Issue 14; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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