Benzylideneacetone

Benzylideneacetone is the organic compound described by the formula C6H5CH=CHC(O)CH3. Although both cis- and trans-isomers are possible for the α,β-unsaturated ketone, only the trans isomer is observed. Its original preparation demonstrated the scope of condensation reactions to construct new, complex organic compounds.[1] Benzylideneacetone is used as a flavouring ingredient in food and perfumes.[2]

Benzylideneacetone
Names
Preferred IUPAC name
(3E)-4-Phenylbut-3-en-2-one
Other names
Benzalacetone
Benzylideneacetone
Methyl styryl ketone
Benzylidene acetone
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.015.989
EC Number
  • 204-555-1 (trans)
RTECS number
  • EN0330000
UNII
  • InChI=1S/C10H10O/c1-9(11)7-8-10-5-3-2-4-6-10/h2-8H,1H3/b8-7+ checkY
    Key: BWHOZHOGCMHOBV-BQYQJAHWSA-N checkY
  • InChI=1/C10H10O/c1-9(11)7-8-10-5-3-2-4-6-10/h2-8H,1H3/b8-7+
    Key: BWHOZHOGCMHOBV-BQYQJAHWBQ
  • CC(=O)/C=C/c1ccccc1
Properties
C10H10O
Molar mass 146.19 g/mol
Appearance pale yellow solid
Density 1.008 g/cm3
Melting point 39 to 42 °C (102 to 108 °F; 312 to 315 K)
Boiling point 260 to 262 °C (500 to 504 °F; 533 to 535 K)
1.3 g/L
Solubility in other solvents nonpolar solvents
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 irritant
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H317, H319, H335
P261, P264, P271, P272, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P333+P313, P337+P313, P362, P363, P403+P233, P405, P501
Flash point 116 °C (241 °F; 389 K)
Related compounds
Related compounds
 Dibenzylideneacetone
cinnamaldehyde
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

Preparation

Benzylideneacetone can be efficiently prepared by the base-induced condensation of acetone and benzaldehyde:[3]

CH3C(O)CH3 + C6H5CHO → C6H5CH=CHC(O)CH3 + H2O

However, the benzylideneacetone formed via this reaction can undergo another Claisen-Schmidt condensation with another molecule of benzaldehyde to form dibenzylideneacetone. Because relatively weak bases such as NaOH make very little of the enolate ion at equilibrium, there is still a lot of unreacted base left in the reaction mixture, which can go on and remove protons from the alpha carbon of benzylideneacetone, allowing it to undergo another Claisen-Schmidt condensation and make dibenzylideneacetone.[4]

If, on the other hand, lithium diisopropylamide (LDA) is used as the base, all of the acetone will deprotonated, making enolate ion quantitatively. Therefore, a more efficient, but more expense way to make benzylideneacetone is to combine equimolar amounts of LDA (in THF), acetone, and benzaldehyde.[5]

Reactions

As with most methyl ketones, benzylideneacetone is moderately acidic at the alpha position, and it can be readily deprotonated to form the corresponding enolate[6]

The compound undergoes the reactions expected for its collection of functional groups: e.g., the double bond adds bromine, the heterodiene adds electron-rich alkenes in Diels-Alder reactions to give dihydropyrans, the methyl group undergoes further condensation with benzaldehyde to give dibenzylideneacetone, and the carbonyl forms hydrazones. It reacts with Fe2(CO)9 to give (benzylideneacetone)Fe(CO)3, a reagent for transferring the Fe(CO)3 unit to other organic substrates.[7]

References
  1. Claisen, L. "Über die Einwirkung von Aceton auf Furfural und auf Benzaldehyd bei Gegenwart von Alkalilauge" Berichte der deutschen chemischen Gesellschaft 1881, volume 14, p 2468-2471.
  2. Opdyke, D. L. J. (2013). Monographs on Fragrance Raw Materials: A Collection of Monographs Originally Appearing in Food and Cosmetics Toxicology. Elsevier. p. 135. ISBN 9781483147970.
  3. Drake, N. L.; Allen, Jr. P. "Benzalacetone". Organic Syntheses. 3: 17. doi:10.15227/orgsyn.003.0017.
  4. Moya-Barrios, R. CHEM 2402 Lab Manual, Winter 2016. Dalhousie University, Department of Chemistry
  5. Bruice, Paula Yurkanis. Organic Chemistry, 7th Edition. Pearson Education, 2014. ISBN 0-321-80322-1
  6. Danheiser, R. L.; Miller, R. F.; Brisbois, R. G. (1990). "Detrifluoroacetylative Diazo Group Transfer: (E)-1-Diazo-4-phenyl-3-buten-2-one". Organic Syntheses. 73: 134.; Collective Volume, vol. 9, p. 197
  7. Knölker, H.-J. "(η4-Benzylideneacetone)tricarbonyliron" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. Onlinedoi:10.1002/047084289X.rb058.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.