Prolonged heating of 2-vitro-4-chlorophenylurea (I) with aqueous alkali has been reported^[1] to yield the corresponding isocyanate (Ⅱ).However, the experimental conditions employed should not have led to the formation of such a structure, since an isocyanate would be too reactive to have survived the drastic alkali treatment.By similar treatment, we obtained from 2-vitro-4-chlorophenylurethan a product melting at the same temperature (87°) as the alleged isocyanate, but was definitely identified as 2-vitro-4-chlorophenol.Similar treatment of 2-vitro-4-chloroaniline and o-nitroaniline invariably led to the formation of the corresponding phenols, Tishler et al.might have been misled by the nitrogen analysis reported, which is possibly erroneous.The phenol was formed by hydrolytic removal of the amino function, which must be strongly activated by the o-vitro group.