Sulfonation of 4′-acetyl-, 4′-(tert-butyl)-dibenzo-18-crown-6 and (dibenzo-18-crown-6)-4′-sulfonic acid with potassium sulfate in polyphosphoric acid

Abstract

The sulfonation of monosubstituted derivatives of dibenzo-18-crown-6 with potassium sulfate in polyphosphoric acid has been carried out. Sulfonic acids with various functional groups in the second nucleus of dibenzo-18-crown-6 have been obtained. A qualitative comparison of the reactivity of the substrates gave information on the transfer of the electronic influence of a substituent through the macrocycles. The displacement of electron density in the benzene nuclei of the substrates and the products of sulfonation was assessed from the value of the displacement of the proton signals in the 1 H NMR spectra. acid, PPA (polyphosphoric acid), potassium sulfate, sulfonation.Derivatives of dibenzo-18-crown-6 (DB18C6) in which substitution is only in one benzene nucleus, are of considerable interest as substrates for carrying out electrophilic substitution reactions. These reactions open a route to disubstituted compounds with mixed functions which, as is evident from literature data [1], relate to few studied substances. At the same time the presence of two benzene nuclei with different functional groups makes these derivatives extremely promising substances for subsequent directed modification as a result of conversions of the functional groups. Study of electrophilic substitution of the hydrogen atoms of the unsubstituted benzene nucleus in monosubstituted derivatives of DB18C6 is also of considerable theoretical interest, since comparison of the reactivity of substrates with substituents of different electronic effect enables clarification of the influence of a substituent from the substituted nucleus on the unsubstituted through the macrocycle, which was called by us a "transannular transfer" [2].An investigation was carried out previously of nitration reactions of ethyl-, nitro-, and acetyl-DB18C6 with nitrates of certain alkali metals in PPA. It was demonstrated that the nitration reaction proceeds regioselectively and depends on the nature of the substituent and the metal cation [3].