Acetophenone

Acetophenone is the organic compound with the formula C6H5C(O)CH3. It is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances.[2]

Acetophenone
Skeletal formula of the acetophenone molecule
Ball-and-stick model of the acetophenone molecule
Ball-and-stick model of the acetophenone molecule
Space-filling model of the acetophenone molecule
Space-filling model of the acetophenone molecule
sample of acetophenone
Names
Preferred IUPAC name
1-Phenylethan-1-one[1]
Other names
Acetophenone
Phenylethanone
Methyl phenyl ketone
Identifiers
3D model (JSmol)
Abbreviations ACP
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.002.462
EC Number
  • 202-708-7
KEGG
RTECS number
  • AM5250000
UNII
UN number 1993
  • InChI=1S/C8H8O/c1-7(9)8-5-3-2-4-6-8/h2-6H,1H3 checkY
    Key: KWOLFJPFCHCOCG-UHFFFAOYSA-N checkY
  • InChI=1/C8H8O/c1-7(9)8-5-3-2-4-6-8/h2-6H,1H3
    Key: KWOLFJPFCHCOCG-UHFFFAOYAT
  • O=C(c1ccccc1)C
  • CC(=O)c1ccccc1
Properties
C8H8O
Molar mass 120.151 g·mol−1
Density 1.028 g/cm3
Melting point 19–20 °C (66–68 °F; 292–293 K)
Boiling point 202 °C (396 °F; 475 K)
5.5 g/L at 25 °C
12.2 g/L at 80 °C
-72.05·10−6 cm3/mol
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H319
P264, P270, P280, P301+P312, P305+P351+P338, P330, P337+P313, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
1
2
0
Flash point 77 °C (171 °F; 350 K)
Safety data sheet (SDS) MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
Infobox references

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:

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.[2]

Acetophenone is also generated from ethylbenzene hydroperoxide. Ethylbenzene hydroperoxide is primarily converted to 1-phenylethanol (α-methylbenzyl alcohol) in the process with a small amount of by-product acetophenone. Acetophenone is recovered or hydrogenated to 1-phenylethanol which is then dehydrated to produce styrene.[2]

Uses

Precursor to resins

Commercially significant resins are produced from treatment of acetophenone with formaldehyde and a base. The resulting copolymers are conventionally described with the formula [(C6H5COCH)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.[2] The modified resins are found in coatings, inks and adhesives.

Niche uses

Acetophenone is an ingredient in fragrances that resemble almond, cherry, honeysuckle, jasmine, and strawberry. It is used in chewing gum.[3] It is also listed as an approved excipient by the U.S. FDA.[4]

Laboratory reagent

In instructional laboratories,[5] acetophenone is converted to styrene in a two-step process that illustrates the reduction of carbonyls using hydride and the dehydration of alcohols:

A similar two-step process is used industrially, but reduction step is performed by hydrogenation over a copper catalyst.[2]

Being prochiral, acetophenone is also a popular test substrate for asymmetric hydrogenation experiments.

Drugs

Acetophenone is used for the synthesis of many pharmaceuticals.[6][7]

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.[8]

Pharmacology

In the late 19th and early 20th centuries, acetophenone was used in medicine.[9] It was marketed as a hypnotic and anticonvulsant under brand name Hypnone. The typical dosage was 0.12 to 0.3 milliliters.[10] It was considered to have superior sedative effects to both paraldehyde and chloral hydrate.[11] In humans, acetophenone is metabolized to benzoic acid, carbonic acid, and acetone.[12] Hippuric acid occurs as an indirect metabolite and its quantity in urine may be used to confirm acetophenone exposure,[13] although other substances, like toluene, also induce hippuric acid in urine.[14]

Toxicity

The LD50 is 815 mg/kg (oral, rats).[2] Acetophenone is currently listed as a Group D carcinogen indicating that there is no evidence at present that it causes cancer in humans.

References
  1. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 723. doi:10.1039/9781849733069-00648. ISBN 978-0-85404-182-4. The names acetophenone and benzophenone are retained only for general nomenclature, but no substitution is allowed.
  2. Siegel, Hardo; Eggersdorfer, Manfred. "Ketones". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_077.
  3. Burdock, George A. (2005), Fenaroli's Handbook of Flavor Ingredients (5th ed.), CRC Press, p. 15, ISBN 0-8493-3034-3, archived from the original on 2014-09-25
  4. "Inactive Ingredient Search for Approved Drug Products". Archived from the original on 2013-05-04.
  5. Wilen, Samuel H.; Kremer, Chester B.; Waltcher, Irving (1961). "Polystyrene—A multistep synthesis: For the undergraduate organic chemistry laboratory". J. Chem. Educ. 38 (6): 304–305. Bibcode:1961JChEd..38..304W. doi:10.1021/ed038p304.
  6. Sittig, Marshall (1988). Pharmaceutical Manufacturing Encyclopedia. pp. 39, 177. ISBN 978-0-8155-1144-1.
  7. Gadamasetti, Kumar; Tamim Braish (2007). Process Chemistry in the Pharmaceutical Industry, Volume 2. pp. 142–145. ISBN 978-0-8493-9051-7.
  8. Müller-Schwarze, D.; Houlihan, P. W. (April 1991). "Pheromonal activity of single castoreum constituents in beaver, Castor canadensis". Journal of Chemical Ecology. 17 (4): 715–34. doi:10.1007/BF00994195. PMID 24258917. S2CID 29937875.
  9. Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
  10. Bartholow, Roberts (1908). A Practical Treatise on Materia Medica and Therapeutics. Appleton & Co.
  11. Norman, Conolly (1887). "Cases illustrating the sedative effects of aceto-phenone". Journal of Mental Science. 32: 519. doi:10.1192/bjp.32.140.519.
  12. "Hypnone – The new hypnotic". Journal of the American Medical Association. 5 (23): 632. 1885. doi:10.1001/jama.1885.02391220016006.
  13. CID 7410 from PubChem
  14. "The Netherlands Center for Occupational Diseases (NCvB): toluene (Dutch)" (PDF). beroepsziekten.nl. Retrieved 19 April 2018.
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