 Zinc and hydrochloric acid decompose it with formation of orthoxylylene diamine.The keto-hydro derivative phthalazone (C8H6ON2), is obtained by condensing hydrazine with orthophthalaldehydoacid.On treatment with phosphorus oxychloride, it yields a chlorphthalazine, which with zinc and hydrochloric acid gives isoindole (C8H7N), and with tin and hydrochloric acid, phthalimidine (C8H7ON), the second nitrogen atom being eliminated as ammonia.