Classical carbonium ions. Part II. Synthesis, properties, and solvolysis of alkyl picrates and related compounds. A comparison of arenesulphonate and phenoxide leaving groups

Abstract

Alkyl picrates can be prepared from picryl fluoride and a wide variety of primary, secondary, and bridgehead tertiary alcohols in the presence of tertiary amines. They can be cleaved, with aryl–oxygen fission, by aqueous ammonia, but solvolyse, with exclusive alkyl–oxygen fission, at rates comparable with those of corresponding toluenesulphonates, in ethanol and acetic acid. Chromophoric changes make these reactions easy to follow; the picrate leaving group could have synthetical applications. In solvolysis, rate- and product-studies suggest that nucleophilic participation by neighbouring groups or solvent is more important than in the corresponding reactions of arenesulphonates.