Ethylene cyanohydrin

Structural formula
General
Surname	Ethylene cyanohydrin
other names	3-hydroxypropanenitrile ( IUPAC ); β-cyanoethanol; Hydracrylonitrile; Hydracrylic acid nitrile; 3-hydroxypropiononitrile; 3-hydroxypropionitrile; ECH;
Molecular formula	C 3 H 5 NO
Brief description	colorless liquid with a characteristic odor
External identifiers / databases
EC number	203-704-8
ECHA InfoCard	100.003.369
PubChem	8011
ChemSpider	7720
Wikidata	Q904204
properties
Molar mass	71.08 g mol −1
Physical state	liquid
density	1.06 g cm −3
Melting point	−46 ° C
boiling point	228 ° C
Vapor pressure	0.10 h Pa (20 ° C); 0.20 hPa (30 ° C); 0.80 hPa (50 ° C);
solubility	very easily soluble in water (1000 g l −1 at 20 ° C); miscible with ethanol , acetone , methyl ethyl ketone , chloroform and diethyl ether ;
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	3200 mg kg −1 ( LD 50 , rat , oral ) ; 5200 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 .

Ethylene cyanohydrin (according to IUPAC nomenclature: 3-hydroxypropane nitrile , often also referred to as β-cyanoethanol ) is an organic-chemical compound from the group of aliphatic nitriles and alcohols . The compound used to be an important intermediate in the manufacture of acrylic acid and acrylonitrile .

Extraction and presentation

The large-scale production of ethylene cyanohydrin takes place by reacting ethylene oxide with hydrocyanic acid at temperatures of 100–110 ° C and pressures of 11–25 bar in the presence of sodium hydroxide as a catalyst in the liquid phase.

The reaction is carried out in a reactor column made of pipe coils and the pH is controlled by adding the sodium hydroxide solution. In this process, yields of 90-98% can be achieved. The product is purified and worked up by multi-stage distillation in downstream columns .

properties

Physical Properties

Ethylene cyanohydrin has a relative gas density of 2.45 (density ratio to dry air at the same temperature and pressure ) and a relative density of the steam-air mixture of 1.00 (density ratio to dry air at 20 ° C and normal pressure ). The density is 1.06 g / cm ³ . Ethylene cyanohydrin has a vapor pressure of 0.10 hPa at 20 ° C, 0.20 hPa at 30 ° C and 0.80 hPa at 50 ° C. The dynamic viscosity is less than 10 mPa · s at 20 ° C.

Chemical properties

Ethylene cyanohydrin is a flammable, but hardly inflammable liquid from the substance group of nitriles and alcohols . It is very easily soluble in water and can also be mixed well with some organic solvents such as ethanol , acetone , methyl ethyl ketone , chloroform and diethyl ether . 3-Hydroxypropanitril is difficult or very difficult to volatilize . At a temperature of> 228 ° C the substance decomposes and releases highly toxic hydrogen cyanide as a gas. Contact with alkali hydroxide , oxidizing agents , acids and water can lead to dangerous reactions which usually also release hydrogen cyanide. As a pure substance, ethylene cyanohydrin has a pH value between 3.0 and 4.5 at a temperature of 20 ° C. As a result, aqueous solutions are weakly acidic .

use

Ethylene cyanohydrin used to be an important intermediate in the production of acrylonitrile and acrylic acid . This process was, however, by the currently dominant ammoxidation replaced, one in which the cheaper starting material propene used as a reaction base and this in an ammoxidation to acrylonitrile or partial oxidation reacted to acrylic acid. Nowadays, ethylene cyanohydrin is mainly used as a solvent for cellulose esters and many inorganic salts . It is also considered a preliminary product in the pharmaceutical and cosmetics industry .

safety instructions

Ethylene cyanohydrin is mainly absorbed through the respiratory tract and the skin . This leads to acute irritative effects on the mucous membranes and the skin. Insufficient information is available on reproductive toxicity , mutagenicity and carcinogenicity . Ethylene cyanohydrin has a lower explosion limit (LEL) of 1.1% by volume and an upper explosion limit (UEL) of 12.1% by volume. With a flash point of 128 ° C, ethylene cyanohydrin is considered flame retardant.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o Entry on ethylene cyanohydrin in the GESTIS substance database of the IFA , accessed on April 18, 2019 (JavaScript required)
↑ ^a ^b Entry on ethylene cyanohydrin in the Hazardous Substances Data Bank , accessed on April 18, 2019.
↑ ^a ^b ^c Volker Schleep, Benedikt Laux: Device and method for the continuous preparation of ethylene cyanohydrin. In: Google Patents. Evonik Roehm GmbH, February 25, 2009, accessed April 18, 2019 .
↑ Entry on hydroxypropionitrile. In: Römpp Online . Georg Thieme Verlag, accessed on April 18, 2019.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o Entry on ethylene cyanohydrin in the GESTIS substance database of the IFA , accessed on April 18, 2019 (JavaScript required)

[HSDB-2] Entry on ethylene cyanohydrin in the Hazardous Substances Data Bank , accessed on April 18, 2019.

[Verfahren-3] Volker Schleep, Benedikt Laux: Device and method for the continuous preparation of ethylene cyanohydrin. In: Google Patents. Evonik Roehm GmbH, February 25, 2009, accessed April 18, 2019 .

[RÖMPP-4] Entry on hydroxypropionitrile. In: Römpp Online . Georg Thieme Verlag, accessed on April 18, 2019.