Acid in inert solvents

Miscellaneous. Tetramethylphosphonium salts have been generated from methylenetrimethylphosphorane by treatment with acid in inert solvent, or with ammonium salts in inert solvents or in aqueous ethanol. Details have appeared of the preparation of ]8y-unsaturated ketones using lithiated phen-acylidenetriphenylphosphorane. Alkylation of the metallated ylide (32) has... 

In aprotic solvents. The mechanism of protonation is basically the same as that discussed above. The second order term observed by Bronsted (1928, see above) is due to an equilibrium of the acid catalyst forming dimeric aggregates. Therefore, fastest rates are measured in dipolar aprotic solvents, e.g., dimethyl sulfoxide (Blues et al., 1974). All these kinetic measurements verify a prediction made by Staudinger and Gaule at a very early date (1916), namely, that with acetic acid or trichloroacetic acid in inert solvents the reactivity of substituted diazoalkanes and a-diazo-carbonyl and a,a -dicarbonyl diazo compounds increases as the protonation equilibrium is shifted towards the corresponding alkanediazo-nium ion. This prediction includes the compounds listed in sequence 4-23 ... 

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