Halocarbon compounds are chemicals in which one or more carbon atoms are linked by covalent bonds with one or more halogen atoms: fluorine, chlorine, bromine or iodine. A chemical substance is a Material with a definite chemical composition. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Chlorine halocarbons are the most common and are called organochlorides. Applications The simplest form of organochlorides are chlorinated Hydrocarbons These consist of simple Hydrocarbons in which one or more hydrogen atoms have There are also compounds such as methylammonium chloride that include carbon atoms and noncovalent halogen atoms, also called inorganic halogens. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 A noncovalent bond is a type of Chemical bond, typically between Macromolecules that does not involve the sharing of pairs of electrons but rather involves more dispersed Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions Traditionally inorganic compounds are considered to be of mineral not biological origin Unlike halocarbon halogens, noncovalent halogen atoms will usually dissociate and ionize in water. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Dissociation in Chemistry and Biochemistry is a general process in which ionic compounds ( complexes, Molecules, or Salts) separate Ionization is the physical process of converting an Atom or Molecule into an Ion by adding or removing charged particles such as Electrons Water is a common Chemical substance that is essential for the survival of all known forms of Life. Halocarbons are a class of organic compounds containing covalently bonded fluorine, chlorine, bromine, or iodine.

Many synthetic organic compounds such as plastic polymers, and a few natural ones, contain halogen atoms; they are known as halogenated compounds. Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Chlorine is by far the most abundant of the halogens, and the only one needed in relatively large amounts (as chloride ions) by humans. For example, chloride ions play a key role in brain function by mediating the action of the inhibitory transmitter GABA and are also used by the body to produce stomach acid. Gamma-aminobutyric acid (GABA is the chief inhibitory Neurotransmitter in the Mammalian Central nervous system. Iodine is needed in trace amounts for the production of thyroid hormones such as thyroxine. The thyroid is one of the largest Endocrine glands in the body Thyroxine, or 353'5'-tetra­iodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the On the other hand, neither fluorine nor bromine are believed to be really essential for humans, although small amounts of fluoride does make teeth enamel somewhat more resistant to attack.

Contents 1 Chemical families 2 Origins 2.1 Natural halocarbons 3 Uses 4 Hazards 5 See also 6 Notes 7 References

Chemical families

Halocarbons are typically classified in the same ways as the similarly structured organic compounds that have hydrogen atoms occupying the molecular sites of the halogen atoms in halocarbons. Chemical structure refers to Molecular geometry, Electronic structure and Crystal structure. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Among the chemical families are:

• haloalkanes -- compounds with carbon atoms linked by single bonds
• haloalkenes -- compounds with one or more double bonds between carbon atoms
• haloaromatics -- compounds with carbons linked in one or more aromatic rings with alternating single and double bonds

The halogen atoms in halocarbon molecules are often called "substituents," as though those atoms had been substituted for hydrogen atoms. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic A vinyl halide in Chemistry is any Alkene with at least one Halide Substituent bonded directly on one of the unsaturated carbons Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Organic chemistry, a halogenoarene, haloarene, or aryl halide, is an organic compound in which a Halogen atom is bonded to a Carbon Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In Organic chemistry, a substituent is an atom or group of atoms substituted in place of a Hydrogen atom on the Parent chain of a Hydrocarbon Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 However halocarbons are prepared in many ways that do not involve direct substitution of halogens for hydrogens. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1

Origins

A few halocarbons, including methyl chloride, are produced in large amounts by natural interactions between halogen salts and debris from plants and animals, but most are created in anything more than minuscule traces only through human efforts. Chloromethane, also called Methyl chloride, R-40 or HCC 40 is a Chemical compound of the group of Organic compounds called Haloalkanes. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants English and French chemists, among others, began to synthesize halocarbons in the 1820s and 1830s and soon discovered halocarbon polymers as well, molecules with long chains of halocarbon groups linked by covalent bonds. A chemist is a Scientist trained in the Science of Chemistry. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by

Natural halocarbons

A large amount of the naturally occurring halocarbons are created by wood fire, dioxine for example, or volcanic activities. Not to be confused with Dioxane or Digoxin. Dioxin is a heterocyclic, organic, antiaromatic compound A second large source are marine algae which produce several chlorinated methane and ethane derivates. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. ETHANE is a mnemonic indicating a protocol used by Emergency services to report situations which they may be faced with especially as it relates to major incidents where There are several thousand more complex halocarbons known, produced mainly by marine species. Although chlorine compounds are the majority of the discovered compounds, bromides iodides and fluorides have also been found. The tyrian purple, which is a dibromoindigo, is representative of the bromides, while the thyroxine secreted from the thyroid gland, is an iodide, and the highly toxic fluoroacetate is one of the rare organofluorides. Thyroxine, or 353'5'-tetra­iodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the The thyroid is one of the largest Endocrine glands in the body Sodium fluoroacetate (also known as sodium monofluoroacetate, compound 1080 or 1080) is a potent metabolic poison that occurs naturally as an These three representatives, thyroxine from humans, tyrian purple from snails and fluoroacetate from plants, also show that unrelated species use halocarbons for several purposes. ^[1][2][3]

Uses

The first halocarbon commercially used was Tyrian purple a natural organobromide of the Murex brandaris marine snail. Haustellum brandaris, also known as Bolinus brandaris or Murex brandaris, and commonly known as the purple dye murex

Common uses for halocarbons have been as solvents, pesticides, refrigerants, fire-resistant oils, ingredients of elastomers, adhesives and sealants, electrically insulating coatings, plasticizers, and plastics. A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. A pesticide is a substance or mixture of substances used to kill a pest. A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back An elastomer is a Polymer with the property of Elasticity. The term which is derived from elastic polymer, is often used interchangeably with the term Glue or adhesive is a compound that adheres or bonds two items together Plasticizers are additives that increase the Plasticity or Fluidity of the material to which they are added these include plastics cement concrete wallboard and Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products Many halocarbons have specialized uses in industry.

Before they became strictly regulated, the general public often encountered haloalkanes as paint and cleaning solvents such as trichloroethane (1,1,1-trichloroethane) and carbon tetrachloride (tetrachloromethane), pesticides like 1,2-dibromoethane (EDB, ethylene dibromide), and refrigerants like Freon-22 (duPont trademark for chlorodifluoromethane). The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane Carbon tetrachloride, also known by many other names (see Table is the Organic compound with the formula CCl4 A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back Freon is DuPont 's trade name for its odorless colorless nonflammable and noncorrosive Chlorofluorocarbon and Hydrochlorofluorocarbon Refrigerants E I du Pont de Nemours and Company (,) is an American chemical company that was founded in July 1802 as a Gunpowder mill by Eleuthère Irénée Some haloalkanes are still widely used for industrial cleaning, such as methylene chloride (dichloromethane), and as refrigerants, such as R-134a (1,1,1,2-tetrafluoroethane). Dichloromethane ( DCM) or methylene chloride is the Chemical compound with the formula CH2Cl2

Haloalkenes have also been used as solvents, including perchloroethylene (Perc, tetrachloroethene), widespread in dry cleaning, and trichloroethylene (TCE, 1,1,2-trichloroethene). A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. Tetrachloroethylene, also known under its systematic name tetrachloroethene and as perchloroethylene, perchloroethene, perc, and PCE The Chemical compound trichloroethylene is a chlorinated Hydrocarbon commonly used as an industrial Solvent. Other haloalkenes have been chemical building blocks of plastics such as polyvinyl chloride ("vinyl" or PVC, polymerized chloroethene) and Teflon (duPont trademark for polymerized tetrafluoroethene, PTFE). E I du Pont de Nemours and Company (,) is an American chemical company that was founded in July 1802 as a Gunpowder mill by Eleuthère Irénée In Chemistry, poly(tetrafluoroethene or poly(tetrafluoroethylene ( PTFE) is a synthetic Fluoropolymer which finds numerous applications

Haloaromatics include the former Aroclors (Monsanto trademark for polychlorinated biphenyls, PCBs), once widely used in power transformers and capacitors and in building caulk, the former Halowaxes (Union Carbide trademark for polychlorinated naphthalenes, PCNs), once used for electrical insulation, and the chlorobenzenes and their derivatives, used for disinfectants, pesticides such as dichloro-diphenyl-trichloroethane (DDT, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane), herbicides such as 2,4-D (2,4-dichlorophenoxyacetic acid), askarel dielectrics (mixed with PCBs, no longer used in most countries), and chemical feedstocks. Polychlorinated biphenyls ( PCB s are a class of Organic compounds with 1 to 10 Chlorine atoms attached to Biphenyl which is a molecule composed The Monsanto Company ( is a multinational Agricultural biotechnology Corporation. Polychlorinated biphenyls ( PCB s are a class of Organic compounds with 1 to 10 Chlorine atoms attached to Biphenyl which is a molecule composed Halowax is a New York-based company that was later owned by Union Carbide. Union Carbide Corporation ( Union Carbide) is one of the oldest chemical and polymers companies in the United States, currently employing more than 3800 people Polychlorinated naphthalene (PCN products are made by chemically reacting Chlorine with Naphthalene, a soft pungent solid made from coal or petroleum and often Chlorobenzene is an Aromatic Organic compound with the chemical formula C6H5Cl Disinfectants are Antimicrobial agents that are applied to non-living objects to destroy Microorganisms, the process of which is known as disinfection. A pesticide is a substance or mixture of substances used to kill a pest. DDT (from its trivial name D ichloro- D iphenyl- T richloroethane is one of the best known synthetic Pesticides It is a chemical with a long A herbicide is used to kill unwanted Plants Selective herbicides kill specific targets while leaving the desired Crop relatively unharmed 24-Dichlorophenoxyacetic acid (24-D is a common systemic Herbicide used in the control of broadleaf weeds A dielectric is a nonconducting substance ie an insulator. The term was coined by William Whewell in response to a request from Michael Faraday.

A few halocarbons, including acid halides like acetyl chloride, are highly reactive; these are rarely found outside chemical processing. Acetyl chloride, also known as ethanoyl chloride, is an Acid chloride (also known as an Acyl chloride) derived from Acetic acid ( Ethanoic The widespread uses of halocarbons were often driven by observations that most of them were more stable than other substances. They may be less affected by acids or alkalis; they may not burn as readily; they may not be attacked by bacteria or molds; or they may not be affected as much by sun exposure. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have WikipediaManual_of_Style#National_varieties_of_English --> Molds (or

Hazards

The stability of halocarbons tended to encourage beliefs that they were mostly harmless, although in the mid-1920s physicians reported workers in PCN manufacturing suffering from chloracne (Teleky 1927), and by the late 1930s it was known that workers exposed to PCNs could die from liver disease (Flinn & Jarvik 1936) and that DDT would kill mosquitos and other insects (Müller 1948). Chloracne is an acne -like eruption of Blackheads Cysts and Pustules associated with over-exposure to certain Halogenated Aromatic Liver disease is a broad term describing any number of Diseases affecting the Liver. DDT (from its trivial name D ichloro- D iphenyl- T richloroethane is one of the best known synthetic Pesticides It is a chemical with a long Mosquitoes are insects in the family Culicidae. They have a pair of scaled wings a pair of Halteres, a slender body and long legs Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described By the 1950s, there had been several reports and investigations of workplace hazards. In 1956, for example, after testing hydraulic oils containing PCBs, the U. For the mechanical technology see Hydraulic machinery and Hydraulic cylinder Hydraulics is a topic of science and Engineering S. Navy found that skin contact caused fatal liver disease in animals and rejected them as "too toxic for use in a submarine" (Owens v. Monsanto 2001). Liver disease is a broad term describing any number of Diseases affecting the Liver. A submarine is a Watercraft that can operate independently below water as distinct from a Submersible that has only limited underwater capability

In 1962 a book by U. S. biologist Rachel Carson (Carson 1962) started a storm of concerns about environmental pollution, first focused on DDT and other pesticides, some of them also halocarbons. Rachel Louise Carson (May 27 1907 – April 14 1964 was an American marine biologist and Nature writer whose writings are credited with advancing the global Pollution is the introduction of contaminants into an environment that causes instability disorder harm or discomfort to the physical systems or living organisms they are in DDT (from its trivial name D ichloro- D iphenyl- T richloroethane is one of the best known synthetic Pesticides It is a chemical with a long A pesticide is a substance or mixture of substances used to kill a pest. These concerns were amplified when in 1966 Swedish chemist Soren Jensen reported widespread residues of PCBs among Arctic and sub-Arctic fish and birds (Jensen 1966). In 1974, U. S. chemists Mario Molina and Sherwood Rowland predicted that common halocarbon refrigerants, the chlorofluorocarbons (CFCs), would accumulate in the upper atmosphere and destroy protective ozone (Molina & Rowland 1974). José Mario Molina-Pasquel Henríquez (born March 19, 1943 in Mexico City) is a Mexican -born U Frank Sherwood Rowland (born June 28, 1927) is an American Nobel laureate and a professor of Chemistry at the University of California A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " OZONE is an object oriented Operating system written in the C programming language. Within a few years, ozone depletion was being observed above Antarctica, leading to bans on production and use of chlorofluorocarbons in many countries. OZONE is an object oriented Operating system written in the C programming language. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane In 2007, the Intergovernmental Panel on Climate Change (IPCC) said halocarbons were a direct cause of global warming. Climate Change 2007, the Fourth Assessment Report (AR4 of the United Nations Intergovernmental Panel on Climate Change ( IPCC) is the fourth ^[4]

Since the 1970s there have been longstanding, unresolved controversies over potential health hazards of trichloroethylene (TCE) and other halocarbon solvents that had been widely used for industrial cleaning (Anderson v. Grace 1986) (Scott & Cogliano 2000) (U.S. National Academies of Science 2004) (United States 2004). The Chemical compound trichloroethylene is a chlorinated Hydrocarbon commonly used as an industrial Solvent. A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. More recently perfluorooctanoic acid (PFOA), a precursor in the most common manufacturing process for Teflon and also used to make coatings for fabrics and food packaging, has become a health and environmental concern (United States 2006), suggesting that halocarbons thought to be among the most inert may also present hazards. Perfluorooctanoic acid (PFOA also known as C8, is a man-made Surfactant.

Halocarbons, including those that might not be hazards in themselves, can present waste disposal issues. Waste management is the collection Transport, processing, Recycling or disposal of Waste materials Because they do not readily degrade in natural environments, halocarbons tend to accumulate. Incineration and accidental fires can create corrosive byproducts like hydrochloric acid and hydrofluoric acid and poisons like halogenated dioxins and furans. Incineration is a waste treatment technology that involves the Combustion of organic materials and/or substances Hydrochloric acid is the Solution of Hydrogen chloride ( H[[Chlorine Cl]] in water Hydrofluoric acid is a Solution of Hydrogen fluoride in Water. In the context of Biology, poisons are substances that can cause damage, Illness, or Death to Organisms usually by Not to be confused with Dioxane or Digoxin. Dioxin is a heterocyclic, organic, antiaromatic compound Furan, also known as furane and furfuran, is a heterocyclic Organic compound.

See also

• Halogenation

Notes

References

• Anderson v. Grace, Massachusetts, USA (1986), 628 F. Supp. 1219, settled between the parties, reviewed in Harr, J. , Ed. & M. , Ed. Asher (1996), written at Minneapolis, MN, USA, A Civil Action, Sagebrush Education Resources
• Carson, R. (1962), written at Boston, MA, USA, Silent Spring, Houghton Mifflin
• Flinn, F. B. & N. E. Jarvik (1936), "Action of certain chlorinated naphthalenes on the liver", Proceedings of the Society for Experimental Biology and Medicine 35: 118
• Jensen, S. (1966), "Report of a new chemical hazard", New Scientist 32: 612
• Molina, M. J. & F. S. Rowland (1974), "Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone", Nature 249: 810
• Müller, P. H. (1948), "Dichloro-diphenyl-trichloroethane and newer insecticides", Nobel Lecture, <http://nobelprize.org/medicine/laureates/1948/muller-lecture.pdf>
• Owens v. Monsanto, Alabama, USA (2001), 96-CV-440, Exhibit 3A03F, <http://www.chemicalindustryarchives.org/search/pdfs/anniston/19570121_171.pdf>, cited in Chemical Industry Archives, Anniston Case, by Environmental Working Group, Washington, DC, 2002
• Scott, C. S. , Ed. & V. J. , Ed. Cogliano (2000), "Trichloroethylene Health Risks--State of the Science", Environmental Health Perspectives 108 (S2), <http://ehp.niehs.nih.gov/docs/2000/suppl-2/toc.html>
• Teleky, L. (1927), "Die pernakrankheit", Klinische Wochenschrift (Berlin: Springer) Jahrgänge 6: 845
• U. S. National Academies of Science, Current Projects System (2004), Assessing the Human Health Risks of Trichloroethylene, <http://www4.nas.edu/webcr.nsf/0/1dc1b9eb32716bf685256f7f00622ec2?OpenDocument&Highlight=0,trichloroethylene>
• United States, Environmental Protection Agency (2004), Integrated Risk Information System, Trichloroethylene (CASRN 79-01-6), <http://www.epa.gov/iris/subst/0199.htm#refinhal>
• United States, Environmental Protection Agency (2006), PFOA Stewardship Program, <http://www.epa.gov/opptintr/pfoa/pfoastewardship.htm>

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