Reduction of cinnamic acid with water-sodium borohydride-Raney nickelReduction of cinnamic acid with water-sodium borohydride-Raney nickel
SyntheticPage 521
Published Jan 11, 2012
In a 5 L four necked round bottom flask equipped with a mechanical stirrer, 250 mL dropping funnel, thermometer and inlet port open to the atmosphere on a water bath wascharged with 2250 mL of distilled water. Stirring was started and the following reagents added in the order indicated through a funnel: sodium hydroxide (81 g, 2.026 mol, 1.2 equiv), cinnamic acid (250 g, 1.689 mol, 1 equiv), slurry containing activated W-6 Raney nickel (25 g wet) in distilled water. This was stirred for 15 min. Sodium borohydride solution (17.89 g, 0.472 mol, 0.28 equiv, in 1% aqueous NaOH solution 100 mL) was added dropwise through dropping funnel over a period of 45 min. The reaction mixture was stirred for additional 30 min at 40-45 oC. TLC analysis revealed that reaction was complete. The reaction flask was removed from the water bath, and the mixture cooled to a room temperature. Then solution was filtered through a Buchner funnel fitted with 2 L. filtration flask under vacuum and the W-6 Raney nickel in the flask rinsed with distilled water (200 mL). The cooled filtrate and washings were poured slowly with mechanical stirring into ice cold concentrated hydrochloric acid (250 mL) in a open 5 L flask . The resulting white colored solid precipitate was collected by Buchner filtration under vacuum, washed with distilled water (250 mL) and air dried to give 245.4 g (96.9 %) of 3-phenyl propionic acid .