Substituent Effects on Dissociation Constants oftrans-3-Hydroxy-6-styryl-4-pyrones
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چکیده
منابع مشابه
Acid dissociation constants of N - alkyl pia - hydroxy styryl pyridinium dyes in surfactant solutions
Some N-alkyl pia-hydroxy styryl pyridinium halides, the alkyl moieties being methyl, hexyl and decyl, have been synthesised and the acid dissociation constants of these compounds in aqueous and surfactant solutions have been determined using spectrophotometric method . The alkyl chain does not have any substantial effect on the pKa values in aqueous and cationic surfactant (cetyl trimethylammon...
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interesting results because of the regular arrangement of the molecules in the environment.1–3 We previously reported on the photocycloaddition reaction of 4-methoxy-6-methyl-2-pyrone (1a) (Fig. 1) with maleimide (2) in the solid state to give a highly stereoselective [2 + 2] cycloadduct4 owing to the formation of two sets of 1:1 complex crystals between (1a) and (2) (Fig. 1).5 The crystal show...
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The acid dissociation constants of the hydroxyl groups in 25, 26, 27, 28-tetrahydroxy-5, 11, 17, 23-tetrasulphonic-calix[4]arene (SC4) were determined at 25οC by a combination of potentiometric and spectrophotometric titration method. The first and second acid dissociation constants (pKa1, pKa2) were found to be 3.19 and 12.1, which demonstrated pKa shift due to intramolecular hydrogen bonding ...
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calix(6)arene hydroxamic acids (iii) are synthesised for the first time by reactingcalix(6)arene acid chloride(ii) with substituted hydroxylamines at low temperature in the presence ofsodium bicarbonate. the p-carboxycalix(6)arene(i) is obtained by an acid catalysed condensationreaction of p-hydroxybenzoic acid and formaldehyde. these calixarenes are characterised by meltingpoint, uv, ir, 1h nm...
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Two mild and efficient strategies have been developed for the O-functionalisation of 4-hydroxy-6-alkyl-2-pyrones, by using them as nucleophilic partners in oxa-Michael additions and the Mitsunobu reaction. The reactions proceed in moderate to excellent yields on a range of substrates containing useful functionality. The reactions serve as practical and valuable synthetic methods to construct co...
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ژورنال
عنوان ژورنال: Bulletin of the Chemical Society of Japan
سال: 1977
ISSN: 0009-2673,1348-0634
DOI: 10.1246/bcsj.50.2161