Kinetics of reactions in heterocycles. Part X. Reactions of substituted N-methylpyridinium salts with hydroxide ions
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 7,p. 790-797
- https://doi.org/10.1039/p29740000790
Abstract
Kinetics of the reactions of halogeno-, methoxy-, methylthio-, and methylsulphonyl-substituted N-methylpyridinium salts with hydroxide ions have been determined. The salts with the leaving group in the 2-position were the most reactive: e.g. the k2 values for 2-, 3-, and 4-methoxypyridine methiodides at 20° were 2·9 × 10–2, 5·0 × 10–9, and 7·6 × 10–4 l mol–1 s–1, respectively. Quaternisation of 4-methylsulphonylpyridine by methylation increased its reactivity to hydroxide ions by 7·3 × 108-fold at 20°, owing to a decrease in energy of activation of 7·1 kcal mol–1, and an increase in log A 3·5 units. U.v. and 1H n.m.r. spectra are recorded and discussed.Keywords
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