The reactions of ring-activated alkyl aryl ethers with nucleophiles have been examined. The main pathways involve attack by the nucleophiles at the alkyl carbon to give substituted phenoxide ions, or at ring carbon atoms to give σ-adducts. The dealkylation reactions have been observed by both (^1)H nuclear magnetic resonance spectroscopy and spectrophotometrically using dimethyl sulphoxide as solvent. The reactivity order for nucleophiles in this solvent is SCN- Ca(^2+) > K(^+) > Na(^+) > Li(^+). This explains a longstanding discrepancy in the literature between the values of equilibrium constants for attack of lithium methoxide and of sodium methoxide. In concentrated solutions of sodium or potassium methoxide in methanol nitro-activated anisoles form adducts with 2:1 and 3:1 stoichiometry. Here methoxide addition occurs at two or three ring positions respectively. Such equilibria have been examined spectrophotometrically for 2,4,6-trinitroanisole, the isomeric cyanodinitroanisoles and the spiro-adduct formed by cyclisation of picryl glycol ether. For these equilibria the "basicity" of sodium methoxide solutions jn methanol is appreciably greater than that of corresponding potassium methoxide solutions. This is in contrast with other measures of basicity and is attributed to the association of the multi-charged adducts with cations which is stronger with sodium ions than with potassium ions. The infrared spectra of the parent and nitro-cyanoanisoles and their Meisenheimer complexes have been examined in the N0(_2) group, benzene ring and CN group regions. In order to attempt to understand their chemical and spectral behaviour the corresponding phenols and their Na(^+) and K(^+) salts have also been studied both in solution in dimethyl sulphoxide and in the solid state. Band shifts, widths and intensities have been interpreted in terms of the nature and extent of intra-molecular electronic rearrangements caused by the intermolecular interactions (hydrogen-bonding and cation coordination). Interesting, although not fully understood, differences in behaviour between the 2 and 4-CN substituted dinitrophenols and anisoles have been noted
