Reaction of 2,4-Dinitrophenylhydrazones of Triphenyl(2-aroylethyl)phosphonium Bromides with Aqueous Alkali and Some Transformations of the Betaines Formed

摘要

Triphenyl(2-p-toluoylethyl)-and triphenyl(2-p-bromobenzoylethyl)phosphonium bromide 2,4-dinitro-phenylhydrazones were established to form a bipolar compounds with a negatively charged nitrogen atom and a positively charged phosphonium atom,under the action of aqueous alkali at 0°C.When refluxed in acetonitrile,the product formed from triphenyl(2-p-toluoylethyl)phosphonium bromide undergoes cleavage by a five-membered ring mechanism to give triphenylphosphine and tolyl vinyl ketone 2,4-dinitrophenylhydrazone.The reactions of the above betains with methyl iodide give rise to N-alkylation and cleavage products,but,in addition,iodide analogs of the starting phosphonium salt 2,4-dinitrophenylhydrazones which are probably formed via N->C negative charge transfer,C-methylation,and reaction of the resulting products with N-betaines.