Amines

Question 1

What are amines

Answer 1

Are organic compounds that contain one or more organic groups attached to the nitrogen

Question 2

What is the general formula of saturated mono-amines

Answer 2

CnH2n+1NH2

Question 3

What are primary amines

Answer 3

Nitrogen attached to only one organic group

Question 4

What are seconary amines

Answer 4

Nitrogen attached to two organic groups

Question 5

What are tertiary amines

Answer 5

Nitrogen attached to three organic groups

Question 6

What are quaternary amines

Answer 6

Nitrogen attached to 4 organic groups (+ve charge)

Question 7

How do you name primary amines

Answer 7

Using the prefix amino.

Question 8

How do you name secondary and tertiary amines

Answer 8

N-alkylaminoalkanes. e.g. N-methylamino-1-propane

Question 9

What are the physical properties of primary and secondary amines

Answer 9

They can form hydrogen bonds between molecules so have higher boiling points (like alcohols)

Question 10

What are the physical properties of tertiary amines

Answer 10

Are subject only to van der Waals forces, but have permanent dipoles so strong attraction

Question 11

Why do amines have higher boiling points that alkanes

Answer 11

They have permanent dipoles so the attraction is stronger than in alkanes

Question 12

Which size amines give higher boiling points and why

Answer 12

Larger amines give higher boiling points. The larger the molecule the greater the surface area the more van der Waals forces the higher the boiling point

Question 13

Why are amines basic

Answer 13

The lone pair on the nitrogen can become protonated. This makes amines weak bases

Question 14

What do amines form when protonated

Answer 14

Alkylammonium salts (e.g. ethlyammonium salt)

Question 15

What is the significance of the fact that amines can form alkylammonium salts

Answer 15

The ammonium salts are much more water-soluble than amines so this can be used to purify amines

Question 16

How can you form amines

Answer 16

By nucleophilic substitution of halogenoalkanes using ammonia

Question 17

Why is the mechanism either Sn1 or Sn2

Answer 17

Depends on whether the halogenoalkane is primary, secondary or tertiary. Primary = Sn2, Secondary = Sn1 & Sn2, Tertiary = Sn1

Question 18

Describe the mechanism of forming amines by nucleophilic substitution of halogenoalkanes using ammonia

Answer 18

Ammonia (nucleophile) attacks bromometane (electrophile). Forms CH3NH2 + HBr. CH3NH2 (nucleophile) attacks bromomethane forms N-methylaminomethane and HBr. CH3NCHCH3 (nucleophile) attacks bromomethane (electrophile) forms N-dimethyl-aminomethane. N-dimethylaminomethane (nucleophile) attacks bromomethane (electrophile) forms quaternary amine.

Question 19

Describe the nature of the reaction of forming amines by nucleophilic substitution of halogenoalkanes using ammonia

Answer 19

The reaction is not reliable and makes a mixture of products

Question 20

How do you form an aminde

Answer 20

Reaction of an amine with a carboxylic acid derivative

Question 21

What is produced when you react an amine with acyl chloride

Answer 21

Amide and HCl

Question 22

Why are amides not nucleophilic or basic

Answer 22

Resonance stabilised the amide meaning that it is unreactive (not basic or nucleophilic)

Question 23

How do you form a polyamide

Answer 23

Reaction of a di-amine with a di-acid derivative