Chlorendic acid

Chlorendic acid
Names
	IUPAC name 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic acid
	Other names Chlorendic acid, HET acid, hexachloroendomethylenetetrahydrophthalic acid
Identifiers
CAS Number	115-28-6;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:76603;
ChemSpider	7968;
ECHA InfoCard	100.003.708
KEGG	C19204;
PubChemCID	8266;
UNII	IAC1H0N39L;
CompTox Dashboard(EPA)	DTXSID2020268;
	InChI InChI=1S/C9H4Cl6O4/c10-3-4(11)8(13)2(6(18)19)1(5(16)17)7(3,12)9(8,14)15/h1-2H,(H,16,17)(H,18,19) Key: DJKGDNKYTKCJKD-UHFFFAOYSA-N;
	SMILES C1(C(C2(C(=C(C1(C2(Cl)Cl)Cl)Cl)Cl)Cl)C(=O)O)C(=O)O;
Properties
Chemical formula	C9H4Cl6O4
Molar mass	388.84366
Melting point	232 °C (450 °F; 505 K)
	Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa). verify(what is?) Infobox references

Chlorendic acid,or1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic acid,is achlorinated carboxylic acidused in the synthesis of someflame retardantsandpolymers.^[1]It is a common breakdown product of severalorganochlorine insecticides.

Properties and identification

Chlorendic acid is a white crystalline material with chemical formulaC₉H₄Cl₆O₄.It is also called HET acid, hexachloroendomethylenetetrahydrophthalic 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.^[1]

It is produced both as acid and as itsanhydride.The anhydride has CAS number115-27-5.

Chlorendic acid is slightly soluble in water and nonpolar organic solvents (e.g.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 topyrolysis,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 theDiels-Alder reaction.It is used as an intermediate in synthesis of unsaturated flame-retardantpolyester resinsandplasticizers,and as a finishing flame-retardant treatment forwool.A major use is in the production offiberglass-reinforced resins for chemical-industry equipment. It can be used to makealkyd resinsfor use in specialinksandpaints.It is used as a hardening agent inepoxy resinsused in the manufacture ofprinted circuit boards.When reacted with nonhalogenatedglycols,it forms halogenatedpolyolsthat can be used asflame retardantsinpolyurethane foams.It is also used for producingdibutyl chlorendateanddimethyl chlorendate,which are used as reactive flame retardants inplastics.In limited amounts, it is used as an additive inacrylonitrile butadiene styrene copolymer.

Esters and amine salts of chlorendic acid are used asextreme pressure additivesin syntheticlubricants.

When used in polymers, whether as a curing agent or as a flame retardant, it bonds covalently to the polymer matrix, which reduces itsleachingto the environment. It may, however, be released when such materials are subjected to hydrolysis, and it can be formed by oxidation of chlorinated cyclodiene insecticides (e.g.endosulfan,chlordane,heptachlor,aldrin,dieldrin,endrin,andisodrin). Its half-life insoilis 140–280 days.

In Europe, 80% of chlorendic acid is used in the production of flame-resistant composites for building and transportation, while 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.

References

^^a ^bPubChem."Chlorendic acid".pubchem.ncbi.nlm.nih.gov.Retrieved2022-11-25.

External links

[:0-1] PubChem."Chlorendic acid".pubchem.ncbi.nlm.nih.gov.Retrieved2022-11-25.

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