Acetophenone is the organic compound with the formula C<sub>6</sub>H<sub>5</sub>C(O)CH<sub>3</sub>. It is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances.
Production
Acetophenone is formed as a byproduct of the cumene process, the industrial route for the synthesis of phenol and acetone. In the Hock rearrangement of isopropylbenzene hydroperoxide, migration of a methyl group rather than the phenyl group gives acetophenone and methanol as a result of an alternate rearrangement of the intermediate:
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The cumene process is conducted on such a large scale that even the small amount of acetophenone by-product can be recovered in commercially useful quantities.
It is also listed as an approved excipient by the U.S. FDA. More common as a fragrance is the closely related 4-methylacetophenone.
Laboratory reagent
In instructional laboratories, acetophenone is converted to styrene in a two-step process that illustrates the reduction of carbonyls using sodium borohydride and the dehydration of alcohols:
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A similar two-step process is used industrially, but reduction step is performed by hydrogenation over a copper chromite catalyst:
Natural occurrence
Acetophenone occurs naturally in many foods including apple, cheese, apricot, banana, beef, and cauliflower.
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, although other substances, like toluene, also induce hippuric acid in urine.
Toxicity
The is 815 mg/kg (oral, rats).