General Description
A colorless liquid with a sweet pungent taste and odor resembling the odor of oranges. Melting point 20.5°C (68.9°F); freezes under cool conditions. Slightly soluble in water and denser than water. Hence sinks in water. Vapor heavier than air. Flash point 180°F. A mild irritant to skin and eyes. Vapors can be narcotic in high concentrations. Used as a flavoring, solvent, and polymerization catalyst.
Reactivity Profile
ACETOPHENONE(98-86-2) reacts with many acids and bases liberating heat and flammable gases (e.g., H2). Reacts with many oxidizing agents. Reacts with reducing agents such as hydrides, alkali metals, and nitrides to produce flammable gas (H2) and heat. The amount of heat in these reactions may be sufficient to start a fire in the unreacted portion. Incompatible with isocyanates, aldehydes, cyanides, peroxides, and anhydrides.
Air & Water Reactions
Slightly soluble in water.
Health Hazard
No toxicity expected from inhalation or ingestion except slight narcotic effect. Liquid can cause eye and skin irritation on contact.
Potential Exposure
Acetophenone is used as a solvent and in perfume manufacture to impact a pleasant jasmine or orange-blossom odor. It is used as a catalyst in olefin polymerization and as a flavorant in tobacco. It is also used in the synthesis of pharmaceuticals
First aid
Remove any contact lenses at once, then flush eyes, wash contaminated areas of body with soap and water. If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Shipping
UN1993 Flammable liquids, n.o.s., Hazard Class: 3; Labels: 3-Flammable liquid, Technical Name Required.
Incompatibilities
May form explosive mixture with air. See flash point, above. Reacts violently with strong oxidizers, many acids, bases, amines, amides, and inorganic hydroxides; alkali metals; hydrides, and nitrides. Reacts with reducing agents; alkali metals; hydrides, nitrides. Contact with all preceding materials release heat and flammable gases, including hydrogen; the heat may be sufficient enough to result in fire. Incompatible with aldehydes, aliphatic amines, alkanolamines, cyanides, isocyanates, organic acids, peroxides; perchloric acid. May attack plastics, and some rubbers and coatings
Waste Disposal
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration, preferably with a flammable solvent
Occurrence
Reported found in cocoa, beef, raspberry, peas, and concord grape
Definition
ChEBI: A methyl ketone that is acetone in which one of the hydrogens of the methyl group has been replaced by a phenyl group.
Preparation
From benzene and acetylchloride in the presence of aluminum chloride or by catalytic oxidation of ethyl benzene; also
prepared by fractional distillation and crystallization from the essential oil of Stirlingia latifolia.
Production Methods
Most methyl phenyl ketone originates from the Hock process for the production of phenol from isopropylbenzene (→Phenol); it is isolated from the residue of this process. In addition, acetophenone can be obtained as a main product by selective decomposition of cumene hydroperoxide in the presence of copper catalysts at 100℃:
A second possibility is the oxidation of ethylbenzene with air or oxygen at 130℃ and 0.5 MPa. Catalysts used include cobalt salts or manganese salts of naphthenic or fatty acids. Conversion of ethylbenzene is limited to ca. 25 % to minimize the byproducts 1-phenylethanol and benzoic acid. A third method is the Friedel – Crafts acetylation of benzene with acetic anhydride, but this is not of industrial importance.
Aroma threshold values
Detection: 170 ppb; Recognition: 2.9 ppm
Taste threshold values
Taste characteristics at 10 ppm: sweet, nutty, benzaldehyde with musty, fruity notes
Fire Hazard
Combustible liquid; flash point (closed cup)
82°C (180°F); vapor pressure 1 torr at
37°C (98.6°F); vapor density 4.1 (air = 1);
autoignition temperature 570°C (1058°F);
fire-extinguishing agent: dry chemical, foam,
or CO2; water may cause frothing, but it can
be used to flush and dilute the spill. Its reaction
with strong oxidizers may be violent.
Flammability and Explosibility
Notclassified
Carcinogenicity
No carcinogenicity studies were
identified for acetophenone. The U.S. EPA has classified
acetophenone as a Category D, not classifiable as to human
carcinogenicity.
Environmental Fate
It is unclear what mechanism is responsible for the central
nervous system depression observed following high doses of
acetophenone. In vitro evaluations have demonstrated that
acetophenone suppresses voltage-gated ion channels in olfactory
receptor cells and retinal neurons; however, it is unclear if
this is related to any of the observed toxicity in animal studies.
Metabolism
At one time, acetophenone was used as a hypnotic. Its conversion to benzoic acid and methylphenylcarbinol in dogs and rabbits was observed by a number of early workers. Small amounts are also excreted as mandelic acid. In the rabbit about half the dose is excreted as methylphenylcarbinyl glucuronide and about 20 % as hippuric acid. It is probable that the ketone is first asymmetrically reduced to the carbinol, which is the precursor of benzoic and mandelic acids.
Solubility in organics
miscible with ethyl alcohol, essential oils and perfume chemicals. Sp.Gr. = 1.033.
Purification Methods
Dry it by fractional distillation or by standing with anhydrous CaSO4 or CaCl2 for several days, followed by fractional distillation under reduced pressure (from P2O5, optional), and careful, slow and repeated partial crystallisations from the liquid at 0o excluding light and moisture. It can also be crystallised at low temperatures from isopentane. Distillation can be followed by purification using gas-liquid chromatography [Earls & Jones J Chem Soc, Faraday Trans 1 71 2186 1975.] [Beilstein 7 H 271, 7 IV 619.] § A commercial polystyrene supported version is available — scavenger resin (for diol substrates).
Toxicity evaluation
The production and use of acetophenone as a specialty solvent
and fragrance and flavor additive may result in environmental
releases to the air, water, and soil. Acetophenone is slightly
soluble in water and freely soluble in alcohol, chloroform, fatty
oils, and glycerol. The vapor pressure at 25 °C is 0.4 mmHg,
the Henry’s law constant is estimated to be 1.04×105
atmm3 mol-1, and the octanol/water partition coefficient
(log Kow) is 1.58.
If released to the soil, acetophenone is expected to have high
mobility, with volatilization from moist soils. If released to the
water, volatilization is anticipated from the surface and acetophenone
is not anticipated to adsorb to sediment. The potential
for bioconcentration in aquatic organisms is predicted to
be low. If released to the atmosphere, the half-life is anticipated
to be 6 days, with degradation occurring by reaction with
photochemically produced hydroxyl radicals.
Toxics Screening Level
The initial threshold screening level (ITSL) for acetophenone is 490 μg/m3 based
on an 8 hr. averaging time.
