3-hydroxybutanal

Structural formula
	Simplified structural formula without stereochemistry
General
Surname	3-hydroxybutanal
other names	3-hydroxybutyraldehyde; Acetaldol; Aldol;
Molecular formula	C 4 H 8 O 2
Brief description	oily, colorless to yellowish liquid with a pungent odor
External identifiers / databases
EC number	203-530-2
ECHA InfoCard	100.003.210
PubChem	7897
Wikidata	Q223087
properties
Molar mass	88.11 g mol −1
Physical state	liquid
density	1.11 g cm −3 (20 ° C)
Melting point	−88 ° C
boiling point	Decomposition from 85 ° C
Vapor pressure	0.10 hPa (20 ° C); 10 hPa (50 ° C); 15 hPa (65 ° C);
solubility	completely miscible with water and ethanol
Refractive index	1.4238 (20 ° C)
safety instructions
GHS hazard labeling from Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger
H and P phrases	H: 310-319
	P: 280-302 + 350-305 + 351 + 338-310
Toxicological data	2180 mg kg −1 ( LD 50 , rat , oral ) ; 140 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

3-Hydroxybutanal (also aldol or acetaldol ) is an organic-chemical compound from the group of hydroxylated aldehydes , more precisely the aldols (also β-hydroxyaldehydes ).

Extraction and presentation

Racemic 3-hydroxybutanal is produced on an industrial scale by a base-catalyzed aldol addition reaction of acetaldehyde at low temperatures of about 5 ° C. Aqueous sodium hydroxide solution is usually used as the catalyst , but any other base can also be used.

The reaction can only be carried out at low temperatures of 5 ° C. and less, since water is immediately split off when the temperature is increased and the aldol condensation product is formed. The yield of 3-hydroxybutanal is between 50 and 60%. The work-up takes place with the help of a multi-stage distillation .

properties

Physical Properties

3-Hydroxybutanal has a density of 1.11 g · cm ⁻³ at 20 ° C and a relative gas density (density ratio to dry air at the same temperature and pressure) of 3.04. It has a vapor pressure of 0.1 hPa at 20 ° C, 10 hPa at 50 ° C and 15 hPa at 65 ° C.

Chemical properties

3-Hydroxybutanal is completely miscible with water and ethanol . At temperatures above the boiling point of 85 ° C, it reacts to form but-2-enal with elimination of water , or it breaks down again into acetaldehyde in a retro- aldol addition . Aldol tends to exothermic reactions and polymerizes in the presence of alkalis , acids , oxidizing agents or iodine with the development of heat.

use

3-Hydroxybutanal is an intermediate in the chemical industry . It is a precursor in the production of crotonaldehyde , crotonic acid , butane-1,3-diol and polyester plasticizers . It was also used as a sleeping aid and sedative .

safety instructions

Acetaldol is classified as acutely toxic . In the event of skin contact there is already a danger to life. It also causes serious eye irritation. The substance also has a tendency to strongly exothermic reactions . With an ignition temperature of 245 ° C, it falls into temperature class T3. The flash point is 83 ° C. Special ADR regulations apply to road transport as part of the European Agreement on the International Carriage of Dangerous Goods by Road . 3-Hydroxybutanal falls into ADR class 6.1 for toxic substances and is assigned UN number 2839 and hazard number 60. The name for international road and rail transport is "Aldol; 3-Hydroxybutyraldehyde (ADR)".

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p Entry on 3-hydroxybutyraldehyde in the GESTIS substance database of the IFA , accessed on December 24, 2018(JavaScript required) .
↑ ^a ^b ^c Entry on Aldol. In: Römpp Online . Georg Thieme Verlag, accessed on December 24, 2018.
↑ David R. Lide: CRC Handbook of Chemistry and Physics, 85th Edition . CRC Press, 2004, ISBN 978-0-8493-0485-9 , pp. 566 ( limited preview in Google Book search).
↑ Entry on 3-hydroxybutanal in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 24, 2018. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ K. Peter C. Vollhardt, Neil E. Schore: Organic chemistry . Ed .: Holger Butenschön. 5th edition. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim / Germany 2011, ISBN 978-3-527-32754-6 , p. 896 .

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p Entry on 3-hydroxybutyraldehyde in the GESTIS substance database of the IFA , accessed on December 24, 2018(JavaScript required) .

[RÖMPP-2] Entry on Aldol. In: Römpp Online . Georg Thieme Verlag, accessed on December 24, 2018.

[David_R._Lide-3] David R. Lide: CRC Handbook of Chemistry and Physics, 85th Edition . CRC Press, 2004, ISBN 978-0-8493-0485-9 , pp. 566 ( limited preview in Google Book search).

[CLP_100.003.210-4] Entry on 3-hydroxybutanal in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 24, 2018. Manufacturers or distributors can expand the harmonized classification and labeling .

[5] K. Peter C. Vollhardt, Neil E. Schore: Organic chemistry . Ed .: Holger Butenschön. 5th edition. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim / Germany 2011, ISBN 978-3-527-32754-6 , p. 896 .