Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Diacetyl: Difference between pages

{{redirect|Butanedione|1,4-butanedione|succinaldehyde}}

{{Chembox

| verifiedrevid = 477166423

| Reference = <ref>{{cite book|title=Merck Index|edition=11th|page=2946|title-link=Merck Index}}</ref>

| ImageFile1 = Diacetyl.svg

| PIN = Butane-2,3-dione <!-- Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) -->

| OtherNames = Diacetyl<br />Biacetyl<br />Dimethyl diketone<br />2,3-Diketobutane

|Section1={{Chembox Identifiers

| UNII_Ref = {{fdacite|correct|FDA}}

| 3DMet = B00164

| EC_number = 207-069-8

| RTECS = EK2625000

| UNNumber = 2346

| Beilstein = 605398

| PubChem = 650

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChEBI_Ref = {{ebicite|correct|EBI}}

| SMILES = CC(=O)C(=O)C

|Section2={{Chembox Properties

| C=4 | H=6 | O=2

| Appearance = Yellow liquid

| Density = 0.990 g/mL at 15&nbsp;°C

| MeltingPtC = −2 to −4

| BoilingPtC = 88

| Solubility = 200 g/L (20 °C)

}}

|Section3={{Chembox Hazards

| ExternalSDS = [https://fscimage.fishersci.com/msds/03275.htm External MSDS]

| MainHazards = Harmful, flammable

| FlashPt =

| AutoignitionPt =

| NFPA-H = 2

| NFPA-F = 3

| NFPA-R = 0

| GHSPictograms = {{GHS02}}{{GHS05}}{{GHS06}}{{GHS07}}{{GHS08}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|225|302|315|317|318|331|373}}

| PPhrases = {{P-phrases|210|233|240|241|242|243|260|261|264|270|271|272|280|301+312|302+352|303+361+353|304+340|305+351+338|310|311|314|321|330|332+313|333+313|362|363|370+378|403+233|403+235|405|501}}

}}

'''Diacetyl''' ({{IPAc-en|d|aɪ|j|ə|'|s|iː|t|ə|l}} {{respell|dy|yuh|SEE|tuhl}}; [[IUPAC]] systematic name: '''butanedione''' or '''butane-2,3-dione''') is an [[organic compound]] with the chemical formula (CH₃CO)₂. It is a yellow liquid with an intensely buttery flavor. It is a [[Vicinal (chemistry)|vicinal]] [[diketone]] (two [[Carbonyl|C=O]] groups, side-by-side). Diacetyl occurs naturally in alcoholic beverages and some cheeses and is added as a [[flavoring]] to some foods to impart its buttery flavor.

==Chemical structure==

A distinctive feature of diacetyl (and other vicinal diketones) is the long C–C bond linking the carbonyl centers. This bond distance is about 1.54&nbsp;Å, compared to 1.45&nbsp;Å for the corresponding C–C bond in [[1,3-butadiene]]. The elongation is attributed to repulsion between the polarized carbonyl carbon centers.<ref>{{cite journal | vauthors = Eriks K, Hayden TD, Yang SH, Chan IY | title = Crystal and molecular structure of biacetyl (2,3-butanedione), (H₃CCO)₂, at −12 and −100 °C | journal = [[J. Am. Chem. Soc.]] | date = 1983 | volume = 105 | issue = 12 | pages = 3940–3942 | doi = 10.1021/ja00350a032}}</ref>

==Occurrence and biosynthesis==

Diacetyl arises naturally as a byproduct of [[fermentation (biochemistry)|fermentation]]. In some fermentative bacteria, it is formed via the [[thiamine pyrophosphate]]-mediated condensation of [[pyruvate]] and [[acetyl CoA]].<ref>{{cite journal | vauthors = Speckman RA, Collins EB | title = Diacetyl Biosynthesis in ''Streptococcus diacetilactis'' and ''Leuconostoc citrovorum'' | journal = Journal of Bacteriology | volume = 95 | issue = 1 | pages = 174–80 | date = January 1968 | pmid = 5636815 | pmc = 251989 | doi = 10.1128/JB.95.1.174-180.1968 }}</ref> Sour (cultured) cream, cultured buttermilk, and cultured butter are produced by inoculating pasteurized cream or milk with a lactic starter culture, churning (agitating) and holding the milk until a desired pH drop (or increase in acidity) is attained. Cultured cream, cultured butter, and cultured buttermilk owe their tart flavour to lactic acid bacteria and their buttery aroma and taste to diacetyl. [[Malic acid]] can be converted to lactic acid to make diacetyl.<ref>{{cite web | url=https://scottlab.com/managing-diacetyl-production-during-malolactic-fermentation | title=Scott Labs &#124; Managing Diacetyl Production During MLF | access-date=2022-07-11 | archive-date=2022-07-05 | archive-url=https://web.archive.org/web/20220705130934/https://scottlab.com/managing-diacetyl-production-during-malolactic-fermentation | url-status=live }}</ref><ref>{{Cite book|title=Modern Food Microbiology|url=https://archive.org/details/modernfoodmicrob00jayj_401|url-access=limited|last=Jay|first=James M|date=2000|publisher=Aspen Publishers|isbn=978-0834216716|location=Gaithersburg, Md|pages=[https://archive.org/details/modernfoodmicrob00jayj_401/page/n125 120]|language=en|oclc = 42692251}}</ref>

==Production==

Diacetyl is produced industrially by [[dehydrogenation]] of [[2,3-butanediol]]. [[Acetoin]] is an intermediate.<ref name="ketones">{{Ullmann | vauthors = Siegel H, Eggersdorfer M | title = Ketones | doi = 10.1002/14356007.a15_077}}</ref>

==Applications==

===In food products===

Diacetyl and [[acetoin]] are two compounds that give [[butter]] its characteristic taste. Because of this, manufacturers of [[artificial butter flavoring]], [[margarine]]s or similar oil-based products typically add diacetyl and acetoin (along with [[beta-carotene]] for the yellow color) to make the final product butter-flavored, because it would otherwise be relatively tasteless.<ref>{{cite book | vauthors = Pavia DL | title = Introduction to Organic Laboratory Techniques | year = 2006 | publisher = Cengage Learning | edition = 4th | isbn = 978-0-495-28069-9 }}</ref>

===Electronic cigarettes===

Diacetyl is used as a flavoring agent in some [[construction of electronic cigarettes#E-cigarette liquid|liquids]] used in [[electronic cigarette]]s.<ref name="EatonChapt5">{{cite book|title=Public Health Consequences of E-Cigarettes|author1=Committee on the Review of the Health Effects of Electronic Nicotine Delivery Systems, National Academies of Sciences|date=2018|publisher=National Academies Press|isbn=9780309468343|page=175|language=en|chapter=Chapter 5: Toxicology of E-Cigarette Constituents|pmid=29894118|veditors=Eaton DL, Kwan LY, Stratton K|chapter-url=https://www.nap.edu/read/24952/chapter/9|access-date=2019-11-30|archive-date=2020-01-07|archive-url=https://web.archive.org/web/20200107150221/https://www.nap.edu/read/24952/chapter/9|url-status=live}}</ref> People nearby may be exposed to it in the exhaled aerosol at levels near the limit set for occupational exposure.<ref name=EatonChapt3>{{cite book |chapter-url=https://www.nap.edu/read/24952/chapter/6?term=Diacetyl#82 |author1=Committee on the Review of the Health Effects of Electronic Nicotine Delivery Systems, National Academies of Sciences |veditors=Eaton DL, Kwan LY, Stratton K |title=Public Health Consequences of E-Cigarettes |date=2018 |publisher=National Academies Press |isbn=9780309468343 |page=82 |language=en |pmid=29894118 |chapter=Chapter 3: E-Cigarette Devices, Uses, and Exposures |access-date=2018-11-17 |archive-date=2018-11-18 |archive-url=https://web.archive.org/web/20181118035323/https://www.nap.edu/read/24952/chapter/6?term=Diacetyl#82 |url-status=live }}</ref>

===In alcoholic beverages===

In some styles of beer (e.g. in many beer styles produced in the United Kingdom, such as stouts, English bitters, and Scottish ales), the presence of diacetyl can be acceptable or desirable at low or, in some cases, moderate levels. In other styles, its presence is considered a flaw or undesirable.<ref>{{cite book|last1=Janson|first1=Lee|name-list-style=vanc|title=Brew Chem 101|date=1996|publisher=Storey Books|isbn=978-0-88266-940-3|pages=[https://archive.org/details/brewchem1010000jans/page/64 64–67]|url=https://archive.org/details/brewchem1010000jans/page/64}}</ref>

Diacetyl is produced during fermentation as a byproduct of [[valine]] synthesis, when yeast produces [[Acetolactate|α-acetolactate]], which escapes the cell and is spontaneously [[decarboxylation|decarboxylated]] into diacetyl. The yeast then absorbs the diacetyl, and reduces the [[ketone]] groups to form [[acetoin]] and 2,3-butanediol.{{Cn|date=January 2021}}

Beer sometimes undergoes a "diacetyl rest", in which its temperature is raised slightly for two or three days after fermentation is complete, to allow the yeast to absorb the diacetyl it produced earlier in the fermentation cycle. The makers of some wines, such as [[chardonnay]], deliberately promote the production of diacetyl because of the feel and flavor it imparts.<ref>{{cite web|title=Diacetyl|url=http://www.ecmdb.ca/compounds/ECMDB21446|work=E. coli Metabolome Database|publisher=ECMDB|access-date=20 October 2013|archive-date=20 October 2013|archive-url=https://web.archive.org/web/20131020215012/http://www.ecmdb.ca/compounds/ECMDB21446|url-status=live}}</ref> Diacetyl is present in some chardonnays known as "butter bombs", although there is a trend back toward the more traditional French styles.<ref>{{Cite web|url = http://www.sonomacutrer.com/content/trends-chardonnay|title = Trends in Chardonnay|access-date = December 2, 2015|website = Sonoma-Cutrer Vineyards}} {{Dead link|date=March 2018}}</ref>

Concentrations from 0.005&nbsp;mg/L to 1.7&nbsp;mg/L were measured in chardonnay wines, and the amount needed for the flavor to be noticed is at least 0.2&nbsp;mg/L.<ref>{{cite journal | vauthors = Nielsen JC, Richelieu M | title = Control of flavor development in wine during and after malolactic fermentation by Oenococcus oeni | journal = Applied and Environmental Microbiology | volume = 65 | issue = 2 | pages = 740–745 | date = February 1999 | pmid = 9925610 | pmc = 91089 | doi = 10.1128/AEM.65.2.740-745.1999 | bibcode = 1999ApEnM..65..740N }}</ref><ref>{{cite journal |vauthors=Martineau B, Henick-Kling T, Acree T |title=Reassessment of the Influence of Malolactic Fermentation on the Concentration of Diacetyl in Wines |journal=Am. Soc. Enol. Vitic. |volume=46 |issue=3 |pages=385–388 |year=1995 |doi=10.5344/ajev.1995.46.3.385 |s2cid=88263667 |url=http://ajevonline.org/cgi/content/abstract/46/3/385 |access-date=2009-04-24 |archive-date=2009-01-07 |archive-url=https://web.archive.org/web/20090107123610/http://www.ajevonline.org/cgi/content/abstract/46/3/385 |url-status=live }}</ref>

==Use as butter flavoring==

{{main|Artificial butter flavoring}}

[[File:Butter-Vanille-Aroma.JPG|thumb|180px|Butter-Vanilla flavor, a combination of butter flavor and vanilla flavor]]

===Butter-flavoring controversy===

Chronic industrial exposure to diacetyl fumes, such as in the [[microwave popcorn]] production industry, has been associated with [[Bronchiolitis obliterans#Diacetyl (popcorn worker's lung)|bronchiolitis obliterans]], a rare and life-threatening form of non-reversible obstructive [[lung]] disease in which the [[bronchiole]]s (small airway branches) are compressed and narrowed by [[fibrosis]] (scar tissue) and/or [[inflammation]].<ref>[http://www.merriam-webster.com/medical/bronchiolitis%20obliterans Merriam-Webster Medical Dictionary > bronchiolitis obliterans] {{Webarchive|url=https://web.archive.org/web/20170801123741/http://www.merriam-webster.com/medical/bronchiolitis%20obliterans |date=2017-08-01 }} Retrieved on August, 2010</ref><ref name="pmid17288497">{{cite journal |vauthors=Harber P, Saechao K, Boomus C |title=Diacetyl-induced lung disease |journal=Toxicol Rev |volume=25 |issue=4 |pages=261–272 |year=2006 |pmid=17288497 |doi=10.2165/00139709-200625040-00006|s2cid=42169510 }}</ref>

===Regulation===

The [[European Commission]] has declared diacetyl is legal for use as a [[flavouring]] substance in all EU states.<ref>{{cite web | title = Adopting a register of flavouring substances used in or on foodstuffs drawn up in application of Regulation (EC) No 2232/96 of the European Parliament and of the Council | date = 28 October 1996 | url = http://www.fsai.ie/legislation/food/eu_docs/Flavourings/Dir99.217.pdf | archive-url = https://web.archive.org/web/20071119011834/http://www.fsai.ie/legislation/food/eu_docs/Flavourings/Dir99.217.pdf | archive-date=November 19, 2007 }}</ref> As a diketone, diacetyl is included in the EU's flavouring classification Flavouring Group Evaluation 11 (FGE.11). A Scientific Panel of the EU Commission evaluated six flavouring substances (not including diacetyl) from FGE.11 in 2004.<ref>{{cite journal | journal = The EFSA Journal | year = 2004 | volume = 166 | pages = 1–44 | title = Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in contact with Food (AFC) on a request from the Commission | url = http://www.efsa.europa.eu/EFSA/Scientific_Opinion/afc_opinionflav_ej166_en1.pdf}}</ref> As part of this study, the panel reviewed available studies on several other flavourings in FGE.11, including diacetyl. Based on the available data, the panel reiterated the finding that there were no safety concerns for diacetyl's use as a flavouring.{{Cn|date=January 2021}}

In 2007, the [[European Food Safety Authority]] (EFSA), the EU's food safety regulatory body, stated its scientific panel on food additives and flavourings (AFC) was evaluating diacetyl along with other flavourings as part of a larger study.<ref name=cpld2007>{{Cite web|url=https://www.foodnavigator.com/Article/2007/10/31/Europe-takes-wait-and-see-stance-on-diacetyl-flavouring|title=Europe takes 'wait-and-see' stance on diacetyl flavouring|date=October 31, 2007|website=foodnavigator.com|access-date=December 4, 2023|archive-date=March 8, 2023|archive-url=https://web.archive.org/web/20230308214838/https://www.foodnavigator.com/Article/2007/10/31/Europe-takes-wait-and-see-stance-on-diacetyl-flavouring|url-status=live}}</ref>

In 2007, the [[Flavor and Extract Manufacturers Association]] recommended reducing diacetyl in [[butter]] flavorings.<ref>{{cite web|url=http://www.femaflavor.org/sites/default/files/statements-releases/FEMA_Statement_9407.pdf|title=Comments of the Flavor and Extract Manufacturers Association of the United States on New Information on Butter Flavored Microwave Popcorn|publisher=[[Flavor and Extract Manufacturers Association|FEMA]]|type=press release|access-date=2012-07-25|archive-url=https://web.archive.org/web/20151018143518/http://www.femaflavor.org/sites/default/files/statements-releases/FEMA_Statement_9407.pdf|archive-date=2015-10-18|url-status=dead}}</ref> Manufacturers of butter flavored popcorn including [[Pop Weaver]], [[Weaver Popcorn Company|Trail's End]], and [[ConAgra Foods]] (maker of [[Orville Redenbacher's]] and [[Act II (popcorn)|Act II]]) began removing diacetyl as an ingredient from their products.<ref>Weaver Popcorn Company. Press Release: [http://www.popweaver.com/NoDiacetylPressRelease.pdf Pop Weaver introduces first microwave popcorn with flavoring containing no diacetyl] {{webarchive |url=https://web.archive.org/web/20070928001111/http://www.popweaver.com/NoDiacetylPressRelease.pdf |date=September 28, 2007 }}</ref><ref>ConAgra Foods Press Release [http://media.conagrafoods.com/phoenix.zhtml?c=202310&p=irol-newsArticle&ID=1087864&highlight= ConAgra Foods press release announcing removal of added diacetyl] {{Webarchive|url=https://web.archive.org/web/20151018143518/http://media.conagrafoods.com/phoenix.zhtml?c=202310&p=irol-newsArticle&ID=1087864&highlight= |date=2015-10-18 }}</ref>

A 2010 U.S. OSHA Safety and Health Information Bulletin and companion Worker Alert recommend employers use safety measures to minimize exposure to diacetyl or its substitutes.<ref>[http://ehstoday.com/standards/osha/osha-safety-measures-diacetyl-exposure-5161/ OSHA Recommends Safety Measures to Protect Workers from Diacetyl Exposure] {{Webarchive|url=https://web.archive.org/web/20101221223512/http://ehstoday.com/standards/osha/osha-safety-measures-diacetyl-exposure-5161/ |date=2010-12-21 }}, EHS Today, December 10, 2010.</ref>

In 2016, diacetyl was banned in e-liquids/e-cigarettes in the EU under the EU Tobacco Products Directive.<ref>{{Cite web | url=http://europa.eu/rapid/press-release_IP-16-1762_en.htm | title=European Commission – Press Releases – 10 key changes for tobacco products sold in the EU | access-date=2018-11-17 | archive-date=2018-10-20 | archive-url=https://web.archive.org/web/20181020114540/http://europa.eu/rapid/press-release_IP-16-1762_en.htm | url-status=live }}</ref>

== See also ==

* [[Acetylpropionyl]], a similar diketone

* [[Acetoin]]

* [[Bronchiolitis obliterans]]

== References ==

{{Reflist|2}}

== Further reading ==

{{refbegin}}

* {{cite journal | vauthors = Harber P, Saechao K, Boomus C | title = Diacetyl-induced lung disease | journal = Toxicological Reviews | volume = 25 | issue = 4 | pages = 261–272 | year = 2006 | pmid = 17288497 | doi = 10.2165/00139709-200625040-00006 | s2cid = 42169510 }}

{{refend}}

== External links ==

* [https://web.archive.org/web/20070927234524/http://www2.siri.org/msds/tox/f/q34/q996.html Toxicology data]

* NIOSH Alert: [https://www.cdc.gov/niosh/docs/2004-110/ Preventing Lung Disease and Workers who Use or Make Flavorings]

* [https://web.archive.org/web/20061218165226/http://defendingscience.org/case_studies/A-Case-of-Regulatory-Failure-Popcorn-Workers-Lung.cfm A Case of Regulatory Failure – Popcorn Workers Lung], from ''[[SKAPP|www.defendingscience.org]]''.

* [https://web.archive.org/web/20061219091118/http://www.defendingscience.org/case_studies/Diacetyl-Press-Release-July.cfm Scientists Urge Secretary of Labor to Protect Workers from Diacetyl], a press release from ''[[SKAPP|defendingscience.org]]''. Links to studies on the health effects of diacetyl, and to a variety of related documents including the recent OSHA petition and the scientists' letter of support may be found here.

* [https://www.washingtonpost.com/wp-dyn/content/article/2007/05/06/AR2007050601089.html Flavoring suspected in illness], Washington Post, May 7, 2007.

* [https://web.archive.org/web/20170614205128/https://www.cdc.gov/niosh/ipcsneng/neng1168.html NIOSH International Safety Card for 2,3-butanedione]

* [https://www.cdc.gov/niosh/topics/flavorings/ National Institute for Occupational Safety and Health – Flavorings-Related Lung Disease]

* [https://web.archive.org/web/20071011220931/http://ific.org/publications/qa/diactylqa.cfm IFIC – Diacetyl]

{{Authority control}}

[[Category:Diketones]]

[[Category:Flavors]]

[[Category:Popcorn]]

[[Category:Chemical hazards]]

[[Category:Conjugated ketones]]