2-Butanol

Butan-2-ol
2-Butanol	2-Butanol
Names
	IUPAC name Butan-2-ol
	Other names 2-Butanol; sec-Butanol; sec-Butyl alcohol
Identifiers
CAS Number	78-92-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:35687;
ChEMBL	ChEMBL45462 ;
ChemSpider	6320 ;
DrugBank	DB02606;
ECHA InfoCard	100.001.053
PubChem CID	6568;
RTECS number	EO1750000;
UN number	1120
CompTox Dashboard (EPA)	DTXSID9021762 ;
	InChI InChI=1S/C4H10O/c1-3-4(2)5/h4-5H,3H2,1-2H3 Key: BTANRVKWQNVYAZ-UHFFFAOYSA-N ; InChI=1/C4H10O/c1-3-4(2)5/h4-5H,3H2,1-2H3 Key: BTANRVKWQNVYAZ-UHFFFAOYAZ;
	SMILES OC(C)CC;
Properties
Chemical formula	C4H10O
Molar mass	74.122 g/mol
Density	0.8063 g/cm3 (20 °C)
Melting point	−114.7 °C (−174.5 °F; 158.5 K)
Boiling point	99 °C (210 °F; 372 K)
Solubility in water	35 g/100 ml (20 °C) 29 g/100 ml (25 °C)
Refractive index (nD)	1.3978 (20 °C)
Hazards
NFPA 704 (fire diamond)	1 3 0
Flash point	24 °C (75 °F)
Explosive limits	1.7–9.0%
Related compounds
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

2-Butanol, or sec-butanol, is an organic compound with formula C H₃CH(OH)CH₂CH₃. This secondary alcohol is a flammable, colorless liquid that is soluble in 12 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.^[5]

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 sec-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. As petty of an error as this may seem, teachers and students have been frustrated by the error for years. ^[4]

Safety

Several explosions have been reported^[6] 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.

References

^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X, 1541
^ Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. C-192. ISBN 0-8493-0462-8..
^ ^a ^b 2-Butanol, International Chemical Safety Card 0112, Geneva: International Programme on Chemical Safety, April 2005.
^ ^a ^b The Water Solubility of 2-butanol: A widespread Error by Donald B. Alger of California State University
^ Hahn, Heinz-Dieter; Dämbkes, Georg; Rupprich, Norbert. "Butanols". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. ISBN 978-3527306732..
^ Doyle, R. R. (1986). "2-Butanol safety warning". Journal of Chemical Education. 63 (2): 186. doi:10.1021/ed063p186.2., and references cited therein.

External links

International Chemical Safety Card 0112
NIOSH Pocket Guide to Chemical Hazards. "#0077". National Institute for Occupational Safety and Health (NIOSH).
IPCS Environmental Health Criteria 65: Butanols: four isomers
IPCS Health and Safety Guide 4: 2-Butanol

[1] The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X, 1541

[2] Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. C-192. ISBN 0-8493-0462-8..

[ICSC-3] 2-Butanol, International Chemical Safety Card 0112, Geneva: International Programme on Chemical Safety, April 2005.

[ReferenceA-4] The Water Solubility of 2-butanol: A widespread Error by Donald B. Alger of California State University

[5] Hahn, Heinz-Dieter; Dämbkes, Georg; Rupprich, Norbert. "Butanols". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. ISBN 978-3527306732..

[6] Doyle, R. R. (1986). "2-Butanol safety warning". Journal of Chemical Education. 63 (2): 186. doi:10.1021/ed063p186.2., and references cited therein.

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