| 2-Butanol | |
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Butan-2-ol[1] |
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Other names
sec-Butanol |
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| Identifiers | |
| CAS number | 78-92-2 , 14898-79-4 (R), 4221-99-2 (S) |
| PubChem | 6568, 84682 (R), 444683 (S) |
| ChemSpider | 6320 , 76392 (R) , 392543 (S) |
| EC number | 201-158-5 |
| UN number | 1120 |
| DrugBank | DB02606 |
| MeSH | 2-butanol |
| ChEBI | CHEBI:35687 |
| ChEMBL | CHEMBL45462 |
| RTECS number | EO1750000 |
| Beilstein Reference | 773649 1718764 (R) |
| Gmelin Reference | 1686 396584 (R) |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C4H10O |
| Molar mass | 74.12 g mol−1 |
| Exact mass | 74.073164942 g mol−1 |
| Density | 0.808 g cm−3 |
| Melting point |
-115 °C, 158 K, -175 °F |
| Boiling point |
98-100 °C, 371-373 K, 208-212 °F |
| Solubility in water | 290 g dm−3[2] |
| log P | 0.683 |
| Vapor pressure | 1.67 kPa (at 20 °C) |
| Refractive index (nD) | 1.3978 (at 20 °C) |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−343.3–−342.1 kJ mol-1 |
| Std enthalpy of combustion ΔcH |
−2.6611–−2.6601 MJ mol−1 |
| Standard molar entropy S |
213.1 J K-1 mol−1 |
| Specific heat capacity, C | 197.1 J K−1 mol−1 |
| Hazards | |
| MSDS | inchem.org |
| GHS pictograms | |
| 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 | Xi |
| R-phrases | R10, R36/37, R67 |
| S-phrases | (S2), S7/9, S13, S24/25, S26, S46 |
| NFPA 704 |
3
1
0
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| Flash point | 22–27 °C |
| Autoignition temperature |
405 °C |
| Explosive limits | 1.7–9.8% |
| Related compounds | |
| Related butanols | n-Butanol Isobutanol tert-Butanol |
| Related compounds | Butanone |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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 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.
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Contents |
2-Butanol is manufactured industrially by the hydration of 1-butene or 2-butene:
Sulfuric acid is used as a catalyst for this conversion.[3]
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.
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.[2]
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.
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