2-methylbutyric acid

Structural formula
	( R ) shape (left) and ( S ) shape (right)
General
Surname	2-methylbutyric acid
other names	2-methylbutanoic acid ( IUPAC ); 2-ethyl propionic acid; 2-methylbutyrate;
Molecular formula	C 5 H 10 O 2
Brief description	colorless liquid with an unpleasant odor
External identifiers / databases
EC number	204-145-2
ECHA InfoCard	100,003,769
PubChem	8314
ChemSpider	8012
DrugBank	DB03741
Wikidata	Q209433
properties
Molar mass	102.13 g mol −1
Physical state	liquid
density	0.94 g cm −3
Melting point	−70 ° C
boiling point	176 ° C
Vapor pressure	1 mbar (20 ° C)
solubility	little in water (20 g l −1 at 20 ° C)
Refractive index	1.406 (20 ° C, 589 nm)
safety instructions
H and P phrases	H: 302-312-314
	P: 280-301 + 330 + 331-303 + 361 + 353-304 + 340-305 + 351 + 338-310
Toxicological data	1750 mg kg −1 ( LD 50 , rat , oral ) ; 1372 mg kg −1 ( LD 50 , rabbit , transdermal ) ;
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

2-Methylbutyric acid is a chemical compound from the group of carboxylic acids , more precisely pentanoic acids . It occurs in two stereoisomeric forms.

Occurrence

( R ) -2-methylbutyric acid occurs naturally in cocoa beans, ( S ) -2-methylbutyric acid in many fruits such as apples and apricots. The ethyl ester is found in pineapples and oranges.

Cocoa beans contain ( R ) -2-methylbutyric acid.
Apricots contain ( S ) -2-methylbutyric acid.

Extraction and presentation

Both enantiomers of 2-methyl butyric acid may be prepared by asymmetric hydrogenation of tiglic acid by means of a Ru - BINAP - catalyst are recovered.

properties

2-methylbutyric acid is a slightly volatile, colorless liquid with an unpleasant odor and is not very soluble in water. The smell differs significantly in the two forms. ( S ) -2-methylbutyric acid has a pleasantly sweet, fruity odor. Whereas ( R ) -2-methylbutyric acid has a penetrating cheesy, sweaty odor. 2-methylbutyric acid was the product of the first enantioselective synthesis when the German chemist Marckwald in Berlin in 1905 heated ethylmethylmalonic acid with the chiral base brucine and obtained an optically active product mixture.

Web links

Commons : 2-Methylbutyric acid - Collection of pictures, videos and audio files

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on 2-methylbutyric acid in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .
↑ Data sheet 2-methylbutyric acid (PDF) from Merck , accessed on November 22, 2012.
↑ Martin Heil: How does apple juice get its aroma? In: Aktuell-wochenschau.de. GDCh , accessed May 26, 2018 .
^ ^A ^b Karl AD Swift: Current Topics in Flavors and Fragrances: Towards a New Millennium of Discovery . Springer, 1999, ISBN 0-7514-0490-X , p. 52 ( limited preview in Google Book search).
↑ Wolfgang Legrum: Fragrances, between stench and fragrance: Occurrence, properties and use of fragrances and their mixtures . Springer DE, 2011, ISBN 3-8348-1245-5 , p. 86 ( limited preview in Google Book search).
^ H. Günzler: Analytiker-Taschenbuch 21 . Springer DE, 2000, ISBN 3-540-66232-4 , pp. 39 ( limited preview in Google Book search).
^ W. Marckwald: About asymmetric synthesis . In: Ber. German Chem. Ges. Volume 37 , no. 1 , 1905, pp. 349-354 , doi : 10.1002 / cber.19040370165 .

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on 2-methylbutyric acid in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .

[Merck-2] Data sheet 2-methylbutyric acid (PDF) from Merck , accessed on November 22, 2012.

[3] Martin Heil: How does apple juice get its aroma? In: Aktuell-wochenschau.de. GDCh , accessed May 26, 2018 .

[Karl_A._D._Swift-4] A ^b Karl AD Swift: Current Topics in Flavors and Fragrances: Towards a New Millennium of Discovery . Springer, 1999, ISBN 0-7514-0490-X , p. 52 ( limited preview in Google Book search).

[Wolfgang_Legrum-5] Wolfgang Legrum: Fragrances, between stench and fragrance: Occurrence, properties and use of fragrances and their mixtures . Springer DE, 2011, ISBN 3-8348-1245-5 , p. 86 ( limited preview in Google Book search).

[H._Günzler-6] H. Günzler: Analytiker-Taschenbuch 21 . Springer DE, 2000, ISBN 3-540-66232-4 , pp. 39 ( limited preview in Google Book search).

[W._Marckwald-7] W. Marckwald: About asymmetric synthesis . In: Ber. German Chem. Ges. Volume 37 , no. 1 , 1905, pp. 349-354 , doi : 10.1002 / cber.19040370165 .