Uses of Alkyl Halides Freons,chlorofluorocarbons or CFC's Freon 12,CF2Cl2,now replaced with Freon 22, CF,CHCl,not as harmful to ozone layer. Pesticides DDT banned in U.S. extremely toxic to insects but not as toxic to mammalsUses 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