Acetophenone

Acetophenone
Names
Preferred IUPAC name
1-Phenylethan-1-one[1]
Other names
Acetophenone[1]
Methyl phenyl ketone
Phenylethanone
Identifiers
3D model (JSmol)
Abbreviations ACP
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.002.462
KEGG
UNII
Properties
C8H8O
Molar mass 120.15 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
Safety data sheet MSDS
Xn
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
2
1
0
Flash point 77 °C (171 °F; 350 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Acetophenone is the organic compound with the formula C6H5C(O)CH3 (also represented by the letters PhAc or BzMe). It is the simplest aromatic ketone. This colourless, viscous liquid is a precursor to useful resins and fragrances.[2]

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.[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] These modified resins are again found in coatings, inks, as well as 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] 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.[5]

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.[2]

C6H5CH(OH)CH3 → C6H5CH=CH2 + H2O

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

Drugs

Acetophenone is used for the synthesis of many pharmaceuticals, for example: pyrrobutamine, dextropropoxyphene, trihexyphenidyl, pridinol, aspaminol, Cycrimine, Biperiden, Procyclidine, acifran, Amixetrine, Mesuximide, and Benmoxin. Allegedly also for phenylpropanolamine[6][7] (note: in this case it is actually propiophenone not PhAc).

Mannich reaction with dimethylamine and formaldehyde was described.[8] This is used to prepare 1-chloro-1-phenyl-3-dimethylaminopropane, which is used to prepare such antidepressants as Ansoxetine, fluoxetine, atomoxetine, and nisoxetine. Using diethylamine instead gives the diethyl analog.

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.[9]

Pharmacology

In the late 19th and early 20th centuries, acetophenone was used in medicine.[10] It was marketed as a hypnotic and anticonvulsant under brand name Hypnone. The typical dosage was 0.12 to 0.3 milliliters.[11] It was considered to have superior sedative effects to both paraldehyde and chloral hydrate.[12] In humans, acetophenone is metabolized to benzoic acid, carbonic acid, and acetone.[13] Hippuric acid occurs as an indirect metabolite and its quantity in urine may be used to confirm acetophenone exposure,[14] although other substances, like toluene, also induce hippuric acid in urine.[15]

Toxicity

The LD50 is 815 mg/kg (oral, rats).[2] Acetophenone is currently listed as a Group D carcinogen (Not Classifiable as to Human Carcinogenicity), 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.[14]

References

  1. 1 2 Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 723. ISBN 978-0-85404-182-4. doi:10.1039/9781849733069-FP001.
  2. 1 2 3 4 5 Siegel, Hardo; Eggersdorfer, Manfred (2005), "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
  4. ↑ "Inactive Ingredient Search for Approved Drug Products".
  5. ↑ "What's in a cigarette?". Archived from the original on 23 May 2006. Retrieved 2006-05-31.
  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. ↑ Maxwell, Charles E. (1943). "β-Dimethylaminopropiophenone Hydrochloride". Org. Synth. 23: 30.
  9. ↑ 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. PMID 24258917. doi:10.1007/BF00994195.
  10. ↑ Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
  11. ↑ Bartholow, Roberts (1908). A Practical Treatise on Materia Medica and Therapeutics. Appleton & Co.
  12. ↑ Norman, Conolly (1887). "Cases illustrating the sedative effects of aceto-phenone". Journal of Mental Science. 32: 519.
  13. ↑ "Hypnone – The new hypnotic". Journal of the American Medical Association. 5: 632. 1885. doi:10.1001/jama.1885.02391220016006.
  14. 1 2 CID 7410 from PubChem
  15. ↑ The Netherlands Center for Occupational Diseases (NCvB): toluene (Dutch)
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