Propargyl alcohol

Propargyl alcohol
3D ball-and-stick structure of propargyl alcohol
Preferred IUPAC name
Other names
propynol, 2-propynol, 2-propyn-1-ol, hydroxymethylacetylene.
3D model (JSmol)
ECHA InfoCard 100.003.157 Edit this at Wikidata
EC Number
  • 203-471-2
RTECS number
  • UK5075000
UN number 1986 2929
  • InChI=1S/C3H4O/c1-2-3-4/h1,4H,3H2 checkY
  • InChI=1/C3H4O/c1-2-3-4/h1,4H,3H2
  • C#CCO
Molar mass 56.064 g·mol−1
Appearance Colorless to straw-colored liquid
Odor geranium-like
Density 0.9715 g/cm3
Melting point −51 to −48 °C (−60 to −54 °F; 222 to 225 K)
Boiling point 114 to 115 °C (237 to 239 °F; 387 to 388 K)
Vapor pressure 12 mmHg (20 °C)
GHS labelling:
GHS02: Flammable GHS06: Toxic GHS05: Corrosive GHS08: Health hazard GHS09: Environmental hazard
H226, H301, H310, H314, H330, H373, H411
P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P312, P321, P322, P330, P361, P363, P370+P378, P391, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
Flash point 36 °C; 97 °F; 309 K (open cup)
NIOSH (US health exposure limits):
PEL (Permissible)
REL (Recommended)
TWA 1 ppm (2 mg/m3) [skin]
IDLH (Immediate danger)
Safety data sheet (SDS) External SDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Propargyl alcohol, or 2-propyn-1-ol, is an organic compound with the formula C3H4O. It is the simplest stable alcohol containing an alkyne functional group. Propargyl alcohol is a colorless viscous liquid that is miscible with water and most polar organic solvents.

Reactions and applications

Propargyl alcohol polymerizes with heating or treatment with base. It is used as a corrosion inhibitor, a metal complex solution, a solvent stabilizer and an electroplating brightener additive. It is also used as an intermediate in organic synthesis. Secondary and tertiary substituted propargylic alcohols undergo catalyzed rearrangement reactions to form α,β-unsaturated carbonyl compounds via the Meyer–Schuster rearrangement and others. It can be oxidized to propynal or propargylic acid.

As an indication of the electronegativity of an sp carbon, propargyl alcohol is significantly more acidic (pKa = 13.6) compared to its sp2-containing analog allyl alcohol (pKa = 15.5), which is in turn more acidic than the fully saturated (sp3 carbons only) n-propyl alcohol (pKa = 16.1).


Propargyl alcohol is produced by the copper-catalysed addition of formaldehyde to acetylene as a by-product of the industrial synthesis of but-2-yne-1,4-diol. It can also be prepared by dehydrochlorination of 3-chloro-2-propen-1-ol by NaOH.


Propargyl alcohol is a flammable liquid, toxic by inhalation, highly toxic by ingestion, toxic by skin absorption, and corrosive.[citation needed]

See also

This page was last updated at 2023-12-06 23:46 UTC. Update now. View original page.

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