Jarvis, A. G., Sparkes, H. A., Tallentire, S. E., Hatcher, L. E. ![]() |
Abstract
A novel unsymmetrical dibenzylidene acetone (monothiophos-dba, compound 3), containing two chemically different alkene moieties, undergoes a selective photochemically-induced [2+2] cycloaddition solid-state transformation (single crystal and powder), as shown by X-ray diffraction methods. In the single crystal the rate constant for the cycloaddition reaction was determined {k = (2.3 ± 0.1) × 10−4 s−1}, with a 69% conversion attained, which compares well with a two-photon irradiation experiment using a Nd:YAG laser pumped dye laser at 605 nm radiation (66% conversion). Full conversion was attained using powdered 3 after 43 h. A similar conversion was noted between the single crystal and powder forms (59% and 66% conversion after 5 h irradiation). Irradiation of monothiophos-dba in solution using a 325 nm laser, and monitoring by 1H NMR spectroscopy, showed that no cycloaddition occurred, but exclusive photochemically-induced trans → cis isomerisation of the alkene bond connecting the unsubstituted aryl group (cis → trans isomerisation in these electron-deficient and polarised C[double bond, length as m-dash]C bonds occurs rapidly by thermal equilibration).
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Chemistry |
Publisher: | Royal Society of Chemistry |
ISSN: | 1466-8033 |
Date of Acceptance: | 13 June 2012 |
Last Modified: | 07 Nov 2022 09:52 |
URI: | https://orca.cardiff.ac.uk/id/eprint/130479 |
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