2,3-butanediol

Structural formula
	Structural formula without stereochemistry
General
Surname	2,3-butanediol
other names	2,3-butylene glycol; Dimethylethylene glycol; Butane-2,3-diol; 2,3-dihydroxybutane; 2,3-BUTANEDIOL ( INCI ) ;
Molecular formula	C 4 H 10 O 2
Brief description	slightly viscous, colorless, almost odorless liquid
External identifiers / databases
EC number	208-173-6
ECHA InfoCard	100.007.431
PubChem	262
Wikidata	Q209157
properties
Molar mass	90.12 g mol −1
Physical state	liquid
density	1.01 g cm −3
Melting point	19 ° C
boiling point	180 ° C
Vapor pressure	0.23 h Pa (20 ° C); 2.29 hPa (50 ° C);
solubility	miscible with water
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: no H-phrases
	P: no P-phrases
Toxicological data	> 5000 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 .

2,3-Butanediol is an aliphatic alcohol with two hydroxyl groups (-OH) and the empirical formula C ₄ H ₁₀ O ₂ .

The arrangement of the hydroxyl groups can be spatially different. There are therefore three stereoisomers .

Occurrence

2,3-butanediol is formed e.g. B. during the brewing process by metabolizing the diacetyl by the brewing yeast. Top-fermented beers can contain 2,3-butanediol in a concentration between 50 and 130 mg / l.

Extraction and presentation

2,3-Butanediol is obtained from corn sugar through acid hydrolysis . With biotechnological methods (conversion with bacteria which are capable of 2,3-butanediol fermentation , e.g. Klebsiella aerogenes (formerly Enterobacter aerogenes )) the individual enantiomers can also be represented in pure form.

properties

Stereoisomerism

2,3-Butanediol is chiral and contains two equally substituted stereogenic centers, so there are three stereoisomers : ( R , R ) -2,3-butanediol [synonym: D - (-) - 2,3-butanediol] and the enantiomeric one ( S , S ) -2,3-butanediol [synonym: L - (+) - 2,3-butanediol] and meso -2,3-butanediol.

The physical properties such as the melting or boiling point of the three isomeric 2,3-butanediols differ and, in the case of mixtures of the isomers, vary with their composition.

2,3-butanediols
Surname	D - (-) - 2,3-butanediol	L - (+) - 2,3-butanediol	meso -2,3-butanediol	DL -2,3-butanediol ( racemate from D- and L -form)
Structural formula
other names	(2 R , 3 R ) -2,3-butanediol	(2 S , 3 S ) -2,3-butanediol		rac -2,3-butanediol
CAS number	24347-58-8	19132-06-0	5341-95-7	513-85-9
Melting point	25 ° C	19.7 ° C	32-34 ° C	7.6 ° C
boiling point	180-182 ° C	178-181 ° C	183-184 ° C	182 ° C
Density in g / cm³	0.9872 (25 ° C)	0.9869 (25 ° C)	1,0003 (20 ° C)	1.0033 (20 ° C)
Refractive index at 25 ° C	1.4306	1.4340	1.4367	1.4310
Rotation value [α] _D^{25 ° C}	+ 12.5 ° (undiluted)	−13 ° (undiluted)	± 0 °	± 0 °

Safety-related parameters

2,3-Butanediol forms flammable vapor-air mixtures at high temperatures. The compound has a flash point of 85 ° C. The explosion range is between 3.1 vol.% As the lower explosion limit (LEL) and 11.4 vol.% As the upper explosion limit (UEL). The ignition temperature is 400 ° C. The substance therefore falls into temperature class T2.

use

2,3-Butanediol is mostly used as a substitute for glycerine . It is also used as a solvent , mostly for paints and as a raw material for the production of butadiene , plastics and epoxy resins . In toiletries, it is used as an additive in hair tonics, shampoos and fixatives, as well as in shaving foam and toothpaste.

Individual evidence

↑ Entry on 2,3-BUTANEDIOL in the CosIng database of the EU Commission, accessed on March 11, 2020.
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Entry on 2,3-butanediol in the GESTIS substance database of the IFA , accessed on May 29, 2018(JavaScript required) .
↑ Data sheet 2,3-butanediol (PDF) from Merck , accessed on January 18, 2011.
^ CRC Handbook of Chemistry and Physics , 60th Edition, CRC Press, 1980.
^ ^A ^b ^c E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.
↑ Chemielexikon, Hermann Römpp, Fifth Edition, Franckh'sche Verlagshandlung, 1962.

[CosIng-1] Entry on 2,3-BUTANEDIOL in the CosIng database of the EU Commission, accessed on March 11, 2020.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Entry on 2,3-butanediol in the GESTIS substance database of the IFA , accessed on May 29, 2018(JavaScript required) .

[merck-3] Data sheet 2,3-butanediol (PDF) from Merck , accessed on January 18, 2011.

[4] CRC Handbook of Chemistry and Physics , 60th Edition, CRC Press, 1980.

[Brandes-5] A ^b ^c E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.

[6] Chemielexikon, Hermann Römpp, Fifth Edition, Franckh'sche Verlagshandlung, 1962.