Acetyl durene

Electron-rich aromatic compounds such as durene, p-dimethoxybenzene, mesitylene, anisole, thiophene, and fluorene can be benzoylated or acetylated by the corresponding Af-acylimidazole in trifluoroacetic acid to give the corresponding benzophenone or acetophenone derivative in good yield (Method A). As the actual acylating agent, a mixed anhydride of trifluoroacetic acid and benzoic acid has been proposed 1973... 

Derivatives of durene and mesitylene— In Chapter 9 it was pointed out that in derivatives of durene and mesitylene stcric factors due to the methyl groups may hinder the resonance of the substituent group with the ring system. In Tables Cl and C//the dipole moments of these compounds are compared with the corresponding aromatic and aliphatic derivatives. The dipole moments of the acetyl derivatives of durene and mesitylene are very similar to the value for acetone but lower than that for acetophenone, where resonance with the ring occurs. In aldehydes, on the other hand, where apparently there is no steric hindrance, the moment is almost identical with that of benzaldehyde. 

Diphenylcyclopropenecarboxylic acid gives the corresponding diphenylcyclopro-penyl cation using acetyl perchlorate however, the major product is durene when the tetrafluoroborate salt is used. With triphenylmethyl perchlorate in methylene chloride and lithium carbonate this acid is converted into l,2-diphenyl-3-triphenylmethylcyclopropenyl cation (15) (equation 7). 

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