Amides

Question 1

What are the 3 ways of converting a carboxylic acid to an amide?

Answer 1

From the acid chloride

From dehydration of ammonium salt

From an ester (reacts with NH3)

Question 2

A carboxylic acid can be converted to an amide, give one way in which this can be done

Answer 2

From the acid chloride

Convert acid to acid chloride via SOCl2, reflux and dry conditions

Then add dry or concentrated NH3 to the acid chloride to produce an amide and HCl - NUCLEOPHILIC sub in both

Question 3

Why would the NH3 used in converting acids to amides via acid chlorides need to be dry or concentrated?

Answer 3

Otherwise hydrolysis would occur and the acid chloride would hydrolyse back to the acid

Question 4

Another way to convert acid to amide is by dehydration of ammonium salt- explain how this works

Answer 4

First add excess acid and reflux with ammonium carbonate to form an ammonium salt

Acid + carbonate – > salt + CO2 + H2O

Ammonium salt then dries on heating to produce amide and H2O

Question 5

Describe acid hydrolysis

Answer 5

Amide via water,
hydrochloric acid
and reflux

To produce a carboxylic acid and NH4Cl

Question 6

Describe alkaline hydrolysis

Answer 6

2 steps

Step 1 - amide via water sodium hydroxide and reflux to produce sodium salt and ammonia

Salt is then converted to an acid by adding hydrochloric acid

Question 7

Describe the reduction of primary amides

Answer 7

Use LiAlH4 - dry solvent, room temp

This will form a primary AMINE

Question 8

What bonding occurs between amide molecules?

What is its bonding stronger than?

Answer 8

Amides have hydrogenbonding - it’s stronger bonding than that in carboxylic acids so amides have higher MP AND BP when comparing molecules of similar molecular size

Question 9

Describe the solubility of amides I

Answer 9

Amide are soluble in water due to hydrogen bonding

Solubility decreases as hydrocarbon chain length increases and the polar affect of the amide group Decreases

Question 10

Describe the melting points and boiling points of amides

Answer 10

Melting point and boiling point of amides increase as the hydrocarbon chain length increases due to an increase in van der waals between molecules

Question 11

Define condensation polymerisation

Answer 11

1 large molecule is formed (polymer) and one small molecule lost e.g water, this means the atom economy is less than 100%. 2 functional groups needed in the monomers

Question 12

Define addition polymerisation

Answer 12

Only 1 large molecule formed and no molecules lost so atom economy is 100%- only 1 functional group needed in each monomer- c=c e.g polythene —> ethene

Question 13

How are polyesters made?

Answer 13

By a condensation polymerisation reaction- small molecule eliminated or produced, if small molecule is water than it’s also called dehydration

Question 14

Nylon-6,6 monomers produce a polymer in what kind of reaction?

Answer 14

The polymer is made from a condensation reaction - condensation polymer- a small molecule is produced or eliminated in this

Question 15

Why are nylons classed as poly amides/polypeptides?

Answer 15

Because the linkage between the monomers is the amide/peptide link

Question 16

Draw monomers that create Nylon-6,6 and itself

Answer 16

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Question 17

Draw monomers that create polyamide Kevlar and itself

Answer 17

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Question 18

Draw monomers that make polyester terylene PET and itself

Answer 18

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Question 19

How is 1,6-diaminohexane (used in production of nylon-6,6) made?

Answer 19

By the reduction of a nitrile (NC(CH2)4CN) using LiAlH4 anhydrous via [8H]