Reduction of Undecylinic acid to Undecanoic acid using NaBH4-Ni in water
In a 3 Lt 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 was charged under stirring distilled water(1200 mL), sodium hydroxide (88 g, 2.2 mol), undecylinic acid acid (368 g, 2 mol), activated W-6 Raney nickel (70 g wet in water) and stirred for 10 min. The reaction mass was cooled to about 25-30oC . To the above aqueous solution, freshly prepared Sodium borohydride solution (21 g, 0.55 mol, in 1% aqueous NaOH solution 100 mL) was added drop wise through dropping funnel over a period of 45-60 min. The reaction mixture was stirred for additional 60 min at 25-30 oC. And then further stirred at 40-45oC for 1 h. 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 and the W-6 Raney rinsed with distilled water (100 mL, Raney nickel thus obtained is pyrophoric and should be kept under water immediately). The filtrate was acidified with concentrated Hydrochloric acid to pH-2. The resulting oily layer was extracted with toluene (1 Lt twice) and washed with water 500 mL (2 times). The toluene layer thus obtained was concentrated under reduced pressure to get Undecanoic acid 353 g (95%).Which is normally pure by NMR.
