Acetophenone

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Acetophenone
Acetophenone structure.svg Acetophenone-from-xtal-3D-balls.png
Identifiers
CAS number 98-86-2 YesY
PubChem 7410
ChemSpider 7132 YesY
UNII RK493WHV10 YesY
DrugBank DB04619
KEGG C07113 YesY
ChEBI CHEBI:27632 YesY
ChEMBL CHEMBL274467 YesY
Jmol-3D images Image 1
Image 2
Properties
Molecular formula C8H8O
Molar mass 120.15 g mol−1
Density 1.028 g/cm³
Melting point 19–20 °C
Boiling point 202 °C
Solubility in water 5.5 g/L at 25 °C
12.2 g/L at 80 °C
Hazards
MSDS MSDS
EU classification Harmful 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
Flash point 77 °C (171 °F; 350 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

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.[1]

Production[edit]

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.[1]

Uses[edit]

Precursor to resins[edit]

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

Use in pharmaceutical and related areas[edit]

Acetophenone is a raw material for the synthesis of some pharmaceuticals, examples include dextropropoxyphene and phenylpropanolamine.[2] [3]

Niche uses[edit]

Acetophenone is an ingredient in fragrances that resemble almond, cherry, honeysuckle, jasmine, and strawberry. It is used in chewing gum.[4] It is also listed as an approved excipient by the U.S. FDA.[5] 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.[6]

Laboratory reagent[edit]

In instructional laboratories,[citation needed] acetophenone is converted to styrene in a two step process that illustrates the reduction of carbonyls and the dehydration of alcohols:[clarification needed]

4 C6H5C(O)CH3 + NaBH4 + 4 H2O → 4 C6H5CH(OH)CH3 + NaOH + B(OH)3

A similar process is used industrially but the hydrogenation step to 1-phenylethanol is done over a copper catalyst.[1]

C6H5CH(OH)CH3 → C6H5CH=CH2 + H2O

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

Natural occurrence[edit]

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.[7]

Pharmacology[edit]

In the late 19th and early 20th centuries, acetophenone was used in medicine.[8] It was marketed as a hypnotic and anticonvulsant under brand name Hypnone. The typical dosage was 0.12 to 0.3 milliliters.[9] It was considered to have superior sedative effects to both paraldehyde and chloral hydrate.[10] In humans, acetophenone is metabolized to benzoic acid, carbonic acid, and acetone.[11] Hippuric acid occurs as an indirect metabolite and its quantity in urine may be used to confirm acetophenone exposure.[12]

Toxicity[edit]

The LD50 is 815 mg/kg (oral, rats).[1] 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.[12]

References[edit]

  1. ^ a b c d e Hardo Siegel, Manfred Eggersdorfer “Ketones” in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, 2002, Wienheim. doi:10.1002/14356007.a15_077
  2. ^ Sittig, Marshall (1988). Pharmaceutical Manufacturing Encyclopedia. pp. 39,177. ISBN 978-0-8155-1144-1. 
  3. ^ Gadamasetti, Kumar; Tamim Braish (2007). Process Chemistry in the Pharmaceutical Industry, Volume 2. pp. 142–145. ISBN 978-0-8493-9051-7. 
  4. ^ Burdock, George A. (2005), Fenaroli's Handbook of Flavor Ingredients (5th ed.), CRC Press, p. 15, ISBN 0-8493-3034-3 
  5. ^ http://www.accessdata.fda.gov/scripts/cder/iig/index.cfm
  6. ^ "What's in a cigarette?". Archived from the original on 23 May 2006. Retrieved 2006-05-31. 
  7. ^ Pheromonal activity of single castoreum constituents in beaver,Castor canadensis., Müller-Schwarze, D and Houlihan, P.W., Journal of Chemical Ecology, April 1991, Volume 17, Number 4, Springer Netherlands, doi:10.1007/BF00994195
  8. ^ The Merck Index, 12th Edition
  9. ^ Bartholow, Roberts. "A Practical Treatise On Materia Medica And Therapeutics." Appleton & Co, 1908.
  10. ^ Norman, Conolly "Cases illustrating the sedative effects of aceto-phenone." Journal of Mental Science, Vol 32, p 519. 1887.
  11. ^ "Hypnone - The new hypnotic." J Am Med Assoc. Vol 5, p 632. 1885. doi:10.1001/jama.1885.02391220016006
  12. ^ a b "Acetophenone Compound Summary".