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Dibenzylideneacetone

Dibenzylideneacetone


IUPAC name	1,5-diphenylpenta-1,4-dien-3-one
Other names	Dibenzalacetone
Identifiers
CAS number	538-58-9
SMILES	O=C(/C=C/c1ccccc1)/C=C/c2ccccc2
Properties
Molecular formula	C₁₇H₁₄O
Molar mass	234.29 g/mol
Appearance	Yellow solid
Melting point	110–112 °C (trans,trans isomer)
Solubility in water	Insoluble
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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 it is used as a ligand in organometallic chemistry for instance in tris(dibenzylideneacetone)dipalladium(0). In this case, it is a labile ligand which is easily displaced by stronger ligands like triphenylphosphine, hence it serves a useful entry point into palladium(0) chemistry.

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Preparation

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 107–111 °C).^[1]

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

^ Conard, C. R.; Dolliver, M. A. (1943). "Dibenzalacetone". Org. Synth.; Coll. Vol. 2: 167.
^ 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.