6. Amides

Question 1

What is a reaction in which two molecules combine to form a single molecule?

Answer 1

Condensation reaction.

Question 2

Primary amides can be formed from a condensation reaction between a carboxylic acid (an ester or acid chloride) and what?

Answer 2

Ammonia.

Question 3

Secondary amides can be formed when a condensation reaction occurs between a carboxylic acid or acyl chloride and what?

Answer 3

A primary amine.

Question 4

The addition of ammonia (NH3​) to a carboxylic acid forms a primary amide. However, this reaction is very slow in the laboratory at room temperature, which is why what is required to complete the condensation reaction?

Answer 4

Heat.

Question 5

When ethanoic acid and ammonia react, the ammonium salt ammonium ethanoate is formed. When this salt is heated, the primary amide ethanamide (CH3​CONH2​) and what are produced?

Answer 5

Water (H2​O).

Question 6

When an ester reacts with concentrated aqueous ammonia, a primary amide and an alcohol are formed. For example, the ester methyl ethanoate (CH3​COOCH3​) reacts with concentrated aqueous ammonia (NH3​) to produce the primary amide ethanamide (CH3​CONH2​) and what?

Answer 6

Methanol (CH3​OH).

Question 7

When an acyl chloride, or acid chloride, reacts with excess ammonia, a primary amide and ammonium chloride are formed. For example, acetyl chloride (CH3​COCl) reacts with excess ammonia (NH3​) to produce the primary amide ethanamide (CH3​CONH2​) and what?

Answer 7

Ammonium chloride (NH4​Cl).

Question 8

When a primary amine reacts with a carboxylic acid at high temperatures, what forms?

Answer 8

Secondary amide.

Question 9

When an acid-base reaction between ethanoic acid and methylamine occurs, which ammonium carboxylate salt is produced?

Answer 9

Methylammonium ethanoate.

Question 10

Primary amines can also produce secondary amides if they undergo a reaction with what?

Answer 10

An acyl chloride, or acid chloride.

In the second stage, since amines are basic, the primary amine reacts with hydrogen chloride to produce an ammonium chloride salt.

So, overall from this condensation reaction between a primary amine and an acyl chloride, we get a secondary amide and an ammonium chloride salt.

Question 11

When ethanoyl chloride and methanamine undergo a condensation reaction, the secondary amide N-methanacetamide and hydrochloric acid are produced.

Remember, methanamine is basic, so any excess methanamine will react with what to form the salt methanammonium chloride?

Answer 11

Hydrogen chloride.

Question 12

Simply put, hydrolysis1 is a reaction with what?

Answer 12

Water.

Question 13

Amides are able to undergo hydrolysis reactions in a similar way to esters.

Since the reaction for forming amides is reversible, under certain conditions, primary amides can react with water to produce the original acid, what from which they were made?

Answer 13

Ammonia or ammonium salt.

Question 14

Amides undergo hydrolysis in hot aqueous acid to give a carboxylic acid and what?

Answer 14

An ammonia ion (NH4​+) (or depending how the amide was formed, an amine).

This ammonium ion (NH4​+) can go on to form a salt, or remain dissolved in the solution.

Question 15

If an amide undergoes hydrolysis in basic conditions (e.g in the presence of heat and sodium hydroxide), the amide is reduced to an ammonia molecule (NH3​) and what?

Answer 15

A carboxylate ion (R-COO−).

Question 16

When learning about the basic properties of amines, it helps to think of amines as what?

Answer 16

A modified ammonia molecule.

Question 17

Amines are weak bases, and in chemical reactions behave similarly to ammonia, -NH3.

Amines are considered weak bases in solution, as they can take what from other compounds?

Answer 17

H+ ions.

Question 18

Strong bases completely react with water but weak bases only partially react with water, so their reactions are considered reversible and what must be used?

Answer 18

An equilibrium arrow.

Question 19

Why can amines react with water?

Answer 19

Because they are weak bases.

Question 20

When an amine reacts with water, a proton is removed from a water molecule and transferred to the amine creating what?

Answer 20

An ammonium ion a molecule with a NH3​+ group.

Question 21

Because of their lone pair of electrons, amines are also considered what?

Answer 21

Nucleophilic.

It is due to these nucleophilic properties that amines are able to undergo substitution reactions with haloalkanes. These reactions are called nucleophilic substitution reactions.

Question 22

Primary amines are formed when a haloalkane and ammonia undergowhat?

Answer 22

A substitution reaction.

Question 23

Haloalkanes are also called what?

Answer 23

Alkyl halides.

Question 24

Ethylamine takes a hydrogen ion from a hydronium ion and forms what?

Answer 24

An ethylammonium ion.

Question 25

An important reaction occurs when a primary amine reacts with a carboxylic acid (-COOH) at high temperatures.

In this reaction, a water molecule is removed and what is formed?

Answer 25

An amide molecule is formed.

Question 26

When an acid-base reaction of ethanoic acid and methylamine occurs, the salt methylammonium ethanoate is produced. When this salt is heated to over 100°C, a condensation reaction occurs in which a water molecule is removed and what is formed?

Answer 26

The amide N-methylacetamide.