CID 6338

C₂H₃Cl

Vinyl chloride

C 2
H 3
Cl 1

Ball-and-stick Stick Space-filling

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6 atoms, 5 bonds.

IUPAC name: chloroethene
Molar mass: 62.496(15) g/mol
Atoms: 6
SMILES: C=CCl
InChIKey: BZHJMEDXRYGGRV-UHFFFAOYSA-N
PubChem CID: 6338

Made of

C H Cl

Structural formula of vinyl chloride. Each unlabelled corner is a carbon atom, and the one hydrogen on carbon is not drawn. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Vinyl chloride is made for one purpose above all. About 99 per cent of the world’s capacity goes to poly(vinyl chloride), or PVC, and copolymers mixing it with other monomers, according to the Hazardous Substances Data Bank (HSDB). The monomer, the small molecule PVC’s chains are built from, is a gas of carbon, hydrogen and chlorine, with a molar mass of 62.5 g/mol. Its systematic name is chloroethene, and chloroethylene and VCM, for vinyl chloride monomer, are other names in use. The National Toxicology Program (NTP) places it with vinyl bromide and vinyl fluoride among the simple vinyl halides.

CAMEO Chemicals, a hazardous-materials database, lists it as colourless with a sweet odour. HSDB gives a boiling point of −13.8 °C, well below room temperature, and a vapour 2.15 times as dense as air, so the gas sinks rather than rising. Water takes up only a little of it, while hydrocarbons, oils and chlorinated solvents dissolve it.

Structure and bonding

Vinyl chloride carries a chlorine and a hydrogen on one carbon, two hydrogens on the other, and a double bond between the carbons. The Labels button prints C on the central pair, H on three outer atoms and Cl on the last. ChEBI, the database of Chemical Entities of Biological Interest, defines chloroethene as ethene with one hydrogen swapped for a chloro group, the very swap the model draws. The double stick is the same bond as in ethylene.

From the side, the computed model shows all six atoms in one plane. At the CH₂ carbon the angles stay within about 2° of 120°. At the other carbon, H–C–Cl narrows to 113° and the two angles beside the double bond widen to about 123° and 124°. The C–Cl stick, 1.71 Å in the model, is the longest.

The Stick view drops the spheres to leave the bare skeleton. In the Space-filling view the green chlorine, a shade larger than a carbon, fills one end of the merged cluster.

Where it turns up

Vinyl chloride does not occur in nature, reports ATSDR, the US Agency for Toxic Substances and Disease Registry. It can, however, form when trichloroethane, trichloroethylene or tetrachloroethylene break down. Tobacco smoke carries it as a product of burning, the National Cancer Institute notes. Plastics plants, hazardous waste sites and landfills give it off, and its vapour can reach the indoor air of homes and businesses built on contaminated ground.

Drinking water flowing through PVC pipe made before 1977 can pick up the monomer, the US Environmental Protection Agency (EPA) states. Product standards have controlled its release from PVC pipe since that year. In open air the gas lasts only a few days before breaking down, in some cases into harmful substances. Levels usually found in the environment sit below those known to cause health problems, ATSDR adds.

Why it matters

Industry chlorinates ethylene to 1,2-dichloroethane and then cracks it, or breaks it apart, into the monomer, HSDB records; the other route combines acetylene with hydrogen chloride. China’s coal-based production used mercury compounds as catalysts, according to the US Geological Survey. Phenol is added as a stabiliser that keeps the monomer from polymerising. Rigid PVC makes pipes, house siding and flooring; softened with plasticisers, it makes upholstery, electrical insulation and shower curtains, according to Chem1.

Workers heavily exposed to the monomer while cleaning reaction vessels developed more angiosarcoma of the liver, a cancer of its blood vessels. In the liver the enzyme cytochrome P450 2E1 turns vinyl chloride into chloroethylene oxide, which can rearrange into chloroacetaldehyde. Both can bind to DNA bases, and these attachments, left unrepaired, can lead to mutations and tumours. The main attachment does not cause mutations, but four minor ones do. Concern over its health effects led Congress to write the Toxic Substances Control Act in 1976, the EPA says, and in December 2024 the agency designated it a high-priority chemical.

Properties

Properties of vinyl chloride Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 6338.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₂H₃Cl
Molar mass	62.496(15) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	2
Hydrogen atoms	3
Chlorine atoms	1
Bonds	5
Single bonds	4
Double bonds	1
PubChem molecular weight	62.5 g/mol	g/mol	PubChem

Safety

A flammable gas and a known human carcinogen, vinyl chloride carries the signal word Danger in the EU’s hazard classification. Burning decomposes it, releasing toxic and corrosive hydrogen chloride and phosgene, and the liquid can cause frostbite, the International Chemical Safety Card warns. NIOSH, the US National Institute for Occupational Safety and Health, treats it as a potential occupational carcinogen. The PubChem Laboratory Chemical Safety Summary for vinyl chloride and the NIOSH Pocket Guide card hold the full hazard data.

Questions

Is vinyl chloride the same as PVC?

No. Vinyl chloride is a gas, and PVC, poly(vinyl chloride), is the plastic made from it, found in pipes, coatings on wire and cable, and packaging. The National Cancer Institute does not count PVC as a known or suspected carcinogen. The plastic raises a different concern when it burns: Chem1 notes that open burning of chlorine-containing polymers such as PVC gives off dioxins, compounds that linger in the environment.

What is vinyl chloride disease?

It is a set of symptoms that the US Environmental Protection Agency (EPA) reports in a small share of workers heavily exposed to vinyl chloride in air. Its mark is Raynaud's phenomenon: the fingers turn white, numb and painful in the cold. The set also includes changes in the bones at the ends of the fingers, pain in joints and muscles, and thickened, less elastic skin.

Does vinyl chloride cause cancer?

Yes. The US Department of Health and Human Services counts it as known to be a human carcinogen. IARC, the International Agency for Research on Cancer, places it in Group 1, carcinogenic to humans. It causes angiosarcoma of the liver, a cancer rare enough that the National Toxicology Program estimates only about 25 US cases a year. The National Cancer Institute also links exposure to a higher risk of primary liver cancer, brain and lung cancers, lymphoma and leukaemia.

What else has vinyl chloride been used for?

The Hazardous Substances Data Bank records past service as a refrigerant and a spray-can propellant, and Haz-Map, an occupational health database, notes that it was once tested as an anaesthetic. Sales of aerosols containing it were banned in 1974, after it was confirmed to cause cancer in humans and animals. Outside polymers, its main uses are in making vinylidene chloride, vinyl stearate, trichloroethylene and tetrachloroethylene.

Made of the same elements

CH₂Cl₂ Dichloromethane 5 atoms, 4 single bonds, tetrahedral.
CHCl₃ Chloroform 5 atoms, 4 single bonds, tetrahedral.