| tert-Butanol | |
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2-Methylpropan-2-ol[1] |
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Other names
tert-Butyl alcohol Dimethylethanol |
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| Identifiers | |
| CAS number | 75-65-0 |
| PubChem | 6386 |
| ChemSpider | 6146 |
| UNII | MD83SFE959 |
| EC number | 200-889-7 |
| UN number | 1120 |
| DrugBank | DB03900 |
| MeSH | tert-Butyl+Alcohol |
| ChEBI | CHEBI:45895 |
| ChEMBL | CHEMBL16502 |
| RTECS number | EO1925000 |
| Beilstein Reference | 906698 |
| Gmelin Reference | 1833 |
| 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 |
| Appearance | Colorless liquid |
| Odor | Camphorous |
| Density | 780.9 mg cm−3 |
| Melting point |
25-26 °C, 298-299 K, 77-79 °F |
| Boiling point |
82-83 °C, 355-356 K, 179-181 °F |
| log P | 0.584 |
| Vapor pressure | 4.1 kPa (at 20 °C) |
| Refractive index (nD) | 1.387 |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−360.04–−358.36 kJ mol−1 |
| Std enthalpy of combustion ΔcH |
−2.64479–−2.64321 MJ mol−1 |
| Standard molar entropy S |
189.5 J K−1 mol−1 |
| Specific heat capacity, C | 215.37 J K−1 mol−1 |
| Hazards | |
| MSDS | inchem.org |
| GHS pictograms | |
| GHS signal word | DANGER |
| GHS hazard statements | H225, H319, H332, H335 |
| GHS precautionary statements | P210, P261, P305+351+338 |
| EU Index | 603-005-00-1 |
| EU classification | F Xn |
| R-phrases | R11, R20, R36/37 |
| S-phrases | (S2), S9, S16, S46 |
| NFPA 704 |
3
1
0
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| Flash point | 11 °C |
| Autoignition temperature |
480 °C |
| Explosive limits | 2.4–8.0% |
| Related compounds | |
| Related butanols | 2-Butanol |
| Related compounds | 2-Methyl-2-butanol |
| (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 | |
tert-Butanol, or 2-methyl-2-propanol, is the simplest tertiary alcohol. It is one of the four isomers of butanol. tert-Butanol is a clear liquid (or a colorless solid, depending on the ambient temperature) with a camphor-like odor. It is very soluble in water and miscible with ethanol and diethyl ether. It is unique among the isomers of butanol because it tends to be a solid at room temperature, with a melting point slightly above 25 °C.
Contents |
tert-Butanol is derived commercially from isobutane as a co-product of propylene oxide production. It can also be produced by the catalytic hydration of isobutylene.
tert-Butanol is used as a solvent, as a denaturant for ethanol, as an ingredient in paint removers, as an octane booster for gasoline, as an oxygenate gasoline additive, and as an intermediate in the synthesis of other chemical commodities such as MTBE, ETBE, TBHP, other flavors and perfumes.
As a tertiary alcohol, tert-butanol is more stable to oxidation and less reactive than the other isomers of butanol.
When tert-butanol is deprotonated with a strong base, the product is an alkoxide anion. In this case, it is tert-butoxide. For example, the commonly used organic reagent potassium tert-butoxide is prepared by refluxing dry tert-butanol with potassium metal.[2]
The tert-butoxide species is itself useful as a strong, non-nucleophilic base in organic chemistry. It is able to abstract acidic protons from the substrate molecule readily, but its steric bulk inhibits the group from participating in nucleophilic substitution, such as in a Williamson ether synthesis or an SN2 reaction.
tert-Butanol reacts with hydrogen chloride to form tert-butyl chloride and water via an SN1 mechanism.
The overall reaction, therefore, is:
Because tert-butanol is a tertiary alcohol, the relative stability of the tert-butyl carbocation in the Step 2 allows the SN1 mechanism to be followed. Primary alcohols generally undergo an SN2 mechanism because the relative stability of a primary carbocation intermediate is very low. The tertiary carbocation in this case is stabilized through hyperconjugation where the neighboring C–H sigma bonds donate electrons into the empty p-orbital of the carbocation.
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