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Dicinnamalacetone is a conjugated
This intermediate compound then condenses with another molar equivalent of ''trans''-cinnamaldehyde to form dicinnamalacetone, which is insoluble in the reaction mixture:
The first condensation is believed to be relatively slow compared to the second, hence the delay between the addition of all of the reactants and the formation of a precipitate.
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
. It is used as an indicator for the presence of hydrogen halides in solvents, and its preparation is used as an example of the aldol condensation
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration t ...
in organic chemistry teaching labs.
Preparation
Dicinnamalacetone (specifically the all-''trans'' isomer) may be prepared by the reaction ofacetone
Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...
and '' trans-''cinnamaldehyde
Cinnamaldehyde is an organic compound with the formula or . Occurring naturally as predominantly the ''trans'' (''E'') isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shikimate pathway ...
catalyzed by a strong base, such as potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash.
Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...
. The reaction is typically conducted in a mixture of water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
and ethanol
Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
.
Clock reaction
The preparation of dicinnamalacetone is an example of a clock reaction. Upon the addition of acetone to a solution of ''trans''-cinnamaldehyde and potassium hydroxide in ethanol and water, aprecipitate
In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...
of dicinnamalacetone forms spontaneously after a delay.
The formation of dicinnamalacetone constitutes two separate aldol condensations. In the first, one molar equivalent of ''trans''-cinnamaldehyde and one molar equivalent of acetone condense
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor ...
to form a soluble intermediate compound:
This intermediate compound then condenses with another molar equivalent of ''trans''-cinnamaldehyde to form dicinnamalacetone, which is insoluble in the reaction mixture:
The first condensation is believed to be relatively slow compared to the second, hence the delay between the addition of all of the reactants and the formation of a precipitate.
References
{{reflist Indicators Enones