General Description
A clear colorless liquid with a strong chlorine-like odor. Flash point 80°F. Less dense than water. Vapors heavier than air.
Reactivity Profile
DIACETYL(431-03-8) is a flammable liquid, b.p. 88° C, moderately toxic. When heated to decomposition DIACETYL(431-03-8) emits acrid smoke and fumes [Sax, 9th ed., 1996, p. 544].
Air & Water Reactions
Highly flammable. Soluble in water.
Health Hazard
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.
Fire Hazard
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.
Description
Diacetyl 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.
Occurrence
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.
Definition
ChEBI: An alpha-diketone that is butane substituted by oxo groups at positions 2 and 3. It is a metabolite produced during the malolactic fermentation.
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.
Aroma threshold values
Detection: 0.3 to 15 ppb: recognition: 5 ppb
Taste threshold values
Taste characteristics at 50 ppm: sweet, buttery, creamy and milky.
Toxicology
Diacetyl is an intensely yellowish or greenish-yellow mobile liquid. It has a very powerful and diffusive, pungent, buttery odor and typically used in flavor compositions, including butter, milk, cream, and cheese. Diacetyl was found to be mutagenic in Ames test conducted under various different conditions with Salmonella typhimurium strains. For example, diacetyl was mutagenic by TA100 in the absence of S9 metabolic activation at doses up to 40 mM/plate. It was mutagenic in a modified Ames assay in Salmonella typhimurium strains TA100 with and without S9 activation. The acute oral LD50 of diacetyl in guinea pigs was calculated to be 990 mg/kg. The acute oral LD50 of diacetyl 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 diacetyl 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 diacetyl GRAS as a flavoring agent, low molecular weight carbonyls, such as formaldehyde, acetaldehyde, and glyoxal have been reported to possess a certain chronic toxicity.
Potential Exposure
Tumorigen,Drug, Mutagen, Primary Irritant. Butanedione is used as anaroma carrier food additive in butter, vinegar, coffee, andother foods.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contactsthe skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove fromexposure, begin rescue breathing (using universal precautions,including resuscitation mask) if breathing hasstopped and CPR if heart action has stopped. Transferpromptly to a medical facility. When this chemical hasbeen swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Carcinogenicity
Diacetyl was tested for its ability
to induce primary lung tumors in strain A/He mice. The
mice received three IP injections of diacetyl per week for
8 weeks and were killed 24 weeks after the first injection. The
total dose of diacetyl given was 1.7 or 8.4 g/kg. The number
of lung tumors in diacetyl exposed mice was not significantly
different from the control mice.
Inhalation carcinogenicity bioassays withWistar Han rats
and B6C3F1 mice at exposure levels of 0, 12.5, 25, and
50 ppm are underway according to the National Toxicology
Program.
Environmental Fate
Mechanisms of diacetyl-induced toxicity are not known, but
some possible mechanisms of toxicity have been postulated.
The adjacent carbonyl groups on diacetyl make it a reactive
compound. In vitro studies have demonstrated that diacetyl can
bind to arginine and inactivate proteins. The electron affinity of
diacetyl suggests that it can undergo electron transfer activity,
which can lead to oxidative stress by oxygen redox cycling.
Redox cycling and oxidative stress may also be initiated during
metabolism of diacetyl by DCXR (dicarbonyl/L-xylulose
reductase). Reactive oxygen species are known to be produced
from metabolic activation of dicarbonyl substrates by related
carbonyl reductase enzymes in the presence of O2.
storage
Color Code—Red: Flammability Hazard: Storein a flammable liquid storage area or approved cabinetaway from ignition sources and corrosive and reactivematerials. Store in tightly closed containers in a cool,well-ventilated area. Sources of ignition, such as smokingand open flames, are prohibited where Butanedione isused, handled, or stored in a manner that could createa potential fire or explosion hazard. Metal containersinvolving the transfer of=gallons or more of butanedioneshould be grounded and bonded. Drums must be equippedwith self-closing valves, pressure vacuum bungs andflame arresters. Use only nonsparking tools and equipment,especially when opening and closing containers ofButanedione. Wherever butanedione is used, handled,manufactured, or stored, use explosion-proof electricalequipment and fittings.
Shipping
Butanedione must be labeled “FLAMMABLELIQUID.” It falls in Hazard Class 3 and Packing Group II.
Purification Methods
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.]
Toxicity evaluation
Diacetyl released to the environment is expected to be highly
mobile in soil and is not expected to adsorb to suspended sediments and solids in water. Diacetyl is degraded by
a bacterium tentatively identified as Pseudomonas. Bioconcentration
of diacetyl by aquatic organisms is not likely.
Diacetyl is expected to volatilize from soil and water surfaces,
and diacetyl is likely to exist solely as a vapor in the ambient
atmosphere. In the atmosphere, diacetyl is degraded by
photochemically produced hydroxyl radicals and it undergoes
photolysis.
Incompatibilities
Contact with oxidizers may cause fireand explosions. High heat may cause violent combustion orexplosion.
