Piperonal or Benzaldehyde From Grignard Reagent

To make piperonal or benzaldehyde the chemist uses the same Grignard solution and the same apparatus except that the Grig-nard solution is poured from the three-neck flask into the separa-tory funnel. The three-neck flask is then cleaned and dried and put back in place or, if the chemist has a spare, swapped with a second flask. Into the flask is poured 30g of N-methylformanilide (no, that's not the same as N-methylformamide) and the ice bath tray is put back into place. The chemist is going to need to cool the N-methylformanilide down to -20°C so the chemist is going to have to stock the ice bath with dry ice and ethanol. The Grignard solution is dripped in so that the temperature of the reaction flask contents never rises far from -20°C. After addition, the solution is allowed to come to room temperature and stirred at that temperature for 12 hours. From here the solution is processed exactly like what was done for safrole except that 300mL cold 30% H2S04 solution is used for hydrolysis instead of ammonium chloride (yield=67%). Get it? Good.

Continue reading here: Isosafrole or Propenylbenzene From Grignard Reagent

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