6. Amides Flashcards
What is a reaction in which two molecules combine to form a single molecule?
Condensation reaction.
Primary amides can be formed from a condensation reaction between a carboxylic acid (an ester or acid chloride) and what?
Ammonia.
Secondary amides can be formed when a condensation reaction occurs between a carboxylic acid or acyl chloride and what?
A primary amine.
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?

Heat.
When ethanoic acid and ammonia react, the ammonium salt ammonium ethanoate is formed. When this salt is heated, the primary amide ethanamide (CH3CONH2) and what are produced?
Water (H2O).

When an ester reacts with concentrated aqueous ammonia, a primary amide and an alcohol are formed. For example, the ester methyl ethanoate (CH3COOCH3) reacts with concentrated aqueous ammonia (NH3) to produce the primary amide ethanamide (CH3CONH2) and what?
Methanol (CH3OH).

When an acyl chloride, or acid chloride, reacts with excess ammonia, a primary amide and ammonium chloride are formed. For example, acetyl chloride (CH3COCl) reacts with excess ammonia (NH3) to produce the primary amide ethanamide (CH3CONH2) and what?
Ammonium chloride (NH4Cl).

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

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

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

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?
Hydrogen chloride.

Simply put, hydrolysis1 is a reaction with what?
Water.
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?
Ammonia or ammonium salt.
Amides undergo hydrolysis in hot aqueous acid to give a carboxylic acid and what?
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.

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?
A carboxylate ion (R-COO−).

When learning about the basic properties of amines, it helps to think of amines as what?
A modified ammonia molecule.
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?
H+ ions.
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?
An equilibrium arrow.

Why can amines react with water?
Because they are weak bases.
When an amine reacts with water, a proton is removed from a water molecule and transferred to the amine creating what?
An ammonium ion a molecule with a NH3+ group.
Because of their lone pair of electrons, amines are also considered what?
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.

Primary amines are formed when a haloalkane and ammonia undergowhat?
A substitution reaction.

Haloalkanes are also called what?
Alkyl halides.
Ethylamine takes a hydrogen ion from a hydronium ion and forms what?
An ethylammonium ion.

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?
An amide molecule is formed.

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?
The amide N-methylacetamide.
