Properties of hydrogen bonds in 5,8-dihydroxy-1,4-naphthoquinone and 1,4-dihydroxy-9,10-anthraquinone; reaction with bases in aqueous solution
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 11,p. 1617-1620
- https://doi.org/10.1039/p29870001617
Abstract
Rate coefficients and equilibrium constants for the dissociation of 5,8-dihydroxy-1,4-naphthoquinone (1),pK1 08.51 and pK2 0 11.49, and 1,4-dihydroxy-9,10-anthraquinone (3), pK1 0 9.85 and pK2 0 12.28, have been measured in aqueous solution. The effects of a methyl substituent in (1) and a sulphonate substituent in (3) have been studied. The rate coefficient for the first and second dissociation are 25- and 1 000-fold respectively lower than those for normal proton transfers because of a weak intramolecular hydrogen bond in the undissociated acids and a moderately strong hydrogen bond in the monoanions.Keywords
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