Chloroform (CHCl3): Solvent, anesthetic (historical). Oxidized by air to phosgene (COCl2, toxic) → stored in dark bottles with ethanol (which reacts with phosgene to give diethyl carbonate).

Iodoform (CHI3): Yellow solid, antiseptic. Produced by iodoform reaction of methyl ketones/ethanol.

Carbon tetrachloride (CCl4): Solvent, fire extinguisher (historical). Toxic — causes liver damage.

Freons (CFCs, e.g., CF2Cl2): Refrigerants. UV cleaves C-Cl → Cl· radicals catalytically destroy O3 (ozone). Montreal Protocol bans CFC production.

DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane): Insecticide. Non-biodegradable, bioaccumulates. Banned in many countries.

BHC (hexachlorocyclohexane, C6H6Cl6): Made by Cl2/UV addition to benzene. Gamma-isomer (Lindane) is the active insecticide.