organic synthesis

Question 1

List the ways of forming a C–C bond to increase the length of a carbon chain in synthesis

Answer 1

1. Haloalkane + CN- in ethanol à nitrile 2. Carbonyl + HCN à hydroxynitrile 3. Benzene + haloalkane with AlCl3 à benzene with an alkyl chain 4. Benzene + acyl chloride with AlCl3 à phenyl ketone

Question 2

example of when distillation would be used

Answer 2

used as the final stage in purifying an organic liquid or to produce an aldehyde from the oxidation of a primary alcohol

Question 3

example of when heating under reflux would be used

Answer 3

used in most organic reactions, such as oxidation of a primary alcohol to a carboxylic acid

Question 4

Explain the steps involved in the purification of an organic solid by recrystallization. Explain why and how the melting point of the solid would be carried out.

Answer 4

1. Dissolve the organic solid in the minimum volume of hot solvent
2. Cool the solution slowly. Pure crystals form.
3. Filter under reduced pressure. Wash with cold solvent.
4. Leave to dry. A sharp melting point indicates that the solid is pure. The melting point can also be compared with a database value. Impurities lower the melting point

A Thiele tube can be used to find the melting point of a solid. The solid is heated slowly until it begins to melt. The melting point is measured using a thermometer.