Halogen benzenes Reactions

Wallington, T.J., Neuman, D.M., Kurylo, M.J. (1987) Kinetics of the gas phase reaction of hydroxyl radicals with ethane, benzene, and a series of halogenated benzenes over the temperature range 234 -38 K. Int. J. Chem. Kinet. 19, 725-739. 

The reacting species is a rather weak electrophile and, therefore, only particularly reactive aromatics are suitable substrates. Consequently, the reaction is restricted for polyhydric phenols and their ethers, and reactive heterocycles. With strong acidic systems, such as AICI3 in halogenated benzene solvents, alkylben-zenes can react at more elevated temperatures (>50°C). Trichloroacetonitrile works also well with nonactivated aromatics. The 12 chloroimine, the protonated nitrile (13), or the nitrile coordinated with the Lewis acid are possible involved electrophiles. 

Reaction pathway for halogenated benzenes reacting with hydroxyl radical. 

Originally, pyromellitic and mellophanic dianhydrides were thought to go to benzadiyne in possibly a concerted rather than stepwise fashion, because no products retaining an anhydride function could be found. In the reactions with halogenated benzenes, however, such products do appear evidently, at least in some environments, these dianhydrides first decompose to benzynedicarboxylic anhydride, followed by further loss of C02 and CO. 

In halogenation, benzene reacts with CI2 or Br2 in the presence of a Lewis acid catalyst, such as FeCl or FeBr3, to give the aryl halides chlorobenzene or bromobenzene, respectively. Analogous reactions with I2 and F2 are not synthetically useful because I2 is too unreactive and F2 reacts too violently. 

Kinetic and spectral parameters of the radical cation formed on reaction of OH radicals with halogenated benzenes in aerated acidic (HCK>4 = 7.8... 

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