BUTANEDIONE

Butanedione, also known as Diacetyl, is a reactive diketone in artificial butter flavors. 
Butanedione is a water-soluble and volatile, alpha-diketone compound that has a buttery odor. 
Butanedione occurs naturally in plants, fruits, coffee, honey, cocoa, and dairy products. 

CAS:    431-03-8
MF:    C4H6O2
MW:    86.09
EINECS:    207-069-8

Synonyms
Butandione;DIACETYL 95+% NATURAL FCC;DiacetylForSynthesis;2,3-Buranedione;2,3-Butanedione,99%;diacetyl,2,3-butanedione;Diacetyl, Butane-2,3-dione;2,3-BUTANEDIONE,;SYNTHETIC;2,3-butanedione;diacetyl;biacetyl;Butane-2,3-dione;431-03-8;Butanedione;dimethylglyoxal;dimethyl diketone;2,3-diketobutane;Dimethyl glyoxal;2,3-Butadione;butadione;2,3-dioxobutane;Glyoxal, dimethyl-;Diacetyl (natural);2,3-butandione;FEMA No. 2370;Butan-2,3-dione;CCRIS 827;HSDB 297;NSC 8750;2,3-Butanedione-13C2;MFCD00008756;UN2346;AI3-03313;2,3 butandione;EINECS 207-069-8;UNII-K324J5K4HM;BRN 0605398;Buta-2,3-dione;K324J5K4HM;DTXSID6021583;CHEBI:16583;DIACETYL [FHFI];DIACETYL [HSDB];DIACETYL [FCC];DIACETYL [MI];NSC-8750;(CH3CO)2;DTXCID701583;4-01-00-03644 (Beilstein Handbook Reference);butanodiona;Diketobutane;Dimethyldiketone;2.3-butanedione;2,3 Butanedione;2,3butanedione;2,3Diketobutane;2,3Dioxobutane;butane 2;butane-2;Glyoxal, dimethyl;Biacetyl; BDM;2,3Butadione;Butanedione (DOT);Butanodiona (Spanish);Butanedione [UN2346] [Flammable liquid];Lopac-D-3634;Butanedione [UN2346];2,3-Butanedione, 97%;Lopac0_000387;Diacetyl, natural, >=95%;WLN: 1VV1;CHEMBL365809;SGCUT00113;2,3-Butanedione (8CI,9CI);BDBM22725;NSC8750;HMS3261M15;to_000005;Tox21_201218;Tox21_500387;LMFA12000012;2,3-Butanedione, analytical standard;AKOS000118816;Diacetyl 1000 microg/mL in Methanol;CCG-204481;LP00387;SDCCGSBI-0050374.P002;NCGC00015336-01;NCGC00015336-02;NCGC00015336-03;NCGC00015336-04;NCGC00015336-05;NCGC00015336-06;NCGC00015336-07;NCGC00090746-01;NCGC00090746-02;NCGC00090746-03;NCGC00258770-01;NCGC00261072-01;CAS-431-03-8;DB-003226;B0682;Butanedione [UN2346] [Flammable liquid];EU-0100387;NS00003558;EN300-19494;C00741;D 3634;W18292;A826155;Q408916;SR-01000075811;SR-01000075811-1;DEE64962-0BD5-454C-8BDA-FDBD33C47181;F0001-1188;Flavor and Extract Manufacturers' Association No. 2370;2,3-butanedione, 2,3-butadione, 2,3-diketobutane, dimethyl diketone, dimethylglyoxal,;glyoxal, dimethyl-;BUO

Butanedione is a natural by-product of fermentation and is found in beer and wine. 
Butanedione is also present in cigarette smoke.
Butanedione can be synthesized by converting 2-butanone to an isonitroso compound and then hydrolyzing it with hydrochloric acid. 
Other methods for producing Butanedione include oxidation of 2-butanone over a copper catalyst at 300°C and dehydrogenation of 2,3-butanediol over a copper or silver catalyst. 
In addition, Butanedione can be synthesized through the acid catalyzed condensation of 1-hydroxyacetone and formaldehyde. 
Naturally occurring Butanedione is also available from starter distillate, a by-product of dairy product fermentation. 

Although Butanedione and starter distillates are liquids, they can be converted to a powdered form by encapsulating them within a solid material to prevent volatility. 
Butanedione in powdered form is also found in flavorings that have been spray dried. 
The boiling point of diacetyl is 88°C with a calculated vapor pressure of 55 mmHg at 20°C.
Butanedione is an alpha-diketone that is butane substituted by oxo groups at positions 2 and 3. 
Butanedione is a metabolite produced during the malolactic fermentation. 
Butanedione has a role as a Saccharomyces cerevisiae metabolite and an Escherichia coli metabolite.

Butanedione is an organic compound with the chemical formula (CH3CO)2. 
Butanedione is a yellow liquid with an intensely buttery flavor. 
Butanedione is a vicinal diketone (two C=O groups, side-by-side). 
Butanedione occurs naturally in alcoholic beverages and some cheeses and is added as a flavoring to some foods to impart its buttery flavor. 
Chronic inhalation exposure to Butanedione fumes is a causative agent of the lung disease bronchiolitis obliterans, commonly known as "popcorn lung".

Butanedione is an alpha-diketone that is butane substituted by oxo groups at positions 2 and 3. 
Butanedione is a metabolite produced during the malolactic fermentation.
Butanedione has a role as a Saccharomyces cerevisiae metabolite and an Escherichia coli metabolite.
Butanedione is mainly used in the preparation of food flavors. 
Butanedione is the main flavor of cream flavors. 
Butanedione can also be used in milk, cheese and other flavors in Chemicalbook. 
Such as berries, caramel, chocolate, coffee, cherries, vanilla beans, honey, cocoa, fruity, wine, smoke, rum, nuts, almonds, ginger, etc.

Butanedione Chemical Properties
Melting point: -4--2 °C
Boiling point: 88 °C(lit.)
Density: 0.985 g/mL at 20 °C
Vapor density: 3 (vs air)
Vapor pressure: 52.2 mm Hg ( 20 °C)
Refractive index: n20/D 1.394(lit.)
FEMA: 2370 | DIACETYL
Fp: 45 °F
Storage temp.: Store at +2°C to +8°C.
Solubility: 200g/l
Form: Liquid
Color: Clear yellow
Odor: at 1.00 % in propylene glycol. strong butter sweet creamy pungent caramel
Odor Type: buttery
Odor Threshold: 0.00005ppm
Explosive limit: 2.4-13.0%(V)
Water Solubility: 200 g/L (20 ºC)
Merck: 14,2966
JECFA Number: 408
BRN: 605398
Exposure limits    ACGIH: TWA 0.01 ppm; STEL 0.02 ppm
NIOSH: TWA 5 ppb; STEL 25 ppb
Stability: Stable. Flammable. Incompatible with acids, strong bases, metals, reducing agents, oxidizing agents. Protect from moisture and water. Note low flashpoint.
InChIKey: QSJXEFYPDANLFS-UHFFFAOYSA-N
LogP: -1.340
CAS DataBase Reference: 431-03-8(CAS DataBase Reference)
NIST Chemistry Reference: Butanedione(431-03-8)
EPA Substance Registry System: Butanedione (431-03-8)

Yellow to yellow green liquid, a creamy fragrance after bulk dilution (1mg/kg), high vapor pressure is, evaporate quickly at room temperature, melting point-3～-4℃， boiling point 87～88℃, flash point 13℃. 
Soluble in ethanol, ether, most non-volatile oil and propylene glycol, soluble in glycerin and water, insoluble in mineral oil. 
Natural products exist in laurel oil, ajawa oil, angelica root oil, raspberry, strawberry, cream, Wine etc. 
Because Butanedione is volatile, it only exists in in the primary distillate and distilled water.

Butanedione has a very strong buttery odor in very dilute solution. 
Butanedione is a constituent of many fruit and food aromas and well-known as a constituent of butter. 
Many methods are known for itsmanufacture, for example, dehydrogenation of Butanedione with a copper chromite catalyst. 
Biotechnological production on an industrial scale is referred. 
Butanedione is used mainly in aromas for butter and roasted notes. 
Large quantities are used for flavoring margarine; small amounts are used in perfumes.

Content analysis    
The content of Butanedione is analyzed according to method 1(hydroxylamine method) of the aldehyde and ketone analyzing methods (OT-7). 
The sample weight is 500mg. 
The equivalent factor (e) in calculation is 21.52.
Butanedione is Fit to be analyzed using nonpolar column in GT-10-4.

Occurrence and biosynthesis
Butanedione arises naturally as a byproduct of fermentation. 
In some fermentative bacteria, Butanedione is formed via the thiamine pyrophosphate-mediated condensation of pyruvate and acetyl CoA.
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 Butanedione. 
Malic acid can be converted to lactic acid to make Butanedione.

Chemical structure
A distinctive feature of Butanedione is the long C–C bond linking the carbonyl centers. 
Butanedione bond distance is about 1.54 Å, compared to 1.45 Å for the corresponding C–C bond in 1,3-butadiene. 
The elongation is attributed to repulsion between the polarized carbonyl carbon centers.

Uses    
Butanedione is a naturally occurring product and can be found in numerous foods such as butter, milk, cheese, smoked or roasted meats, breads, fruits, vegetables, coffee, beer, and wine. 
Butanedione is synthesized to be used as a food additive to impart a buttery flavor and has been designated as a generally recognized as safe (GRAS) substance with low acute toxicity. 
Desirable flavor concentrations in food are approximately 0.05–5.0 ppm and above that range Butanedione imparts a disagreeable taste. 
The most recognized recent use has been in microwave popcorn, but Butanedione has also been used for many other products. 
Butanedione may be used in additives as a liquid, paste, or powder.
Butanedione meets GB 2760—1996 standards of edible spices for the moment. 
Butanedione is mainly used for the preparation of food essence like cream, cheese fermentation and coffee typed essence,used in milk, butter, margarine, cheese, sweets and other flavors, such as berry, caramel, chocolate, coffee, cherry, vanilla bean, honey, cocoa, fruit, wine, aroma, rum, nuts, almonds, ginger and so on. 
Butanedione can also be used in fresh fruit fragrance essence for makeup or new type essence in trace amount, and be used as gelatin hardening agent and photographic adhesive agent.

Butanedione is a flavoring agent that is a clear yellow to yellowish green liquid with a strong pungent odor. 
Butanedione is chemically synthesized from methyl ethyl ketone. 
Butanedione is miscible in water, glycerin, alcohol, and ether, and in very dilute water solution it has a typical buttery odor and flavor. 
Butanedione is used as Carrier of aroma of butter, vinegar, coffee, and other foods. 
Butanedione is also used Inactivates aminopeptidase-N, precursor to α-diones, Cyclocondensation with amines has been used to form triazine and pteridine ring systems.

Butanedione is very common in Nature, although usually in trace amounts only: in essential oils, flower absolutes, dairy products, meat and fruits, etc.
Butanedione finds some use in perfumery - mainly in the re-construction of essential oils (artificial essential oils and flower absolutes). 
Lavender, Lavandin, Bay, Orris and many other oils contain traces of this ketone.
Finds extensive use in flavor compositions, primarily in imitation Butter, Milk, Cream. Cheese, etc. 
Also in Berry flavors, Butterscotch, Caramel, Chocolate, CotTee, Cherry, Fruit, Honey, Liquor, Tobacco, Rum, Wine, Nut, Almond, Spice, Ginger Ale, Cream Soda, Vinegar, Vanilla, Buttermilk, etc.
Normal concentration in consumer product will be about 3 to 30 ppm, while Butanedione may be as high as 40 to 50 ppm in baked goods. 
imitation Butter may contain about 6 to 9 prm.

In food products
Butanedione and acetoin are two compounds that give butter its characteristic taste. 
Because of this, manufacturers of artificial butter flavoring, margarines 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.

Electronic cigarettes
Butanedione is used as a flavoring agent in some liquids used in electronic cigarettes.
People nearby may be exposed to it in the exhaled aerosol at levels near the limit set for occupational exposure.

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, Butanedione's presence is considered a flaw or undesirable.
Butanedione is produced during fermentation as a byproduct of valine synthesis, when yeast produces α-acetolactate, which escapes the cell and is spontaneously decarboxylated into diacetyl.
The yeast then absorbs the Butanedione, and reduces the ketone groups to form acetoin and 2,3-butanediol.

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 Butanedione 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.
Butanedione is present in some chardonnays known as "butter bombs", although there is a trend back toward the more traditional French styles.
Concentrations from 0.005 mg/L to 1.7 mg/L were measured in chardonnay wines, and the amount needed for the flavor to be noticed is at least 0.2 mg/L.

Production    
In nature, Butanedione exists widely in many Plant essential oils, such as iris oil, angelica oil, laurel oil, etc. 
Butanedione is the main component of butter and other natural products fragrance.
In industry, methyl ethyl ketone was treated with nitrite acid to generate diacetylmonoxime. 
Butanedione is then decomposed by sulfuric acid to produce Butanedione.
Butanedione can be obtained by chemical ionization method from high content of essential oil. 
Two parts of phosphoric acid were added to one part of essential oil to
produce crystalline adduct CH3CO-COCH3. 
Butanedione was released after the addition of water. 
Excessive addition of phosphoric acid will lead to liquid adduct product.
Butanedione can be obtained by special fermentation of glucose.
Butanedione can be synthesized using methyl ethyl ketone as raw material.
Butanedione was oxidized by sodium nitrite in the presence of hydrochloric acid,
Then, the process of istillation is carried out after hydrolysis in the presence of sulfuric acid to produce Butanedione.

Preparation    
From methyl ethyl ketone by converting to the isonitroso compound and then decomposing to diacetyl by hydrolysis with HCl; by fermentation of glucose via methyl acetyl carbinol.

Toxicology    
Butanedione is an intensely yellowish or greenish-yellow mobile liquid. 
Butanedione has a very powerful and diffusive, pungent, buttery odor and typically used in flavor compositions, including butter, milk, cream, and cheese. 
Butanedione was found to be mutagenic in Ames test conducted under various different conditions with Salmonella typhimurium strains. 
For example, Butanedione was mutagenic by TA100 in the absence of S9 metabolic activation at doses up to 40 mM/plate. 
Butanedione was mutagenic in a modified Ames assay in Salmonella typhimurium strains TA100 with and without S9 activation. 
The acute oral LD50 of Butanedione in guinea pigs was calculated to be 990 mg/kg. 
The acute oral LD50 of Butanedione in male rats was calculated to be 3400 mg/kg, and in female rats, the LD50 was calculated to be 3000 mg/kg. 
When male and female rats were administered via gavage a daily dose of 1, 30, 90, or 540 mg/kg/day of Butanedione in water for 90 days, the high-dose produced anemia, decreased weight gain, increased water consumption, increased leukocyte count, and an increase in the relative weights of liver, kidneys, and adrenal and pituitary glands. 
The data for teratogenicity and carcinogenicity are not available. 
Although the FDA has affirmed Butanedione GRAS as a flavoring agent, low molecular weight carbonyls, such as formaldehyde, acetaldehyde, and glyoxal have been reported to possess a certain chronic toxicity.

Reactivity Profile    
Butanedione is a flammable liquid, b.p. 88° C, moderately toxic. 
When heated to decomposition Butanedione emits acrid smoke and fumes.