2-Butanol

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2-Butanol
Skeletal formula of 2-butanol
Identifiers
CAS number 78-92-2 YesY, 14898-79-4 (R), 4221-99-2 (S)
PubChem 6568, 84682 (R), 444683 (S)
ChemSpider 6320 YesY, 76392 (R) YesY, 392543 (S) YesY
EC number 201-158-5
UN number 1120
DrugBank DB02606
MeSH 2-butanol
ChEBI CHEBI:35687 YesY
ChEMBL CHEMBL45462 YesY
RTECS number EO1750000
Beilstein Reference 773649

1718764 (R)
1718763 (S)

Gmelin Reference 1686

396584 (R)
25655 (S)

Jmol-3D images Image 1
Properties
Molecular 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[2]
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
Hazards
MSDS inchem.org
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word WARNING
GHS hazard statements H226, H319, H335, H336
GHS precautionary statements P261, P305+351+338
EU Index 603-127-00-5
EU classification Irritant Xi
R-phrases R10, R36/37, R67
S-phrases (S2), S7/9, S13, S24/25, S26, S46
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 22–27 °C
Explosive limits 1.7–9.8%
Related compounds
Related butanols n-Butanol
Isobutanol
tert-Butanol
Related compounds Butanone
Except where noted otherwise, 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-butan-2-ol 2D skeletal.png
S-butan-2-ol 2D skeletal.png
R-Butan-2-ol-3D-balls.png
S-Butan-2-ol-3D-balls.png
(R)-(−)-2-butanol
(S)-(+)-2-butanol

Manufacture and applications[edit]

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

But-2-ene-hydration-2D-skeletal.png

Sulfuric acid is used as a catalyst for this conversion.[3]

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[edit]

The solubility of 2-butanol is incorrect in most sources,[2] 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[edit]

Several explosions have been reported[4] 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[edit]

  1. ^ "2-butanol - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 12 October 2011. 
  2. ^ a b Alger, Donald B. (November 1991). "The water solubility of 2-butanol: A widespread error". Journal of Chemical Education (USA: ACS Publications) 68 (11): 939. doi:10.1021/ed068p939.1. Retrieved 12 October 2011. 
  3. ^ Hahn, Heinz-Dieter; Dämbkes, Georg; Rupprich, Norbert (2005), "Butanols", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH .
  4. ^ 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[edit]