1,4-Butynediol

1,4-Butynediol is an organic compound that is an alkyne and a diol. It is a colourless, hygroscopic solid that is soluble in water and polar organic solvents. It is a commercially significant compound in its own right and as a precursor to other products.

1,4-Butynediol^[1]

Names
Preferred IUPAC name But-2-yne-1,4-diol
Other names Butynediol 2-Butyne-1,4-diol 1,4-Dihydroxy-2-butyne
Identifiers
CAS Number	110-65-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:16413 Y
ChEMBL	ChEMBL3187551
ChemSpider	7775 Y
ECHA InfoCard	100.003.445
EC Number	203-788-6
KEGG	C02497 Y
PubChem CID	8066
RTECS number	ES0525000
UNII	AXH202FPQM
UN number	2716
CompTox Dashboard (EPA)	DTXSID4021921
InChI InChI=1S/C4H6O2/c5-3-1-2-4-6/h5-6H,3-4H2 Y Key: DLDJFQGPPSQZKI-UHFFFAOYSA-N Y InChI=1/C4H6O2/c5-3-1-2-4-6/h5-6H,3-4H2 Key: DLDJFQGPPSQZKI-UHFFFAOYAT
SMILES OCC#CCO
Properties
Chemical formula	C4H6O2
Molar mass	86.090 g·mol−1
Appearance	Colorless crystalline solid[2]
Density	1.11 g/cm3 (at 20 °C)[2]
Melting point	58 °C (136 °F; 331 K)[2]
Boiling point	238 °C (460 °F; 511 K)[2]
Solubility in water	3740 g/L[2]
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H312, H314, H317, H331, H373
Precautionary statements	P260, P261, P264, P270, P271, P272, P280, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P312, P314, P321, P322, P330, P333+P313, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	2 1 0
Flash point	~136 °C (277 °F)[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Synthesis

1,4-Butynediol can be produced in the Reppe synthesis, where formaldehyde and acetylene are the reactants:^[3]

2 CH₂O + HC≡CH → HOCH₂CCCH₂OH

Several patented production methods use copper bismuth catalysts coated on an inert material. The normal temperature range for the reaction is 90 °C up to 150 °C, depending on the pressure used for the reaction which can range from 1 to 20 bar.^[4]

Applications

1,4-Butynediol is a precursor to 1,4-butanediol and 2-butene-1,4-diol by hydrogenation. It is also used in the manufacture of certain herbicides, textile additives, corrosion inhibitors, plasticizers, synthetic resins, and polyurethanes. It is the major raw material used in the synthesis of vitamin B₆.^[5] It is also used for brightening, preserving, and inhibiting nickel plating.^[3]

It reacts with a mixture of chlorine and hydrochloric acid to give mucochloric acid, HO₂CC(Cl)=C(Cl)CHO (see mucobromic acid).

Safety

1,4-Butynediol is corrosive and irritates the skin, eyes, and respiratory tract.

See also

• Acetylenedicarboxylic acid (but-2-ynedioic acid, 2-butynedioic acid)
• cis-Butene-1,4-diol
• 2-Butyne (but-2-yne)