Tetrafluoroethane (a haloalkane) is a clear liquid which boils well below room temperature (as seen here) and can be extracted from common canned air canisters by simply inverting them during use.

The haloalkanes (also known as halogenalkanes or alkyl halides) are a group of chemical compounds, consisting of alkanes, such as methane or ethane, with one or more halogens linked, such as chlorine or fluorine, making them a type of organic halide. They are known under many chemical and commercial names. As fire extinguishants, propellants and solvents they have or had wide use. Some haloalkanes (those containing chlorine or bromine) are believed to have negative effects on the environment such as ozone depletion. The most widely known family within this group are the chlorofluorocarbons (CFCs). Image File history File linksMetadata Size of this preview: 294 × 599 pixel Image in higher resolution (943 × 1920 pixel, file size: 349 KB, MIME type: image/jpeg) Boiling liquid tetrafluoroethane in a small graduated cylinder. ... Image File history File linksMetadata Size of this preview: 294 × 599 pixel Image in higher resolution (943 × 1920 pixel, file size: 349 KB, MIME type: image/jpeg) Boiling liquid tetrafluoroethane in a small graduated cylinder. ... Tetrafluoroethane (CH2FCF3, technically 1,1,1,2-Tetrafluoroethane) is an inert gas found in cans of air used for blow-dusting computers and other miscellaneous items that are hard to reach or access. ... A can of canned air Canned air, also called duster or Mega-Duster, is a product consisting of liquified difluoroethane, trifluoroethane, or tetrafluoroethane in a spray can, with a very long nozzle that enables the user to direct a precisely focused blast of air. ... A chemical compound is a chemical substance of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... Chemical structure of methane, the simplest alkane Alkanes are chemical compounds that consist only of the elements carbon (C) and hydrogen (H) (i. ... Methane is a chemical compound with the molecular formula CH4. ... This article is about a chemical compound. ... This article is about the chemical series. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Distinguished from fluorene and fluorone. ... An organic halide is an organic compound containing one or more halogen atoms. ... Fire extinguisher A fire extinguisher is a device used to put out a fire, often in an emergency situation. ... A propellant is a material that is used to move an object by applying a motive force. ... For other uses, see Solvent (disambiguation). ... Global monthly average total ozone amount Ozone depletion describes 14 distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths...

General

A haloalkane also known as alkyl halogenide, halogenalkane or halogenoalkane, and alkyl halide is a chemical compound derived from an alkane by substituting one or more hydrogen atoms with halogen atoms. Substitution with fluorine, chlorine, bromine and iodine results in fluoroalkanes, chloroalkanes, bromoalkanes and iodoalkanes, respectively. Mixed compounds are also possible, the best-known examples being the chlorofluorocarbons (CFCs) which are mainly responsible for ozone depletion. Haloalkanes are used in semiconductor device fabrication, as refrigerants, foam blowing agents, solvents, aerosol spray propellants, fire extinguishing agents, and chemical reagents. A chemical compound is a chemical substance of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... Chemical structure of methane, the simplest alkane Alkanes are chemical compounds that consist only of the elements carbon (C) and hydrogen (H) (i. ... Substitution in the context of organic chemistry has the general meaning of replacing an atom, a functional group, or a substituent in a molecule. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... This article is about the chemical series. ... Distinguished from fluorene and fluorone. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Bromo redirects here. ... For the record label, see Iodine Recordings. ... For other uses, see Ozone (disambiguation). ... Nasas Glenn Research Center clean room. ... A refrigerant is a compound used in a heat cycle that undergoes a phase change from a gas to a liquid and back. ... Sea foam on the beach Foam on a cappuccino Fire-retardant, foamed plastic being used as a temporary dam for firestop mortar in a cable penetration in a pulp and paper mill on Vancouver Island, British Columbia, Canada. ... A foaming agent is a material that will decompose to release a gas under certain conditions (typically high temperature), which can be used to turn a liquid into a foam. ... For other uses, see Solvent (disambiguation). ... Aerosol spray can Aerosol spray is a type of canister that sprays an aerosol when its button is pressed or held down. ... Fire extinguisher A fire extinguisher is a device used to put out a fire, often in an emergency situation. ... A reagent is any substance used in a chemical reaction. ...

Freon is a trade name for a group of chlorofluorocarbons used primarily as a refrigerant. The word Freon is a registered trademark belonging to DuPont. Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. ... “(TM)” redirects here. ... Dupont, DuPont, Du Pont, or du Pont may refer to: // E.I. du Pont de Nemours and Company, the worlds third largest chemical company Du Pont Motors Gilbert Dupont, a French stock brokerage part of retail banking network Crédit du Nord ST Dupont, a French manufacturer of fine...

There are 3 types of haloalkane. In primary (1°) haloalkanes the carbon which carries the halogen atom is only attached to one other alkyl group. However CH₃Br is also a primary haloalkane, even though there is no alkyl group. In secondary (2°) haloalkanes the carbon that carries the halogen atom is attached to 2 alkyl groups. In tertiary (3°) haloalkanes the carbon that carries the halogen atom is attached to 3 alkyl groups. For other uses, see Carbon (disambiguation). ... The chemical compound bromomethane is an organic halogen compound with formula CH3Br. ...

Chloro fluoro compounds (CFC, HCFC)

CFC molecules

Chlorofluorocarbons (CFC) are compounds containing chlorine, fluorine and carbon only, that is they contain no hydrogen. They were formerly used widely in industry, for example as refrigerants, propellants, and cleaning solvents. Their use has been regularly prohibited by the Montreal Protocol, because of effects on the ozone layer (see ozone depletion). They are also a powerful greenhouse gas, in terms of carbon dioxide equivalence (over a time period of one hundred years) between 5000 and 8100 per kg. ^[1] CFC molecules - PD image from science. ... CFC molecules - PD image from science. ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Distinguished from fluorene and fluorone. ... For other uses, see Carbon (disambiguation). ... A refrigerant is a compound used in a heat cycle that undergoes a phase change from a gas to a liquid and back. ... The largest Antarctic ozone hole recorded as of September 2000 For other similarly-named agreements, see Montreal Protocol (disambiguation). ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Global monthly average total ozone amount Ozone depletion describes 14 distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths... co2e is Carbon Dioxide Equivalent - an internationally accepted measure that encapsulates all GHGs (Greenhouse Gases) that contribute to Global Warming (e. ...

Hydrochlorofluorocarbons (HCFCs) are of a class of haloalkanes where not all hydrogen has been replaced by chlorine or fluorine. They are used primarily as chlorofluorocarbon (CFC) substitutes, as the ozone depleting effects are only about 10% of the CFCs.

Hydro fluoro compounds (HFC)

Hydrofluorocarbons (HFCs) contain no chlorine. They are composed entirely of carbon, hydrogen, and fluorine. They have an even lower global warming potential than HCFCs, and no known effects at all on the ozone layer. Only compounds containing chlorine and bromine are thought to harm the ozone layer. Fluorine itself is not ozone-toxic. [1] However, HFCs and perfluorocarbons do have activity in the entirely different realm of greenhouse gases, which do not destroy ozone, but do cause global warming. Two groups of haloalkanes, hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), are targets of the Kyoto Protocol. ^[2] Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Kyoto Protocol Opened for signature December 11, 1997 in Kyoto, Japan Entered into force February 16, 2005. ...

Polymer haloalkanes

Chlorinated or fluorinated alkenes can be used for polymerization, resulting in polymer haloalkanes with notable chemical resistance properties. Important examples include polychloroethene (polyvinyl chloride, PVC), and polytetrafluoroethylene (PTFE, Teflon), but many more halogenated polymers exist. Polyvinyl chloride Polyvinyl chloride, (IUPAC Polychloroethene) commonly abbreviated PVC, is a widely used thermoplastic polymer. ... In chemistry, polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer which finds numerous applications. ... Teflon is a trademark of DuPont and is commonly used for the chemical compound polytetrafluoroethylene. ...

History

Original development

Carbon tetrachloride was used in fire extinguishers and glass "anti-fire grenades" from the late nineteenth century until around the end of World War II. Experimentation with chloroalkanes for fire suppression on military aircraft began at least as early as the 1920s. R-phrases , , , , S-phrases , , , , , Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... Flying machine redirects here. ...

American engineer Thomas Midgley developed chlorofluorocarbons (CFC) in 1928 as a replacement for ammonia (NH₃), chloromethane (CH₃Cl), and sulfur dioxide (SO₂), which are toxic but were in common use at the time as refrigerants. The new compound developed had to have a low boiling point and be non-toxic and generally non-reactive. In a demonstration for the American Chemical Society, Midgley flamboyantly demonstrated all these properties by inhaling a breath of the gas and using it to blow out a candle.^{[citation needed]} Thomas Midgley, Jr. ... For other uses, see Ammonia (disambiguation). ... Chloromethane or Methyl chloride is a chemical compound once widely used as a refrigerant. ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... Italic text This article is about the boiling point of liquids. ... The American Chemical Society (ACS) is a learned society (professional association) based in the United States that supports scientific inquiry in the field of chemistry. ...

Midgley specifically developed CCl₂F₂. However, one of the attractive features is that there exists a whole family of the compounds, each having a unique boiling point which can suit different applications. In addition to their original application as refrigerants, chlorofluoroalkanes have been used as propellants in aerosol cans, cleaning solvents for circuit boards, and blowing agents for making expanded plastics (such as the expanded polystyrene used in packaging materials and disposable coffee cups). Polystyrene (IPA: ) is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. ...

Development of alternatives

During World War II, various early chloroalkanes were in standard use in military aircraft by some combatants, but these early halons suffered from excessive toxicity. Nevertheless, after the war they slowly became more common in civil aviation as well. Image File history File links This is a lossless scalable vector image. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000...

In the 1960s, fluoroalkanes and bromofluoroalkanes became available and were quickly recognized as being among the most effective fire-fighting materials discovered. Much early research with Halon 1301 was conducted under the auspices of the US Armed Forces, while Halon 1211 was, initially, mainly developed in the UK. By the late 1960s they were standard in many applications where water and dry-powder extinguishers posed a threat of damage to the protected property, including computer rooms, telecommunications switches, laboratories, museums and art collections. Beginning with warships, in the 1970s, bromofluoroalkanes also progressively came to be associated with rapid SMACKDOWN knockdown of severe fires in confined spaces with minimal risk to personnel. Halon 1301 is a trade name for Bromotrifluoromethane, it is also known as BTM, Halon 1301 BTM, or Freon 13BI. The chemical formula is CF3Br. ... Halon 1211 is a trade name for Bromochlorodifluoromethane, it is also known as BCF,Halon 1211 BCF, or Freon 12B1. ... This article does not cite any references or sources. ...

Work on alternatives for chlorofluorocarbons in refrigerants began in the late 1970s after the first warnings of damage to stratospheric ozone were published in the journal Nature in 1974 by Molina and Rowland (who shared the 1995 Nobel Prize for Chemistry for their work). Adding hydrogen and thus creating hydrochlorofluorocarbons (HCFC), chemists made the compounds less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer. Later alternatives dispense with the chlorine, creating hydrofluorocarbons (HFC) with even shorter lifetimes in the lower atmosphere. Atmosphere diagram showing stratosphere. ... “Natural” redirects here. ... Mario José Molina Henríquez (born March 19, 1943) was awarded the 1995 Nobel Prize in Chemistry for his role in elucidating the threat to the Earths ozone layer of chlorofluorocarbon gases (or CFCs). ... Frank Sherwood Rowland (born June 28, 1927) is a Nobel laureate and a professor of chemistry at the University of California, Irvine. ... List of Nobel Prize laureates in Chemistry from 1901 to the present day. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...

By the early 1980s, bromofluoroalkanes were in common use on aircraft, ships and large vehicles as well as in computer facilities and galleries. However, concern was beginning to be felt about the impact of chloroalkanes and bromoalkanes on the ozone layer. The Vienna Convention on Ozone Layer Protection did not cover bromofluoroalkanes as it was thought, at the time, that emergency discharge of extinguishing systems was too small in volume to produce a significant impact, and too important to human safety for restriction. The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ...

However, by the time of the Montreal Protocol it was realised that deliberate and accidental discharges during system tests and maintenance accounted for substantially larger volumes than emergency discharges, and consequently halons were brought into the treaty, albeit with many exceptions. The largest Antarctic ozone hole recorded as of September 2000 For other similarly-named agreements, see Montreal Protocol (disambiguation). ...

Phase out

Use of certain chloroalkanes as solvents for large scale application, such as dry cleaning, have been phased out, for example, by the IPPC directive on greenhouse gases in 1994 and by the Volatile Organic Compounds (VOC) directive of the EU in 1997. Permitted chlorofluoroalkane uses are medicinal only. The Internation Plant Protection Convention (IPPC) is an international treaty organization that works to prevent the international spread of plant diseases. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ...

Finally, bromofluoroalkanes have been largely phased out and the possession of such equipment is prohibited in some countries like the Netherlands and Belgium, from 1 January 2004, based on the Montreal Protocol and guidelines of the European Union. The largest Antarctic ozone hole recorded as of September 2000 For other similarly-named agreements, see Montreal Protocol (disambiguation). ...

Production of new stocks ceased in most (probably all) countries as of 1994. However many countries still require aircraft to be fitted with halon fire suppression systems because no safe and completely satisfactory alternative has been discovered for this application. There are also a few other, highly specialised, uses. These programs recycle halon through "halon banks" coordinated by the Halon Recycling Corporation^[3] to ensure that discharge to the atmosphere occurs only in a genuine emergency and to conserve remaining stocks.

On September 21, 2007, approximately 200 countries agreed to accelerate the elimination of hydrochlorofluorocarbons entirely by 2020 in a United Nations-sponsored Montreal summit. Developing nations were given until 2030. Many nations, such as the United States and China, who had previously resisted such efforts, signed the treaty. ^[4] is the 264th day of the year (265th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... UN and U.N. redirect here. ... Nickname: Motto: Concordia Salus (well-being through harmony) Coordinates: , Country Province Region Montréal Founded 1642 Established 1832 Government  - Mayor Gérald Tremblay Area [1][2][3]  - City 365. ... The global warming controversy is a dispute regarding the nature and consequences of global warming. ...

Nomenclature

IUPAC nomenclature

The formal naming of haloalkanes should follow IUPAC nomenclature, which put the halogen as a prefix to the alkane. For example, ethane with bromine becomes bromoethane, methane with four chlorine groups becomes tetrachloromethane. However, many of these compounds have already an established trivial name, which is endorsed by the IUPAC nomenclature, for example chloroform (trichloromethane) and methylene chloride (dichloromethane). For unambiguity, this article follows the systematic naming scheme throughout. IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... In linguistics, a prefix is a type of affix that precedes the morphemes to which it can attach. ... This article is about a chemical compound. ... Bromo redirects here. ... R-phrases , , S-phrases , Flash point −20 °C Autoignition temperature 511 °C Explosive limits 6. ... Methane is a chemical compound with the molecular formula CH4. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... R-phrases , , , , S-phrases , , , , , Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ... R-phrases , , , S-phrases , Flash point Non-flammable U.S. Permissible exposure limit (PEL) 50 ppm (240 mg/m3) (OSHA) Supplementary data page Structure and properties n, εr, etc. ... R-phrases S-phrases , , Flash point None Supplementary data page Structure and properties n, εr, etc. ...

Alternative nomenclature for refrigerants

The refrigerant naming system is mainly used for fluorinated and chlorinated short alkanes for refrigerant use. In the US the standard is specified in ANSI/ASHRAE Standard 34-1992, with additional annual supplements.^[5] The specified ANSI/ASHRAE prefixes were FC (fluorocarbon) or R (refrigerant), but today most are prefixed by a more specific classification:

• CFC—list of chlorofluorocarbons
• HCFC—list of hydrochlorofluorocarbons
• HFC—list of hydrofluorocarbons
• FC—list of fluorocarbons
• PFC—list of perfluorocarbons (completely fluorinated)

The decoding system for CFC-01234a is: Some important fluorocarbons. ... Fluorotelomer alcohol FTOH 8:2 Perfluorocarbons (PFCs) are compounds derived from hydrocarbons by replacement of hydrogen atoms by fluorine atoms. ...

• 0 = Number of double bonds (omitted if zero)
• 1 = Carbon atoms -1 (omitted if zero)
• 2 = Hydrogen atoms +1
• 3 = Fluorine atoms
• 4 = Replaced by Bromine ("B" prefix added)
• a = Letter added to identify isomers, the "normal" isomer in any number has the smallest mass difference on each carbon, and a, b, or c are added as the masses diverge from normal.

Other coding systems are in use as well.

Overview of named compounds

Halomethane compounds are molecules of methane (CH4) with one or more of the hydrogen atoms replaced with halogen atoms. ... R-phrases , , S-phrases , , Flash point -46 °C Autoignition temperature 625 °C Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Chloromethane, also called Methyl chloride, or simply R-40 or HCC 40, is a chemical compound... R-phrases S-phrases , , Flash point None Supplementary data page Structure and properties n, εr, etc. ... R-phrases , , , S-phrases , Flash point Non-flammable U.S. Permissible exposure limit (PEL) 50 ppm (240 mg/m3) (OSHA) Supplementary data page Structure and properties n, εr, etc. ... R-phrases , , , , S-phrases , , , , , Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ... Carbon tetrafluoride, CF4, is a carbon fluoride. ... R-11 redirects here, for the ballistic missile, see Scud. ... R-phrases S-phrases , Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Dichlorodifluoromethane (R-12), usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane, commonly known as CFC, used as a refrigerant and... Chlorotrifluoromethane, R-13, CFC-13, or Freon 13, is a chlorofluorocarbon (CFC). ... Cl | F--C--F | H Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon (HCFC) with chemical formula CHClF2 and CAS number 75-45-6. ... Fluoroform CHF3; CAS number, also known as trifluoromethane, is one of the haloalkanes with zero ozone depletion, as it does not contain any chlorine. ... Chlorofluoromethane or Freon 31 is a mixed halomethane (fluorochlorocarbon - FCC). ... Difluoromethane is an organic compound of the di-halogenoalkane variety. ... Fluoromethane, also known as methyl fluoride, Freon 41 and HFC-41, is a toxic, liquefiable, and flammable gas at standard temperature and pressure. ... R-phrases , S-phrases , , Flash point None Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Dibromomethane or methylene bromide, or methylene dibromide is a halomethane. ... R-phrases , , , , S-phrases , , U.S. Permissible exposure limit (PEL) 0. ... Bromochloromethane or methylene bromochloride and Halon 1011 is a mixed halomethane. ... Bromochlorodifluoromethane, also known by the trade name Halon 1211, or BCF, or Halon 1211 BCF, or Freon 12B1, is a haloalkane with the chemical formula is CF2ClBr. ... Halon 1301 is a trade name for bromotrifluoromethane, it is also known as BTM, Halon 1301 BTM, or Freon 13BI. The chemical formula is CF3Br. ... Trifluoroiodomethane, also referred to as trifluoromethyl iodide is a halomethane with the formula CF3I. It is an experimental alternative to Halon 1301 (CBrF3) in unoccupied areas [2]. It would be used as a flooding agent for in-flight aircraft and electronic equipment fires. ... The chemical compound 1,1,1-trichloroethane is a chlorinated hydrocarbon that was until recently widely used as an industrial solvent. ... 1,2-Dichlorotetrafluoroethane, or R-114, is a chlorofluorocarbon (CFC) with the molecular formula ClF2CCF2Cl. ... Ball-and-stick model of 2-chloro-1,1,1,2-tetrafluoroethane 2-Chloro-1,1,1,2-tetrafluoroethane, C2HClF4, also called R-124, is a hydrochlorofluorocarbon used as a refrigerant. ... 1,1,2,2,2-Pentafluoroethane, also called simply pentafluoroethane, HFC-125, or R-125, is a refrigerant that has zero ozone depletion potential. ... 1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane, R-134a or HFC-134a, is a refrigerant without an ozone depletion potential and thermodynamic properties similar to R-12 (dichlorodifluoromethane). ... The chemical compound 1,2-dichloroethane, commonly known by its old name of ethylene dichloride (EDC), is a chlorinated hydrocarbon, mainly used to produce vinyl chloride monomer (VCM, chloroethene), the major precursor for PVC production. ... 1,1-Dichloroethane, commonly known by its older name ethylidene dichloride, or ethylidene chloride is a chlorinated hydrocarbon, a colorless aromatic oily liquid. ... 1,1,1,2,3,3,3-Heptafluoropropane, also called heptafluoropropane, HFC-227 or HFC-227ea (ISO name), is a colourless odourless gaseous halocarbon. ... Polyvinyl chloride (PVC) is a widely-used plastic. ... Teflon is the brand name of a polymer compound discovered by Roy J. Plunkett (1910–1994) of DuPont in 1938 and introduced as a commercial product in 1946. ...

Synthesis

Alkyl halides can be synthesized from alkanes, alkenes, alcohols or carboxylic acids.

From alkanes

Main article: free radical halogenation

Alkanes react with halogens by free radical halogenation. In this reaction a hydrogen atom is removed from the alkane, then replaced by a halogen atom by reaction with a diatomic halogen molecule. The reactive intermediate in this reaction is a free radical and the reaction is called a radical chain reaction. This reaction is typical of alkanes and alkyl-substituted aromatics. ... This reaction is typical of alkanes and alkyl-substituted aromatics. ... In chemistry a reactive intermediate is a short-lived high energy highly reactive molecule. ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ...

From alkenes

• In hydrohalogenation, an alkene reacts with a dry hydrogen halide (HX) like hydrogen chloride (HCl) or hydrogen bromide (HBr) to form a haloalkane. The double bond of the alkene is replaced by two new bonds, one with the halogen and one with the hydrogen atom of the hydrohalic acid. Markovnikov's rule states that in this reaction, the halogen is more likely to become attached to the more substituted carbon. This is a electrophilic addition reaction. Water must be absent otherwise there will be a side product(water). The reaction is necessarily to be carried out in a dry inert solvent such as CCl₄ or directly in the gaseous phase.
• Alkenes also react with halogens (X₂) to form haloalkanes with two neighboring halogen atoms in a halogen addition reaction. This is sometimes known as "decolorizing" the halogen, since the reagent X₂ is colored and the product is usually colorless.

Hydrohalogenation is the electrophilic addition of acids like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes. ... This article is about the chemical compound. ... R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Flash point Non flammable Supplementary data page Structure and properties n, εr, etc. ... In chemistry, Markovnikovs rule is an observation based on Zaitsevs rule. ... In organic chemistry, an electrophilic addition reaction is an addition reaction where in chemical compound a pi bond is removed by the creation of two new covalent bonds. ... A by-product is a secondary or incidental product deriving from a manufacturing process or chemical reaction, and is not the primary product or service being produced. ... A halogen addition reaction is a simple organic reaction where a halogen molecule is added to the carbon-carbon double bond of an alkene functional group. ...

From alcohols

• Tertiary alkanol reacts with hydrochloric acid directly to produce tertiary chloroalkane, but if primary or secondary alkanol is used, an activator such as zinc chloride is needed. Alternatively the conversion may be performed directly using thionyl chloride which is called the Darzen's process.The Darzen's process is one of the most convenient methods known because the bi-products are gaseous and thus escape, leaving behind pure alkyl chloride. Alkanol may likewise be converted to bromoalkane using hydrobromic acid or phosphorus tribromide or iodoalkane using red phosphorus and iodine (equivalent to phosphorus triiodide). Other halogenating agents are phosphorus pentachloride, Phosphorus with Bromine or Phosphorus with Iodine.

The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride gas (HCl). ... Zinc chloride (ZnCl2) is a colorless or white compound of zinc and chlorine that is extremely hygroscopic. ... R-phrases , , , S-phrases , , , Flash point non flammable Supplementary data page Structure and properties n, εr, etc. ... It has been suggested that this article or section be merged into hydrogen bromide. ... Phosphorus tribromide is a colourless liquid with the formula PBr3. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ... For the record label, see Iodine Recordings. ... Phosphorus triiodide (PI3) is an unstable red solid which reacts violently with water. ... Halogenation is a chemical reaction that replaces a hydrogen atom with a halogen atom. ... Phosphorus pentachloride is the chemical compound with the formula PCl5. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ... Bromo redirects here. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ... For the record label, see Iodine Recordings. ...

From Carboxylic acids

• Two methods for the synthesis of alkyl halides from carboxylic acids are the Hunsdiecker reaction and the Kochi reaction

Structure of a carboxylic acid The 3D structure of the carboxyl group A space-filling model of the carboxyl group Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. [1] Carboxylic acids are Bronsted... The Hunsdiecker reaction (also called the Borodin reaction after Alexander Borodin) is the organic reaction of silver salts of carboxylic acids with halogens to give organic halides. ... The Kochi reaction is an organic reaction for the decarboxylation of carboxylic acids to alkyl halides with lead tetraacetate and a lithium chloride or other lithium salts [1]. The reaction is a variation of the Hunsdiecker reaction. ...

Reactions of haloalkanes

Haloalkanes are reactive towards nucleophiles. They are polar molecules: the carbon to which the halogen is attached is slightly electropositive where the halogen is slightly electronegative. This results in an electron deficient (electrophilic) carbon which, inevitably, attracts nucleophiles. In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ... The polarity of an object is, in general, its physical alignment of atoms. ... An electropositive atom, or element, is one that easily loses electrons. ... It has been suggested that this article or section be merged with electronegativity. ... Electron deficiency occurs when a compound has too few valence electrons for the connections between atoms to be described as covalent bonds. ... In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ...

Substitution reactions

Substitution reactions involve the replacement of the halogen with another molecule - thus leaving saturated hydrocarbons, as well as the halogen product. In a substitution reaction, a group of a particular compound is replaced by another group. ... An alkane in organic chemistry is a type of hydrocarbon in which the molecule has the maximum possible number of hydrogen atoms and so has no double bonds (they are saturated). ...

Hydrolysis - a reaction in which water breaks a bond--is a good example of the nucleophilic nature of halogenoalkanes. The polar bond attracts a hydroxide ion, OH^-. (NaOH_(aq) being a common source of this ion). This OH^- is a nucleophile with a clearly negative charge, as it has excess electrons it donates them to the carbon, which results in a covalent bond between the two. Thus C-X is broken by heterolytic fission resulting in a halide ion, X^-. As can be seen, the OH is now attached to the alkyl group, creating an alcohol. (Hydrolysis of bromoethane, for example, yields ethanol). Hydrolysis is a chemical reaction or process in which a chemical compound reacts with water. ... H2O and HOH redirect here. ... Hydroxide is a polyatomic ion consisting of oxygen and hydrogen: OH− It has a charge of −1. ... Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. ... In chemistry, heterolysis is chemical bond cleavage of a neutral molecule generating a cation and an anion. ... This article does not cite any references or sources. ... Grain alcohol redirects here. ...

One should note that within the halogen series, the C-X bond weakens as one goes to heavier halogens, and this affects the rate of reaction. Thus, the C-I of an iodoalkane generally reacts faster than the C-F of a fluoroalkane.

Apart from hydrolysis, there are a few other isolated examples of nucleophilic substitution:

• Ammonia (NH₃) and bromoethane yields a mixture of ethylamine, diethylamine, and triethylamine (as their bromide salts), and tetraethylammonium bromide.
• Cyanide (CN^-) added to bromoethane will form propionitrile (CH₃CH₂CN), a nitrile, and Br^-. Nitriles can be further hydrolyzed into carboxylic acids.

For other uses, see Ammonia (disambiguation). ... Ethylamine is a volatile amine with the molecular structure CH3CH2NH2. ... Diethylamine is a secondary amine with the molecular structure CH3CH2NHCH2CH3. ... Triethylamine, also known as N,N-diethylethanamine, TEN or N,N,N-Triethylamine, is a colorless, volatile liquid with a strong, unpleasant and fishy smell reminiscent of ammonia. ... For other uses, see Salt (disambiguation). ... Tetraethylammonium bromide is a quaternary ammonium salt. ... This article is about the chemical compound. ... Propionitrile, or ethyl cyanide, has formula C2H5CN. It melts at -93 °C and boils at 97 °C. Template:Organic-chem-stub Categories: Nitriles ... A nitrile is any organic compound which has a -C≡N functional group. ... Structure of a carboxylic acid The 3D structure of the carboxyl group A space-filling model of the carboxyl group Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. [1] Carboxylic acids are Bronsted...

Elimination reactions

Rather than creating a molecule with the halogen substituted with something else, one can completely eliminate both the halogen and a nearby hydrogen, thus forming an alkene. For example, with bromoethane and NaOH in ethanol, the hydroxide ion OH^- attracts a hydrogen atom - thus removing a hydrogen and bromine from bromoethane. This results in C₂H₄ (ethylene), H₂O and Br^-. An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism. ... This article is about the chemical compound. ... Hydroxide is a polyatomic ion consisting of oxygen and hydrogen: OH− It has a charge of −1. ... Ethylene (or IUPAC name ethene) is the chemical compound with the formula C2H4. ...

Applications

Propellant

One major use of CFCs has been as propellants in aerosol inhalers for drugs used to treat asthma. The conversion of these devices and treatments from CFC to halocarbons that do not have the same effect on the ozone layer is well under way. The hydrofluoroalkane propellant's ability to solubilize medications and excipients is markedly different from CFCs and as a result requires a considerable amount of effort to reformulate (a significant amount of development effort has also been required to develop non-CFC alternatives to CFC-based refrigerants, particularly for applications where the refrigeration mechanism cannot be modified or replaced). They have now been outlawed in all 50 U.S. states universally. Aerosol spray can Aerosol spray is a type of canister that sprays an aerosol when its button is pressed or held down. ... An excipient is an inactive substance used as a vehicle for medication, or an active ingredient. ...

Fire extinguishing

At high temperatures, halons decompose to release halogen atoms that combine readily with active hydrogen atoms, quenching the flame propagation reaction even when adequate fuel, oxygen and heat remains. The chemical reaction in a flame proceeds as a free radical chain reaction; by sequestering the radicals which propagate the reaction, halons are able to "poison" the fire at much lower concentrations than are required by fire suppressants using the more traditional methods of cooling, oxygen deprivation, or fuel dilution. For other uses, see Chemical reaction (disambiguation). ... Flame generated by the burning of a candle. ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ... A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions. ... For other uses, see Concentration (disambiguation). ...

For example, Halon 1301 total flooding systems are typically used at concentrations no higher than 7% v/v in air, and can suppress many fires at 2.9% v/v. By contrast, carbon dioxide fire suppression flood systems are operated from 34% concentration by volume (surface-only combustion of liquid fuels) up to 75% (dust traps). Carbon dioxide can cause severe distress at concentrations of 3 to 6%, and has caused death by respiratory paralysis in a few minutes at 10% concentration. Halon 1301 causes only slight giddiness at its effective concentration of 5%, and even at 15% persons remain conscious but impaired and suffer no long term effects. (Experimental animals have also been exposed to 2% concentrations of Halon 1301 for 30 hours per week for 4 months, with no discernible health effects at all.) Halon 1211 also has low toxicity, although it is more toxic than Halon 1301, and thus considered unsuitable for flooding systems. Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

However, Halon 1301 fire suppression is not completely non-toxic; very high temperature flame, or contact with red-hot metal, can cause decomposition of Halon 1301 to toxic byproducts. The presence of such byproducts is readily detected because they include hydrobromic acid and hydrofluoric acid, which are intensely irritating. Halons are very effective on Class A (organic solids), B (flammable liquids and gases) and C (electrical) fires, but they are totally unsuitable for Class D (metal) fires, as they will not only produce toxic gas and fail to halt the fire, but in some cases pose a risk of explosion. Halons can be used on Class K (kitchen oils and greases) fires, but offer no advantages over specialised foams. It has been suggested that this article or section be merged into hydrogen bromide. ... R-phrases , S-phrases , , , , Flash point nonflammable Related Compounds Other anions Hydrochloric acid Hydrobromic acid Hydroiodic acid Related compounds Hydrogen fluoride fluorosilicic acid Supplementary data page Structure and properties n, εr, etc. ...

Halon 1211 is typically used in hand-held extinguishers, in which a stream of liquid halon is directed at a smaller fire by a user. The stream evaporates under reduced pressure, producing strong local cooling, as well as a high concentration of halon in the immediate vicinity of the fire. In this mode, extinguishment is achieved by cooling and oxygen deprivation at the core of the fire, as well as radical quenching over a larger area. After fire suppression, the halon moves away with the surrounding air, leaving no residue.

Halon 1301 is more usually employed in total flooding systems. In these systems, banks of halon cylinders are kept pressurised to about 4 MPa (600 PSI) with compressed nitrogen, and a fixed piping network leads to the protected enclosure. On triggering, the entire measured contents of one or more cylinders are discharged into the enclosure in a few seconds, through nozzles designed to ensure uniform mixing throughout the room. The quantity dumped is pre-calculated to achieve the desired concentration, typically 3-7% v/v. This level is maintained for some time, typically with a minimum of ten minutes and sometimes up to a twenty minute 'soak' time, to ensure all items have cooled so reignition is unlikely to occur, then the air in the enclosure is purged, generally via a fixed purge system that is activated by the proper authorities. During this time the enclosure may be entered by persons wearing SCBA. (There exists a common myth that this is because halon is highly toxic; in fact it is because it can cause giddiness and mildly impaired perception, and also due to the risk of combustion byproducts.) MPA is a TLA (three-letter acronym) that may mean: Macedonian Press Agency Marine Protected Area Maritime Patrol Aircraft Maryland and Pennsylvania Railroad (AAR reporting mark MPA) Master of Public Administration Master of Public Affairs Max Planck Institute for Astrophysics Metropolitan Police Authority Mid-atlantic Pagan Alliance Motion Picture Association... Psi has multiple meanings: Psi (letter) (Ψ, ψ) of the Greek alphabet Psi (Cyrillic) (Ñ°, ѱ), letter of the early Cyrillic alphabet, adopted from Greek Psi (parapsychology) Psi (instant messaging client), a popular Jabber client program J/ψ particle, a subatomic particle Wavefunction in Quantum Mechanics, ψ In mathematics, Ψ is used to denote the angle between... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Rocket Nozzle A nozzle is a mechanical device designed to control the characteristics of a fluid flow as it exits from an enclosed chamber into some medium. ... SCBA is an acronym for Self Contained Breathing Apparatus. ...

Flooding systems may be manually operated or automatically triggered by a VESDA or other automatic detection system. In the latter case, a warning siren and strobe lamp will first be activated for a few seconds to warn personnel to evacuate the area. The rapid discharge of halon and consequent rapid cooling fills the air with fog, and is accompanied by a loud, disorienting noise. Image:Vesda. ... For other uses, see Fog (disambiguation). ...

Due to environmental concerns, alternatives are being deployed.^[6]

Halon 1301 is also used in the F-16 fighters to prevent the fuel vapors in the fuel tanks from becoming explosive; when the aircraft enters area with the possibility of unfriendly fire, Halon 1301 is injected into the fuel tanks for one-time use. Due to environmental concerns, trifluoroiodomethane (CF₃I) is being considered as an alternative.^[7] The F-16 Fighting Falcon is a modern multi-role jet fighter aircraft built in the United States and used by dozens of countries all over the world. ... For other uses, see Tank (disambiguation). ... Trifluoroiodomethane, also referred to as trifluoromethyl iodide is a halomethane with the formula CF3I. It is an experimental alternative to Halon 1301 (CBrF3) in unoccupied areas [2]. It would be used as a flooding agent for in-flight aircraft and electronic equipment fires. ...

Environmental issues

Since the late 1970s the use of CFCs has been heavily regulated because of their destructive effects on the ozone layer. After the development of his electron capture detector, James Lovelock was the first to detect the widespread presence of CFCs in the air, finding a concentration of 60 parts per trillion of CFC-11 over Ireland. In a self-funded research expedition ending in 1973, Lovelock went on to measure the concentration of CFC-11 in both the Arctic and Antarctic, finding the presence of the gas in each of 50 air samples collected, but incorrectly concluding that CFC's are not hazardous to the environment. The experiment did however provide the first useful data on the presence of CFC's in the atmosphere. The damage caused by CFC's discovered by Sherry Rowland and Mario Molina who, after hearing a lecture on the subject of Lovelocks work, embarked on research resulting in the first published paper suggesting the connection in 1974. It turns out that one of CFCs' most attractive features—their unreactivity—has been instrumental in making them one of the most significant pollutants. CFCs' lack of reactivity gives them a lifespan which can exceed 100 years in some cases. This gives them time to diffuse into the upper stratosphere. Here, the sun's ultraviolet radiation is strong enough to break off the chlorine atom, which on its own is a highly reactive free radical. This catalyzes the break up of ozone into oxygen by means of a variety of mechanisms, of which the simplest is: Air pollution Pollution is the introduction of pollutants (whether chemical substances, or energy such as noise, heat, or light) into the environment to such a point that its effects become harmful to human health, other living organisms, or the environment. ... Air pollution is a chemical, particulate matter, or biological agent that modifies the natural characteristics of the atmosphere. ... The term acid rain is commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles. ... An air quality measurement station in Edinburgh, Scotland The Air Quality Index (AQI) is a standardized indicator of the air quality in a given location. ... Atmospheric dispersion modeling is performed with computer programs that use mathematical equations and algorithms to simulate how pollutants in the ambient atmosphere disperse in the atmosphere. ... Tetrafluoroethane (a haloalkane) is a clear liquid which boils well below room temperature (as seen here) and can be extracted from common canned air canisters by simply inverting them during use. ... Global dimming is the gradual reduction in the amount of global direct irradiance at the Earths surface that was observed for several decades after the start of systematic measurements in 1950s. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Haze is an atmospheric phenomenon where dust, smoke and other pollutant particles obscure the normal clarity of the sky. ... Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. ... Global monthly average total ozone amount Ozone depletion describes 14 distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths... Particulates, alternatively referred to as particulate matter (PM), aerosols or fine particles, are tiny particles of solid or liquid suspended in a gas. ... It has been suggested that Haze be merged into this article or section. ... Raw sewage and industrial waste flows into the U.S. from Mexico as the New River passes from Mexicali, Baja California to Calexico, California Water pollution is a large set of adverse effects upon water bodies such as lakes, rivers, oceans, and groundwater caused by human activities. ... Eutrophication, strictly speaking, means an increase in chemical nutrients -- typically compounds containing nitrogen or phosphorus -- in an ecosystem. ... It has been suggested that Anoxic sea water, Oxygen minimum zone, and Hypoxic zone be merged into this article or section. ... Pumping of highly toxic (dark black) sludge, much seeps back into the ocean in the form of particles. ... Change in sea surface pH caused by anthropogenic CO2 between the 1700s and the 1990s Ocean acidification is the name given to the ongoing decrease in the pH of the Earths oceans, caused by their uptake of anthropogenic carbon dioxide from the atmosphere. ... Subsequent to an Oil Spill An oil spill is the unintentional release of liquid petroleum hydrocarbon into the environment as a result of human activity. ... Ship pollution is the pollution of water by shipping! It is a problem that has been accelerating as trade has become increasingly globalized. ... Runoff flowing into a stormwater drain Surface runoff is water, from rain, snowmelt, or other sources, that flows over the land surface, and is a major component of the water cycle[1][2]. Runoff that occurs on surfaces before reaching a channel is also called overland flow. ... Thermal pollution is a temperature change in natural water bodies caused by human influence. ... Wastewater is any water that has been adversely affected in quality by anthropogenic influence. ... Waterborne diseases are caused by pathogenic microorganisms which are directly transmitted when contaminated drinking water is consumed. ... Water quality is the physical, chemical and biological characteristics of water, characterized through the methods of hydrometry. ... Standing water redirects here. ... Excavation of leaking underground storage tank causing soil contamination Soil contamination is the presence of man-made chemicals or other alteration of the natural soil environment. ... Bioremediation can be defined as any process that uses microorganisms, fungi, green plants or their enzymes to return the environment altered by contaminants to its original condition. ... A herbicide is a pesticide used to kill unwanted plants. ... A cropduster spreading pesticide. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The radiation warning symbol (trefoil). ... This article about actinides in the environment is about the sources, environmental behaviour and effects of actinides in the environment. ... The environmental radioactivity page is devoted to the subject of radioactive materials in man and his environment. ... Fission products are the residues of fission processes. ... Fallout is the residual radiation hazard from a nuclear explosion, so named because it falls out of the atmosphere into which it is spread during the explosion. ... To meet Wikipedias quality standards, this article may require cleanup. ... Radiation poisoning, also called radiation sickness, is a form of damage to organ tissue due to excessive exposure to ionizing radiation. ... // Radium Radium in quack medicine See the story of Eben Byers for details of one very nasty case which involved a product called Radithor this contained 1 mCi of 226Ra and 1 mCi of 228Ra per bottle. ... Uranium in the environment, this page is devoted to the science of uranium in the environment and in animals (including humans). ... Lantana invasion of abandoned citrus plantation; Moshav Sdey Hemed, Israel The term invasive species refers to a subset of introduced species or non-indigenous species that are rapidly expanding outside of their native range. ... This time exposure photo of New York City shows sky glow, one form of light pollution. ... Noise pollution (or environmental noise in technical venues) is displeasing human or machine created sound that disrupts the environment. ... Radio spectrum pollution is the straying of waves in the radio and electromagnetic spectrums outside their allocations that cause problems for some activities. ... Visual pollution is the term given to unattractive visual elements of a vista, a landscape, or any other thing that a person might want to look at. ... The largest Antarctic ozone hole recorded as of September 2000 For other similarly-named agreements, see Montreal Protocol (disambiguation). ... Protocol to the 1979 Convention on Long-Range Transboundary Air Pollution Concerning the Control of Emissions of Nitrogen Oxides or Their Transboundary Fluxes, opened for signature on 31 October 1988 and entered into force on 14 February 1991, was to provide for the control or reduction of nitrogen oxides and... Kyoto Protocol Opened for signature December 11, 1997 in Kyoto, Japan Entered into force February 16, 2005. ... note - abbreviated as Air Pollution opened for signature - 13 November 1979 entered into force - 16 March 1983 objective - to protect the human environment against air pollution and to gradually reduce and prevent air pollution, including long-range transboundary air pollution parties - (48) Armenia, Austria, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria... This list is incomplete; you can help by expanding it. ... The Department for Environment, Food and Rural Affairs (Defra) is the United Kingdom government department responsible for environmental protection, food production and standards, agriculture, fisheries and rural communities in England. ... EPA redirects here. ... Global Atmosphere Watchs logo The Global Atmosphere Watch (GAW) is a worldwide system established by the World Meteorological Organization – a United Nations agency – to monitor trends in the Earths atmosphere. ... Greenpeace protest against Esso / Exxon Mobil. ... The National Ambient Air Quality Standards (NAAQS) are standards established by the United States Environmental Protection Agency that apply for outdoor air throughout the country. ... This article is about the natural environment. ... The electron capture detector (ECD) is based on the emission of electrons from a foil containing radioactive nickel-63. ... James Lovelock in front of a statue of Gaia in 2000 Dr James Ephraim Lovelock, CH, CBE, FRS (born 26 July 1919) is an independent scientist, author, researcher, environmentalist, and futurologist who lives in Cornwall, in the south west of Great Britain. ... For the song by James Blunt, see 1973 (song). ... Frank Sherwood Rowland (born June 28, 1927) is a Nobel laureate and a professor of chemistry at the University of California, Irvine. ... Mario J. Molina (born March 19, 1943) was awarded the 1995 Nobel Prize in Chemistry for his role in elucidating the threat to the Earths ozone layer of chlorofluorocarbon gases (or CFCs). ... Atmosphere diagram showing stratosphere. ... For other uses, see Ultraviolet (disambiguation). ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ... It has been suggested that this article or section be merged into Catalysis. ...

Cl· + O₃ → ClO· + O₂

ClO· + O₃ → Cl· + 2 O₂

Since the chlorine is regenerated at the end of these reactions, a single Cl atom can destroy many thousands of ozone molecules. Reaction schemes similar to this one (but more complicated) are believed to be the cause of the ozone hole observed over the poles and upper latitudes of the Earth. Decreases in stratospheric ozone may lead to increases in skin cancer. Image of the largest antarctic ozone hole ever recorded in September 2000. ... Skin cancer is a malignant growth on the skin which can have many causes. ...

In 1975, the US state of Oregon enacted the world's first ban of CFCs (legislation introduced by Walter F. Brown). The United States and several European countries banned the use of CFCs in aerosol spray cans in 1978, but continued to use them in refrigeration, foam blowing, and as solvents for cleaning electronic equipment. By 1985, scientists observed a dramatic seasonal depletion of the ozone layer over Antarctica. International attention to CFCs resulted in a meeting of world diplomats in Montreal in 1987. They forged a treaty, the Montreal Protocol, which called for drastic reductions in the production of CFCs. On March 2, 1989, 12 European Community nations agreed to ban the production of all CFCs by the end of the century. In 1990, diplomats met in London and voted to significantly strengthen the Montreal Protocol by calling for a complete elimination of CFCs by the year 2000. By the year 2010 CFCs should be completely eliminated from developing countries as well. Motto: (traditional) In God We Trust (official, 1956–present) Anthem: The Star-Spangled Banner Capital Washington, D.C. Largest city New York City Official language(s) None at the federal level; English de facto Government Federal Republic  - President George W. Bush (R)  - Vice President Dick Cheney (R) Independence - Declared - Recognized... A U.S. state is any one of the 50 states which have membership of the federation known as the United States of America (USA or U.S.). The separate state governments and the U.S. federal government share sovereignty. ... Official language(s) (none)[1] Capital Salem Largest city Portland Area  Ranked 9th  - Total 98,466 sq mi (255,026 km²)  - Width 260 miles (420 km)  - Length 360 miles (580 km)  - % water 2. ... Walter Frederick Brown (born July 28, 1926) was the presidential candidate of the Socialist Party USA in 2004. ... Nickname: Motto: Concordia Salus (well-being through harmony) Coordinates: , Country Province Region Montréal Founded 1642 Established 1832 Government  - Mayor Gérald Tremblay Area [1][2][3]  - City 365. ... The largest Antarctic ozone hole recorded as of September 2000 For other similarly-named agreements, see Montreal Protocol (disambiguation). ... is the 61st day of the year (62nd in leap years) in the Gregorian calendar. ... Year 1989 (MCMLXXXIX) was a common year starting on Sunday (link displays 1989 Gregorian calendar). ... The European Community (EC) was originally founded on March 25, 1957 by the signing of the Treaty of Rome under the name of European Economic Community. ... This article is about the capital of England and the United Kingdom. ...

Ozone-depleting gas trends

Because the only available CFC gases in countries adhering to the treaty is from recycling, their prices have gone up considerably. A worldwide end to production should also terminate the smuggling of this material, such as from Mexico to the United States. Download high resolution version (1139x1577, 23 KB)CFC gas trends and equivalent chlorine effect. ... Download high resolution version (1139x1577, 23 KB)CFC gas trends and equivalent chlorine effect. ...

A number of substitutes for CFCs have been introduced. Hydrochlorofluorocarbons (HCFCs) are much more reactive than CFCs, so a large fraction of the HCFCs emitted break down in the troposphere, and hence are removed before they have a chance to affect the ozone layer. Nevertheless, a significant fraction of the HCFCs do break down in the stratosphere and they have contributed to more chlorine buildup there than originally predicted. Development of non-chlorine based chemical compounds as a substitute for CFCs and HCFCs continues. One such class are the hydrofluorocarbons (HFCs), which contain only hydrogen and fluorine. One of these compounds, HFC-134a, is now used in place of CFC-12 in automobile air conditioners; which itself may contribute to global warming (see HFC-134a). Atmosphere diagram showing stratosphere. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... 1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane or R-134a, is a refrigerant that has zero ozone depletion potential and thermodynamic properties similar to R-12. ... 1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane or R-134a, is a refrigerant that has zero ozone depletion potential and thermodynamic properties similar to R-12. ...

There is concern that halons are being broken down in the atmosphere to bromine, which reacts with ozone, leading to depletion of the ozone layer (this is similar to the case of chlorofluorocarbons such as freon). These issues are complicated: the kinds of fires that require halon extinguishers to be put out will typically cause more damage to the ozone layer than the halon itself, not to mention human and property damage. However, fire extinguisher systems must be tested regularly, and these tests may lead to damage. As a result, some regulatory measures have been taken, and halons are being phased out in most of the world. Earths atmosphere is the layer of gases surrounding the planet Earth and retained by the Earths gravity. ... For other uses, see Ozone (disambiguation). ... Global monthly average total ozone amount Ozone depletion describes 14 distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ...

In the United States, purchase and use of freon gases is regulated by the Environmental Protection Agency, and substantial fines have been levied for their careless venting. Also, licenses, good for life, are required to buy or use these chemicals. The EPA website discusses these rules in great detail, and also lists numerous private companies that are approved to give examinations for these certificates. EPA redirects here. ...

There are two kinds of licenses. Obtaining a "Section 609" license to use CFCs to recharge old (pre-1993 model year) car air conditioners is fairly easy and requires only an online multiple choice test offered by several companies. Companies that use unlicensed technicians for CFC recharge operations are subject to a US$15,000 fine per technician by the EPA.

The "Section 608" license, needed to recharge CFC-using stationary and non-automobile mobile units, is also multiple choice but more difficult. A general knowledge test is required, plus separate exams for small size (such as home refrigerator) units, and for high and low pressure systems. These are respectively called Parts I, II, and III. A person who takes and passes all tests receives a "Universal" license; otherwise, one that is endorsed only for the respectively passed Parts. While the general knowledge and Part I exams can be taken online, taking them before a proctor (which has to be done for Parts II and III) lets the applicant pass these tests with lower scores.

Safety

Haloalkanes in copper tubing open to the environment can turn into phosgene gas after coming in contact with extreme heat, such as while brazing or in a fire situation. Other ways that phosgene can be created is by passing the haloalkane through an internal combustion engine, or by inhaling it through a lit cigarette, cigar or pipe. Phosgene is a substance that was used as a chemical weapon in World War I. Low exposure can cause irritation, but high levels cause fluid to collect in the lungs, possibly resulting in death. For other uses, see Copper (disambiguation). ... Phosgene is a highly toxic chemical compound with the formula COCl2. ... This article is about the metal joining process. ... Dressing the wounded during a gas attack by Austin O. Spare, 1918. ... “The Great War ” redirects here. ... Human respiratory system The lungs flank the heart and great vessels in the chest cavity. ...

See also

• Halogenation
• Halomethane
• Halogenoarene

Halogenation is a chemical reaction that replaces a hydrogen atom with a halogen atom. ... Halomethane compounds are molecules of methane (CH4) with one or more of the hydrogen atoms replaced with halogen atoms. ... In organic chemistry, a Halogenoarene, Haloarene, or Aryl Halide, is an organic compound in which a halogen atom is bonded to a carbon atom which is part of an aromatic ring. ...

References

1. ^ http://www.epa.gov/fedrgstr/EPA-AIR/1995/October/Day-11/pr-1117.html
2. ^ Lerner & K. Lee Lerner, Brenda Wilmoth (2006). Environmental issues : essential primary sources.". Thomson Gale. Retrieved on 2006-09-11.
3. ^ http://www.halon.org/
4. ^ http://ap.google.com/article/ALeqM5jSMKuV-tCweZi386Aiz07LHT0yFQ
5. ^ http://resourcecenter.ashrae.org/store/ashrae/newstore.cgi?itemid=23260&view=item&categoryid=311&categoryparent=311&page=1&loginid=2022241
6. ^ http://p2library.nfesc.navy.mil/P2_Opportunity_Handbook/3_III_2.html
7. ^ http://www.afrlhorizons.com/Briefs/0012/ML0008.html

• Information on Fluorocarbons and their applications
• B. S. Furnell et al., Vogel's Textbook of Practical Organic Chemistry, 5th edition, Longman/Wiley, New York, 1989.

• Nomenclature FAQ
• Numbering Scheme for Ozone-Depleting Substances and their Substitutes
• Class I Ozone-Depleting Substances
• CFC Smuggling
• CFC Illegal Trade
• Numbering Scheme for Ozone-Depleting Substances and their Substitutes
• Class I Ozone-Depleting Substances
• Class II Ozone-Depleting Substances (HCFC's)
• History of Halon use by the US Navy
• Ozone Loss: The Chemical Culprits