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Étude du Mécanisme de la Réaction de Formation de Semicarbazones en Solution Méthanolique Mise en Évidence D'Une Réaction parasite et Origine du pH Optimum de Réactivité

par Figeys, Hubert ;Nasielski, Jacques
Référence Bulletin des Sociétés chimiques belges, 75, 9-10, page (601-619)
Publication Publié, 1966

Article révisé par les pairs

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Résumé :

The rate of formation of 2‐naphtaldehyde semicarbazone in methanol solution is dependent on the pH and passes through a maximum. It is shown that in acidic media (pH < pHopt), the reaction undergoes specific and general acid catalysis, and that an important side reaction occurs (formation of the corresponding acetal). The rate's maximum is quantitatively accounted for by the rate equation found for acid media and its validity apparently extends beyond this optimum pH. For more strongly alcaline solution, it is necessary to assume a change of mechanism (or rate determining step); the position of the optimum pH might be influenced to a variable degree by this modification, depending on the structure of the aldehyde. Copyright © 1966 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim