2,3-бутандион

Описание

2,3-Butanedione, also known as Diacetyl, is a reactive diketone in artificial butter flavors. It is a water-soluble and volatile, alpha-diketone compound that has a buttery odor. Diacetyl occurs naturally in plants, fruits, coffee, honey, cocoa, and dairy products. It is a natural by-product of fermentation and is found in beer and wine. Diacetyl is also present in cigarette smoke.
Diacetyl can be synthesized by converting 2-butanone to an isonitroso compound and then hydrolyzing it with hydrochloric acid. Other methods for producing diacetyl 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, diacetyl can be synthesized through the acid catalyzed condensation of 1-hydroxyacetone and formaldehyde. Naturally occurring diacetyl is also available from starter distillate, a by-product of dairy product fermentation. Although diacetyl and starter distillates are liquids, they can be converted to a powdered form by encapsulating them within a solid material to prevent volatility. Diacetyl 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.

Химические свойства

2,3-Butanedione has a very strong buttery odor in very dilute solution. It 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 2,3-butanediol with a copper chromite catalyst. Biotechnological production on an industrial scale is referred. It is used mainly in aromas for butter and roasted notes. Large quantities are used for flavoring margarine; small amounts are used in perfumes.

Вхождение

Reported in the oils of: Finnish pine, angelica and lavender; in the flowers of Polyalthia canangioides Boerl. var. angustifolia and Fagroea racemosa Jack. The following plants are also reported to contain diacetyl: Monodora grandiflora Benth., Magnolia tripetale L., Ximenia aegyptiaca L., Petasites fragrans Presl., various narcissi and tulips. It has been identified in certain types of wine, the natural aromas of raspberry and strawberry, and the oils of lavender, lavandin, Réunion geranium, Java citronella, and Cistus ladaniferus L. It is also reported to be found in ligonberry, guava, raspberry, strawberry, cabbage, peas, tomato, vinegar, various cheeses, yogurt, milk, butter, chicken, beef, mutton, pork, cognac, beer, wines, whiskies, tea and coffee.

Использование

2,3-Butanedione is a flavoring agent that is a clear yellow to yellowish green liquid with a strong pungent odor. It is chemically synthesized from methyl ethyl ketone. It is miscible in water, glycerin, alcohol, and ether, and in very dilute water solution it has a typical buttery odor and flavor. It is used as Carrier of aroma of butter, vinegar, coffee, and other foods. It is also used Inactivates aminopeptidase-N, precursor to α-diones, Cyclocondensation with amines has been used to form triazine and pteridine ring systems.

Определение

ChEBI: 2,3-Butanedione is an alpha-diketone that is butane substituted by oxo groups at positions 2 and 3. It is a metabolite produced during the malolactic fermentation. It has a role as a Saccharomyces cerevisiae metabolite and an Escherichia coli metabolite.

Подготовка

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.

прикладной

2,3-Butanedione is very common in Nature, although usually in trace amounts only: in essential oils, flower absolutes, dairy products, meat and fruits, etc.
It 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 it may be as high as 40 to 50 ppm in baked goods. imitation Butter may contain about 6 to 9 prm.

Общее описание

2,3-Butanedione appears as a clear colorless liquid with a strong?chlorine-like odor. Flash point 80 °F. Less dense than?water. Vapors heavier than air.

Реакции воздуха и воды

Highly flammable. Soluble in water.

Профиль реактивности

2,3-Butanedione is a flammable liquid, b.p. 88° C, moderately toxic. When heated to decomposition 2,3-Butanedione emits acrid smoke and fumes [Sax, 9th ed., 1996, p. 544].

Угроза здоровью

Inhalation or contact with material may irritate or burn skin and eyes. Fire may produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control may cause pollution.

Пожароопасность

HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

Профиль безопасности

A poison by ingestion and intraperitoneal routes. A skin irritant. Human inhalation hazard in popcorn manufacture. Human mutation data reported. Flammable liquid. Dangerous fire hazard when exposed to heat or flame. To fight fire, use alcohol foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and fumes. See also KETONES.

Методы очистки

Dry biacetyl over anhydrous CaSO4, CaCl2 or MgSO4, then distil it in a vacuum under nitrogen, taking the middle fraction and storing it at Dry-Ice temperature in the dark (to prevent polymerization). [Beilstein 1 IV 3644.]