Acetophenone is the organic compound with the formula C6H5C(O)CH3. It is the
simplest aromatic ketone. This colourless, viscous liquid is a
precursor to useful resins and fragrances.
Production Acetophenone can be obtained by a
variety of methods. In industry, acetophenone is recovered as a
by-product of the oxidation of ethylbenzene, which mainly gives
ethylbenzene hydroperoxide for use in the production of propylene oxide.
Uses = Precursor to resins =
Commercially significant resins are produced from treatment of acetophenone
with formaldehyde and base. The resulting polymers are conventionally
described with the formula [C6H5C(O)CH]x(CH2)x]n, resulting from
aldol condensation. These substances are components of coatings and inks.
Modified acetophenone-formaldehyde resins are produced by the hydrogenation
of the aforementioned ketone-containing resins. The resulting polyol can be
further crosslinked with diisocyanates. These modified resins are again found in
coatings, inks, as well as adhesives. = Use in pharmaceutical and related
areas = Acetophenone is a raw material for the
synthesis of some pharmaceuticals, examples include dextropropoxyphene and
phenylpropanolamine. = Niche uses =
Acetophenone is an ingredient in fragrances that resemble almond, cherry,
honeysuckle, jasmine, and strawberry. It is used in chewing gum. It is also
listed as an approved excipient by the U.S. FDA. In a 1994 report released by
five top cigarette companies in the U.S., acetophenone was listed as one of
the 599 additives to cigarettes. = Laboratory reagent =
In instructional laboratories, acetophenone is converted to styrene in
a two-step process that illustrates the reduction of carbonyls and the
dehydration of alcohols: 4 C6H5C(O)CH3 + NaBH4 + 4 H2O → 4
C6H5CH(OH)CH3 + NaOH + B(OH)3 → C6H5CH=CH2
A similar process is used industrially but the hydrogenation step to
1-phenylethanol is done over a copper catalyst.
C6H5CH(OH)CH3 → C6H5CH=CH2 + H2O Being prochiral, acetophenone is also a
popular test substrate for asymmetric hydrogenation experiments.
Natural occurrence Acetophenone occurs naturally in many
foods including apple, cheese, apricot, banana, beef, and cauliflower. It is
also a component of castoreum, the exudate from the castor sacs of the
mature beaver. Pharmacology
In the late 19th and early 20th centuries, acetophenone was used in
medicine. It was marketed as a hypnotic and anticonvulsant under brand name
Hypnone. The typical dosage was 0.12 to 0.3 milliliters. It was considered to
have superior sedative effects to both paraldehyde and chloral hydrate. In
humans, acetophenone is metabolized to benzoic acid, carbonic acid, and
acetone. Hippuric acid occurs as an indirect metabolite and its quantity in
urine may be used to confirm acetophenone exposure.
Toxicity The LD50 is 815 mg/kg. Acetophenone is
currently listed as a Group D carcinogen, indicating that it does not
produce carcinogenic effects in humans, although no studies on humans have ever
been conducted on acetophenones' carcinogenic potential. Studies have
shown that acetophenone causes chromosomal damage in hamsters.
References