Question

QUESTION:

1. Write a flow scheme for the work-up.

THE WORK UP:

C. Work-up (save all layers) and Isolation of Product MgBrCl Benzoic acid Transfer the mixture into a test tube. Rinse the beaker with about 3 mL of regular (not anhydrous) diethyl ether and pour the washings into the test tube. There should be two distinct layers in the test tube Remove the aqueous layer (to be discarded) and shake the ether layer with about 2 mL of 3 M NaOEH solution. Draw off the aqueous layer with a Pasteur pipet and place the solution in a clean small beaker Add about 1 mL of NaOH to the ether layer, mix well, and draw off the aqueous layer into the same beaker. Repeat the extraction with about 1 mL water, remove the aqueous layer and add into the same beaker Heat the beaker containing the combined aqueous extracts to about 50°C on a hot plate to drive off the dissolved ether. Remove the beaker from the hot plate and let the solution cool to 30 Acidify the aqueous solution by adding excess conc. HCl dropwise while stirring until no more solid precipitates out. Cool the mixture in an ice bath for at least ten minutes and collect the benzoic acid by vacuum filtration in a Hirsch funnel. Wash benzoic acid with 1 mL of ice cold water and dry the solid under vacuum. Weigh the dry benzoic acid. Save a small quantity in a capillary tube for melting point determination. Transfer the remaining crude benzoic acid into a test tube. Place a boiling stick in the test tube and recrystallize the product from boiling water or from hot methanol-water solvent pair. SAFETY NOTE. Methanol is flanmable-a water bath at 60 %, should be used to heat methanol. Allow the solution to cool undisturbed to room temperature and cool the test tube further in an ice-water bath. Collect the product in a Hirsh funnel allowing the vacuum to pull until the solid crystals are completely dry. Determine the mass and melting point range. Obtain an IR spectrum of the product. Save the product for titration experiment

Answer 1

obtaining text tube reb asative step (es anytuing to 4est tube Remove agerob ai exto cion H 2 0 Decision t Deloy or Naitiw oftert ber Zoic Cool the rru and mote tne Recuystale crude benzo menthol-rde So net ing Pa detemi ne mau and lo Cob