Interaction of title compound (I) with pyrazolone (II) yields the dipyrazolylmethane (III) as major product besides the two-halogen replacement product (IV). The unusually easy reaction of (I) with indole (V) is explained by evolving hydrogen chloride, which catalyzes indole addition and disintegration of the intermediate yielding salt (VI). The tris(indolyl)methane (VII) results from addition of the third methylindole molecule to diindolylmethane (VI). Replacement of one indolyl moiety occurs in the reaction course of salt (VI) with dimethylbarbituric acid (VIII). The latter compound reacts with dimethylsulfoxide (X) to betaine (XI) in the presence of (I) as dehydrating reagent.-(AZEV*, Y. A.; DUELCKS, T.; LORK, E.; GABEL, D.; Mendeleev Commun. 2005, 5, 193-196; Ural State Tech. Univ., Ekaterinburg 620002, Russia; Eng.) -H. Hoennerscheid 03-043