Pivalic acid

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Pivalic acid
Pivalic acid.svg
Pivalic-acid-3D-balls.png
Names
Preferred IUPAC name
2,2-Dimethylpropanoic acid
Other names
Pivalic acid
Dimethylpropanoic acid
Neopentanoic acid
Trimethylacetic acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.000.839
Properties
C5H10O2
Molar mass 102.132 g/mol
Density 0.905 g/cm3
Melting point 35 °C (95 °F; 308 K)
Boiling point 163.7 °C (326.7 °F; 436.8 K)
Related compounds
Related compounds
neopentyl alcohol
neopentane
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

Pivalic acid is a carboxylic acid with a molecular formula of (CH3)3CCO2H. This colourless, odiferous organic compound is solid at room temperature. The acronym for pivalate is Piv[1] & for pivalic acid it is PivH.

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.[2] 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[3] and by the hydrolysis of tert-butyl cyanide.[4] Convenient laboratory routes proceed via t-butyl chloride via carbonation of the Grignard reagent[5] and by oxidation of pinacolone.[6]

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. Pivalic acid is sometimes used as an internal chemical shift standard for NMR spectra of aqueous solutions. While DSS is more commonly used for this purpose, the minor peaks from protons on the three methylene bridges in DSS can be problematic. The 1H NMR spectrum at 25 °C and neutral pH is a singlet at 1.08 ppm.

Alcohol protection[edit]

Pivaloyl (Pv) group is used as a protecting group in organic synthesis. See for example, it is employed in the preparation of Sivelestat.

Common protection methods include treatment of alcohol with pivaloyl chloride (PvCl) in presence of pyridine.[7]

PvProtectedAlcohol.png

Alternatively, the esters can be prepared using pivaloic anhydride in the presence of Sc(OTf)3 or VO(OTf)2

Common deprotection methods involve hydrolysis with the base or other nucleophiles.[8][9][10][11]

PvProtection.png

References[edit]

  1. ^ http://www.springer.com/cda/content/document/cda_downloaddocument/Abbreviations+9781849730549.pdf?SGWID=0-0-45-932039-p174009688[full citation needed]
  2. ^ Riemenschneider, Wilhelm (2000). "Ullmann's Encyclopedia of Industrial Chemistry". ISBN 3527306730. doi:10.1002/14356007.a05_235.  |chapter= ignored (help)
  3. ^ Friedel and Silva, Ber. 6, 146, 826 (1873).[full citation needed]
  4. ^ Butlerow, Ann. 165, 322 (1873).[full citation needed]
  5. ^ S. V. Puntambeker, E. A. Zoellner, L. T. Sandborn, and E. W. Bousquet (1941). "Trimethylacetic acid from tert.- Butyl Chloride". Org. Synth. doi:10.15227/orgsyn.008.0104. ; Coll. Vol., 1, p. 524 
  6. ^ L. T. Sandborn and E. W. Bousquet (1941). "Trimethylacetic acid from Pinacolone". Org. Synth. doi:10.15227/orgsyn.008.0104. ; Coll. Vol., 1, p. 524 
  7. ^ Robins, Morris J.; Hawrelak, S. D.; Kanai, Tadashi; Siefert, Jan Marcus; Mengel, Rudolf (1979). "Nucleic acid related compounds. 30. Transformations of adenosine to the first 2',3'-aziridine-fused nucleosides, 9-(2,3-epimino-2,3-dideoxy-.beta.-D-ribofuranosyl)adenine and 9-(2,3-epimino-2,3-dideoxy-.beta.-D-lyxofuranosyl)adenine". The Journal of Organic Chemistry. 44 (8): 1317–22. doi:10.1021/jo01322a026. 
  8. ^ Van Boeckel, C.A.A.; Van Boom, J.H. (1979). "Synthesis of glucosylphosphatidylglycerol via a phosphotriester intermediate". Tetrahedron Letters. 20 (37): 3561–4. doi:10.1016/S0040-4039(01)95462-0. 
  9. ^ Griffin, B.E.; Jarman, M.; Reese, C.B. (1968). "The Synthesis of oligoribonucleotides—IV". Tetrahedron. 24 (2): 639–62. PMID 5637486. doi:10.1016/0040-4020(68)88015-9. 
  10. ^ Ogilvie, Kelvin K.; Iwacha, Donald J. (1973). "Use of the tert-butyldimethylsilyl group for protecting the hydroxyl functions of nucleosides". Tetrahedron Letters. 14 (4): 317–9. doi:10.1016/S0040-4039(01)95650-3. 
  11. ^ Paquette, Leo A.; Collado, Iván; Purdie, Mark (1998). "Total Synthesis of Spinosyn A. 2. Degradation Studies Involving the Pure Factor and Its Complete Reconstitution". Journal of the American Chemical Society. 120 (11): 2553–62. doi:10.1021/ja974010k. INIST:10388970.