2,3-Butanediol

2,3-Butanediol is the organic compound with the formula (CH₃CHOH)₂. It is classified as a vic-diol (glycol). It exists as three stereoisomers, a chiral pair and the meso isomer. All are colorless liquids. Applications include precursors to various plastics and pesticides.

2,3-Butanediol

2,3-butanediol
Names
Preferred IUPAC name Butane-2,3-diol
Other names 2,3-Butylene glycol Pseudobutylene glycol 2,3-Dihydroxybutane Butan-2,3-diol Diethanol[citation needed] & Bis-ethanol
Identifiers
CAS Number	513-85-9 Y 19132-06-0 (2S,3S)-(+) Y 24347-58-8 (2R,3R)-(−) Y 5341-95-7 (2R,3S) Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:62064 N
ChEMBL	ChEMBL2312529
ChemSpider	257 Y
ECHA InfoCard	100.007.431
EC Number	208-173-6
PubChem CID	262
UNII	45427ZB5IJ Y 7E9UXG71S1 (2S,3S)-(+) Y OR02B2286A (2R,3R)-(−) Y F5IA8X9O8M (2R,3S) Y
CompTox Dashboard (EPA)	DTXSID8041321
InChI InChI=1S/C4H10O2/c1-3(5)4(2)6/h3-6H,1-2H3 Key: OWBTYPJTUOEWEK-UHFFFAOYSA-N
SMILES CC(C(C)O)O
Properties
Chemical formula	C4H10O2
Molar mass	90.122 g·mol−1
Appearance	Colorless liquid
Odor	odorless
Density	0.987 g/mL
Melting point	19 °C (66 °F; 292 K)
Boiling point	177 °C (351 °F; 450 K)
Solubility in water	Miscible
Solubility in other solvents	Soluble in alcohol, ketones, ether
log P	−0.92
Vapor pressure	0.23 hPa (20 °C)
Acidity (pKa)	14.9
Refractive index (nD)	1.4366
Thermochemistry
Heat capacity (C)	213.0 J/K mol
Std enthalpy of formation (ΔfH⦵298)	−544.8 kJ/mol
Hazards
NFPA 704 (fire diamond)	1 1 0
Flash point	85 °C (185 °F; 358 K)
Autoignition temperature	402 °C (756 °F; 675 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	5462 mg/kg (rat, oral)
Related compounds
Related butanediols	1,4-Butanediol 1,3-Butanediol
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

Isomerism

Of the three stereoisomers, two are enantiomers (levo- and dextro-2,3-butanediol) and one is a meso compound.^[1][2] The enantiomeric pair have (2R, 3R) and (2S, 3S) configurations at carbons 2 and 3, while the meso compound has configuration (2R, 3S) or, equivalently, (2S, 3R).

Industrial production and uses

2,3-Butanediol is prepared by hydrolysis of 2,3-epoxybutane:^[3]

(CH₃CH)₂O + H₂O → CH₃(CHOH)₂CH₃

The isomer distribution depends on the stereochemistry of the epoxide.

The meso isomer is used to combine with naphthalene-1,5-diisocyanate. The resulting polyurethane is called "Vulkollan".^[3]

Biological production

The (2R,3R)-stereoisomer of 2,3-butanediol is produced by a variety of microorganisms in a process known as butanediol fermentation.^[4] It is found naturally in cocoa butter, in the roots of Ruta graveolens, sweet corn, and in rotten mussels. It is used in the resolution of carbonyl compounds in gas chromatography.^[5]

During World War II research was done towards producing 2,3-butanediol by fermentation in order to produce 1,3-butadiene, the monomer of the polybutadiene used in a leading type of synthetic rubber.^[6] It can be derived from the fermentation of sugarcane molasses.^[7]

Fermentative production of 2,3-butanediol from carbohydrates involves a network of biochemical reactions that can be manipulated to maximize production.^[8]

2,3-butanediol has been proposed as a rocket fuel that could be created on Mars by means of cyanobacteria and E. coli, shipped from Earth, working on resources available at the surface of Mars.^[9]

2,3-Butanediol has been detected, in peppers, grape wine, anatidaes.

Reactions

2,3-Butanediol undergo dehydration to form butanone (methyl ethyl ketone):^[10]

(CH₃CHOH)₂ → CH₃C(O)CH₂CH₃ + H₂O

It can also undergo deoxydehydration to form butene:^[11]

(CH₃CHOH)₂ + 2 H₂ → C₄H₈ + 2 H₂O