4.1.4- Amines

Question 0

How are primary aliphatic amines prepared

Answer 0

In a nucleophilic substitution reaction of halogenoalkanes with excess ammonia (reagent) and ethanol as the solvent (condition) and warming (condition) (Not reflux as Ammonia gas would escape!)

Question 1

Why are amines organic bases

Answer 1

Due to their ability to accept a proton (H+) due to the lone pair of electrons on the nitrogen which can form a dative covalent bond

Question 2

What are the conditions for preparing aromatic amines

Answer 2

Mixture of tin, concentrated hydrochloric acid (act as the reducing agent: [H]) and heating under reflux

Question 3

How are aromatic amines prepared

Answer 3

By reducing nitroarenes eg. Nitrobenzene.

Question 4

What are the two steps in the synthesis of Azo-dyes

Answer 4

Diazoisation (formation of the diatonic ion) and then coupling.

Question 5

How is the nitrous acid formed

Answer 5

In a mixture of sodium nitrite and hydrochloric acid:

NaNO2 + HCl -> HNO2 + NaCl

Question 6

Give the reaction and condition for diazoisation

Answer 6

C6H5NH2 + HNO2 + HCl -> C6H5N+(Cl-)N (benzenediazonium chloride)+ 2H2O

Below 10°C

Question 7

Give the reaction and condition for coupling

Answer 7

CC6H5N+(Cl-)N (benzenediazonium chloride) + phenol (or other aromatic compound eg. Amine) + NaOH -> the Azo-dye (C6H5-N=N-C6H4-OH) + NaCl + H2O

Alkaline conditions.