2,2,7,7-tetrachlorocyclohept-4-en-1-one 4-cyclohepten-1-one, 2,2,7,7-tetrachloro- InChI=1/C7H6Cl4O/c8-6(9)3-1-2-4-7(10,11)5(6)12/h1-2H,3-4H