6.33 - Halogenoalkane reactions and mechanisms

Question 1

What happens when a halogenoalkane reacts with potassium hydroxide (aqueous), and is heated under reflux?

Answer 1

An alcohol is formed

Question 2

Describe the mechanism for this reaction:

Answer 2

C-X bond is polar, with carbon having a slight positive charge
OH- ion with a lone pair of electrons attacks the carbon (curly arrow)
A curly arrow from the centre of C-X bond to the halogen
OH replaces X

Question 3

What happens when a halogenoalkane is reacted with potassium cyanide (ethanolic) and heated under reflux?

Answer 3

A primary amine is formed

Question 4

What is the first step in the mechanism of this reaction?

Answer 4

Same as reaction with KOH, but NH3 group with N+ ion replaces the halogen

Question 5

What happens after this?

Answer 5

Another NH3 nucleophile attacks a hydrogen bonded to the N+
Electrons in this N+-H bond go entirely to N+
NH4+ is formed as bi product
NH3 group on halogenoalkane is reduced to NH2

Question 6

What is the functional group of amines?

Answer 6

C-NH2