(Hive Bee)
11-07-04 23:22
No 540244
(Rated as: good idea!)
Due to poverty, a bee had to lower her morals and turn into a wasp... She did use less AA and got a higher yield due to some variation of procedure.
- 86 g Phenylacetic Acid
- 800 mL Acetic Anhydride (fresh)
- 43 g sodium acetate
- Oven dried molecular sieves
In a three neck 1 L flask fitted with a nitrogen purge line and a thermometer, all above were quickly thrown in while under a stream of N2. The flask was then fitted with a water condenser with a drierite drying tube. The N2 purge was slowed to minimal positive pressure and the oil bath heated for 46 hrs to ~170°C, such that rxn temp was ~145°C. Reflux and gas evolution was slight. Color slowly went from clear to yellow. Afterward, solution was rotovaped down to about 300-400 mL dissolved in ~200 mL DCM and stirred vigorously with and excess of 4M NaOH, until no more hydrolysis (noted by vigorous bubbling) occurred. Organic layer separated, aqueous extracted 3 x with DCM, pooled extracts dried w/ mag sulfate, filtered (which also got rid of some insoluble junk) and rotovaped off DCM. Yield 64.4 g (76%), very pure by 1H-NMR and TLC.
Reasoning for higher yield: fresh (not wet) AA, continuous positive pressure of N2, drying tube, and mol seives = very dry rxn
*Please don't PM Dopey any questions about this procedure.
something for your mind.......
