Title: Dibenzalacetone
CAS Registry Number: 538-58-9
CAS Name: 1,5-Diphenyl-1,4-pentadien-3-one
Additional Names: dibenzylidene acetone; distyryl ketone
Molecular Formula: C17H14O
Molecular Weight: 234.29
Percent Composition: C 87.15%, H 6.02%, O 6.83%
Line Formula: C6H5CH=CHCOCH=CHC6H5
Literature References: Prepn from benzaldehyde + acetone: Conrad, Dolliver, Org. Synth. 12, 22 (1939); Haslam, US 2719863 (1955 to du Pont); Tokár et al., Acta Chim. Acad. Sci. Hung. 19, 83 (1959). Prepn of geometrical isomers: Dinwiddie et al., J. Org. Chem. 27, 327 (1962).
Derivative Type: trans-trans-Form
Properties: Crystals from hot ethyl acetate, mp 110-111°. uv max: 330 nm (e 34,300). Practically insol in water. Slightly sol in alc, ether; sol in acetone, chloroform.
Melting point: mp 110-111°
Absorption maximum: uv max: 330 nm (e 34,300)
Derivative Type: cis-trans-Form
Properties: Light yellow needles from ethanol, mp 60°. uv max: 295 nm (e 20,000).
Melting point: mp 60°
Absorption maximum: uv max: 295 nm (e 20,000)
Derivative Type: cis-cis-Form
Properties: Yellow oil, bp0.02 130°. uv max: 287 nm (e 11,000).
Boiling point: bp0.02 130°
Absorption maximum: uv max: 287 nm (e 11,000)
Use: In sun protection preparations.
Dibenzepin Dibenzoylmethane Dibenzyl Chlorophosphonate Dibenzyl Disulfide Dibenzyl Phosphite

Dibenzalacetone crystals.jpg
CAS number 538-58-9 YesY
PubChem 1549622
ChemSpider 1266463 YesY
Jmol-3D images Image 1
Image 2
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 (cis,cis isomer) *Merck
Solubility in water Insoluble
Main hazards Irritant
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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.