1,2-Benzenedicarbonitrile, 3,4,5,6-tetrachloro- (9CI) 1953-99-7 3,4,5,6-Tetrachloro-1,2-benzenedicarbonitrile 3,4,5,6-Tetrachlorobenzene-1,2-dicarbonitrile 3,4,5,6-Tetrachlorophthalonitrile BRN 1882303 EINECS 217-783-1 Tetrachlorophthalonitrile o-PHTHALODINITRILE, TETRACHLORO- o-TCPN o-Tetrachlorophthalodinitrile