Tetrachlorophthalic Anhydride; niagathal; 4,5,6,7-Tetrachloro-1,3-isobenzofurandione; tetrachloro-1,2-benzenedicarboxylic acid anhydride; 1,3-dioxy-4,5,6,7-tetrachloroisobenzofuran; Tetrathal; cas no: 117-08-8