Polymers of Life 1+2: Amines & Amides

Question 1

Functional group of amine

Answer 1

NH2

Question 2

Describe ammonia ( = type of amine )

Answer 2

• NH3
• 1 lone pair
• tetrahedral shape = 109.5° = 3bp + 1lp = 107° = pyramidal

Question 3

Describe primary amine

Answer 3

• 1 R group attached to nitrogen and 2 hydrogens

= R- N - H
I
H

Eg. = CH2 CH3 - N - H
I
H

= ethylamine

Question 4

Describe secondary amine

Answer 4

• 2 R groups attached
• 1 lone pair

= R- N - H
I
R

eg. = CH3- N - H
I
CH2 CH3

= ethylmethyl amine

Question 5

Describe tertiary amine

Answer 5

• 3 R groups attached
• 1 Lone pair

= R- N - R
I
R

Eg. = CH3 - N - CH3
I
CH3

= Trimethylamine

Question 6

What must all amines have

Answer 6

A lone pair

( no lone pair = not an amine )

Eg. Nitrogen with 4 R groups = ammonium salt

Question 7

What is a nitrogen with 4 R groups

Answer 7

Ammonium salt not amine as no lone pair ( but can take part in hydrogen bonding)

Question 8

What kind of bonding can be found in primary & secondary bonding

Answer 8

Hydrogen bonding = exists in molecules that contain a H attached to either an N, O or F

( N-H, O-H, F-H )

Question 9

What is the proper name for aromatic amines ( N joined to benzene ring )

Answer 9

Pheynylamine = benzene ring with NH2

Question 10

Learn how to draw diagrams showing hydrogen bonding between amines including lone pairs and partial charges

Answer 10

Look at sheet

Question 11

Describe the solubility of amines

Answer 11

Amines will dissolve in water as they can hydrogen bond to water

( make sure can can draw diagram showing hydrogen bonding between amine and water )

Question 12

Are amines considered as bases or acids

Answer 12

Weak bases

Question 13

Why are amines considered as weak bases

Answer 13

Lone pair on N can accept a proton

Question 14

What does bass strength depend on

Answer 14

How well the the N lone pair can accept H+

= the higher the electron density of the N lone pair the stringer the base

Question 15

What is the trend for stability / base strength of amines

Answer 15

• as no. of R groups ( alkyl groups ) increases = stability / base strength increases
• alkyl groups push electrons towards the N better than H ( remember carbocation stability )

Question 16

List amines in terms of base strength strongest to weakest

Answer 16

• tertiary amine
• secondary amine
• primary amine
• ammonia
• aromatic amines

( base strength decreases as no. of R groups decrease )

Question 17

Describe base strength of aromatic amines

Answer 17

N lone pair is partially delocalised into the benzene ring lowering base strength

= lowest bases strength compared to other amines

Question 18

General functional group of amides

Answer 18

=         O 
            II
       R- C- N - R 
                  |
                 R

Question 19

Structure of primary secondary & tertiary ( same principle as amines in terms of R groups

Answer 19

=         O 
            II
       R- C- N - H
                  |
                 H

=         O 
            II
       R- C- N - R 
                  |
                 H

=         O 
            II
       R- C- N - R 
                  |
                 R