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16.2 Synthesis of methyl 3-nirobenzoate in 2 steps, p484.

Step 1 Formation of the ester methyl benzoate, Procedure:

1.     To 50 cm3 pear-shaped flask add 8g of benzoic acid, 15 cm3 of methanol, 2 cm conc. H2SO4

2.     Reflux for 45 min-s

3.     cool mixture to room temp and poor into separating funnel containing 30 cm cold H2O, rinse flask with HC solvent and add to funnel

4.     Shake the funnel (release pressure) and poor lower aqueous to conical flask

5.     Wash HC layer with 15cm H2O, then 15 cm 0.5M Na2CO3(aq)

6.     Dry the HC over anhydrous Na2SO4 and filter under gravity

7.     Distillate with condenser collecting methyl benzoate above 190C

8.     Weigh the product:                               

Yield:                                   (70%)

Bond C-O in benzoic acid is broken

CH3OH+HOC(:O)<> -->CH3OC(:O)<>

Step 2 The nitration of methyl benzoate , Procedure:

1.     Measure 9 cm conc. H2SO4 into 100 cm conical flask and cool below 10C in ice bath

2.     Add 4 cm of methyl benzoate while swirling the flask

3.     Prepare in another small flask 3 cm conc. HNO3 and 3 cm conc. H2SO4 and cool

4.     Add by dropping pipette HNO3 and H2SO4 over 15 min to 1st flask. Temp. must be between 5-15C.

5.     Remove mixture from bath and allow to stand for 10 min-s

6.     Pour it over crushed ice, stir until solidifies

7.     Wait until ice melts and collect product by suction filtration, wash with 3 portions of H2O (disconnect pump before each addition)

8.     Change the Buchner flask to a small clean one, wash the product with 2 portions of ice cold ethanol, keep liquid for chromatography.

9.     Recrystalise by adding ethanol and heat in a boiling water-bath (turn off the Bunsen)

10.   Cool in an ice-bath and collect by suction filtration

11.   Product is a pale yellow solid melting 78C

12.   Weigh dry product and calculate yield:                           

13.   Chromatography is at 485 ask

14.   Determine melting point

15.   Work out overall yield

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