tert-Butyl alcohol

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tert-Butyl alcohol
Skeletal formula of tert-butyl alcohol
Ball and stick model of 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
  • Trimethyl carbinol[1]
  • 2-Methyl-2-propanol
  • 2M2P
Identifiers
3D model (JSmol)
906698
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.000.809
EC Number 200-889-7
1833
MeSH tert-Butyl+Alcohol
RTECS number EO1925000
UNII
UN number 1120
Properties
C4H10O
Molar mass 74.12 g·mol−1
Appearance Colorless liquid
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]
-57.42·10−6 cm3/mol
1.387
Thermochemistry
215.37 J K−1 mol−1
189.5 J K−1 mol−1
−360.04–−358.36 kJ mol−1
−2.64479–−2.64321 MJ mol−1
Hazards
Safety data sheet 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 DANGER
H225, H319, H332, H335
P210, P261, P305+351+338
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 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]
US health exposure limits (NIOSH):
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]
Related compounds
Related butanols
2-Butanol

n-Butanol
Isobutanol

Related compounds
2-Methyl-2-butanol
Trimethylsilanol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

tert-Butyl alcohol (TBA), also called tert-butanol, is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). It is one of the four isomers of butanol.[5] 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.[6] It is also found in cassava[7] which is used as fermentation ingredient in certain alcoholic beverages.

Preparation[edit]

tert-Butyl alcohol is derived commercially from isobutane as a co-product 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.[8]

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]

As a tertiary alcohol, tert-butyl alcohol is more resistant to oxidation and less reactive than the other isomers of butanol.

When tert-butyl alcohol 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.[9]

K + tBuOH → tBuOK+ + 0.5 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.

It also reacts with sodium in liquid ammonia.

References[edit]

  1. ^ a b c d "NIOSH Pocket Guide to Chemical Hazards #0078". National Institute for Occupational Safety and Health (NIOSH). 
  2. ^ http://www.inchem.org/documents/icsc/icsc/eics0114.htm
  3. ^ Reeve, W.; Erikson, C.M.; Aluotto, P.F. Can. J. Chem, 1979, 57, 2747.
  4. ^ "Tert-Butyl alcohol". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH). 
  5. ^ In tert-butyl alcohol, three methyl groups substitute for three hydrogen atoms in methanol, just as two methyl groups substitute for two hydrogen atoms in isopropyl alcohol, and one methyl group substitutes for one hydrogen atom in ethanol.
  6. ^ http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+50
  7. ^ http://www.sc.mahidol.ac.th/scbc/bc_internet/publication/696.pdf
  8. ^ D.D. Perrin, W.L.F. Armarego (1988). Purification of Laboratory Chemicals (3rd ed.). Pergamon Press Ltd. 
  9. ^ Johnson, W. S.; Schneider, W. P. (1950). "β-Carbethoxy-γ,γ-diphenylvinylacetic acid". Org. Synth. 30: 18. ; Coll. Vol., 4, p. 132 

External links[edit]