Aromatic reactivity. Part LIX. Substituent effects of groups of type CH2Y in acid cleavage of p-YCH2·C6H4SiMe3compounds and on the charge-transfer maxima of YCH2Ph–tetracyanoethylene complexes
- 1 January 1975
- journal article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 8,p. 874-878
- https://doi.org/10.1039/p29750000874
Abstract
The rates of cleavage of p-YCH2·C6H4·SiMe3 compounds by a mixture of acetic acid (4 vol.) and aqueous sulphuric acid (3 vol.) have been measured in order to provide information about the influence of substituents of the type p-CH2Y in electrophilic aromatic substitution; the rates at 50° relative to that for trimethyl(phenyl)silane, with, in parentheses, the approximate derived values of σ+ for CH2Y, are: (Y =) CN, 0·20 (+0·12); Br, 1·35 (–0·06); OH, 0·64 (+0·01); OMe, 1·27 (–0·05); OEt, 0·70 (0·00); CO2H, 0·93 (–0·02); CO2Me, 0·84 (–0·01); NMe2H+, 0·0043 (+0·50); NMe3 +, 0·0042 (+0·50). The charge-transfer maxima for YCH2Ph–tetracyano-ethylene complexes have been determined for the Y groups mentioned above and also for Y = Cl and SH; the effects of the substituents are in accord with those on the cleavage, and the frequencies of the charge-transfer maxima are linearly related to the σI constants for Y.Keywords
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