Dibenzylideneacetone or dibenzalacetone, often abbreviated dba, is an organic compound with the formula C17H14O. It is a pale-yellow solid insoluble in water, but soluble in ethanol. It was first prepared in 1881 by the German chemist Rainer Ludwig Claisen (1851–1930) and the Swiss chemist Charles-Claude-Alexandre Claparède (14 April 1858 – 1 November 1913). Claisen wrote that the German chemist Adolf Baeyer might have synthesized dibenzylideneacetone as early as 1866, although the evidence wasn't clear.

Preparation

The trans,trans isomer can be prepared in high yield and purity by condensation of benzaldehyde and acetone with sodium hydroxide in a water/ethanol medium followed by recrystallization. This reaction, which proceeds via the intermediacy of benzylideneacetone, is often performed in organic chemistry classes, and is called Claisen-Schmidt condensation.

Reactions and derivatives

Prolonged exposure to sunlight initiates [2+2] cycloadditions, converting it to a mixture of dimeric and trimeric cyclobutane cycloadducts.

Uses

Dibenzylideneacetone is used as a component in sunscreens and as a ligand in organometallic chemistry. For example, it is a component of the catalyst tris(dibenzylideneacetone)dipalladium(0). It is a labile ligand that is easily displaced by triphenylphosphine, hence it serves a useful entry point into palladium(0) chemistry.