2-Butanol

2-Butanol

Names
IUPAC name Butan-2-ol
Other names sec-Butanol sec-Butyl alcohol, 2-Butanol 2-Butyl alcohol
Identifiers
CAS Number	78-92-2 Y 14898-79-4 (R) Y 4221-99-2 (S) Y
Beilstein Reference	773649 1718764 (R) 1718763 (S)
ChEBI	CHEBI:35687 Y
ChEMBL	ChEMBL45462 Y
ChemSpider	6320 Y 76392 (R) Y 392543 (S) Y
DrugBank	DB02606 Y
EC Number	201-158-5
Gmelin Reference	1686 396584 (R) 25655 (S)
Jmol 3D model	Interactive image
MeSH	2-butanol
PubChem	6568 84682 (R) 444683 (S)
RTECS number	EO1750000
UN number	1120
InChI InChI=1S/C4H10O/c1-3-4(2)5/h4-5H,3H2,1-2H3 Y Key: BTANRVKWQNVYAZ-UHFFFAOYSA-N Y
SMILES CCC(C)O
Properties
Chemical formula	C4H10O
Molar mass	74.12 g·mol−1
Density	0.808 g cm−3
Melting point	−115 °C; −175 °F; 158 K
Boiling point	98 to 100 °C; 208 to 212 °F; 371 to 373 K
Solubility in water	290 g/L
log P	0.683
Vapor pressure	1.67 kPa (at 20 °C)
Refractive index (nD)	1.3978 (at 20 °C)
Thermochemistry
Specific heat capacity (C)	197.1 J K−1 mol−1
Std molar entropy (So298)	213.1 J K−1 mol−1
Std enthalpy of formation (ΔfHo298)	−343.3–−342.1 kJ mol−1
Std enthalpy of combustion (ΔcHo298)	−2.6611–−2.6601 MJ mol−1
Vapor pressure	{{{value}}}
Related compounds
Related butanols	n-Butanol Isobutanol tert-Butanol
Related compounds	Butanone
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

2-Butanol, or sec-butanol, is an organic compound with formula CH₃CH(OH)CH₂CH₃. This secondary alcohol is a flammable, colorless liquid that is soluble in 3 parts water and completely miscible with polar organic solvents such as ethers and other alcohols. It is produced on a large scale, primarily as a precursor to the industrial solvent methyl ethyl ketone. 2-Butanol is chiral and thus can be obtained as either of two stereoisomers designated as (R)-(−)-2-butanol and (S)-(+)-2-butanol. It is normally found as an equal mixture of the two stereoisomers — a racemic mixture.

(R)-(−)-2-butanol	(S)-(+)-2-butanol

Manufacture and applications

2-Butanol is manufactured industrially by the hydration of 1-butene or 2-butene:

Sulfuric acid is used as a catalyst for this conversion.

In the lab it can be prepared via Grignard reaction by reacting ethylmagnesium bromide with acetaldehyde in dried diethyl ether or tetrahydrofuran.

Although some 2-butanol is used as a solvent, it is mainly converted to butanone ("MEK"), which is an important industrial solvent and found in many domestic cleaning agents and paint removers. Volatile esters of 2-butanol have pleasant aromas and are used in small amounts as perfumes or in artificial flavors.

Solubility

The solubility of 2-butanol is incorrect in most sources, including some of the most well-known references such as the Merck Index, the CRC Handbook of Chemistry and Physics, and Lange's Handbook of Chemistry. Even the International Programme on Chemical Safety lists the wrong solubility. This widespread error originated because of Beilstein's Handbuch der Organischen Chemie (Handbook of Organic Chemistry). This work cites a false solubility of 12.5 g/100 ml water. Many other sources used this solubility, which has snowballed into a widespread error in the industrial world. The correct data (35.0 g/100 ml at 20 °C, 29 g/100 ml at 25 °C, and 22 g/100 ml at 30 °C) was first published in 1886 by Alexejew and then similar data was reported by other scientists including Dolgolenko and Dryer in 1907 and 1913, respectively.

Safety

Several explosions have been reported during the conventional distillation of 2-butanol, apparently due to the buildup of peroxides with the boiling point higher than that of pure alcohol (and therefore concentrating in the still pot during distillation). As alcohols, unlike ethers, are not widely known to be capable of forming peroxide impurities, the danger is likely to be overlooked.

External links

• International Chemical Safety Card 0112
• IPCS Environmental Health Criteria 65: Butanols: four isomers
• IPCS Health and Safety Guide 4: 2-Butanol