Fa-Ching Chen

Orientation in the chlorination of phenol and of anisole with sodium and t-butyl hypochlorites in various solvents

The effects of several factors on orientation in the chlorination of phenol and of anisole have been studied. The ortho/para ratio in the chlorination of phenol with aqueous NaOCl increases with increasing pH (0.64 at pH 4.0 and 4.3 at pH 10.0), whereas the ratio in the chlorination of anisole is almost constant (0.63–0.66) at pH 4.0–10.0. In chlorination with t-butyl hypochlorite, phenol gives an ortho/para ratio of 0.61 in methanol and 0.20 in acetonitrile, whereas anhydrous sodium phenoxide gives 1.23 in methanol and 2.54 in acetonitrile. The chlorination temperature and the concentration of phenol in hydroxylic solvents have virtually no effect on the ortho/para ratio. On the basis of these observations and literature information, the mechanism of reaction is discussed.