348 Mr. C. H. Browning and others. Relationships between 



The dinitro-compound was reduced with tin and hydrochloric acid. On 

 cooling the double stannic chloride salt crystallised and was filtered, dissolved 

 in water, and the tin precipitated by hydrogen sulphide. From the filtrate 

 the base was precipitated by sodium hydroxide. It formed pale yellow plates, 

 m.p. 250°. It is very unstable and oxidises in the air. 



[26.] lA.Na'phtho - dipyridine (Benzophenanthroline) was prepared from 

 1.4 naphtbylene diamine by Karrer's method.* The diamine was obtained 

 by the reduction of benzene-azo-a-naphthylamine with zinc dust and acetic 

 acid ; 14"3 grm. of a-naphthylamine gave 21 - 6 grm. of naphthylenediamine 

 sulphate, from which the base was obtained, m.p. 118°. The naphtho- 

 dipyridine was purified by crystallisation from a mixture of benzene and 

 petroleum ether and separated in long, pale yellow needles, m.p. 160°-164°. 



lANapkfcho-dipvridme. 



[27.] l.b.Naphtho-dipyridine. — The 1.5.naphthylenediamine was prepared 

 by the reduction of 1.5.dinitro-naphthalene with stannous chloride and 

 hydrochloric acid. The naphtho-dipyridine compound was obtained, as 

 previously described, and crystallised from benzene in nearly colourless 

 needles, m.p. 214°-215°. It combines with methyl sulphate in hot benzene 

 solution, from which yellow needles separated on cooling. 



1.5. Naphtho-dipyridine. 



[28.] l.l.Dinaphthyl.2 2-imine was prepared by the method described by 

 Meisenheimer and Wittef from yS-naphthylamine. The latter was converted 

 into azonaphthalene which was reduced with zinc dust and acetic acid. In 

 this way 2.2.diamino-l.l.dinaphthyl was obtained, m.p. 191° ; 2 grins, of the 

 diamino-dinaphthyl hydrochloride were heated in the oil- bath to 240°-250° 



* Marckwald, ' Annalen,' vol. 274, p. 365 (1893). 

 t 'Ber.,' vol. 36, p. 4154 (1903). 



