- ELECTROCHEMICAL BEHAVIOUR OF SUBSTITUTED HYDROQUINONES
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The oxidation potentials of thirteen hydroquinones substituted by chlorine, pyrazol-1-yl and 3,5-dimethylpyrazol-1-yl groups were experimentally determined by cyclic voltammetry.The estimated half-wave potentials E1/2 have been discussed taking into account the inductive and conjugative substituent effects.Key words: Cyclic voltammetry, Hydroquinones, Redox, Pyrazoles
- Claramunt, R. M.,Escolastico, C.,Maria, M. D. Santa,Lopez, V.
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p. 368 - 371
(2007/10/02)
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- Benzoquinones and Related Compounds. Part 4. Thermolysis of the Diels-Alder Adduct of 2-Acetyl-5,6-dichloro-1,4-benzoquinone and Cyclopentadiene: Evidence for a Partial Retro-diene Reaction
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Addition of chlorine to (2-methyl-1,3-dioxolan-2-yl)-1,4-benzoquinone occurs at the unsubstituted double bond.Subsequent enolisation and cleavage of the acetal affords 2-acetyl-5,6-dichlorohydroquinone in 50percent overall yield.Oxidation of this gives the corresponding 1,4-benzoquinone which with cyclopentadiene yields, predominantly, the 1 : 1 Diels-Alder adduct (6) by endo-addition to the 2,3-double bond.Thermolysis of this adduct in benzene results in disproportionation to cyclopentadiene and the spiro-acetal (13); thermolysis in acetic acid also yields (13), but the major product is the dihydrobenzofuran (14), an isomer of the Diels-Alder adduct.Mechanisms for the formation of these products are discussed.
- Beddoes, Roy L.,Bruce, J. Malcolm,Finch, Harry,Heelam, Leslie M. J.,Hunt, Ian D.,Mills, Owen S.
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p. 2670 - 2676
(2007/10/02)
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