- Pivalic acid
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Pivalic acid 
Dimethylpropanoic acidOther namesNeopentanoic acid, trimethylacetic acidIdentifiers CAS number 75-98-9 
PubChem 6417 ChemSpider 6177 ChEBI CHEBI:45133 Jmol-3D images Image 1 - O=C(O)C(C)(C)C
- InChI=1S/C5H10O2/c1-5(2,3)4(6)7/h1-3H3,(H,6,7)
Key: IUGYQRQAERSCNH-UHFFFAOYSA-N
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
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)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.
Contents
Preparation
Industrial route
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]
Laboratory methods
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
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
Like most carboxylic acids pivalic acid is a mild irritant and only weakly toxic (oral LD50 = 900 mg/kg for rats).
References
- ^ Wilhelm Riemenschneider “Carboxylic Acids, Aliphatic” Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a05_235.
- ^ Friedel and Silva, Ber. 6, 146, 826 (1873).
- ^ Butlerow, Ann. 165, 322 (1873).
- ^ S. V. Puntambeker, E. A. Zoellner, L. T. Sandborn, and E. W. Bousquet (1941), "Trimethylacetic acid from tert.- Butyl Chloride", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0524; Coll. Vol. 1: 524
- ^ L. T. Sandborn and E. W. Bousquet (1941), "Trimethylacetic acid from Pinacolone", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0524; Coll. Vol. 1: 524
Categories:- Carboxylic acids
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