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The The Aldol Aldol Condensation Reaction Condensation Reaction Preparation of Preparation of Benzalacetophenon Benzalacetophenon ( (Chalcones Chalcones) ) Assisstant Assisstant lecturer : lecturer : dina dina saleem saleem Department of Pharmaceutical Chemistry/Collage of pharmacy 4 4th thstage: stage: 2 2nd ndlab. lab. 1
Chalcones Chalcones are , unsaturated aromatic ketones containing the reactive keto ethylene CH=CH-. Many of the chalcones are highly biological which have pharmaceutical group CO active and medicinal applications 2
The alternative name given to chalcone are phenyl styryl ketone, benzalacetophenone, -phenylacrylophenone, -oxo- , - diphenyl- -propylene and -phenyl- -benzoylethylene. Chalcones and their derivatives demonstrate wide range of biological activities such as anti-diabetic, anti-neoplastic, anti-hypertensive, anti-retroviral, anti-inflammatory, anti-parasital, anti-histaminic, anti-malarial, anti-oxidant, anti-fungal. 3
anti-obesity, anti-platelet, anti-tubercular, immunosuppressant, anti-arrhythmic, hypnotic, anti- gout, anxiolytic, anti-spasmodic, anti-nociceptive, hypolipidemic, anti-filarial, anti-angiogenic, antiprotozoal, anti-bacterial, anti-steroidal 4
Aldol condensation: is the reaction of two carbonyl compounds to form a new -hydroxy carbonyl compound. This reaction can be performed under acidic or basic conditions. One of the reacting species must contain a protonated -carbon adjacent to the carbonyl centre. Crossed aldol condensation of this type proceed in a high yield, because benzaldehyde cannot with itself by an aldol condensation reaction because it has no -hydrogen. likewise, ketones do not react easily with themselves in aqueous base. Therefore, the only possibility is for a ketone to react with benzaldehyde. 5
Benzalacetophenones (Chalcones) are prepared by the reaction of a substituted benzaldehyde with acetophenone in aqueous base. Chemicals Required: Benzaldehyde , acetophenone , Sodium hydroxide solution (20%, )ethanol. 6
Procedure: 1-Place 1.5 mL of benzaldehyde in abeaker and add 1.5 mL of acetophenone. Add 2 mL of 95% ethanol . 2-stir the mixture (you may need to warm the mixture on a hot plate to dissolve the solids ). 3-Cool the solution to room temperature. 4-Add 1.5 ml of sodium hydroxide solution(60%) to the mixture ,stir the mixture until it solidifies or until it become very cloudy. 5-Add 2ml ice water to the mixture and neutralize with 2N HCL. 6-Transfer the mixture to a small beaker with 3ml of ice water, stir the precipitate to break it up and then collect the solid on a Buchner funnel . 7-Wash the product with cold water. 7
Recrystallization: The product may be recrystallize by dissolving it in a hot ethanol (95%) and filter the hot solution. Cool it and collect the crystals by filtration. 8
