Acetone
(also known as propanone, dimethyl ketone, 2-propanone,
propan-2-one and ¥-ketopropane) is a colorless, mobile, flammable liquid. It is the simplest example of the ketones. Acetone is miscible with water, ethanol, ether, etc., and itself serves as an important solvent. The most familiar
household use of acetone is as the active ingredient in nail polish remover. Acetone is also used to make plastic, fibers, drugs, and other chemicals. In addition to being manufactured as a chemical, acetone is also found naturally
in the environment, including in small amounts in the human body.
Production
Acetone is produced primarily in the cumene process. Previously, acetone was produced by the dry distillation of acetates, for example calcium acetate. During World War I a
new process of producing acetone through bacterial fermentation was developed by Chaim Weizmann, later the first president of Israel, in order to help the British war effort.
Biosynthesis
Small amounts of acetone are produced in the body by the decarboxylation of ketone bodies.
Uses
Cleaning fluid
Acetone is often the primary (or only) component in nail polish remover. Acetonitrile, another organic solvent, is sometimes used as well.
Acetone is also used as a superglue remover. It can be used for thinning and cleaning fiberglass resins and epoxies. It is a strong solvent for most plastics and synthetic fibres.
It is ideal for thinning fiberglass resin,
cleaning fiberglass tools and dissolving two-part epoxies and superglue before hardening. A heavy-duty degreaser, it is useful in the preparation of metal prior to painting; it also thins polyester resins, vinyl and adhesives. It
easily removes residues from glass and porcelain. In biological research contexts, buffers that contain acetone (such as citrate-buffered formalin) use the acetone to lyse cells for further experimentation.
Additionally, acetone is extremely effective when used as a cleaning agent when dealing with permanent markers.
Solvent
Acetone can also dissolve many plastics, including those used in Nalgene bottles made of polystyrene, polycarbonate and
some types of polypropylene.
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 also critical for the successful Jones
oxidation. Technical grade acetone is inexpensive. Because of acetone's medium polarity, it dissolves a wide range of compounds. Thus, it is commonly loaded into squeezebottles and used as a general solvent in rinsing laboratory
glassware.
Acetone is also used extensively for the safe transporting and storing of acetylene. 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.
Feedstock
An important industrial use for acetone involves its reaction with phenol for the manufacture of bisphenol A. Bisphenol A is an important component of many polymers such as
polycarbonates, polyurethanes and epoxy resins. Acetone has also been used in the manufacture of cordite.
Automotive fuel additive
Some automotive enthusiasts add acetone at around 1 part in 500 to their fuel, following claims of dramatic
improvement in fuel economy and engine life. This practice is controversial as there are counterclaims that acetone has no measurable effect or may in fact reduce engine life by adversely affecting fuel system parts. Debates on
this subject and claims of Big Oil cover-up intensified when the practice was addressed on the popular American TV show MythBusters in 2006, and shown to have negative effect in the televised fuel economy test..
Other uses
Acetone is also used as a drying agent, due to the readiness with which it mixes with water, and its volatility.
It can be used as an artistic agent; when rubbed on the back of any laser print or photocopy it produces a roughened effect.
Safety
Acetone peroxide
Main article: acetone peroxide
When oxidized,
acetone forms acetone peroxide as a by-product, which is a highly unstable compound. It may be formed accidentally, e.g. when waste hydrogen peroxide is poured into a carboy containing waste acetone solvent.
Toxicology
Acetone is an
irritant and inhalation may lead to hepatotoxic effects (causing liver damage). The vapors should be avoided. In no circumstance should it be consumed directly or indirectly. Always use goggles when handling acetone; it can cause
permanent eye damage (corneal clouding).
Small amounts of acetone are metabolically produced in the body, mainly from fat. In humans, fasting significantly increases its endogenous production (see ketosis). Acetone can be
elevated in diabetes. Contamination of water, food (e.g. milk), or the air (acetone is volatile) can lead to chronic exposure to acetone. A number of acute poisoning cases have been described. Relatively speaking, acetone is not a
very toxic compound; it can, however, damage the mucosa of the mouth and can irritate and damage skin. Accidental intake of large amounts of acetone may lead to unconsciousness and death.
The effects of long-term exposure to
acetone are known mostly from animal studies. Kidney, liver, and nerve damage, increased birth defects, and lowered reproduction ability of males (only) occurred in animals exposed long-term. It is not known if these same effects
would be exhibited in humans. Pregnant women should avoid contact with acetone and acetone fumes in order to avoid the possibility of birth defects, including brain damage.
Interestingly, 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. |
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