Dibenzylideneacetone

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Dibenzylideneacetone
Dibenzylideneacetone.png
Dibenzylideneacetone-3D-balls.png
Dibenzalacetone crystals.jpg
Identifiers
CAS number 538-58-9 YesY
PubChem 1549622
ChemSpider 1266463 YesY
Jmol-3D images Image 1
Image 2
Properties
Molecular formula C17H14O
Molar mass 234.29 g/mol
Appearance Yellow solid
Melting point
  • Aldrich 110-111 °C (trans,trans isomer)
  • Merck 60 °C (cis,trans isomer)
Boiling point 130 °C (266 °F; 403 K) (cis,cis isomer) *Merck
Solubility in water Insoluble
Hazards
Main hazards Irritant
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references
Drying dibenzalacetone

Dibenzylideneacetone or dibenzalacetone, often abbreviated dba, is an organic compound with the formula C17H14O. It is a bright-yellow solid insoluble in water, but soluble in ethanol. Dibenzylideneacetone is used as a sunscreen component and as a ligand in organometallic chemistry, for instance in tris(dibenzylideneacetone)dipalladium(0). In this case, it is a labile ligand that is easily displaced by stronger ligands like triphenylphosphine, hence it serves a useful entry point into palladium(0) chemistry.

Preparation[edit]

The compound can be prepared in the laboratory by an aldol condensation of benzaldehyde and acetone with sodium hydroxide in a water/ethanol medium with the exclusive formation of the trans,trans isomer (melting point 110–111 °C).[1]

Dibenzalacetone synthesis
Preparation schematics

This reaction is frequently encountered in organic chemistry education as a laboratory procedure. The conversion proceeds via the intermediacy of benzylideneacetone.

Prolonged exposure to sunlight converts the compound in a [2+2] cycloaddition to a mixture of four cyclobutane isomers.[2]

References[edit]

  1. ^ Conard, C. R.; Dolliver, M. A. (1943), "Dibenzalacetone", Org. Synth. ; Coll. Vol. 2: 167 
  2. ^ Rao, G. N.; Janardhana, C.; Ramanathan, V.; Rajesh, T.; Kumar, P. H. (November 2006). "Photochemical Dimerization of Dibenzylideneacetone. A Convenient Exercise in [2+2] Cycloaddition Using Chemical Ionization Mass Spectrometry". J. Chem. Educ. 83 (11): 1667. doi:10.1021/ed083p1667.