C6H4C CH NH  •NHNHz Cli.000H = 0211402 +C7H6N2 . It has also been obtained by

heating ortho-diazoaminotoluene with acetic acid and benzene (F . Heusler, Ber., 1891, 24, p . 4161) . C'H4<NHN NHC7H,=C7H7NI-i 1-c 2 . It crystallizes in needles (from hot water), which melt at 146.5° C. and boil at 269°-270 C . It is readily soluble in hot water, alcohol and dilute hydrochloric acid . Nitrous acid converts it into nitrosoindazole; whilst on heating with the alkyl iodides \/NH ?N . These Isomers are called isindazoles, and may \/\CHI be prepared by the reduction of the nitroso-ortho-alkylaminoacetophenones with zinc dust and water or acetic acid . ' The indazoles are weak bases, which crystallize readily . Phenyl indazole, on reduction with sodium and absolute alcohol, gives a dihydro derivative (K . L .

Paal, Ber., 1891, 24, p . 963) . For other derivatives, see E.`

Fischer and J . Tafel, Ann . 1885, 227, P . 314 .