Reactions of Pseudobases in Aqueous Solution

Spectroscopic techniques which do not influence the position of the equilibrium can more certainly be used to ascertain the composition of the equilibrium tautomeric mixture. The presence of significant amounts of 

In Section II, a strategy was described for the investigation of the ring opening of pseudobases in aqueous solutions on the basis of a comparison of the electronic absorption spectra of the pseudobases formed by a particular heterocyclic cation in aqueous and alcoholic solutions. Similar 

Habermehl, J. Schunck, and G. Schaden, Justus Liebigs Ann. Chem. 742, 138 (1970). 

Hammond, in Steric Effects in Organic Chemistry (M.S. Newman, ed.), p. 460. Wiley, New York, 1956. 

There are numerous reports in the literature187-193 of the isolation of the ring-opened tautomer of a pseudobase upon treatment of an aqueous solution of a heterocyclic cation with base. However, it is usually unclear whether the isolated product accurately reflects the predominant equilibrium solution tautomer or is simply the less soluble species of the tautomeric pair. 

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The following sections will emphasize those systems in which reasonable attempts have been made to conduct detailed investigations of ring-opening reactions of pseudobases in aqueous solution. In addition, there are numerous reactions of heterocyclic molecules, under a wide variety of reaction conditions, which have been postulated to proceed via ring-opening of a pseudobase intermediate.100-194-20 3... 

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