4-Hydroxybenzaldehyde → 4-Hydroxy-alpha-methylcinnamic acid

Participants

Reaction Steps

At 135° C., 122 g of 4-hydroxybenzaldehyde, 163 g of propionic anhydride and 112 g of potassium propionate were reacted with stirring for 30 hours, the reaction mixture was dropped into 1.5 l of distilled water, and sodium carbonate was added to form an aqueous alkaline solution. The unreacted 4-hydroxybenzaldehyde was removed and concentrated hydrochloric acid was added to render the solution acidic and precipitate the reaction product. The precipitate was recovered by filtration and washed with water to obtain 85 g of a crude product. The precipitate was dissolved in a solution comprising 150 g of water, 150 g of ethanol and 30 g of sodium hydroxide, and the solution was refluxed for 2 hours and dropped into a liquid comprising concentrated hydrochloric acid and ice to precipitate the reaction product. The precipitate was recovered by filtration, washed repeatedly with distilled water and dried to obtain 61 g of crude 4-hydroxy-α-methylcinnamic acid. A product (refined 4-hydroxy-α-methylcinnamic acid) obtained by recrystallizing this crude 4-hydroxy-αmethylcinnamic acid from hot water was used for the subsequent reaction.

Provenance & Evidence