Pivalic acid

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Pivalic acid
Pivalic acid.svg Pivalic-acid-3D-balls.png
Identifiers
CAS number 75-98-9 YesY
PubChem 6417
ChemSpider 6177 YesY
ChEBI CHEBI:45133 YesY
ChEMBL CHEMBL322719 YesY
Jmol-3D images Image 1
Properties
Molecular formula C5H10O2
Molar mass 102.132 g/mol
Density 0.905 g/cm3
Melting point 35 °C
Boiling point 163.7 °C
Related compounds
Related compounds neopentyl alcohol
neopentane
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

Pivalic acid is a carboxylic acid with a molecular formula of (CH3)3CCO2H. This colourless, odiferous organic compound is solid at room temperature.

Preparation[edit]

Industrial route[edit]

Pivalic acid is prepared by “hydrocarboxylation” of isobutene via the Koch reaction:

(CH3)2C=CH2 + CO + H2O → (CH3)3CCO2H

Such reactions require an acid catalyst such as hydrogen fluoride. tert-Butyl alcohol and isobutyl alcohol can also be used in place of isobutene. Globally, several million kilograms are produced annually.[1] Pivalic acid is also economically recovered as a by-product from the production of semi-synthetic penicillins like ampicillin and amoxycillin.

Laboratory methods[edit]

It was originally prepared by the oxidation of pinacolone with chromic acid[2] and by the hydrolysis of tert-butyl cyanide.[3] Convenient laboratory routes proceed via t-butyl chloride via carbonation of the Grignard reagent[4] and by oxidation of pinacalone.[5]

Applications[edit]

Relative to esters of most carboxylic acids, esters of pivalic acid are unusually resistant to hydrolysis. Some applications result from this thermal stability. Polymers derived from pivalate esters of vinyl alcohol are highly reflective lacquers. The pivaloyl (abbreviated piv or pv) group is a protective group for alcohols in organic synthesis.

Safety[edit]

Like most carboxylic acids pivalic acid is a mild irritant and only weakly toxic (oral LD50 = 900 mg/kg for rats).

References[edit]

  1. ^ Wilhelm Riemenschneider “Carboxylic Acids, Aliphatic” in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a05_235.
  2. ^ Friedel and Silva, Ber. 6, 146, 826 (1873).
  3. ^ Butlerow, Ann. 165, 322 (1873).
  4. ^ S. V. Puntambeker, E. A. Zoellner, L. T. Sandborn, and E. W. Bousquet (1941), "Trimethylacetic acid from tert.- Butyl Chloride", Org. Synth. ; Coll. Vol. 1: 524 
  5. ^ L. T. Sandborn and E. W. Bousquet (1941), "Trimethylacetic acid from Pinacolone", Org. Synth. ; Coll. Vol. 1: 524