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: 2026-05-28 02:44:15
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 | n |
| 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. |
Computed Descriptors for 2-Butyne
New Products
2-(2-Chlorophenyl)glycine Propiolic Acid 1-(3-Hydroxy-4-methoxyphenyl)-2-nitroethene (±)-amino(2-fluorophenyl)acetic acid trans-3-Benzyloxy-4-methoxy-beta-nitrostyrene 1-Pentadecanol 2,4-Dihydroxybenzaldehyde Obidoxime hydrochloride API Pyrrolo[1,2-a]pyrimidine-6-carboxylic acid, 4,6,7,8-tetrahydro-4-oxo-, sodium salt (1:1), (6S) Dipropyl disulfide 4 pentyn 1 ol N-Vinylformamide Methacrylate-PEG-Methacrylate, Mn:35000 2,4-Dihydroxyacetophenone 2-Chloro 5-Fluoro Pyridine Vasicinone 2-Chloroisonicotinic Acid Tween 80 or Polysorbate 80 2-Butyn-1-oL N-(4-Cyano-3-(trifluoromethyl)phenyl)-2-methyloxirane-2-carboxamide N-(4-fluoro-2-methoxy-5-nitrophenyl)-4-(1-methyl-1H-indol-3-yl)pyrimidin-2-amine Pirtobrutinib intd. 2-Pentyn-1-oL 4-NitrobenzotrifluorideRelated products of tetrahydrofuran








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