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[1]
Odor geranium-like[1]
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)[1]
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)[1]
NIOSH (US health exposure limits):
PEL (Permissible)
REL (Recommended)
TWA 1 ppm (2 mg/m3) [skin][1]
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).
☒N verify (what is checkY☒N ?)

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.[3] 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[4] 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).[5]


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.[6] It can also be prepared by dehydrochlorination of 3-chloro-2-propen-1-ol by NaOH.[7]


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

See also


  1. ^ a b c d e f g h NIOSH Pocket Guide to Chemical Hazards. "#0527". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ Record of Prop-2-yn-1-ol in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 11 March 2020.
  3. ^ Merck Index, 11th Edition, 7819
  4. ^ J. C. Sauer (1956). "Propionaldehyde". Organic Syntheses. 36: 66.; Collective Volume, vol. 4, p. 813
  5. ^ Anslyn, Eric V., 1960- (2006). Modern physical organic chemistry. Dougherty, Dennis A., 1952-. Mill Valley, California: University Science Books. ISBN 1-891389-31-9. OCLC 55600610.((cite book)): CS1 maint: multiple names: authors list (link)
  6. ^ Falbe, Jürgen; Bahrmann, Helmut; Lipps, Wolfgang; Mayer, Dieter. "Alcohols, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_279..
  7. ^ [1] J. Am. Chem. Soc., 1944, 66 (2), pp 285–287