Chemistry:Dicinnamalacetone
Dicinnamalacetone is a conjugated organic compound. It is used as an indicator for the presence of hydrogen halides in solvents,[1][2] and its preparation is used as an example of the aldol condensation in organic chemistry teaching labs.[3][4]
Preparation
Dicinnamalacetone (specifically the all-trans isomer) may be prepared by the reaction of acetone and trans-cinnamaldehyde catalyzed by a strong base, such as potassium hydroxide. The reaction is typically conducted in a mixture of water and ethanol.[1][3]
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, a precipitate 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 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.[3]
References
- ↑ 1.0 1.1 "b-HALOACETALS AND KETALS: 2-(2-BROMOETHYL)-1,3-DIOXANE AND 2,5,5-TRIMETHYL-2-(2-BROMOETHYL)-1,3-DIOXANE". Organic Syntheses 62: 140. 1984. doi:10.15227/orgsyn.062.0140. http://orgsyn.org/demo.aspx?prep=CV7P0059.
- ↑ "Dicinnamalacetone". https://www.sigmaaldrich.com/US/en/product/aldrich/229067.
- ↑ 3.0 3.1 3.2 King, L. Carroll; Ostrum, G. Kenneth (1964-02-01). "A new clock reaction preparation of dicinnamalacetone". Journal of Chemical Education 41 (2): A139. doi:10.1021/ed041pA139.1. ISSN 0021-9584. Bibcode: 1964JChEd..41..139K. https://pubs.acs.org/doi/10.1021/ed041pA139.1.
- ↑ Abraham, Liza; Stachow, Laura; Du, Hechao (2020-10-13). "Cinnamon Oil: An Alternate and Inexpensive Resource for Green Chemistry Experiments in Organic Chemistry Laboratory". Journal of Chemical Education 97 (10): 3797–3805. doi:10.1021/acs.jchemed.0c00851. ISSN 0021-9584. Bibcode: 2020JChEd..97.3797A. https://pubs.acs.org/doi/10.1021/acs.jchemed.0c00851.
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