2-hexenal

Structural formula
	Structural formula of trans -2-hexenal
General
Surname	2-hexenal
other names	3-propylacrolein; Hex-2-enal; ( E ) -hex-2-enal; ( Z ) -hex-2-enal; cis -hex-2-enal; trans -hex-2-enal; Leaf aldehyde; TRANS-2-HEXENAL ( INCI ) ;
Molecular formula	C 6 H 10 O
Brief description	colorless liquid
External identifiers / databases
EC number	229-778-1
ECHA InfoCard	100,027,072
PubChem	5281168
ChemSpider	4444608
Wikidata	Q209405
properties
Molar mass	98.14 g mol −1
Physical state	liquid
density	0.846 g cm −3 (20 ° C)
boiling point	146 ° C
Vapor pressure	13 hPa (20 ° C)
solubility	almost insoluble in water
Refractive index	1.445 (20 ° C, 589 nm)
safety instructions
H and P phrases	H: 226-302-311
	P: 210-280-302 + 352
Toxicological data	780 mg kg −1 ( LD 50 , rat , oral ) ; 600 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-Hexenal is a chemical compound from the group of aldehydes . It occurs in two isomeric forms ( trans - and cis -2-hexenal), with the trans form being of greater importance.

Occurrence

Granny Smith apples

trans -2-Hexenal [( E ) -2-Hexenal, also called leaf aldehyde] is one of the aldehydes that contribute to the taste of apples and which are often referred to as green notes (taste of green apples, such as Granny Smith ). It only arises when chewing or chewing in the mouth through a very rapid enzymatic conversion of fatty acids. At an acidic pH (as found in fruits) auto-oxidation occurs and trans -2-hexenal converts with water into 3-hydroxyhexanal . It also adds to the aroma of cherries. The biosynthesis in the plants is based on the tri-unsaturated linolenic acid .

Bed bugs ( Cimex lectularius ) secrete trans -2-hexenal as an alarm substance.

It also acts as an attractant for insectivorous predatory bugs , which is produced during the digestion of tobacco leaves in the caterpillars of tobacco hawks . trans -2- Hexenal is secreted as an alarm substance by irritated or injured bed bugs .

Extraction and presentation

The trans isomer can be prepared by reacting butanal with ethyl vinyl ether in the presence of boron trifluoride and then hydrolyzing the resulting product with dilute sulfuric acid.

properties

It concerns with trans -2-hexenal an inflammatory, colorless, transparent and air sensitive liquid which is insoluble in water. It has a pungent, vegetable-green odor with a slight pungency that smells like acrolein . When diluted, however, it smells pleasantly green and apple-like.

use

trans -2-hexenal is used to make other chemical compounds. In perfumery it is used to create green notes, in aromas as a green nuance in fruit aromas.

safety instructions

The vapors of trans -2-Hexenal can form an explosive mixture with air ( flash point 35 ° C).

Individual evidence

↑ Entry on TRANS-2-HEXENAL 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 ^m ⁿ data sheet trans-2-Hexenal (PDF) from Merck , accessed on March 18, 2012.
^ Hans-Dieter Belitz, Werner Grosch, Peter Schieberle: Textbook of food chemistry . Springer-Verlag, 2001, ISBN 978-3-86022-558-5 , pp. 366, 390, 825 ( limited preview in Google Book search).
↑ Gordon Hall: Handbook of Flavors and Spices, Volume 1 . 2006, ISBN 978-3-86022-558-5 , pp. 11 ( limited preview in Google Book search).
^ S. Allmann, IT Baldwin: Insects Betray Themselves in Nature to Predators by Rapid Isomerization of Green Leaf Volatiles. In: Science. 329, 2010, p. 1075, doi : 10.1126 / science.1191634 .
↑ Bernd Schäfer: Natural substances in the chemical industry , Spektrum Akademischer Verlag, 2007, p. 519, ISBN 978-3-8274-1614-8 .
↑ Patent US2628257 : Production of unsaturated aldehydes. Published February 10, 1953 , Applicant: Union Carbide, Inventor: RI Hoaglin, DH Hirsh. ‌
↑ Entry on trans-2-Hexenal at TCI Europe, accessed on March 18, 2012.
↑ Ullmann, Flavor and Fragrances, Vol. 15
^ Fahlbusch, Karl-Georg and Hammerschmidt, Franz-Josef and Panten, Johannes and Pickenhagen, Wilhelm and Schatkowski, Dietmar and and Bauer, Kurt and Garbe, Dorothea and Surburg, Horst: Flavors and Fragrances . In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag GmbH & Co. KGaA, 2000, ISBN 978-3-527-30673-2 , doi : 10.1002 / 14356007.a11_141 .

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

[Merck-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ data sheet trans-2-Hexenal (PDF) from Merck , accessed on March 18, 2012.

[Lebensmittelchemie-3] Hans-Dieter Belitz, Werner Grosch, Peter Schieberle: Textbook of food chemistry . Springer-Verlag, 2001, ISBN 978-3-86022-558-5 , pp. 366, 390, 825 ( limited preview in Google Book search).

[buch-4] Gordon Hall: Handbook of Flavors and Spices, Volume 1 . 2006, ISBN 978-3-86022-558-5 , pp. 11 ( limited preview in Google Book search).

[DOI10.1126/science.1191634-5] S. Allmann, IT Baldwin: Insects Betray Themselves in Nature to Predators by Rapid Isomerization of Green Leaf Volatiles. In: Science. 329, 2010, p. 1075, doi : 10.1126 / science.1191634 .

[Schäfer-6] Bernd Schäfer: Natural substances in the chemical industry , Spektrum Akademischer Verlag, 2007, p. 519, ISBN 978-3-8274-1614-8 .

[7] Patent US2628257 : Production of unsaturated aldehydes. Published February 10, 1953 , Applicant: Union Carbide, Inventor: RI Hoaglin, DH Hirsh. ‌

[TCI-8] Entry on trans-2-Hexenal at TCI Europe, accessed on March 18, 2012.

[9] Ullmann, Flavor and Fragrances, Vol. 15

[10] Fahlbusch, Karl-Georg and Hammerschmidt, Franz-Josef and Panten, Johannes and Pickenhagen, Wilhelm and Schatkowski, Dietmar and and Bauer, Kurt and Garbe, Dorothea and Surburg, Horst: Flavors and Fragrances . In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag GmbH & Co. KGaA, 2000, ISBN 978-3-527-30673-2 , doi : 10.1002 / 14356007.a11_141 .