Cinnamic Acid.
Cinnamic acid is 3-phenylpropenoic acid.
Preparation of cinnamic acid. Cinnamic acid is obtained:
By heating benzaldehyde with acetic anhydride at 180C. ( perkin’s Reaction ).
By treatment of benzaldehyde with ethyl acetate in the presence of sodium ethoxide followed by acid-hydrolysis of the resulting ester. ( Claisen Condensation ).
By heating benzaldehyde with malonic acid in alcoholic ammonia solution. ( knoevenagel’s Reaction ).
Properties of cinnamic acid.
Cinnamic acid is a crystalline solid, mp 133C. It is sparingly soluble in water. It behaves as an α,β-unsaturated acid and a benzene derivative.
Cinnamic acid reacts with sodium hydroxide to form sodium cinnamate.
Cinnamic acid reacts with sodium hydroxide to form sodium cinnamate.
Cinnamic acid reacts with ethyl alcohol in the presence of an acid catalyst to give ethyl cinnamate.
Cinnamic acid reacts with PCl5 or SOCl2 to form cinnamoyl chloride.
Cinnamic acid reacts with bromine in carbon tetrachloride to give dibromocinnamic acid.
Cinnamic acid undergoes reduction with sodium amalgam and water to give 3-phenylpropanoic acid.
It undergoes reduction with lithium aluminum hydride to form 3-phenyl-2-propenol.
Cinnamic acid undergoes oxidation with hot acidic KMnO4 to give benzoic acid.
Cinnamic acid undergoes decarboxylation with soda -lime to yield styrene.
It undergoes electrophilic substitution reactions to form o,p-isomers. For example,
Uses.
Cinnamic acid uses. Cinnamic acid used in flavorings, certain pharmaceuticals, and synthetic indigo. Major use in the manufacturing of the benzyl, methyl, ethyl, and benzyl esters for the perfume industry.
Structure.
Cinnamic acid structure. Cinnamic acid is an organic compound with the formula C₆H₅CH=CHCOOH. Cinnamic acid is a white crystalline compound this is slightly soluble in water, or freely soluble in many organic solvents.
Hazards.
Cinnamic acid hazards.
Skin irritation.
Serious eye irritation.
Respiratory irritation.
Avoid breathing fume/ dust/ mist/ gas/ vapours/ spray.