Pivalic acid

Structural formula
General
Surname	Pivalic acid
other names	2,2-dimethylpropanoic acid; Neopentanoic acid; Trimethyl acetic acid ( obsolete );
Molecular formula	C 5 H 10 O 2
Brief description	colorless crystals with an unpleasant odor
External identifiers / databases
EC number	200-922-5
ECHA InfoCard	100,000,839
PubChem	6417
ChemSpider	6177
Wikidata	Q421509
properties
Molar mass	102.13 g mol −1
Physical state	firmly
density	0.91 g cm −3 (20 ° C)
Melting point	35-36 ° C
boiling point	163-164 ° C
Vapor pressure	18.6 Pa (70 ° C)
pK s value	5.03 (20 ° C)
solubility	little in water (25 g l −1 at 20 ° C)
safety instructions
H and P phrases	H: 302-312-315-318
	P: 280-302 + 352-305 + 351 + 338-313
Toxicological data	900 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Pivalic acid is a methyl branched, short-chain carboxylic acid from the group of four isomeric pentanoic acids , as well as the simplest Koch acid ( tertiary saturated monocarboxylic acids).

presentation

Synthetically, pivalic acid can be obtained by oxidation of pinacolone , by the Grignard reaction from tert-butyl chloride (lower illustration) or by the Koch reaction from 2-methylpropene ( isobutene ), carbon monoxide and water:

${\ displaystyle \ mathrm {(H_ {3} C) _ {2} C {=} CH_ {2} + CO + H_ {2} O \ \ longrightarrow \ (H_ {3} C) _ {3} C { -} COOH}}$

Reaction of t -butylmagnesium bromide with carbon dioxide to form pivalic acid

properties

The pivalic acid forms colorless, needle-shaped crystals with a pungent odor, which dissolve little in water, but well in ethanol and diethyl ether . Due to steric effects on the molecule, pivalic acid has some special properties compared to other valeric acids, e.g. B. the ester formation or the hydrolysis of the pivalic acid ester is considerably more difficult.

use

Pivalic acid is used in the manufacture of polyvinyl esters (vinyl pivalate) and pharmaceutical preparations. The effect of steric inhibition is used by the use of esters of medicinally active substances, which are then only slowly split and absorbed in the organism, such as. B. testosterone pivalate .

safety instructions

Pivalic acid is flammable, the ignition temperature is approx. 500 ° C, the flash point in a closed crucible is 64 ° C. The acid is irritating to the eyes, respiratory tract, mucous membranes and skin and can also be absorbed through the skin.

Individual evidence

^ ^A ^b Jürgen Falbe, Manfred Regitz: RÖMPP Lexikon Chemie. Volume 2: Cm-G , 10th edition, Thieme, 1997, ISBN 3-13-734710-6 , p. 991.
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Entry on 2,2-dimethylpropionic acid in the GESTIS substance database of the IFA , accessed on February 22, 2017(JavaScript required) .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 97th edition. (Internet version: 2016), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-220.
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dissociation Constants of Organic Acids and Bases, pp. 8-44.

Web links

Commons : Pivalic Acid - Collection of Images, Videos and Audio Files

Entry to pivalic acid . In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD .
International Chemical Safety Card (ICSC) for Pivalic Acid from the National Institute for Occupational Safety and Health (NIOSH).

[Röm-1] A ^b Jürgen Falbe, Manfred Regitz: RÖMPP Lexikon Chemie. Volume 2: Cm-G , 10th edition, Thieme, 1997, ISBN 3-13-734710-6 , p. 991.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Entry on 2,2-dimethylpropionic acid in the GESTIS substance database of the IFA , accessed on February 22, 2017(JavaScript required) .

[3] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 97th edition. (Internet version: 2016), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-220.

[CRC90_8_44-4] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dissociation Constants of Organic Acids and Bases, pp. 8-44.