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Tert-Butyl alcohol
Tert-Butyl alcohol
Tert-Butyl alcohol
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tert-Butyl alcohol
Skeletal formula of tert-butyl alcohol
Skeletal formula of tert-butyl alcohol
Ball and stick model of tert-butyl alcohol
Ball and stick model of tert-butyl alcohol
Sample of partially crystallized tert-butyl alcohol
Sample of partially crystallized tert-butyl alcohol
Names
Preferred IUPAC name
2-Methylpropan-2-ol
Other names
  • t-Butyl alcohol
  • tert-Butanol
  • t-Butanol
  • t-BuOH
  • Trimethyl carbinol[1]
  • Tertiary butanol
  • 2-Methyl-2-propanol
  • 2M2P
Identifiers
3D model (JSmol)
906698
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.809 Edit this at Wikidata
EC Number
  • 200-889-7
1833
MeSH tert-Butyl+Alcohol
RTECS number
  • EO1925000
UNII
UN number 1120
  • InChI=1S/C4H10O/c1-4(2,3)5/h5H,1-3H3 checkY
    Key: DKGAVHZHDRPRBM-UHFFFAOYSA-N checkY
  • CC(C)(C)O
Properties
C4H10O
Molar mass 74.123 g·mol−1
Appearance Colorless solid
Odor Camphorous
Density 0.775 g/mL
Melting point 25 to 26 °C; 77 to 79 °F; 298 to 299 K
Boiling point 82 to 83 °C; 179 to 181 °F; 355 to 356 K
miscible[2]
log P 0.584
Vapor pressure 4.1 kPa (at 20 °C)
Acidity (pKa) 16.54[3]
5.742×10−5 cm3/mol
1.387
1.31 D
Thermochemistry
215.37 J K−1 mol−1
189.5 J K−1 mol−1
−360.04 to −358.36 kJ mol−1
−2.64479 to −2.64321 MJ mol−1
Hazards
GHS labelling:
GHS02: Flammable GHS07: Exclamation mark
Danger
H225, H319, H332, H335
P210, P261, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 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. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
3
0
Flash point 11 °C (52 °F; 284 K)
480 °C (896 °F; 753 K)
Explosive limits 2.4–8.0%
Lethal dose or concentration (LD, LC):
3559 mg/kg (rabbit, oral)
3500 mg/kg (rat, oral)[4]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 100 ppm (300 mg/m3)[1]
REL (Recommended)
 TWA 100 ppm (300 mg/m3) ST 150 ppm (450 mg/m3)[1]
IDLH (Immediate danger)
 1600 ppm[1]
Safety data sheet (SDS) inchem.org
Related compounds
Related butanols
 2-Butanol

n-Butanol
Isobutanol

Related compounds
 2-Methyl-2-butanol
Trimethylsilanol

Nonafluoro-tert-butyl alcohol

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

tert-Butyl alcohol is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). Its isomers are 1-butanol, isobutanol, and 2-butanol. tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor. It is miscible with water, ethanol and diethyl ether.

Natural occurrence

[edit]

tert-Butyl alcohol has been identified in beer and chickpeas.[5] It is also found in cassava,[6] which is used as a fermentation ingredient in certain alcoholic beverages.

Preparation

[edit]

tert-Butyl alcohol is derived commercially from isobutane as a coproduct of propylene oxide production. It can also be produced by the catalytic hydration of isobutylene, or by a Grignard reaction between acetone and methylmagnesium chloride.

Purification cannot be performed by simple distillation due to formation of an azeotrope with water, although initial drying of the solvent containing large amounts of water is performed by adding benzene to form a tertiary azeotrope and distilling off the water. Smaller amounts of water are removed by drying with calcium oxide (CaO), potassium carbonate (K2CO3), calcium sulfate (CaSO4), or magnesium sulfate (MgSO4), followed by fractional distillation. Anhydrous tert-butyl alcohol is obtained by further refluxing and distilling from magnesium activated with iodine, or alkali metals such as sodium or potassium. Other methods include the use of 4 Å molecular sieves, aluminium tert-butylate, calcium hydride (CaH2), or fractional crystallization under inert atmosphere.[7]

Applications

[edit]

tert-Butyl alcohol is used as a solvent, ethanol denaturant, paint remover ingredient, and gasoline octane booster and oxygenate. It is a chemical intermediate used to produce methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) by reaction with methanol and ethanol, respectively, and tert-butyl hydroperoxide (TBHP) by reaction with hydrogen peroxide.

Reactions

[edit]

Unlike other isomers of butanol, tert-butyl alcohol, as a tertiary alcohol, has no hydrogen atom next to hydroxy-group, which makes it resistant to oxidation to carbonyl compounds.

tert-Butyl alcohol is deprotonated with a strong base to give the alkoxide. Particularly common is potassium tert-butoxide, which is prepared by treating tert-butanol with potassium metal.[8]

K + t-BuOH → t-BuO−K+ + ⁠1/2⁠ H2

The tert-butoxide is a strong, non-nucleophilic base in organic chemistry. It readily abstracts acidic protons from substrates, but its steric bulk inhibits the group from participating in nucleophilic substitution, such as in a Williamson ether synthesis or an SN2 reaction.

tert-Butyl alcohol reacts with hydrogen chloride to form tert-butyl chloride.

O-Chlorination of tert-butyl alcohol with hypochlorous acid to give tert-butyl hypochlorite:[9]

(CH3)3COH + HOCl → (CH3)3COCl + H2O

Pharmacology and toxicology

[edit]

There is limited data on the pharmacology and toxicology of tert-butanol in humans and other animals.[10] Human exposure may occur due to fuel oxygenate metabolism. Tert-butanol is poorly absorbed through skin but rapidly absorbed if inhaled or ingested. Tert-butanol is irritating to skin or eyes. Toxicity of single doses is usually low but high doses of tert-Butyl alcohol can produce a sedative or anesthetic effect.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Tert-Butyl alcohol

View on Grokipedia
from Grokipedia
Tert-butyl alcohol, also known as tert-butanol or 2-methylpropan-2-ol, is a tertiary alcohol with the molecular formula C₄H₁₀O, consisting of a central carbon atom bonded to three methyl groups and a hydroxyl group. It appears as a colorless or crystalline with a camphor-like , has a of approximately 25.7 °C and a of 82.4 °C, and is miscible with , , and . Tert-butyl alcohol is primarily produced industrially through the acid-catalyzed hydration of isobutene (2-methylpropene), often using sulfuric acid, and as a coproduct or byproduct in the synthesis of propylene oxide via isobutane oxidation or in the production of methyl tert-butyl ether (MTBE). Its high production volume exceeded 1 billion pounds annually in the United States as of 2012, reflecting its importance in chemical manufacturing. As a versatile , tert-butyl alcohol finds extensive industrial applications in coatings, adhesives, cleaning products, and lubricants due to its properties and oxidative stability; it is also used as a additive to enhance oxygen content and reduce emissions, in the extraction of pharmaceuticals and drugs, and in the manufacture of perfumes, flavors, and peroxides. Additionally, it serves as a denaturant for ethyl alcohol and a chemical intermediate in processes like the production of methyl methacrylate. Tert-butyl alcohol is classified as highly flammable with a of 11 °C and poses risks of serious eye irritation, irritation, and irritation upon exposure; inhalation or ingestion can cause drowsiness, , or narcotic effects at high concentrations. It exhibits low (oral LD₅₀ > 3,500 mg/kg in rats) and low potential for (log Kₒw = 0.35), is inherently biodegradable, and is not considered mutagenic, genotoxic, or carcinogenic to humans, though species-specific effects have been observed in animal studies. Occupational exposure limits include an OSHA PEL of 100 ppm (8-hour ) to ensure safe handling with proper ventilation and .

Properties

Physical properties

Tert-butyl alcohol has the molecular formula C₄H₁₀O and a molecular weight of 74.12 g/mol. It appears as a or crystalline at , possessing a mild camphor-like . Due to its relatively high , it exists as a below 25.7 °C and as a above this , with a of 82.4 °C. The compound exhibits a density of 0.786 g/cm³ at 20 °C and a refractive index of 1.387. These optical and volumetric properties reflect its non-aromatic, branched structure, which influences light refraction and mass distribution in the liquid phase. Tert-butyl alcohol is fully miscible with water, ethanol, and diethyl ether, indicating strong intermolecular interactions with polar solvents. Its octanol-water partition coefficient (log P) is 0.35, signifying moderate hydrophilicity balanced by limited lipophilicity. Key thermodynamic properties include a heat of vaporization of 41.7 kJ/mol at the and a of approximately 2.95 J/g·K at 25 °C.
PropertyValueConditionsSource
Molecular C₄H₁₀O-PubChem
Molecular weight74.12 g/mol-PubChem
Melting point25.7 °C1 PubChem
82.4 °C1 PubChem
Density0.786 g/cm³20 °CPubChem
1.38720 °C (D line)Sigma-Aldrich
in Miscible20 °CPubChem
log P (octanol-)0.35-PubChem
Heat of vaporization41.7 kJ/molCAMEO Chemicals
()2.95 J/g·K25 °CNIST WebBook

Chemical properties

Tert-butyl alcohol, with the IUPAC name 2-methylpropan-2-ol and CAS number 75-65-0, is a tertiary alcohol characterized by a central carbon atom bonded to three methyl groups and a hydroxyl group. This structural arrangement results in significant steric hindrance around the hydroxyl group, which reduces its reactivity in reactions (such as SN2) compared to primary and secondary alcohols; however, it undergoes elimination reactions like more readily under acidic conditions due to the formation of a stable tertiary carbocation. The hydroxyl group in tert-butyl alcohol exhibits weak acidity, with a pKa value of approximately 18, making it less acidic than primary alcohols like (pKa ~15.9) due to the electron-donating effect of the three alkyl groups stabilizing the neutral molecule over the . This tertiary nature also confers resistance to oxidation under mild conditions, as there is no attached to the carbon bearing the OH group, preventing formation of a carbonyl product without breaking C-C bonds. Additionally, tert-butyl alcohol forms a minimum-boiling with containing about 12 wt% at 79.9 °C and , complicating its purification by . In (IR) spectroscopy, tert-butyl alcohol displays a characteristic broad O-H stretching absorption band centered around 3400 cm⁻¹, indicative of hydrogen bonding, along with C-O stretching near 1200 cm⁻¹. The ¹H (NMR) spectrum features a sharp singlet at approximately 1.2 ppm for the nine equivalent methyl protons and a broader, variable singlet around 1.5-2.0 ppm for the hydroxyl proton, reflecting its exchangeable nature.

Sources

Natural occurrence

Tert-butyl alcohol, also known as tert-butanol, occurs naturally in trace amounts in various foods derived from and animals, including fresh apples, , cheese, , , grapes ( species), , feijoa, ( species), walnuts ( species), and wine. These occurrences reflect its presence as a minor volatile compound in natural matrices, often at levels below 1 ppm, contributing to the complex flavor profiles without significant biological roles. In processes, tert-butanol is detected in fusel oils, which are by-products of alcohol , comprising a of higher alcohols including amyl, butyl, and propyl variants; concentrations can reach up to 0.25% in certain liquors. It also appears as an intermediate metabolite during the of methyl tert-butyl (MTBE) by certain aerobic , such as propane-oxidizing strains, where MTBE is first oxidized to tert-butanol before further breakdown, aiding in the natural remediation of contaminated environments. In , tert-butanol serves as a primary of ethyl tert-butyl (ETBE) and MTBE, with exposure leading to its detection in ; for instance, in volunteers exposed to ETBE via inhalation or ingestion, tert-butanol levels in urine correlated with dose, reflecting rapid absorption and partial excretion unchanged. This underscores its minor role as an endogenous alcohol derivative, though endogenous production independent of exposure remains unestablished at significant levels.

Commercial production

The primary industrial method for synthesizing tert-butyl alcohol involves the direct hydration of isobutene, which is obtained as a from cracking and refining processes. This proceeds under acidic conditions, utilizing either concentrated as a homogeneous catalyst or catalysts such as zeolites or ion-exchange resins to achieve high selectivity and yields exceeding 95%. The process typically operates in a fixed-bed reactor or via catalytic distillation, where isobutene is absorbed into an aqueous solution or contacted with over the catalyst at temperatures of 50–100°C and pressures of 10–30 bar, minimizing oligomerization side reactions. The balanced equation for the hydration is: (\ceCH3)2\ceC=CH2+\ceH2O→(\ceCH3)3\ceCOH(\ce{CH3})_2\ce{C=CH2} + \ce{H2O} \rightarrow (\ce{CH3})_3\ce{COH} This method accounts for the majority of global production due to its efficiency and integration with existing petrochemical streams. An alternative production route generates tert-butyl alcohol as a coproduct in the manufacture of propylene oxide via the tert-butyl hydroperoxide (TBHP) process. In this pathway, TBHP—derived from the air oxidation of isobutane or tert-butyl alcohol itself—is reacted with propylene in the presence of a titanium-silicalite catalyst to form propylene oxide and tert-butyl alcohol in a 1:1 molar ratio, with overall yields around 90–95%. This co-production approach, commercialized since the 1990s, links tert-butyl alcohol output to the expanding propylene oxide market and avoids the need for separate dehydration steps. Indirect routes from acetone, such as through TBHP intermediates, are less common but contribute marginally in integrated facilities. Global production capacity for tert-butyl alcohol reached approximately 2 million metric tons annually by 2025, driven by demand in fuel additives and solvents, with key facilities operated by companies like LyondellBasell in the United States and integrated plants in China and other Asian regions. Economic viability hinges on feedstock costs from C4 streams and co-product credits, with process optimizations focusing on energy efficiency. Post-reaction, the crude tert-butyl alcohol mixture (typically 70–90% concentration) undergoes purification via multi-stage distillation, often incorporating extractive agents like glycerol to break the water azeotrope and attain 99.5% purity suitable for commercial grades. In zeolite-catalyzed processes, catalyst regeneration through washing and thermal treatment enables recycling rates over 95%, reducing operational costs, while distillation energy demands—around 1–2 GJ per ton—are mitigated by heat recovery systems.

Applications

Industrial applications

Tert-butyl alcohol serves as a versatile in various chemical processes, particularly in the production of paints, coatings, and resins, owing to its ability to dissolve both polar and non-polar substances effectively while exhibiting relatively low compared to other industrial solvents. Its use in water-based paints as a solubilizer enhances formulation stability, and it aids in dewaxing lubricant oils, contributing to efficient industrial cleaning and processing. This low-toxicity profile, supported by its biodegradability, positions it as a preferred in these applications, minimizing environmental impact during . In the fuel industry, tert-butyl alcohol functions as an additive in , blended up to 15% by volume to boost octane ratings and reduce harmful emissions such as and unburned hydrocarbons. It has emerged as an acceptable alternative to methyl tert-butyl ether (MTBE) in certain regions, where regulatory waivers allow its use under similar blending limits to promote cleaner without the contamination risks associated with MTBE. This role supports compliance with emission standards while maintaining performance in spark-ignition engines. As a key chemical intermediate, tert-butyl alcohol is essential in the synthesis of tert-butyl esters, , and fragrances, enabling the production of initiators, alkylating agents, and components. For instance, it reacts with carboxylic acids to form tert-butyl esters used in protecting groups during , and with to yield tert-butyl hydroperoxide for industrial oxidation processes. In fragrance manufacturing, it contributes to essences and formulations, enhancing scent stability. Additionally, tert-butyl alcohol finds application in pharmaceutical synthesis as a solvent and in lyophilization processes to improve drug formulation stability, and as a denaturant for to render it unfit for consumption in industrial alcohol products. Its role in these sectors underscores its utility in high-purity chemical production. The global market for tert-butanol was valued at approximately USD 732 million in 2025, with growth driven by increasing demand for solutions in sustainable manufacturing.

Other applications

In cosmetics and personal care products, tert-butyl alcohol serves primarily as a and fragrance ingredient, aiding in the formulation of perfumes, colognes, hair sprays, lotions, and nail polishes. The Cosmetic Ingredient Review (CIR) Expert Panel assessed its in , finalizing the conclusion in October 2024 that it is safe for use in at current concentrations, with reported levels up to 0.91% in lotions and a margin of safety of 50,000 based on dermal absorption data. Its low profile further supports these applications without significant risks at typical exposure levels. As a pharmaceutical , tert-butyl alcohol is employed in systems, particularly in lyophilization (freeze-drying) processes to enhance the of hydrophobic drugs, improve product stability, and reduce reconstitution times. It functions as a biodegradable in due to its low and environmental compatibility, aligning with sustainable practices in the industry. Emerging applications include its derivatives as electrolyte components in lithium-ion batteries; for instance, lithium nonafluoro-tert-butoxide acts as an additive to enable high-voltage operation in LiNi0.5Mn1.5O4- cells by stabilizing the interface. Additionally, perfluoro-tert-butyl alcohol derivatives, such as bis(perfluoro-tert-butyl) , contribute to nonflammable s for improved battery safety and performance. In settings, tert-butyl alcohol is widely used as an analytical and for its purity and compatibility in classical applications. Historically, tert-butyl alcohol has been incorporated into perfumery to mask undesirable odors in formulations and enhance overall scent profiles. It also plays a minor role as a flavoring agent in food additives, where trace amounts influence product taste without dominating the sensory experience.

Reactions

Elimination reactions

Tert-butyl alcohol primarily undergoes elimination reactions through to produce isobutene (2-methylpropene) and , represented by the equation (CH3)3COH→(CH3)2C=CH2+H2O(CH_3)_3COH \rightarrow (CH_3)_2C=CH_2 + H_2O. This process is acid-catalyzed, typically employing concentrated (H2SO4H_2SO_4) at temperatures of 100–140 °C, which facilitates the reaction under controlled conditions to favor formation. The reaction proceeds via an E1 mechanism, owing to the stability of the intermediate tertiary . of the hydroxyl group by the acid forms an alkyloxonium , followed by the departure of water to generate the (CH3)3C+(CH_3)_3C^+, which then loses a proton from an adjacent to yield the . This stepwise unimolecular elimination is particularly efficient for tertiary alcohols like tert-butyl alcohol, where rearrangement is minimal. In industrial applications, this serves as a key method for isobutene production, a valuable feedstock for polymers and chemicals, achieving selectivities exceeding 99% and conversions over 95% under optimized conditions. Alternative approaches include at higher temperatures (above 200 °C) without catalysts or the use of catalysts such as alumina, which enable cleaner, more selective processes at 200–450 °C by avoiding handling and reducing . Side products are minimal, as the tertiary strongly favors elimination over competing substitution pathways.

Other reactions

Due to its tertiary structure, tert-butyl alcohol resists oxidation under mild conditions, as there is no attached to the alpha carbon for dehydrogenation. However, exposure to strong oxidants like (KMnO₄) in acidic media can induce to isobutene, followed by oxidative cleavage of the , yielding acetone and as products. (\ceCH3)3\ceCOH→\ceH+\ce(CH3)2C=CH2+H2O→\ceKMnO4,H+\ce(CH3)2C=O+CO2(\ce{CH3})_3\ce{COH} \xrightarrow{\ce{H+}} \ce{(CH3)2C=CH2 + H2O} \xrightarrow{\ce{KMnO4, H+}} \ce{(CH3)2C=O + CO2}
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