Chlorendic acid
Encyclopedia
Chlorendic acid, or 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic acid, is a chlorinated hydrocarbon used in the synthesis of some flame retardants and polymer
s. It is a common breakdown product of several organochlorine insecticides.
It is produced both as acid and as its anhydride. The anhydride has CAS number .
Chlorendic acid is slightly soluble in water and nonpolar organic solvents (eg. benzene
, hexane
, carbon tetrachloride
). It is easily soluble in slightly polar organic solvents (ethanol
, methanol
, acetone
). When heated, it loses water at 200 °C, forming an anhydride with melting point of 230-235 °C. When subject to pyrolysis
, it decomposes to hydrochloric acid and various chlorinated compounds. It is resistant to hydrolytic dechlorination. It readily forms salts with metals, and esters.
. It is used as an intermediate in synthesis of unsaturated flame-retardant polyester
resin
s and plasticizer
s, and as a finishing flame-retardant treatment for wool
. A major use is in production of fiberglass
-reinforced resins for chemical industry equipment. It can be used to make alkyd resins for use in special ink
s and paint
s. It is used as a hardening agent in epoxy resins used in manufacture of printed circuit board
s. When reacted with nonhalogenated glycols, it forms halogenated polyol
s used as flame retardant
s in polyurethane
foam
s. it is also used for production of dibutyl chlorendate and dimethyl chlorendate
, which are used as reactive flame retardants in plastic
s. In limited amounts, it is used as an additive in acrylonitrile butadiene styrene
copolymer.
Esters and amine salts of chlorendic acid are used as extreme pressure additives in synthetic lubricant
s.
When used in polymers, whether as a curing agent or as a flame retardant, it bonds covalently to the polymer matrix, which reduces its leaching
to the environment. It may, however, be released when such materials are subjected to hydrolysis, and can be formed by oxidation of chlorinated cyclodiene insecticides (eg. endosulfan
, chlordane
, heptachlor
, aldrin
, dieldrin
, endrin
, and isodrin). Its half-life in soil
is 140-280 days.
In Europe, 80% of chlorendic acid is used in production of flame-resistant composites for building and transportation, the rest is used in materials for corrosion-resistant fluid storage equipment. In the USA, Latin America, and Asia, 20-30% is used in flame retardant applications and the rest is used in corrosion-resistant plastics.
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s. It is a common breakdown product of several organochlorine insecticides.
Properties and identification
Chlorendic acid is a white crystalline material with chemical formula 9464. It is also called HET acid, Hetron 92, Hetron 92C, hexachloro-endo-methylenetetrahydronaphthalic acid, 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid, and 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid.It is produced both as acid and as its anhydride. The anhydride has CAS number .
Chlorendic acid is slightly soluble in water and nonpolar organic solvents (eg. benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
, hexane
Hexane
Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane with six carbon atoms.The term may refer to any of four other structural isomers with that formula, or to a mixture of them. In the IUPAC nomenclature, however, hexane is the unbranched isomer ; the other four structures...
, carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
). It is easily soluble in slightly polar organic solvents (ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
, acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...
). When heated, it loses water at 200 °C, forming an anhydride with melting point of 230-235 °C. When subject to pyrolysis
Pyrolysis
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...
, it decomposes to hydrochloric acid and various chlorinated compounds. It is resistant to hydrolytic dechlorination. It readily forms salts with metals, and esters.
Chemistry and uses
Chlorendic acid is industrially produced in high volumes by Diels-Alder reactionDiels-Alder reaction
The Diels–Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly formed ring are not carbon...
. It is used as an intermediate in synthesis of unsaturated flame-retardant polyester
Polyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
s and plasticizer
Plasticizer
Plasticizers or dispersants are additives that increase the plasticity or fluidity of the material to which they are added; these include plastics, cement, concrete, wallboard, and clay. Although the same compounds are often used for both plastics and concretes the desired effects and results are...
s, and as a finishing flame-retardant treatment for wool
Wool
Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....
. A major use is in production of fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
-reinforced resins for chemical industry equipment. It can be used to make alkyd resins for use in special ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
s and paint
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
s. It is used as a hardening agent in epoxy resins used in manufacture of printed circuit board
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
s. When reacted with nonhalogenated glycols, it forms halogenated polyol
Polyol
A polyol is an alcohol containing multiple hydroxyl groups. In two technological disciplines the term "polyol" has a special meaning: food science and polymer chemistry.- Polyols in food science :...
s used as flame retardant
Flame retardant
Flame retardants are chemicals used in thermoplastics, thermosets, textiles and coatings that inhibit or resist the spread of fire. These can be separated into several different classes of chemicals:...
s in polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
s. it is also used for production of dibutyl chlorendate and dimethyl chlorendate
Dimethyl chlorendate
Dimethyl chlorendate is a chlorendic acid used as a flame retardant additive....
, which are used as reactive flame retardants in plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
s. In limited amounts, it is used as an additive in acrylonitrile butadiene styrene
Acrylonitrile butadiene styrene
Acrylonitrile butadiene styrene is a common thermoplastic. Its melting point is approximately 105 °C ....
copolymer.
Esters and amine salts of chlorendic acid are used as extreme pressure additives in synthetic lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
s.
When used in polymers, whether as a curing agent or as a flame retardant, it bonds covalently to the polymer matrix, which reduces its leaching
Leaching (chemical science)
Leaching is the process of extracting minerals from a solid by dissolving them in a liquid, either in nature or through an industrial process. In the chemical processing industry, leaching has a variety of commercial applications, including separation of metal from ore using acid, and sugar from...
to the environment. It may, however, be released when such materials are subjected to hydrolysis, and can be formed by oxidation of chlorinated cyclodiene insecticides (eg. endosulfan
Endosulfan
Endosulfan is an off-patent organochlorine insecticide and acaricide that is being phased out globally. Endosulfan became a highly controversial agrichemical due to its acute toxicity, potential for bioaccumulation, and role as an endocrine disruptor...
, chlordane
Chlordane
Chlordane, or chlordan, is an organochlorine compound that was used as a pesticide. This white solid was sold in the U.S. until 1983 as an insecticide for crops like corn and citrus and on lawns and domestic gardens.-Production and uses:...
, heptachlor
Heptachlor
Heptachlor is an organochlorine compound that was used as an insecticide. Usually sold as a white or tan powder, heptachlor is one of the cyclodiene insecticides. In 1962, Rachel Carson's Silent Spring questioned the safety of heptachlor and other chlorinated insecticides. Due to its highly...
, aldrin
Aldrin
Aldrin is an organochlorine insecticide that was widely used until the 1970s, when it was banned in most countries. It is a colourless solid. Before the ban, it was heavily used as a pesticide to treat seed and soil...
, dieldrin
Dieldrin
Dieldrin is a chlorinated hydrocarbon originally produced in 1948 by J. Hyman & Co, Denver, as an insecticide. Dieldrin is closely related to aldrin, which reacts further to form dieldrin. Aldrin is not toxic to insects; it is oxidized in the insect to form dieldrin which is the active compound...
, endrin
Endrin
Endrin is an organochloride that was primarily used as an insecticide. It is a colourless odorless solid, although commercial samples are often off-white. It is also a rodenticide. This compound became infamous as persistent organic pollutant and for this reason is banned in many...
, and isodrin). Its half-life in soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
is 140-280 days.
In Europe, 80% of chlorendic acid is used in production of flame-resistant composites for building and transportation, the rest is used in materials for corrosion-resistant fluid storage equipment. In the USA, Latin America, and Asia, 20-30% is used in flame retardant applications and the rest is used in corrosion-resistant plastics.