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Olefins and dienes

But-2-ene

Also known as 2-Butene, beta-Butene, beta-Butylene

CAS 107-01-7Formula C4H8Molar mass 56.11 g/molEC 203-452-9
GHS signal word: Danger. Pictograms: Flammable, Gas under pressure 6 suppliers listed
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But-2-ene chemical structure, C4H8, CAS 107-01-7
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
Colorless gas
Melting point
-139.3 °C
Boiling point
3.7 °C
Solubility
Very soluble in ethanol and ether. Soluble in benzene. /cis- and trans-2-Butene/
HS code
290123
Category
Olefins and dienes
UN number
UN 1012
Illustrative photo, a gas cylinder on a trolley on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is But-2-ene?

Plain description, key identifiers and synonyms

2-butene appears as a colorless liquefied petroleum gas. Asphyxiate gas. Flammability limits in air 1.8-9.7% by volume.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
but-2-ene
CAS number
107-01-7 CAS number cross-checked
EC number
203-452-9
Molecular formula
C4H8
InChIKey
IAQRGUVFOMOMEM-UHFFFAOYSA-N
InChI
InChI=1S/C4H8/c1-3-4-2/h3-4H,1-2H3
SMILES (canonical and isomeric)
CC=CC

Synonyms

  • 2-Butene
  • beta-Butene
  • beta-Butylene

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
Colorless gasexp.
Melting point
-139.3 °Cexp.
Boiling point
3.7 °Cexp.
Solubility
Very soluble in ethanol and ether. Soluble in benzene. /cis- and trans-2-Butene/exp.
Vapour pressure
1600 mm Hg at 25 °C /cis-2-Butene/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
56.11 g/molcalc.
Exact mass
56.0626 Dacalc.
LogP (octanol/water)
1.58calc.
Topological polar surface area
0 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
0calc.
Rotatable bonds
0calc.
Heavy atoms
4calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0.5calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS02: Flammable
Flammable
GHS04: Gas under pressure
Gas under pressure

Hazard statements

  • H220Extremely flammable gas.
  • H280Contains gas under pressure, may explode if heated.
Precautionary statements (8)
  • P203Obtain, read and follow all safety instructions before use.
  • P210Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P222Do not allow contact with air.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P377Leaking gas fire: do not extinguish, unless leak can be stopped safely.
  • P381In case of leakage, eliminate all ignition sources.
  • P403Store in a well-ventilated place.
  • P410 + P403Protect from sunlight. Store in a well-ventilated place.
UN number
UN 1012

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

But-2-ene suppliers

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All 6 suppliers
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Where suppliers are based

6 suppliers in 2 countries

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But-2-ene 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

Intermediate for butadiene, heptenes, sec-butyl alc, butylene oxide, prodn of high-density polyethylene & polymer gasolines.

How it is made

There are two important sources for the commercial production of butylenes: catalytic or thermal cracking, and steam cracking. In these two processes, butylenes are always produced as by-products. (Butylenes)

1-Butene and isobutylene cannot be economically separated into pure components by conventional distillation because they are close boiling isomers. 2-Butene can be separated from the other two isomers by simple distillation.

Read more

There are four types of separation methods available: (1) selective removal of isobutylene by polymerization and separation of 1-butene, (2) use of addition reactions with alcohol, acids, or water to selectively produce pure isobutylene and 1-butene, (3) selective extraction of isobutylene with a liquid solvent, usually an acid, and (4) physical separation of isobutylene from 1-butene by absorbents.

Disproportionation or the metathesis reaction offers an opportunity to convert surplus olefins to other desirable olefins. Phillips Petroleum and Institut Francais du Petrole have pioneered this technology for the dimerization of light olefins. The original metathesis reaction of Phillips Petroleum was intended to convert propylene to 2-butene and ethylene. The reverse reaction that converts 2-butene in the presence of excess ethylene to propylene has also been demonstrated. In this process, ethylene is first dimerized to 2-butene followed by metathesis to yield propylene.

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 But-2-ene is traded under.

HS 2901.23Indicative HS code

Butene (butylene) and isomers thereof

World exports in 2024
$683M
−8.1% vs 2023, imports $584M
2019 to 2024
Top exporters
  1. United States32.2%
  2. Belgium29.4%
  3. South Korea11.5%
Top importers
  1. Canada34.2%
  2. Thailand8.9%
  3. Germany7.7%
Reported customs values in USD, not prices.Full trade data

The HS code shown for But-2-ene is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about But-2-ene, based on the data on this page

What is But-2-ene?

2-butene appears as a colorless liquefied petroleum gas. Asphyxiate gas. Flammability limits in air 1.8-9.7% by volume.

What is the CAS number of But-2-ene?

The CAS registry number of But-2-ene is 107-01-7.

What is the molecular formula and weight of But-2-ene?

The molecular formula of But-2-ene is C4H8 and its molar mass is 56.11 g/mol.

What is But-2-ene used for?

Intermediate for butadiene, heptenes, sec-butyl alc, butylene oxide, prodn of high-density polyethylene & polymer gasolines.

Is But-2-ene hazardous?

But-2-ene carries the GHS signal word "Danger". Main hazards: extremely flammable gas, contains gas under pressure, may explode if heated. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of But-2-ene?

But-2-ene is usually classified under HS code 290123 (Butene (butylene) and isomers thereof). This is indicative, confirm it with your customs broker before shipping.

Where can I buy But-2-ene?

CompoundList lists 6 suppliers of But-2-ene in United States and China. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

What is the price of But-2-ene?

Suppliers quote But-2-ene 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 But-2-ene

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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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