Esterification and
dehydration of
alcohols
Starter:Use molecular models to make various alcohol molecules
Keywords:Esterification, elimination, ester, dehydration
Learning Objectives
A Model the esterification of alcohols with carboxylic acids
B Describe the elimination of H2O from alcohols to form alkenes.
C Name the esters formed by esterification reactions
Esterification – the reaction of an alcohol with a carboxylic acid to produce an ester and water
Elimination – breaking up 1 molecule into 2 molecules
Dehydration – an elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule
Esterification
An ester is formed when an alcohol is warmed with a carboxylic acid in the presence of an acid catalyst
The reaction is known as esterification
Concentrated sulfuric acid is often used as the acid catalyst
The esterification reaction between Propanoic acid and Methanol
In the reaction, the O-H bond in the alcohol is broken and water is formed.
The water molecule comes from the OH of the carboxylic acid group and the H in
the alcohol group
Naming esters
Choose an alcohol and a carboxylic acid card. Name the ester and draw its structure.
X-yl X-anoate
Carboxylic acidAlcohol
Esters are used as adhesives and solvents in the chemical industry. The
flavours and fragrances of different esters are widely used to produce food
flavourings and perfumes.
Preparing an ester
1. In a boiling tube add 1cm3 carboxylic acid to 1cm3 alcohol and
add the catalyst (H2SO4)
2. Place tube in a water bath (80C) for 5 mins
3. Pour the product into a beaker of cold
water4. The oil on the surface
will be the ester
Dehydration of an alcohol
An alcohol can be dehydrated to form an alkene in the presence of an acid catalyst (Conc phosphoric acid or conc sulphuric
acid)
This is an elimination reaction
Alcohol is heated under reflux with the catalyst for 40 minutes.
The dehydration of cyclohexanol is seen below. What is the product?
Plenary
Pg 155
Questions 1, 2 and 3
Methanol Methanoic acid
Ethanol Ethanoic acid
Propanol Propanoic acid
Butanol Butanoic acid
Pentanol Pentanoic acid
Hexanol Hexanoic acid
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