Ozone Depleting Chemicals

CFCs

The destruction of ozone is accelerated by certain trace gases containing nitrogen, hydrogen, bromine, and chlorine. These are referred to as ozone depletion chemicals.

The most commonly known ozone depletion chemicals (ODCs) are the CFCs or chlorofluorocarbons. Over the last 30 years man-made CFCs have been the main cause of stratospheric ozone depletion.

CFCs however, are not the only ozone-depleting chemicals. Other ODCs include the methylhalides, carbon tetrachloride (CCl4), carbon tetrafluoride (CF4), and the halons which contain bromine instead of chlorine. Such compounds are called halocarbons.

Carbon tetrachloride (CCl4), despite its toxicity, was first used in the early 1900s as a fire extinguishing agent, and more recently as an industrial solvent, an agricultural fumigant, and in many other industrial processes including petrochemical refining, and pesticide and pharmaceuticals production. Recently it has also been used in the production of CFC-11 and CFC-12.

Methyl chloroform, also known as 1,1,1 trichloroethane is a versatile, all-purpose industrial solvent used primarily to clean metal and electronic parts. It was introduced in the 1950s as a substitute for carbon tetrachloride.

Halons, unlike CFCs, contain bromine, which also destroys ozone in the stratosphere. Halons are used primarily in fire extinguishers. Halon-1301 has an ozone depleting potential 10 times that of CFC-11. Although the use of halons in developed countries has been phased out since 1996, the atmospheric concentration of these potent, ozone destroyers is still rising because of their long atmospheric lifetimes.

Methyl bromide, another bromine-containing halocarbon, has been used as a pesticide since the 1960s.

Class I and Class II Ozone Depleting Substances

Class I Ozone Depleting Substances

Halocarbon Number	Molecular Formula	Name
CFC-11	CCl₃F	Trichlorofluoromethane
CFC-12	CCl₂F₂	Dichlorodifluoromethane
CFC-113	C₂Cl₃F₃	Trichlorotrifluoroethane
CFC-114	C₂Cl₂F₄	Dichlorotetrafluoroethane
CFC-115	C₂ClF₅	Chloropentafluoroethane
Halon 1011	CH₂BrCl	Bromochloromethane
Halon 1202	CBr₂F₂	Dibromodifluoromethane
Halon 1211	CF₂ClBr	Bromochlorodifluoromethane
Halon 1301	CF₃Br	Bromotrifluoromethane
Halon 2402	C₂F₄Br₂	Dibromotetrafluoroethane
CFC-13	CClF₃	Chlorotrifluoromethane
CFC-111	C₂Cl₅F	Pentachlorofluoroethane
CFC-112	C₂Cl₄F₂	Tetrachlorodifluoroethane
CFC-211	C₃Cl₇F₃	Heptachlorofluoropropane
CFC-212	C₃Cl₆F₂	Hexachlorodifluoropropane
CFC-213	C₃Cl₅F₃	Pentachlorotrifluoropropane
CFC-214	C₃Cl₄F₄	Tetrachlorotetrafluoropropane
CFC-215	C₃Cl₃F₅	Trichloropentafluoropropane
CFC-216	C₃Cl₂F₆	Dichlorohexafluoropropane
CFC-217	C₃ClF₇	Chloroheptafluoropropane
Carbon Tetrachloride	CCl₄	Tetrachloromethane
Methyl Chloroform	CHCl₃	Trichloroethane (1,1,1 Trichloroethane only)
Methyl Bromide	CH₃Br	Bromomethane, monobromomethane

Class II Ozone Depleting Substances

HCFC Number	Molecular Formula	HCFC Number	Molecular Formula
HCFC-21	CHFCl₂	HCFC-224	C₃HF₄Cl₃
HCFC-22	CHF₂Cl	HCFC-225	C₃HF₅Cl₂
HCFC-31	CH₂FCl	HCFC-225ca	CF₃CF₂CHCl₂
HCFC-121	C₂HFCl₄	HCFC-225cb	CF₂ClCF₂CHClF
HCFC-122	C₂HF₂Cl₃	HCFC-226	C₃HF₆Cl
HCFC-123	C₂HF₃Cl₂	HCFC-231	C₃H₂Cl₅
HCFC-123b	CHCl₂CF₃	HCFC-232	C₃H₂F₂Cl₄
HCFC-124	C₂HF₄Cl	HCFC-233	C₃H₂F₃Cl₃
HCFC-124b	CHFClCF₃	HCFC-234	C₃H₂F₄Cl₂
HCFC-131	C₂H₂FCl₃	HCFC-235	C₃H₂F₅Cl
HCFC-132	C₂H₂F₂Cl₂	HCFC-241	C₃H₃FCl₄
HCFC-133	C₂H₂F₃Cl	HCFC-242	C₃H₃F₂Cl₃
HCFC-141	C₂H₃FCl₂	HCFC-243	C₃H₃F₃Cl₂
HCFC-141b	CH₃CFCl₂	HCFC-244	C₃H₃F₄Cl
HCFC-142	C₂H₃F₂Cl	HCFC-251	C₃H₄FCl₃
HCFC-142b	CH₃CF₂Cl	HCFC-252	C₃H₄F₂Cl₂
HCFC-151	C₂H₄FCl	HCFC-253	C₃H₄F₃Cl
HCFC-221	C₃HFCl₆	HCFC-261	C₃H₅FCl₂
HCFC-222	C₃HF₂Cl₅	HCFC-262	C₃H₅F₂Cl
HCFC-223	C₃HF₃Cl₄	HCFC-271	C₃H₆FCl