Dehydracetic acid

Structural formula
General
Surname	Dehydracetic acid
other names	3-acetyl-2-hydroxy-6-methyl-4 H -pyran-4-one ( IUPAC ) DHA Dehydroacetic acid
Molecular formula	C 8 H 8 O 4
Brief description	white to yellow, crystalline odorless powder
External identifiers / databases
CAS number 520-45-6 EC number 208-293-9 ECHA InfoCard 100.007.541 PubChem 54678494 ChemSpider 10177 Wikidata Q920725
properties
Molar mass	168.15 g mol −1
Physical state	firmly
density	1.18 g cm −3
Melting point	111 ° C
boiling point	270 ° C
solubility	heavy in water (2 g l −1 at 20 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary Caution H and P phrases H: 302 P: 301 + 312-280
Toxicological data	500 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 .

Dehydroacetic even dehydroacetic called, is a chemical compound from the group of pyrones . It was discovered by Johann Georg Anton Geuther .

Extraction and presentation

Dehydracetic acid can be synthesized by heating acetoacetic ester with the addition of sodium hydrogen carbonate or barium oxide . It is also formed when diketene is heated in the presence of basic catalysts (e.g. triethylamine, pyridine).

use

In 1947 GH Coleman and PA Wolf recognized the broad fungicidal effect of dehydracetic acid. The compound was therefore used as a preservative in the high pH range, but could never be of great importance because of its toxicity . It was used to a lesser extent as a storage preservative for fruit and vegetables. Due to its better solubility, the sodium salt of dehydroacetic acid ( E266 ) was used. It is not approved as an additive in food in the EU.

Individual evidence

1. ↑ ^{a b c d e f g} Entry on 3-Acetyl-6-methyl-2H-pyran-2,4 (3H) -dione in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
2. ^ Carl L. Yaws: The Yaws Handbook of Physical Properties for Hydrocarbons and Chemicals Physical Properties for More Than 54,000 Organic and Inorganic Chemical Compounds, Coverage for C1 to C100 Organics and Ac to Zr Inorganics . Gulf Professional Publishing, 2015, ISBN 978-0-12-801146-1 , pp. 190 ( limited preview in Google Book Search).
3. ↑ Entry on 3-acetyl-6-methyl-2H-pyran-2,4 (3H) -dione in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 1, 2016. Manufacturers or distributors can use the harmonized classification and expand labeling .
4. ↑ Chemwhat: dehydroacetic. Retrieved April 16, 2020 . 
5. ↑ Fisher Scientific: Dehydroacetic Acid 98%, ACROS Organics ™ - Dehydroacetic Acid 98%, ACROS Organics ™ Carbonyl Compounds. Retrieved April 16, 2020 . 
6. ↑ Ludwig Haitinger : About the dehydracetic acid . In: Reports of the German Chemical Society . tape 18 , no. 1 , January 1885, p. 452–453 , doi : 10.1002 / cber.18850180198 ( PDF ).
7. ↑ Richard Wegler : Chemistry of pesticides and pesticides: history · ecology · research · tropical diseases · textile protection · insecticide resistance · material protection . tape 3 . Springer-Verlag, 1976, ISBN 978-3-642-66415-1 ( limited preview in Google book search).
8. ↑ Erich Lück : Chemical food preservation . Springer Berlin Heidelberg, 1986, ISBN 978-3-642-96925-6 , dehydracetic acid, p. 159-162 , doi : 10.1007 / 978-3-642-96924-9_25 .
9. ↑ External identifiers of or database links to sodium 1- (3,4-dihydro-6-methyl-2,4-dioxo-2H-pyran-3-ylidene) ethanolate : CAS number: 4418-26-2 , EC number: 224-580-1, ECHA InfoCard: 100.022.347 , GESTIS substance database : 494528 , PubChem : 44135708 , ChemSpider : 21172046 , Wikidata : Q7553316 .