Question

I. Provide a curved-arrow mechanism for the first step of the reduction of vanillin with borohydride in methanol. Show and explain the role of the protic solvent in the reaction (10%) 2. Balance the reaction of vanillin with sodium bordride shown below (assuming alth borohydride reacts with the cyclohexanone as shown) and the subsequent hydrolysis under acidic conditions. (15%) RH. CON CHR 3. Because NaBes a mild reducing agent, it must be used with a proti solvent such as methanol to facilitate the reaction. This results in a side reaction between the borohydride and the methanol resulting in the production of hydrogen as the ang you observed during the addition of the reagent. Use curly-arrows to show the Bronsted acid-base reaction of one equivalent of BM with methanol (159) For the reason whown above afar excess of sodium bonohydride was . Neglecting the reaction of the borchide with methan what mass of sodium borchide be required for complete reaction of 5. 10g of an according to the first balance equation above? SHOW YOUR WORK (15) Help with 1-4 please??

Help with explanation of 2, 3 and 4 please??

Answer 1

1 H-B2H ORCH2 Na RCH O-BORCH, ORCH2 OCH3 OCH3 HO он 1 HO-B-OH ORCH2 Nat RCH20-B ORCH ORCH2 + 4 H30 + 4 H20 Y OH OCH3 OH 1) After reduction the borohydride is converted to borate and hence we need protic solvents like alcohol. 3) The side rection is: H2C-O #BH 13 HC-0 Na + H2 (g) v 1

4) moles of 5.10 g of vanilin = 5.10g/152.15g/mol = 0.03352 mol Each mole of BH4 can reduce 4 moles of vanilin so 0.03352 mole of vanilin requires = 0.03352/4 = 0.00838 moles of NaBH4 Mass of 0.00838 mole of NaBH4 = 0.00838 mol * 37.83g/mol = 0.317 g Thus the minimum required mass of NaBH4 is 0.317 g.