This page refers to the chemical compound. For the slowcore band, see Acetone.
Acetone is the organic compound with the formula2CO. It is a colorless, volatile, flammable liquid,
and is the simplest ketone. Acetone is miscible with water and serves
as an important solvent in its own right, typically for cleaning purposes in the laboratory.
About 6.7 million tonnes were produced worldwide in 2010, mainly for use as a solvent and production
of methyl methacrylate and bisphenol A. It is a common building block in organic chemistry.
Familiar household uses of acetone are as the active ingredient in nail polish remover
and as paint thinner. Acetone is produced and disposed of in the
human body through normal metabolic processes. It is normally present in blood and urine.
People with diabetes produce it in larger amounts. Reproductive toxicity tests show
that it has low potential to cause reproductive problems. Pregnant women, nursing mothers
and children have higher levels of acetone. Ketogenic diets that increase acetone in the
body are used to reduce epileptic attacks in infants and children who suffer from recalcitrant
refractory epilepsy.
Metabolism
Biosynthesis Small amounts of acetone are produced in the
body by the decarboxylation of ketone bodies. Certain dietary patterns, including prolonged
fasting and high-fat low-carbohydrate dieting, can produce ketosis, in which acetone is formed
in body tissue. Certain health conditions, such as alcoholism and diabetes, can produce
ketoacidosis, uncontrollable ketosis that leads to a sharp, and potentially fatal, increase
in the acidity of the blood. Since it is a byproduct of fermentation, acetone is a byproduct
of the distillery industry. Metabolic use
Although some biochemistry textbooks and current research publications indicate that acetone
cannot be metabolized, there is evidence to the contrary, some dating back thirty years.
Acetone can be produced from the oxidation of ingested isopropanol, or from the spontaneous/enzymatic
breakdown of acetoacetate in ketotic individuals. It can then be metabolized either by CYP2E1
via methylglyoxal to D-lactate and pyruvate, and ultimately glucose/energy, or by a different
pathway via propylene glycol to pyruvate, lactate, acetate and propionaldehyde.
Production In 2010, the worldwide production capacity
for acetone was estimated at 6.7 million tonnes per year. With 1.56 million tonnes per year,
the United States had the highest production capacity, followed by Taiwan and mainland
China. The largest producer of acetone is INEOS Phenol, owning 17% of the world's capacity,
with also significant capacity by Mitsui, Sunoco and Shell in 2010. INEOS Phenol also
owns the world's largest production site in Beveren. Spot price of acetone in summer 2011
was 1100–1250 USD/tonne in the United States. Current method
Acetone is produced directly or indirectly from propylene. Approximately 83% of acetone
is produced via the cumene process; as a result, acetone production is tied to phenol production.
In the cumene process, benzene is alkylated with propylene to produce cumene, which is
oxidized by air to produce phenol and acetone:
Other processes involve the direct oxidation of propylene, or the hydration of propylene
to give 2-propanol, which is oxidized to acetone. Older methods
Previously, acetone was produced by the dry distillation of acetates, for example calcium
acetate in ketonic decarboxylation. Ca(CH3COO)2 → CaO(s) + CO2(g) +2CO
Before that, during World War I acetone was produced using acetone-butanol-ethanol fermentation
with Clostridium acetobutylicum bacteria, which was developed by Chaim Weizmann in order
to help the British war effort in the preparation of Cordite. This acetone-butanol-ethanol fermentation
was eventually abandoned when newer methods with better yields were found.
Uses About a third of the world's acetone is used
as a solvent, and a quarter is consumed as acetone cyanohydrin a precursor to methyl
methacrylate. Solvent
Acetone is a good solvent for many plastics and some synthetic fibers. It is used for
thinning polyester resin, cleaning tools used with it, and dissolving two-part epoxies and
superglue before they harden. It is used as one of the volatile components of some paints
and varnishes. As a heavy-duty degreaser, it is useful in the preparation of metal prior
to painting. It is also useful for high reliability soldering applications to remove rosin flux
after soldering is complete; this helps to prevent the Rusty bolt effect.
Acetone is used as a solvent by the pharmaceutical industry and as a denaturant in denatured
alcohol. Acetone is also present as an excipient in some pharmaceutical drugs.
Although itself flammable, acetone is used extensively as a solvent for the safe transporting
and storing of acetylene, which cannot be safely pressurized as a pure compound. Vessels
containing a porous material are first filled with acetone followed by acetylene, which
dissolves into the acetone. One liter of acetone can dissolve around 250 liters of acetylene.
Chemical intermediate Acetone is used to synthesize methyl methacrylate.
It begins with the initial conversion of acetone to acetone cyanohydrin:
(CH3)2CO + HCN →2C(OH)CN In a subsequent step, the nitrile is hydrolyzed
to the unsaturated amide, which is esterified: (CH3)2C(OH)CN + CH3OH → CH2=(CH3)CCO2CH3
+ NH3 The third major use of acetone is synthesizing
bisphenol A. Bisphenol A is a component of many polymers such as polycarbonates, polyurethanes,
and epoxy resins. The synthesis involves the condensation of acetone with phenol:
(CH3)2CO + 2 C6H5OH →2C(C6H4OH)2 + H2O Many millions of kilograms of acetone are
consumed in the production of the solvents methyl isobutyl alcohol and methyl isobutyl
ketone. These products arise via an initial aldol condensation to give diacetone alcohol.
22CO →2C(OH)CH2C(O)CH3 Laboratory
In the laboratory, acetone is used as a polar, aprotic solvent in a variety of organic reactions,
such as SN2 reactions. The use of acetone solvent is critical for the Jones oxidation.
It does not form an azeotrope with water). It is a common solvent for rinsing laboratory
glassware because of its low cost and volatility. Despite its common use as a supposed drying
agent, it is not effective except by bulk displacement and dilution. Acetone can be
cooled with dry ice to −78 °C without freezing; acetone/dry ice baths are commonly used to
conduct reactions at low temperatures. Acetone is fluorescent under ultraviolet light, and
its vapor may be used as a fluorescent tracer in fluid flow experiments.
Medical and cosmetic uses Acetone is used in a variety of general medical
and cosmetic applications and is also listed as a component in food additives and food
packaging. Dermatologists use acetone with alcohol for acne treatments to peel dry skin.
Acetone is commonly used in chemical peeling. Common agents used today for chemical peels
are salicylic acid, glycolic acid, 30% salicylic acid in ethanol, and trichloroacetic acid.
Prior to chemexfoliation, the skin is cleaned and excess fat removed in a process called
defatting. Acetone, Septisol, or a combination of these agents is commonly used in this process.
Domestic and other niche uses Acetone is often the primary component in
cleaning agents such as nail polish remover. Acetone is a component of superglue remover
and easily removes residues from glass and porcelain. Make-up artists use acetone to
remove skin adhesive from the netting of wigs and moustaches by immersing the item in an
acetone bath, then removing the softened glue residue with a stiff brush.
This chemical is also used as an artistic agent; when rubbed on the back of a laser
print or photocopy placed face-down on another surface and burnished firmly, the toner of
the image transfers to the destination surface. Acetone can also be used in combination with
automatic transmission fluid to create an effective penetrating oil. Brake fluid is
sometimes used in place of ATF. These mixtures can be useful in loosening rusted or stuck
bolts. Safety
Flammability The most hazardous property of acetone is
its extreme flammability. At temperatures greater than acetone's flash point of −20 °C,
air mixtures of between 2.5% and 12.8% acetone, by volume, may explode or cause a flash fire.
Vapors can flow along surfaces to distant ignition sources and flash back. Static discharge
may also ignite acetone vapors, though acetone has a very high ignition initiation energy
point and therefore accidental ignition is rare. Even pouring or spraying acetone over
red-glowing coal will not ignite it, due to the high concentration of vapour and the cooling
effect of evaporation of the liquid. It auto-ignites at 465 °C. Auto-ignition temperature is
also dependent upon the exposure time, thus at some tests it is quoted as 525 °C. Also,
industrial acetone is likely to contain a small amount of water which also inhibits
ignition. Acetone peroxide
When oxidized, acetone forms acetone peroxide as a byproduct, which is a highly unstable,
primary high explosive compound. It may be formed accidentally, e.g. when waste hydrogen
peroxide is poured into waste solvent containing acetone. Due to its instability, it is rarely
used, despite its easy chemical synthesis. Health information
Acetone has been studied extensively and is generally recognized to have low acute and
chronic toxicity if ingested and/or inhaled. Inhalation of high concentrations in the air
caused irritation of the throat in humans in as little as 5 minutes. Inhalation of concentrations
of 1000 ppm caused irritation of the eyes and of the throat in less than 1 hour; however,
the inhalation of 500 ppm of acetone in the air caused no symptoms of irritation in humans
even after 2 hours of exposure. Acetone is not currently regarded as a carcinogen, a
mutagenic chemical or a concern for chronic neurotoxicity effects.
Acetone can be found as an ingredient in a variety of consumer products ranging from
cosmetics to processed and unprocessed foods. Acetone has been rated as a GRAS substance
when present in beverages, baked foods, desserts, and preserves at concentrations ranging from
5 to 8 mg/L. Additionally, a joint U.S-European study found that acetone's "health hazards
are slight". Toxicology
Acetone is believed to exhibit only slight toxicity in normal use, and there is no strong
evidence of chronic health effects if basic precautions are followed.
At very high vapor concentrations, acetone is irritating and, like many other solvents,
may depress the central nervous system. It is also a severe irritant on contact with
eyes, and a potential pulmonary aspiration risk. In one documented case, ingestion of
a substantial amount of acetone led to systemic toxicity, although the patient eventually
fully recovered. Some sources estimate LD50 for human ingestion at 1.159 g/kg; LD50 inhalation
by mice is given as 44 g/m3, over 4 hours. Acetone has been shown to have anticonvulsant
effects in animal models of epilepsy, in the absence of toxicity, when administered in
millimolar concentrations. It has been hypothesized that the high-fat low-carbohydrate ketogenic
diet used clinically to control drug-resistant epilepsy in children works by elevating acetone
in the brain. EPA EPCRA Delisting. EPA removed acetone from
the list of "toxic chemicals" maintained under Section 313 of the Emergency Planning and
Community Right to Know Act. In making that decision, EPA conducted an extensive review
of the available toxicity data on acetone and found that acetone "exhibits acute toxicity
only at levels that greatly exceed releases and resultant exposures", and further that
acetone "exhibits low toxicity in chronic studies".
Genotoxicity. Acetone has been tested in more than two dozen in vitro and in vivo assays.
These studies indicate that acetone is not genotoxic.
Carcinogenicity. EPA in 1995 concluded, "There is currently no evidence to suggest a concern
for carcinogenicity".. NTP scientists have recommended against chronic toxicity/carcinogenicity
testing of acetone because "the prechronic studies only demonstrated a very mild toxic
response at very high doses in rodents". Neurotoxicity and Developmental Neurotoxicity.
The neurotoxic potential of both acetone and isopropanol, the metabolic precursor of acetone,
have been extensively studied. These studies demonstrate that although exposure to high
doses of acetone may cause transient central nervous system effects, acetone is not a neurotoxicant.
A guideline developmental neurotoxicity study has been conducted with isopropanol, and no
developmental neurotoxic effects were identified, even at the highest dose tested..
Environmental. When the EPA exempted acetone from regulation as a volatile organic compound
in 1995, EPA stated that this exemption would "contribute to the achievement of several
important environmental goals and would support EPA's pollution prevention efforts". 60 Fed.
Reg. 31,634. 60 Fed. Reg. 31,634. EPA noted that acetone could be used as a substitute
for several compounds that are listed as hazardous air pollutants under section 112 of the Clean
Air Act. Environmental effects
Although acetone occurs naturally in the environment in plants, trees, volcanic gases, forest fires,
and as a product of the breakdown of body fat, the majority of the acetone released
into the environment is of industrial origin. Acetone evaporates rapidly, even from water
and soil. Once in the atmosphere, it has a 22-day half-life and is degraded by UV light
via photolysis Consumption by microorganisms contributes to the dissipation of acetone
in soil, animals, or waterways. The LD50 of acetone for fish is 8.3 g/L of water over
96 hours, and its environmental half-life in water is about 1 to 10 days. Acetone may
pose a significant risk of oxygen depletion in aquatic systems due to the microbial consumption.
References
External links International Chemical Safety Card 0087
NIOSH Pocket Guide to Chemical Hazards Acetone Safety Data Sheet
Hazardous substances databank entry at the national library of medicine
SIDS Initial Assessment Report for Acetone from the Organisation for Economic Co-operation
and Development Calculation of vapor pressure, liquid density,
dynamic liquid viscosity, surface tension of acetone