Amines

Question 0

Reaction of ethylamine and HCl

Answer 0

CH3CH2NH2 + HCl –> CH3CH2NH3+Cl-

Question 1

Explain the basicity of amines

Answer 1

Amines have a lone pair on the N atom and can accept a proton

Question 2

How are amines classified into primary, secondary and tertiary?

Answer 2

By how many hydrocarbon chains are attached to the N atom

Question 3

Describe the making of aliphatic amines

Answer 3

An excess of ethanolic ammonia is added to a halogenoalkane and the mixture is warmed gently
The ammonia is substituted for the halogen

Question 4

Describe the making of aromatic amines

Answer 4

A nitroarene, such as nitrobenzene is reduced by a mixture of tin and conc. HCl. The mixture is heated under reflux
Eg C6H5NO2 + 6[H] –> C6H5NH2 + 2H2O

Question 5

Describe the first stage of synthesising azo dyes

Answer 5

Diazotisation
HNO2 is made: NaNO2 + HCl –> HNO2 + NaCl
The reaction must take place under 10 degrees
The HNO2 reacts with phenyl amine to form diazonium salt: C6H5N2+Cl-

Question 6

Describe the second stage of making an azo dye

Answer 6

Coupling
A coupling reagent is added eg phenol under alkaline conditions
Eg C6H5N2+Cl- + C6H5OH + NaOH –> C6H5N=NC6H4OH + NaCl (from previous reaction) + H2O