Transmethylation of 2‐(methylthio)benzothiazole on silver sols: a SERS investigation

Discrepancies between the SERS and the normal Raman spectra of 2‐(methylthio)benzothiazole (MTBT) led to an extension of the SERS study to include an investigation of the reactivity of this molecule on a silver surface. Experimental evidence indicates a surface reaction of MTBT on silver sol. In particular, it undergoes an intramolecular transmethylation, rearranging to 3‐methylbenzothiazoline‐2‐thione. Experimental data suggest that this transmethylation takes place only because of the presence of the silver surface, which acts as a catalyst. In contrast, the hypothesis of a reaction photo‐induced by the silver surface seems very unlikely. 3‐Methylbenzothiazoline‐2‐thione adsorbs on the silver surface via the lone pairs of the exocyclic sulphur atom and, to some extent, also via the π‐system of the benzene ring. The molecular orientation is inclined with respect to the metal surface.