Flashcards in Amides Deck (19):
What are the 3 ways of converting a carboxylic acid to an amide?
From the acid chloride
From dehydration of ammonium salt
From an ester (reacts with NH3)
A carboxylic acid can be converted to an amide, give one way in which this can be done
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
Why would the NH3 used in converting acids to amides via acid chlorides need to be dry or concentrated?
Otherwise hydrolysis would occur and the acid chloride would hydrolyse back to the acid
Another way to convert acid to amide is by dehydration of ammonium salt- explain how this works
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
Describe acid hydrolysis
Amide via water,
To produce a carboxylic acid and NH4Cl
Describe alkaline hydrolysis
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
Describe the reduction of primary amides
Use LiAlH4 - dry solvent, room temp
This will form a primary AMINE
What bonding occurs between amide molecules?
What is its bonding stronger than?
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
Describe the solubility of amides I
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
Describe the melting points and boiling points of amides
Melting point and boiling point of amides increase as the hydrocarbon chain length increases due to an increase in van der waals between molecules
Define condensation polymerisation
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
Define addition polymerisation
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
How are polyesters made?
By a condensation polymerisation reaction- small molecule eliminated or produced, if small molecule is water than it's also called dehydration
Nylon-6,6 monomers produce a polymer in what kind of reaction?
The polymer is made from a condensation reaction - condensation polymer- a small molecule is produced or eliminated in this
Why are nylons classed as poly amides/polypeptides?
Because the linkage between the monomers is the amide/peptide link
Draw monomers that create Nylon-6,6 and itself
Draw monomers that create polyamide Kevlar and itself
Draw monomers that make polyester terylene PET and itself