Halogen Derivatives

Question 1

Sn1 mechanism

Answer 1

2 steps
Unimolecular (rate equation only has the one beginning substance)
Because this is 2 steps, it is concerned with forming carbocation intermediate. The consideration is the stability of the carbocation formed.

Question 2

Sn2 mechanism

Answer 2

1 step
Bimolecular (rate equation has all reactants, depending on the molecularity of the slow step)
Because 1 step, you form the pentavalent transition state. The consideration is the steric hindrance, ease of approach of the incoming nucleophile

Question 3

Nucleophilic substitution to form alcohols

Answer 3

Na/KOH (aq), heat under reflux

Question 4

Nucleophilic substitution to form nitriles

Answer 4

K/NaCN in ethanol, heat under reflux

Question 5

Reduction of nitriles to form amines

Answer 5

H2, Ni cat, heat

LiAlH4 in dry ether, room temp

Question 6

Acidic hydrolysis of nitrile to carboxylic acid

Answer 6

HCl (aq), heat under reflux

Question 7

Alkaline hydrolysis of nitrile to carboxylate salts

Answer 7

NaOH (aq), heat under reflux

Question 8

Nucleophilic substitution to form primary amines

Answer 8

NH3 in excess, in ethanol, heat in a sealed tube to prevent loss of NH3

Question 9

Distinguish between halogenoalkanes and halogenoarenes

Answer 9

Equal volumes of NaOH (aq) to RX, heat in a water bath. Then, cool and add HNO3 in excess, before adding AgNO3 (aq)
Halogenoarenes give no AgX ppt (no reaction, NS)
Yellow, cream and white for I, Br and Cl respectively