junte 1959 STRUCTURE OF POLYAZAINDENES. Ill 793 (I) in 750 ml. of water at 60°there was passed a current of chlorine for 45 min. After cooling to 35°, the solid (3.4 g.) was collected on a filter. It was recrystallized from dimethylformamide (with a Norit decolorizetion) on addition of one-third its volume of water. Yield, 2.7 g. (15%). It begins to char at about 300°but melts >350°.Anal. Caled, for C0HeN4OCl: C, 39.0; H, 2.7; N, 30.4. Found: C, 39.3; H, 2.9; N, 30.4.3. From ethyl a-chloroacetoacetate and S-amino-l,2,4triazole: To 28 ml. (0.15 mole) of ethyl aeetoacetate there was added 24 ml. of sulfuryl chloride and the solution was heated on the steam-bath 2 hr. To this crude ethyl achloroacetoacetate there was added 100 ml. of acetic acid and 12.6 g. (0.15 mole) of 3-amino-l,2,4-triazole; the mixture was refluxed for 4 hr., cooled, and the solid collected and recrystallized from dimethylformamidc. Yield, 25 g. The product was identical with that obtained by chlorination of I, as shown by the infrared absorption curve.5-Hydroxy-6-methyl-4-oxo-l,3,Sa,7-tetrazaindene (XVII).Ammonium persulfate (34 g.; 0.15 mole) in 70 ml. of water was added dropwise over a period of 1 hr. to a stirred, cold solution of 15 g. (0.1 mole) of 6-methyl-4-oxo-l,3,3a,7tetrazaindene (I), dissolved in 220 ml. of 3N sodium hydroxide. The 6-methyl-4-oxo-l,3,3a,7-tctrazainden-5-yl sulfate was collected (15 g.) and recrystallized from water.A mixture of 7 g. of the sulfate and 28 ml. of 5N hydrochloric acid was refluxed 0.5 hr., cooled, and the solid collected. The crude product was recrystallized from dimethylformamide to give 3.5 g. of XVII, m.p. above 330°, with progressive darkening above 300°.Anal. Caled, for C6HeN402: C, 43.4; H, 3.6. Found: C, 44.0; , 4.0. 4-Methyl-6-oxo-l,2,3a,7-tetrazaindene (III); synthesis via