Good second-order kinetics were found with k, values which were ca. 50 times less for piperidine displacements in H,O than in chlorobenzene solutions, as expected from the polarity increase. Rates for thioglycolate dianion displacements were about five times faster than for piperidine. The rate dependence on pyridine leaving group structure paralleled that previously found for non-aqueous solutions except that an additional SO3substituent group showed a small rate-decreasing effect.Earlier Parts have described the preparation of water-soluble pyrylium salts containing one or more sulphonic or carboxylic
Anhand kinetischer Messungen für die nucleophilen Substitutionen der Pyridiniumverbindungen (I) oder (IV) mit Piperidin oder dem reaktiveren Thioglykolat i zeigt sich erwartungsgemäß, daß die Geschwindigkeiten in der angegebenen Reihenfolge von (I) zu (IV) zunehmen und die Geschwindigkeitskonstanten 2. Ordnung der Piperidin‐Reaktion dem Polaritätsunterschied entsprechend in H2O um den Faktor 50 kleiner sind als die der analogen Verbindungen in Chlorbenzol.
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