Super acidic reaction media

Alkyl mesylates undergo alkylation reaction with benzene rings in the presence of Sc(OTf)3. " Allylic acetates undergo alkylation with Mo(CO)g and allylic chlorides react in the presence of ZnCl2/Si02. " Montmorillonite clay (KIO) is an effective medium for alkylation reactions.Nafion-H, a super acidic perfluori-nated resin sulfonic acid, is a very good catalyst for gas phase alkylations with alkyl halides, alcohols,or alkenes. 

I3 can also be prepared in solution, similarly to Brs, by oxidation with S2O5F2 ). However, in this case no super-acid is necessarily required as a solvent and the reaction can already take place in a less acidic medium of fluoro-sulphuiic acid, in accordance with... 

Since both CO and toluene (or anisole or phenol) are nucleophilic/basic compounds and the reaction is performed in a super acidic medium (with excess acid), the formation of the initial electrophile and corresponding nucleophile are by no means trivial and needs careful consideration. Furthermore, the protonation of toluene by the HF/BF3 system has been reported by Olah et (Eq 2.19), while the existence of an HCO containing ion pair has recently been demonstrated by Gladysz ef... 

Chloro-4,6-disubstituted-l,3,5-triazines 1 have been widely used in the activation of carboxylic acids in die formation of peptide bonds. The reaction requires the presence of a tertiary amine in the reaction medium and the participation of quaternary triazinyl ammonium salts 2 as intermediates of the reaction has been demonstrated. The role of fliese species in die activation of the carboxylic acid involves substitution of die amine-leaving group in 2 by the carboxylate ion, to afford triazine super active esters 3, the reagents employed in the peptide bond formation step (Scheme 26.1). 

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