Name: sheet 3. Reaction Scheme (fill in the blanks) (3 points) biphenyl t-BuCl A

Question

Name: sheet 3. Reaction Scheme (fill in the blanks) (3 points) biphenyl t-BuCl Al (foil) 4,4'-di-tert-butylbiphenyl + + -> Mw/Conc 26.98 oo volume 0.35 mL density solid mass 0.16 g Yield Theor etical mmol 1.0 catalytic equivalents 4. Yield Show calculations to determine the maximum theoretical yield of 4,4'-di-tert-butylbiphenyl that could be formed from the amounts of reactants above. (1 point): kup/Purification Very briefly describe how the product from the reaction will be isolated and purified. points)

Explanation / Answer

For biphenyl:

moles = mass/MW = 0.16/154.21 = 0.00104 mol = 1.04 mmol

For t-BuCl:

density = 0.84 g/ml

mass = density*volume = 0.84*0.35 = 0.294 g

mol = mass/MW = 0.294/92.57 = 0.00317 mol = 3.17 mmol

equivalents = 2.0 (as twice of t-BuCl is added to the system)

For 4,4'-di-tert-butylbiphenyl:

4) Theoretical yield:

Moles of biphenyl used = 1.04 mmol

Moles of t-BuCl = 3.17 mmol

As 2 equivalents should be used, so moles of t-BuCl used should be 2(1.04) = 2.08 mmol. But it is 3.17 mmol.

So, biphenyl is limiting reagent.

So, moles of 4,4'-di-tert-butylbiphenyl = moles of biphenyl = 1.04 mmol

Molar mass of 4,4'-di-tert-butylbiphenyl = 266.42 g/mol

So, mass of 4,4'-di-tert-butylbiphenyl produced = moles*molar mass = 1.04*10-3*266.42 = 0.28 g

Theoretical yield = 0.28 g = 1.04 mmol

5) Work-up and purification:

The reaction mixture will be extracted with water. Then add ethanol to the organic layer. Let the product dissolve in it. After dissolving, cool the mixture to crystallize the product. The crystals of the product will be vacuum-filtered after that to recover pure product.

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