Uses of Alkyl Halides Freons,chlorofluorocarbons or CFC's Freon 12,CF2Cl2,now replaced with Freon 22, CF2CHCl,not as harmful to ozone layer. Pesticides-DDT banned in U.S. extremely toxic to insects but not as toxic to mammals Uses of Alkyl Halides ◼Freons, chlorofluorocarbons or CFC’s ⚫Freon 12, CF2Cl2 , now replaced with Freon 22, CF2CHCl, not as harmful to ozone layer. ◼Pesticides – DDT banned in U.S. ⚫extremely toxic to insects but not as toxic to mammals