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Screening compounds

Chlorendic acid

Also known as 1,4,5,6,7,7-Hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, HET acid, Kyselina het

CAS 115-28-6Formula C9H4Cl6O4Molar mass 388.85 g/molEC 204-078-9
GHS signal word: Danger. Pictograms: Corrosive, Harmful or irritant, Serious health hazard 4 suppliers listed
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Chlorendic acid chemical structure, C9H4Cl6O4, CAS 115-28-6
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
Crystalline solid
Melting point
208 to 210
Density
0.95 - Less dense than water, will float
Solubility
In water, 0.35 g/100 g @ 25 °C
HS code
291720
Category
Screening compounds
Illustrative photo, a shrink wrapped pallet of kraft paper sacks in a chemical plant
Typical packagingIllustrative packaging image, not the actual product

What is Chlorendic acid?

Plain description, key identifiers and synonyms

Chlorendic acid is a bridged organochlorine compound resulting from the Diels-Alder reaction of hexachlorocyclopentadiene with maleic anhydride followed by hydrolysis of the resulting anhydride. A chemical intermediate used in the preparation of fire-retardant polyester resins and plasticisers. It has a role as a carcinogenic agent. It is a dicarboxylic acid, a bridged compound and an organochlorine compound.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid
CAS number
115-28-6 CAS number cross-checkedOther or deprecated CAS: 7374-78-9
EC number
204-078-9
Molecular formula
C9H4Cl6O4
MDL number
MFCD00167589
InChIKey
DJKGDNKYTKCJKD-UHFFFAOYSA-N
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)
SMILES (canonical and isomeric)
C1(C(C2(C(=C(C1(C2(Cl)Cl)Cl)Cl)Cl)Cl)C(=O)O)C(=O)O

Synonyms

  • 1,4,5,6,7,7-Hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid
  • HET acid
  • Kyselina het
  • Bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, 1,4,5,6,7,7-hexachloro-
  • Hexachloroendomethylenetetrahydrophthalic acid
  • 1,4,5,6,7,7-Hexachloro-5-norbornene-2,3-dicarboxylic acid
  • Hexachloro-endo-methylenetetrahydrophthalic acid
  • 5-Norbornene-2,3-dicarboxylic acid, 1,4,5,6,7,7-hexachloro-
  • 1,4,5,6,7,7-Hexachloro-8,9,10-trinorborn-5-ene-2,3-dicarboxylic acid
  • 1,4,5,6,7,7-Hexachlorobicyclo(2.2.1)-5-heptene-2,3-dicarboxylic acid
  • Bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid, 1,4,5,6,7,7-hexachloro-
  • Kyselina 3,6-endomethylen-3,4,5,6,7,7-hexachlor-delta(sup 4)-tetrahyroftalova
  • 1,4,5,6,7,7-Hexachlorobicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid
  • 1,4,5,6,7,7-Hexachlorobicyclo-(2,2,1)hept-5-en-2,3-dicarboxylic acid
  • hexachloroentomethylenetetrahydrophthalic acid
  • 2H,3H-Hexachlorobicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid
  • 2H,3H-Hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid
  • 1,4,5,6,7,7-Hexachlorodicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid
  • Prillic acid
  • Kyselina 1,2,3,4,7,7-hexachlorbicyklo(2,2,1)hept-2-en-5,6-dikarboxylova
  • Chlorendic acid (VAN)
  • C9H4Cl6O4
  • Kyselina 3,4,5,6,7,7-hexachlor-delta(sup 4)-tetrahyroftalova
  • 1,2,3,4,7,7-hexachlorobicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic acid
  • Kyselina 3,6-endomethylen-3,4,5,6,7,7-hexachlor-delta(sup 4)-tetrahydroftalova
Show all 31 synonyms
  • 1,5,6,7,7-Hexachloro-5-norbornene-2,3-dicarboxylic acid
  • 1,4,5,6,7,7-hexachlorobicyclo-(2,2,1)-hept-5-ene-2,3-dicarboxylic acid
  • 1,4,5,6,7,7-Hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid #
  • 1,4,5,6,7,7-Hexachlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylicacid
  • 1,2,3,4,7,7-hexakis(chloranyl)bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic acid
  • Bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid, 1,4,5,6,7,7-hexachloro-

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
Crystalline solidexp.
Melting point
208 to 210exp.
Density
0.95 - Less dense than water, will floatexp.
Solubility
In water, 0.35 g/100 g @ 25 °Cexp.
Vapour pressure
1.4 × 10⁻⁸ mm Hg @ 25 °C /Estimated/exp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
388.85 g/molcalc.
Exact mass
385.8241 Dacalc.
LogP (octanol/water)
3.23calc.
Topological polar surface area
74.6 Ųcalc.
Hydrogen bond donors
2calc.
Hydrogen bond acceptors
2calc.
Rotatable bonds
2calc.
Heavy atoms
19calc.
Rings
2calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0.56calc.
Formal charge
0calc.
Stereocentres
4calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Murcko scaffold

The ring system that remains when every side chain is removed

Murcko scaffold of this chemical, C1=CC2CCC1C2

C1=CC2CCC1C2

2 rings, 7 atoms.

1,083 other chemicals share this scaffold

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS05: Corrosive
Corrosive
GHS07: Harmful or irritant
Harmful or irritant
GHS08: Serious health hazard
Serious health hazard

Hazard statements

  • H315Causes skin irritation.
  • H318Causes serious eye damage.
  • H319Causes serious eye irritation.
  • H335May cause respiratory irritation.
  • H350May cause cancer.
  • H351Suspected of causing cancer.
Precautionary statements (20)
  • P203Obtain, read and follow all safety instructions before use.
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P271Use only outdoors or in a well-ventilated area.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P302 + P352If on skin: Wash with plenty of water.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P351 + P338If in eyes: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P317Get medical help.
  • P318If exposed or concerned, get medical advice.
  • P319Get medical help if you feel unwell.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P332 + P317If skin irritation occurs: Get medical help.
  • P337 + P317If eye irritation persists: Get medical help.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P403 + P233Store in a well-ventilated place. Keep container tightly closed.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Chlorendic acid suppliers

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Where suppliers are based

4 suppliers in 3 countries

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Chlorendic acid price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Flame retardant.

Fire-retardant monomer in unsaturated polyester resins, fire retardant monomer in coatings, in epoxy resins, in polyurethane foams, extreme pressure lubricant, chemical intermediate for dibutyl & dimethylchlorendate (plasticizers).

Chlorendic acid used primarily as a chemical intermediate in the manufacture of unsaturated polyester resins, and with special applications in electronic systems, paneling, engineering plastics and paints. A major use is in fiberglass reinforced resins for process equipment in chemical industries. Chlorendic acid is also used to impart flame resistance to polyurethane foams when reacted nonhalogenated glycols to form halogenated polyols and can be used in the manufacture of alkyd resins for special paints and inks.

In Europe, 80% of the chlorendic acid produced is used in composites for flame retardant building and transport materials.

Read more

The remainder issued in composites for the manufacture of anti-corrosion equipment, such as tanks, piping and scrubbers. In the USA, Latin American and Far East, the usage pattern is reversed, 70-80% is used for anti-corrosion equipment and 20-30% for flame retardant applications.

In the textile industry, the primary use for chlorendic acid is for flame retardant treatment of wool fabrics. The natural flame resistance of wool is enhanced by finishing treatments with chlorendic acid in dimethylformamide.

Industrial uses: Other.

Roles

  • aetiopathogenetic role
  • carcinogenic agent

Pharmacology

Chlorendic Acid is a white, crystalline carcinogenic chlorinated hydrocarbon that emits toxic fumes of hydrochloric acid and other chlorinated compounds when heated to decomposition. Chlorendic acid is used as a reactive flame retardant, chemical intermediate, hardening agent and as an extreme pressure lubricant. Exposure to chlorendic acid causes skin, eye and respiratory tract irritation. Chlorendic acid is reasonably anticipated to be a human carcinogen based on evidence of carcinogenicity in experimental animals. (NCI05)

How it is made

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.

Regulatory status

Inventories, regulations and trade controls that list this substance

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Chlorendic acid is traded under.

HS 2917.20Indicative HS code

Cyclanic, cyclenic or cycloterpenic polycarboxylic acids, their anhydrides, halides…

World exports in 2024
$338M
+10.9% vs 2023, imports $464M
2019 to 2024
Top exporters
  1. China37.1%
  2. United States16.2%
  3. Italy15.5%
Top importers
  1. India * partner reported11.6%
  2. China9.4%
  3. Germany8.9%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Chlorendic acid is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Chlorendic acid, based on the data on this page

What is Chlorendic acid?

Chlorendic acid is a bridged organochlorine compound resulting from the Diels-Alder reaction of hexachlorocyclopentadiene with maleic anhydride followed by hydrolysis of the resulting anhydride. A chemical intermediate used in the preparation of fire-retardant polyester resins and plasticisers.

What is the CAS number of Chlorendic acid?

The CAS registry number of Chlorendic acid is 115-28-6. Other or deprecated CAS numbers: 7374-78-9.

What is the molecular formula and weight of Chlorendic acid?

The molecular formula of Chlorendic acid is C9H4Cl6O4 and its molar mass is 388.85 g/mol.

What is Chlorendic acid used for?

Flame retardant. Fire-retardant monomer in unsaturated polyester resins, fire retardant monomer in coatings, in epoxy resins, in polyurethane foams, extreme pressure lubricant, chemical intermediate for dibutyl & dimethylchlorendate (plasticizers).

Is Chlorendic acid hazardous?

Chlorendic acid carries the GHS signal word "Danger". Main hazards: causes skin irritation, causes serious eye damage, causes serious eye irritation. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Chlorendic acid?

Chlorendic acid is usually classified under HS code 291720 (Cyclanic, cyclenic or cycloterpenic polycarboxylic acids, their anhydrides, halides…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Chlorendic acid?

CompoundList lists 4 suppliers of Chlorendic acid in China, Hong Kong and United States. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

What is the price of Chlorendic acid?

Suppliers quote Chlorendic acid on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Chlorendic acid

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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