Taking the lead on tackling climate change, India will eliminate the use of HFC-23, a greenhouse gas that harms the ozone layer, by 2030.
About the HFC 23 :
Fluoroform is the chemical compound with the formula CHF3. It is one of the “haloforms”, a class of compounds with the formula CHX3 (X = halogen). Fluoroform is used in diverse niche applications and is produced as a by-product of the manufacture of Teflon. It is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid.
- CHF3is used in the semiconductor industry in plasma etching of silicon oxide and silicon nitride. Known as R-23 or HFC-23, it is also a useful refrigerant, sometimes as a replacement for chloro trifluoro methane (cfc-13) and is a byproduct of its manufacture.
- When used as a fire suppressant, the fluoroform carries theDuPont trade name, FE-13. CHF3 is recommended for this application because of its low toxicity, its low reactivity, and its high density. HFC-23 has been used in the past as a replacement for Halon 1301[cfc-13b1] in fire suppression systems as a total flooding gaseous fire suppression
- The molecule is weakly acidic with a pKa= 25–28 and quite inert. The main synthetic methods to use CHF3 as a reagent are based on its deprotonation to generate the “CF3−” anion, which is highly reactive and undergoes defluorination to generate F- and CHF2. Recently, some approaches activating it by assisted metallation with copper organometallic species are able to effect the site-selective trifluoro methylation arene halides. It is a precursor of Prakash’s reagent CF3Si(CH3)3 which is the most useful source of the nucleophilic CF3−” anion.
- CHF3is a potent greenhouse gas. The secretariat of the Clean Development Mechanism estimates that a ton of HFC-23 in the atmosphere has the same effect as 11,700 tons of carbon dioxide.
- More recent work (IPCC, 2007) suggests that this equivalency, also called a 100-yrglobal warming potential, is slightly larger at 14,800 for HFC-23. The atmospheric lifetime is 270 years.
- According to the 2007 IPCC climate report, HFC-23 was the most abundant HFC in the global atmosphere until around 2001, which is when the global mean concentration ofHFC-134a (1,1,1,2-tetra fluoro ethane), the chemical now used extensively in automobile air conditioners, surpassed those of HFC-23. Global emissions of HFC-23 have in the past been dominated by the inadvertent production and release during the manufacture of the refrigerant HCFC-22 (chloro difluoro methane).
- Data reported to the United Nations Framework Convention on Climate Change (UNFCCC) greenhouse gas emissions databases indicate substantial decreases in developed or Annex 1 countries HFC-23 emissions from the 1990s to the 2000s (UNFCCC greenhouse gas emissions databases).
- The UNFCCC Clean Development Mechanism projects have provided funding and facilitated the destruction of HFC-23 co-produced from a portion of HCFC-22 produced in developing or non-Annex 1 countries since 2003. Developing countries have become the largest producers of HCFC-22 in recent years according to data compiled by the Ozone Secretariat of the World Meteorological Organization.
- Emissions of all HFCs are included in the UNFCCCs Kyoto Protocol. To mitigate its impact, CHF3can be destroyed with electric plasma arc technologies or by high temperature incineration.
About the Ban :
The announcement came at a meeting of parties to the Montreal Protocol at Kigali in Rwanda where final negotiations are taking place to substantially reduce the use of HFCs (hydro fluoro carbons) by 2030. The Montreal Protocol, which came into force in 1989, is aimed at reducing the production and consumption of ozone depleting substances in order to protect the earth’s fragile ozone layer.
- HFC-23, a potent greenhouse gas with global warming potential of 14,800 times more than that of CO2, is a by-product of HCFC-22, which is used in industrial refrigeration. HCFC stands for hydro chloro fluro carbon.
- Anil Madhav Dave, minister of state for environment, forests and climate change, who is leading the Indian team, has given the go-ahead for releasing the order for incinerating the HFC–23 by producers of HCFC–22 gas.
- It is now hard for the teams from countries which are producers of HCFC-22 to negotiate for funding from Multilateral Funds for creating facility for incineration or financial support for incinerating the gas.
- Signing the orders, Manoj Kumar Singh, joint secretary in the MoEF and lead Indian negotiator, highlighted the fact that even with complete phase out of HCFCs for usage as refrigerants under the Montreal Protocol that its production will continue for feedstock purposes.