FR Types‎ > ‎Chlorinated‎ > ‎

HET Acid

Chlorendic acid [115-28-6] (HET Acid) and its anhydride [115-27-5] are widely used flame retardants. Chlorendic acid is synthesized by a Diels-Alder reaction of maleic anhydride and hexachlorocyclopentadiene in toluene followed by hydrolysis of the anhydride using aqueous base (60). The anhydride can be isolated directly from the reaction mixture or can be prepared in a very pure form by dehydration of the acid. The principal use of chlorendic anhydride and chlorendic acid has been in the manufacture of unsaturated polyester resins. Because the esterification rate of chlorendic anhydride is similar to that of phthalic anhydride , it can be used in place of phthalic anhydride in commercial polyester formulations. Besides having a degree of fire resistance, polyesters containing chlorendic anhydride often exhibit a significant degree of UV stability and corrosion resistance The double bond in chlorendic acid is not reactive as a cross-linking site; hence, reactive monomers such as maleic anhydride must be included in the polyester backbone to achieve cross-linking. Other applications are in alkyds, polyurethanes, and epoxy resins. 


Chlorendic Acid (HET Acid)
 It is a versatile intermediate for many polymers; owing to its hight chlorene content of 54.4%, Chlorendic acid can impart polymers with excellent flame retardant, anti-crossive, and resistance to moisture, alchohol, alkaline and acid.
It will form covalent bonds in polymer matrix when it is added as curing agent or flame retardant, so the resulting products have good stability, no leaching and environment friendly.

Physical and Chemical Properties

1. Product and Name: Chlorendic Acid
2. Chemical Name: 4,5,6,7,8,8-Hexachloro-3a,4,7,7a-tetrahydro-4,7-methanoisobenzofuran-1,3-dione 1,4,5,6,7,7-Hexachloro-endo-5-norbornene-2,3-dicarboxylic anhydride Hexachloro-endo-methylene tetrahydrophthalic anhydride 
3. Synonym: Hetron Acid, Hetron 92
4. CAS No.:115-28-6
5. Structure:



Applications: 
  • Curing agent for epoxy resin and other coating system, especially for PCB applications;
  • Intermediate for synthesis of unsaturated flame-retardant polyester resin and plasticizers; 
  • Composites, fiberglass-reinforced resins for chemical industry equipment(chemical resistance); to produce alkyd resins used in special inks and paints. 
  • react with nonhalogenated glycols to form halogenated polyols used as flame retardants in polyurethane foams; 
  • used for production of dibutyl chlorendate and dimethyl chlorendate, which are used as reactive flame retardants in plastics. 
  • used as an additive in acrylonitrile butadiene styrene copolymer. 
  • Esters and amine salts of chlorendic acid are used as extreme pressure additives in synthetic lubricants; 
  • to produce chlorinated cyclodiene insecticides(eg. endosulfan, chlordane, heptachlor, aldrin, dieldrin,endrin, and isodrin).