Question

Problem set for Competitive Nucleophiles

1) Why does water always enter the bottom of the condenser and exit from the top?

2) Why are boiling stones added to the solvent undergoing reflux?

3) Why are any large clumps of ammonium salts broken down into a powder?

4) Why is it necessary to perform the competing nucleophiles reactions under acidic conditions?

5) Which is the better nucleophile, fluoride or iodide ion? Explain this in the terms of the nature of the fluoride ion and iodide ion.

6) Explain why the product is washed with sodium bicarbonate solution (Procedure A). Support your answer with a chemical equation.

7) What is removed when the organic layer sits over anhydrous sodium sulfate (Procedure A)?

8) What is the purpose of reflux for the competitive nucleophiles experiment? Be explicit.

9) When the following optically active alcohol is treated with HBr, a racemic mixture of alkyl bromides is obtained. Draw a mechanism of this process, and explain the stereochemical outcome.

Answer 1

1) When water entered from the bottom of condenser then condenser always contain cold water. Condenser is used to cool down the vapours formed during distillation to liquid so that sufficient amount of solvent should be present in the reaction mixture. A completely filled condenser will provide maximum cooling and therefore maximum recovery of liquid.

2) Boiling stones are added to the solvent during reflux in order to prevent superheating of solvent and also to prevent bumping of liquid and provide controlled boiling.