Chemistry- Amines and Amides

Question 1

Why is NH3 soluble in water?

Answer 1

Can form many hydrogen bonds with the lone pair and the 3 hydrogen atoms.

Question 2

What is the structure of a primary Amine?

Answer 2

RNH2

Question 3

What is the structure of a secondary Amine?

Answer 3

R2NH

Question 4

What is the structure of a tertiary Amine?

Answer 4

R3N

Question 5

What is the structure of a Quaternary Amine?

Answer 5

R4N^+

Uses the lone pair in a dative covalent bond and therefore becomes positively charged.

Question 6

How do you name an Amine?

Answer 6

• Name Hydrocarbon Alkyl group first
• Add amine as suffix
  Eg. methyl amine

Question 7

What is the boiling point of a molecule about?

in terms of intermolecular forces

Answer 7

Boiling point is about the intermolecular forces between molecules that are the same.

Question 8

What is solubility of a molecule about?

in terms of intermolecular forces

Answer 8

Solubility is about intermolecular forces between molecules and water.

Question 9

What is the boiling point trend for Primary Amines?

Answer 9

Longer the R-group the higher the boiling point due to more van der waals forces between them.

Question 10

What is the boiling point trend for Primary Amines and Alkanes of similar size?

Answer 10

Primary amines have a greater boiling point to an alkane as primary amines can produce van der waals and hydrogen bonds between each amine molecule and alkanes only have van der waals.

Question 11

What is the trend in boiling points between primary, secondary and tertiary amines?

Answer 11

Although the secondary and tertiary amines may be of similar size, branched molecules will have a lower boiling point as there are fewer van der waals forces since the chains of R-groups are not as straight/ long.

Question 12

Define a Bronsted-Lowry Base

Answer 12

A Proton acceptor

Question 13

Define a Lewis Base

Answer 13

An electron pair donor.

Question 14

What is formed when a Phenylamine reacts with an acid?

Answer 14

Forms a Water soluble ionic salt

Question 15

What happens when an aromatic amine ionic salt reacts with sodium hydroxide (OH- ions)?

Answer 15

The water soluble ionic salt is regenerated back and forms the insoluble amine.

Question 16

Put in order of reactivity ammonia, primary amine and an aromatic amine.

Answer 16

Most: Primary amine

               Ammonia

Least: Aromatic amine

Question 17

Why are primary amines more reactive than ammonia?

Answer 17

Primary amines have a lone pair which is more easily available to make a bond, due to R-groups having and “inductive effect” where the alkyl group can release electrons towards the nitrogen atom. Ammonia does not have alkyl groups and therefore is less able to use its lone pair in a bond.

Question 18

Why are aromatic amines less reactive than other amines?

Answer 18

The lone pair of the nitrogen atom becomes part of the delocalised system of electrons when next to an aromatic ring. This makes the molecule more stable but a LESS GOOD BASE as the lone pair of electrons are no longer available to be used instantaneously.

Question 19

Why are secondary amines more reactive than primary amines?

Answer 19

They are more reactive than a primary amine due to having more R-groups bonded to the nitrogen atom. This means that there is a higher “inductive effect” as more alkyl groups are releasing electrons to the nitrogen atom and therefore the lone pair is more easily able to be used in a bond.

Question 20

Why are tertiary amines less reactive?

Answer 20

Less reactive as they are not soluble and therefore do not as easily react.

Question 21

What is one method of making amines from ammonia?

Answer 21

ammonia reacting with a haloalkane

Via Nucleophilic substitution.

Question 22

What is produced when ammonia reacts with a haloalkane?

Answer 22

A Primary Amine

Question 23

What are the products when ammonia reacts with a haloalkane which is in excess?

Answer 23

Primary Amine
Secondary Amine
Tertiary Amine
Quaternary Amine
(All produced if haloalkane is in excess)
Once the first primary amine is formed, this can react again with the excess of haloalkane as the primary amine can act as a nucleophile and therefore will produce a secondary amine. The process will repeat until a Quaternary amine is produced or the haloalkane is not in excess.

Question 24

How is an amine produced from a Haloalkane and KCN?

Answer 24

Haloalkane + KCN —-> Nitrile
This can be reduced to form the amine.
Eg. Bromoethan + KCN —> Propane nitrile
Nitrile + [H] —> Amine

Question 25

What are the Reducing agents and conditions for a nitrile to an amine?

Answer 25

- LiAlH4 in ether ---> then add dilute acid!
Or
- Using Hydrogen (Hydrogenation)
H2/Pd (paladium catalyst better)
H2/Ni (nickle Catalyst)
High temperature and pressure

Question 26

How are Aromatic Amines produced?

Answer 26

From Nitrobenzene —-> Reduction to phenyl amine.

Question 27

What are the conditions of reduction needed to form an aromatic amine?

Answer 27

Sn(Tin)/HCl @ room temperature

Question 28

Which way of producing amines is more efficient and why?

Answer 28

From Nitriles (Haloalkane + KCN)
This reaction only produces one product where as haloalkanes reacting with ammonia produces a mixture of primary, secondary, tertiary and quaternary amines.

Question 29

What are amines used for?

Answer 29

• Manufactor of synthetic materials (nylon, drugs ,dyes)

- Cationic Surfactants ( Hair and fabric conditioners)