Aldol condensation is an important route of organic synthesis because it provides an efficient way to form carbon-carbon bond. In this condensation an enol or enolate ion reacts with a carbonyl compound to form a β-hydroxyketone or β-hydroxyaldehyde which is then followed by dehydration. The reaction is commonly implemented to manufacture solvents, such as isophorone, used in printing inks, lacquers, adhesives, and diacetone alcohol, used in making artificial silk and leather.

It is also used in the manufacture of α, β unsaturated ketones and aromatic ketones known as chalcones. This condensation is generally used to create plasticizers which are used to convert rigid plastic polyvinyl chloride into a soft, flexible and elastic material. This experiment utilizes the above condensation reaction as a means for preparing dibenzalacetone (1,5-Diphenylpenta-1,4-dien-3-one), first prepared in 1881 by German chemist, Rainer Ludwig Claisen and Swiss chemist, Charles-Claude-Alexandre Claparède. Dibenzalacetone is a pale yellow crystalline solid often used as a ligand in preparing organometallic complexes used as catalysts in coupling reactions, It is also a common ingredient in some sunscreens as it absorbs the harmful UV light. Moreover, it does not cause an allergic reaction on a person’s skin.

An important step for obtaining high yield in any synthesis is ensuring purity of starting materials. Many of the organic compounds are found as mixtures and need separation. One of the common techniques used to separate a pure compound from a mixture is solvent extraction. Solvent extraction involves separation of compounds based on their relative solubilities in two different immiscible liquids. It is widely used in the production of fine organic compounds, processing of perfumes, production of vegetable oil and biodiesel, etc.

This experiment tries to capture the essential process steps one encounters during an actual organic synthesis for production. Thus the experiment has four subparts. First part requires identification of functional groups present in the reactants, compound A and B using the supplied reagents. This is then followed by separation of a mixture of compound A and B using solvent extraction method. After isolating the two compounds and regenerating them quantitatively, you will carry out the base catalyzed aldol condensation reaction with one of the compound.

Once you finish with the synthesis, you will perform TLC (Thin Layer Chromatography) to check the purity of the product synthesized by you.

Doing this experiment carefully and developing skills in the processes involved can help you understand how to carry out chemical synthesis to obtain pure products while starting with impure (and sometimes unknown) starting materials.

Prerequisite:Theory

Identification functional group.

Qualitative separation analysis

Aldol reactions conditions and important parameters

Stoichiometric calculations involved in organic reactions

Techniques

Quantitative separation of components in a mixture

Slow addition of one solution to another with stirring

Filtration of product using suction

Thin Layer Chromatorgraphy (A-guide-to-thin-layer-chromatography-technique)

Reference