MECHANISM OF SULPHOMETHYLATION OF BETA-NAPHTHOL - KINETICS OF FORMATION OF SODIUM 2-HYDROXY-1-NAPHTHYLMETHANESULPHONATE FROM BIS-(2-HYDROXY-1-NAPHTHLYL)METHANE

Sulphomethylation of β-naphthol, i.e. the reaction of bis-(2-hydroxy-1-naphthyl)methane (BHNM; I) with sodium sulphite to form 2-hydroxy-1-naphthylmethanesulphonate (SNMS; II), has been studied kinetically by iodometry of sodium sulphite. The rate law, ν = k [BHNM], together with the relation k vs. [OH-] suggests a SN1 mechanism via the dianion of BHNM (V) and quinone-methide (VIII). This shows that quinonemethide (VIII) and not BHNM is an intermediate in the sulphomethylation of β-naphthol. The behaviour of BHNM in aqueous alkali is discussed in terms of the alkalimetric titration and UV spectra. © 1969.