Diacetyl

Structural formula
General
Surname	Diacetyl
other names	2,3-butanedione ( IUPAC ) Dimethylglyoxal Dimethyldiketone
Molecular formula	C 4 H 6 O 2
Brief description	yellow-green liquid with a strong odor
External identifiers / databases
CAS number 431-03-8 EC number 207-069-8 ECHA InfoCard 100.006.428 PubChem 650 ChemSpider 630 Wikidata Q408916
properties
Molar mass	86.09 g mol −1
Physical state	liquid
density	0.99 g cm −3 (20 ° C)
Melting point	−2 ° C
boiling point	88 ° C (thermal decomposition from 110 ° C)
Vapor pressure	58.2 h Pa (20 ° C) 99.8 hPa (30 ° C) 163 hPa (40 ° C) 254 hPa (50 ° C)
solubility	good in water (200 g l −1 at 25 ° C) soluble in ethanol and diethyl ether
Refractive index	1.3951 (20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 225-302-331-315-318-335 P: 210-261-280-305 + 351 + 338-311
MAK	0.02 ml · m −3 ; 0.07 mg m −3
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

Diacetyl is an organic chemical compound from the ketone group and the simplest member of the diketone class . In diluted form it has a pronounced taste and smell of butter and is also part of the natural butter aroma; in high concentrations it smells pronounced rancid. Diacetyl gives a positive iodoform sample .

In the brewing process , brewer's yeasts produce diacetyl from the metabolic intermediate product acetolactate, which they further reduce to 2,3-butanediol . If the latter is not broken down or if the diacetyl release is forced by unfavorable nutrient contents, the beer will have a distinct and unpleasant off-taste. Similar processes with a great influence on the taste of the wine also take place during wine storage by special lactic acid bacteria (see also lactic acid fermentation or malolactic fermentation ) (→ wine error ). On December 8, 2015, researchers at Harvard University published a study that found 39 of 54 liquids used for electronic cigarettes contained diacetyl. However, tobacco cigarettes also contain a much higher proportion of diacetyl and here too is still below the limit values ​​issued by the American NIOSH .

Harmful effect

After the health authorities of the US state of Missouri reported in May 2000 that ten workers in a popcorn factory were suffering from bronchiolitis obliterans , an otherwise rare respiratory disease, and in connection with this , they demanded that the factory be examined by the US occupational safety and health authority, OSHA without any effective consequences - a lawsuit against Symrise Inc. and a number of other butter flavor manufacturers in July 2004 came before a US court in Iowa for claims for damages due to bronchiolitis obliterans caused by inhalation of diacetyl vapors such as those released in the manufacture of artificially flavored microwave popcorn. The complaint was filed by employees of a food manufacturer and intermediaries who used Symrise products in food processing. Additional lawsuits in connection with the disease, now known as "Popcorn Workers Lung", were filed in courts in Illinois and St. Louis, Missouri, in the summer of 2005, until finally in June 2007 a bill was passed in the US Congress, binding limits for diacetyl exposure at the workplace. As Der Spiegel reported a little later, the manufacturers of artificial butter flavors had to pay more than 100 million dollars in compensation to sick employees by this time, and officially even the death of a person was attributed to the disease. At the beginning of September 2007, the case of another bronchiolitis obliterans disease, which had already been diagnosed in July but had been ignored by the authorities until then, became known, this time in a man who had regularly consumed large quantities of self-made microwave popcorn and subsequently fell ill with "Popcorn Workers Lung", presumably because he had inhaled the diacetyl vapors released during preparation. Three weeks later, the US House of Representatives passed the Popcorn Workers Lung Disease Prevention Act , which obliged OSHA to set binding standards for dealing with diacetyl. Recent research shows that diacetyl promotes various aspects of amyloid-β aggregation. Such beta aggregations are associated with Alzheimer's disease.

Trimer diacetyl

Under defined conditions, several structurally different homotrimeric compounds with an identical molecular formula (C ₁₂ H ₁₈ O ₆ ) are obtained from diacetyl :

• In 1902 Otto Diels and Hans Jost described a polymerization product of diacetyl, which is formed by the action of concentrated hydrochloric acid on diacetyl at 0 ° C, as “a splendidly crystallizing compound” with a melting point of 105 ° C. A hydroxyl group , a keto function and “four inaccessible oxygen atoms” were detected by derivatization and further analyzes . A hypothetical, tricyclic structure with two substituted 1,3- dioxetane and one 1,4-dioxane ring was assessed by Beilstein as "not very likely".

Analyzes in 1999 identified the trimeric main compound as 6-hydroxy-1,3,6,7,9-pentamethyl-2,8,10,11-tetraoxa-tricyclo [5.2.1.1 ^3.9 ] undecan-4-one and clarified the Structures of four other by-products. The use of this trimmer and its use in formulations of cosmetics and therapeutic agents has been patented.

• In 1961, Cresswell et al. another trimer is described, which is formed from diacetyl in four to five days at room temperature with catalytic contact of the anion exchanger Amberlite CG-400 (in the OH ^- form).

• In 1968, Yankeelov and co-workers described another trimer that they used to modify arginine residues in proteins.

use

By condensation with 2,3-butanediamine can 2,3,5,6-tetramethylpyrazine are obtained.

Web links

• Background on Diacetyl & Popcorn Workers Lung

Individual evidence

1. ↑ ^{a b} Entry on butane-2,3-dione. In: Römpp Online . Georg Thieme Verlag, accessed on September 2, 2014.
2. ↑ ^{a b c d e f g h i j} Entry on butanedione in the GESTIS substance database of the IFA , accessed on May 2, 2018(JavaScript required) .
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-72.
4. ↑ The MAK Collection for Occupational Health and Safety: Diacetyl MAK Value Documentation in German Language, 2015, doi: 10.1002 / 3527600418.mb43103d0058 .
5. ↑ Joseph G. Allen, Skye S. Flanigan, Mallory LeBlanc, Jose Vallarino, Piers MacNaughton, James H. Stewart, David C. Christiani: Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and Acetoin in a Sample of 51 Products, Including Fruit, Candy, and Cocktail-Flavored E-Cigarettes . In: Environmental Health Perspectives . tape 124 , no. 6 , 2015, p. 733-739 , doi : 10.1289 / ehp.1510185 , PMID 26642857 .
6. ↑ Konstantinos E. Farsalinos, Kurt A. Kistler, Gene Gillman, Vassilis Voudris: Evaluation of Electronic Cigarette Liquids and Aerosol for the Presence of Selected Inhalation Toxins . In: Nicotine & Tobacco Research . tape 17 , no. 2 , February 2015, p. 168-174 , doi : 10.1093 / ntr / ntu176 ( PDF ).
7. ↑ Harmful food additives - Popcorn lung disease , Spiegel report from September 7, 2007.
8. ↑ Background on Diacetyl & Popcorn Workers Lung ( Memento from December 14, 2010 in the Internet Archive ).
9. ↑ Swati S. More, Ashish P. Vartak, Robert Vince: The Butter Flavorant, Diacetyl, Exacerbates β-Amyloid Cytotoxicity . In: Chemical Research in Toxicology . tape 25 , no. 10 , July 2012, p. 2083-2091 , doi : 10.1021 / tx3001016 .
10. ↑ Otto Diels, Hans Jost: About the representation of diacetyl and a polymerization product of the same . In: Reports of the German Chemical Society . tape 35 , no. 3 , July 1902, p. 3290-3299 , doi : 10.1002 / cber.190203503137 .
11. ^ Friedrich Konrad Beilstein, Bernhard Prager, Friedrich Richter: Beilstein's handbook of organic chemistry . tape 1 . Springer, Berlin 1918, p. 771 ( Textarchiv - Internet Archive ).
12. ↑ Ioanna Alexandropoulou, Trevor A. Crabb, Asmita V. Patel, John Hudec: Acid-promoted reactions of butane-2,3-dione . In: Tetrahedron . tape 55 , no. 18 , April 1999, p. 5867-5874 , doi : 10.1016 / S0040-4020 (99) 00249-5 .
13. ↑ Patent WO2007110415 : Use of diacetyl trimers and cosmetic or therapeutic formulations containing these compounds. Registered on March 26, 2007 , published on October 4, 2007 , applicant: Symrise , inventors: Karin Schaper, Sabine Lange, Holger Joppe, Gabriele Vielhaber, Jakob Ley. ‌
14. ↑ RM Cresswell, WRD Smith, HCS Wood: 960. The structure of two trimer of diacetyl . In: Journal of the Chemical Society . 1961, p. 4882-4885 , doi : 10.1039 / JR9610004882 .
15. ↑ John A. Yankeelov, Carolyn Dempsey. Mitchell, Thomas H. Crawford: Simple trimerization of 2,3-butanedione yielding a selective reagent for the modification of arginine in proteins . In: Journal of the American Chemical Society . tape 90 , no. 6 , 1968, p. 1664–1666 , doi : 10.1021 / ja01008a056 .
16. ↑ External identifiers or database links for diacetyl trimer : CAS number: 18114-49-3, PubChem : 193527 , ChemSpider : 167940 , Wikidata : Q89912856 .
17. ^ Roger L. Lundblad: Chemical Reagents for Protein Modification . 4th edition. CRC Press, 2014, ISBN 978-1-4665-7191-4 , pp. 646 ( Google Books ).
18. ↑ George A. Burdock: Fenaroli's Handbook of Flavor Ingredients . CRC Press, 2004, ISBN 978-1-4200-3787-6 , pp. 1786 ( limited preview in Google Book search).