Dibenzylideneacetone

Dibenzylideneacetone
IUPAC name (1E,4E)-1,5-diphenylpenta-1,4-dien-3-one
Other names Dibenzalacetone
Identifiers
CAS number	538-58-9 Y
PubChem	1549622
ChemSpider	1266463 Y
Jmol-3D images	Image 1 Image 2
SMILES O=C(/C=C/c1ccccc1)/C=C/c2ccccc2 O=C(\C=C\c1ccccc1)/C=C\c2ccccc2
InChI InChI=1S/C17H14O/c18-17(13-11-15-7-3-1-4-8-15)14-12-16-9-5-2-6-10-16/h1-14H/b13-11-,14-12+ Y Key: WMKGGPCROCCUDY-HEEUSZRZSA-N Y InChI=1/C17H14O/c18-17(13-11-15-7-3-1-4-8-15)14-12-16-9-5-2-6-10-16/h1-14H/b13-11-,14-12+ Key: WMKGGPCROCCUDY-HEEUSZRZBF
Properties
Molecular formula	C17H14O
Molar mass	234.29 g/mol
Appearance	Yellow solid
Melting point	Aldrich 110-111 ºC (trans,trans isomer) Merck 60ºC (cis,trans isomer)
Boiling point	130ºC(cis,cis isomer) *Merck
Solubility in water	Insoluble
Hazards
Main hazards	Irritant
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox 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 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

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]

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

1. ^ Conard, C. R.; Dolliver, M. A. (1943), "Dibenzalacetone", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0167 ; 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. http://jchemed.chem.wisc.edu/Journal/issues/2006/Nov/abs1667.html.