26.4 carboxylic acid derivatives

naming esters

• remove the -oic acid suffix from the parent carboxylic acid and replace it with -oate

• the alkyl chain attached to the oxygen atom of the COO group is then added as the first word in the name

naming acyl chlorides

remove the -oic acid suffix from the parent carboxylic acid and replace with -oyl chloride

what is an acid anhydrides

it is formed by the removal of water from 2 carboxylic acid molecules as shown in the formation of ethanoic anhydride

esterification

• the reaction of an alcohol with a carboylic acid to form an ester

• an alcohol is warmed with a small amount of concentrated sulphuric acid, which acts as a catalyst

acid hydrolysis of esters

• the ester is heated under reflux with dilute aqueous acid

• the ester is broken down by water, with the acid acting as a catalyst

• the products of acid hydrolysis are a carboxylic acid and an alcohol

alkaline hydrolysis

• is also known as sapification and is reversible

• the ester is heated under reflux with aqueous hydroxide ions

preparation of acyl chlorides

• can be prepared directly from their parent carboxylic acid by reaction with thionyl chloride, SOCl2

• the other products of this reaction, SO2 and HCl are evolved as gases, leaving just the acyl chloride. The reaction should be carried out in a fume cupboard as the products are harmful

• they are very reactive and can easily be converted into carboxylic acid derivatives, such as esters and amides with good yields

• acyl chlorides react with nucleophiles by losing the chloride ion while retaining the C=O double bond

reaction of acyl chlorides to form esters

• acyl chlorides react with alcohols to form esters

reaction of acyl chlorides with phenols to form esters

• carboxylic acids are not reactive enough to form esters with phenols

• acyl chlorides and acid anhydrides are both more reactive than carboxylic acids and react with phenols to produce phenyl esters

reaction of acyl chlorides with water

• a violent reaction takes place with the evolution of dense steamy hydrgoen chloride fumes

• a carboxylic acid is formed

reaction of acyl chlorides with ammonia

• ammonia and amines can act as nucleophiles by donating the lone pair of electrons on the nitrogen atom to an electron-deficient species

• their reaction forms a primary amide (the nitrogen atom is attached to one carbon atom

reaction of acyl chlorides with primary amines

a primary amine reacts with an acyl chloride in the same way as ammonia to form a secondary amide (the nitrogen atom is attached to two carbon atoms)