2-Butyne

Synonym(s):Crotonylene;Dimethylacetylene

CAS NO.：503-17-3
Empirical Formula: C4H6
Molecular Weight: 54.09
MDL number: MFCD00009275
EINECS: 207-962-2
SAFETY DATA SHEET (SDS)
Update Date: 2026-01-13 11:26:12

What is 2-Butyne?

Chemical properties

clear colorless to light yellow liquid

The Uses of 2-Butyne

2-Butyne is used to synthesize alkylated hydroquinones in the total synthesis of Vitamin E. It is also used as pharmaceutical intermediates.

General Description

A clear colorless liquid with a petroleum-like odor. Flash point below -4°F. Boiling point 81°F. Less dense than water and insoluble in water. Vapors heavier than air.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

2-Butyne may react vigorously with strong oxidizing agents. May react exothermically with reducing agents to release hydrogen gas. In the presence of various catalysts (such as acids) or initiators, may undergo exothermic addition polymerization reactions.

Hazard

Flammable, dangerous fire risk. Moderate explosion hazard.

Health Hazard

Inhalation or contact with material may irritate or burn skin and eyes. Fire may produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

Safety Profile

A simple asphyxiant. Very dangerous fire hazard when exposed to heat or flame; can react with oxidzing materials. Moderately explosive in the form of vapor when exposed to heat or flame. To fight fire, use foam, CO2, dry chemicals. See also ACETYLENE COMPOUNDS and ARGON (for a description of simple asphyxiants).

Purification Methods

Stand it over sodium for 24hours, then fractionally distil it under reduced pressure into a cooled receiver. [Beilstein 1 IV 971.]

Properties of 2-Butyne

Melting point:	-32 °C
Boiling point:	27 °C(lit.)
Density	0.691 g/mL at 25 °C(lit.)
vapor pressure	11.47 psi ( 20 °C)
refractive index	n20/D 1.393(lit.)
Flash point:	-25 °C
storage temp.	2-8°C
form	Liquid
color	Clear colorless to light yellow
Specific Gravity	0.691
Water Solubility	Not miscible in water.
BRN	1361340
CAS DataBase Reference	503-17-3(CAS DataBase Reference)
EPA Substance Registry System	2-Butyne (503-17-3)

Safety information for 2-Butyne

Signal word	Danger
Pictogram(s)	Flame Flammables GHS02 Exclamation Mark Irritant GHS07
GHS Hazard Statements	H224:Flammable liquids H315:Skin corrosion/irritation H319:Serious eye damage/eye irritation H335:Specific target organ toxicity, single exposure;Respiratory tract irritation
Precautionary Statement Codes	P210:Keep away from heat/sparks/open flames/hot surfaces. — No smoking. P302+P352:IF ON SKIN: wash with plenty of soap and water. P305+P351+P338:IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P403+P233:Store in a well-ventilated place. Keep container tightly closed.