Propargyl alcohol

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.

Propargyl alcohol

3D ball-and-stick structure of propargyl alcohol
Names
Preferred IUPAC name Prop-2-yn-1-ol
Other names propynol, 2-propynol, 2-propyn-1-ol, hydroxymethylacetylene.
Identifiers
CAS Number	107-19-7 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:28905 Y
ChEMBL	ChEMBL1563026
ChemSpider	21106466 Y
ECHA InfoCard	100.003.157
EC Number	203-471-2
KEGG	C05986 Y
PubChem CID	7859
RTECS number	UK5075000
UNII	E920VF499L N
UN number	1986 2929
CompTox Dashboard (EPA)	DTXSID5021883
InChI InChI=1S/C3H4O/c1-2-3-4/h1,4H,3H2 Y Key: TVDSBUOJIPERQY-UHFFFAOYSA-N Y InChI=1/C3H4O/c1-2-3-4/h1,4H,3H2 Key: TVDSBUOJIPERQY-UHFFFAOYAE
SMILES C#CCO
Properties
Chemical formula	C3H4O
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)
Solubility in water	miscible[1]
Vapor pressure	12 mmHg (20 °C)[1]
Hazards[2]
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H226, H301, H310, H314, H330, H373, H411
Precautionary statements	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)	3 3 3
Flash point	36 °C; 97 °F; 309 K (open cup)[1]
NIOSH (US health exposure limits):
PEL (Permissible)	none[1]
REL (Recommended)	TWA 1 ppm (2 mg/m3) [skin][1]
IDLH (Immediate danger)	N.D.[1]
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 YN ?) Infobox references

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 (pK_a = 13.6) compared to its sp²-containing analog allyl alcohol (pK_a = 15.5), which is in turn more acidic than the fully saturated (sp³ carbons only) n-propyl alcohol (pK_a = 16.1).^[5]

Preparation

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]

Safety

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

See also

• Alkynylation
• Allyl alcohol
• Propargyl
• Propargyl chloride