Amines

Question 1

What is an amine?

Answer 1

An organic compound derived from ammonia where one or more of the H atoms have been replaces by carbon rings or chains

Question 2

What is a primary secondary and tertiary amine?

Answer 2

Primary - Nitrogen bonded to 1 carbon (alkyl) group, 2 H
Secondary - N bonded to 2 C groups, 1 H
3 - N bonded to 3 C groups, 0H

Question 3

In aliphatic amines, what is the N attached to?

Answer 3

At least one straight or branched C chain or non-aromatic ring

Question 4

In aromatic amines what is the N attached to?

Answer 4

Benzene ring (phenyl group C6H5)

Question 5

Why do all amines act as bases?

Answer 5

The N can accept a H+ ion using the lone pair on the N to form a dative covalent bond

Question 6

What the product when amines react as bases (accepting protons)?

Answer 6

An alkylammonium ion. If drawing, put in brackets with the charge outside

Question 7

How do amines form salts?

Answer 7

They neutralise acids. The H+ on the acid is replaced b a metal ion or ammonium ion

Question 8

How do we synthesise aliphatic amines?

Answer 8

Haloalkanes reacted with EXCESS ammonia dissolved in ethanol
Eg: C2H5Cl + 2NH3 —> C2H5NH2 + NH4+ Cl-
This is nucleophillic substitution reaction. NH3 = nucleophile, lone pair on N donated to delta positive C of C-Cl bond

Question 9

Why is ethanol added in synthesising amines from haloalkanes?

Answer 9

Ethanol precents water reacting with haloalkane —> alcohol

Question 10

Why is excess ammonia needed in synthesising amines from haloalkanes?

Answer 10

To prevent further substitution to secondary and tertiary amines. Haloalkanes in excess would react with primary amine produced = further substitution

Question 11

How do we synthesise aromatic amines?

Answer 11

Nitroarenes are reduced by refluxing with tin (Sn) and concentrated HCl.
Nitrophenol + 6[H] —> Phenylamine + 2H2O