By WINIFRED GRACE HURST and JOCELYN FIELD THORPE. THE first reference to the fact that th0 reduction of aromatic nitro-compounds to the corresponding aminoderivatives through the agency of tin and hydrochloric acid often leads to the production of by-products containing chlorine seems to have been made by Fittig (Ber., 1875, 8, 15), who was able t o isolate some chlorobromoaniline by the reduction of pbromonitrobenzene. Subsequently, Kock (Ber., 1887, 20, 1569) obtained considerable quantities of pchloroaniline by the reduction of nitrobenzene under similar experimental conditions. No one who has used this method of reduction can have failed to notice the production of these halogenated by-products, although very few atkempts seem to have been made either to identify them or t o work out an experimental basis for their formation. That, under certain conditions, they may constitute the main product of the reaction, has been shown by Gabriel and Stelzner (Ber., 1896, 29, 305), who, by the reduction of nitromethylindazole, obtained only the chloroaminomethylindazole : c1 Gabriel and Stelzner consider that the reaction is due to, the formation of the intermediate hydroxylamine derivative, which, in the presence of the halogen acid, passes into the halogen substituted amine in accordance with the observation of Bamberger (Ber., 1895, 28, 251). They also observe that if the para-position is occupied, the halogen enters the ortho-position, as, for example, in the productJon of chlorobromoaniline in the manner described by Fittig (Eoc. cit.). During the autumn months, bhe staff and research students of this laboratory have been engaged in the preparation of considerable quantities of phenacetin, and, in the first instance, this substance was prepared by the method recommended by Hinsberg (Amnalen, 1899, 305, 278), in which tin and concentrated hydrochloric acid are used as the reducing agents, and the product is directly acetylated by acetic anhydride :