1
Acid derivatives
The hydroxyl group (-OH) in a carboxylic acid can be replaced by other functional groups forming a series of
compounds that contain the group, RCO- :
X
These molecules are derivatives of carboxylic acids.
X Acid derivative Example Name
-OR
ester
-Cl acyl chloride
(can also be fluoride,
bromide or iodide)
-OCOR
acid anhydride
-NH2
amide
-NHR
N-substituted
amide
, 2
Esters
Esters are quite common naturally occurring molecules that are largely responsible for the fragrance of
flowers. These esters can be extracted and blended with essential oils to make perfumes.
Most esters have a fruity smell.
Esters can be used as a in PVC for instance and as solvents and in food flavourings.
An example of an ester is ethyl ethanoate.
Instead of an –OH (in a carboxylic acid) there is an –OC2H5. This is why we can call it an acid derivative.
Notice that the ester is named the opposite way around from the way the formula is written.
Physical properties of esters
Boiling Point
Esters are polar molecules and the strongest force between their molecules is permanent dipole-dipole.
Explain why the boiling point of butanoic acid is higher than that of ethyl ethanoate.
, 3
Solubility
Esters can form hydrogen bonds with water and the very short chain ones are soluble.
Draw a diagram showing the hydrogen bonding between an ethyl ethanoate and two water molecules.
Formation of esters (RP10 - preparation of an organic liquid)
Esters are made when carboxylic acids are heated with alcohols in the presence of concentrated sulfuric
acid catalyst. For example, an equation for the formation of ethyl propanoate is shown below:
Write equations using displayed formulae for the following esterification reactions and name the ester
produced:
Methanol and propanoic acid
Ethanol and methanoic acid
Acid derivatives
The hydroxyl group (-OH) in a carboxylic acid can be replaced by other functional groups forming a series of
compounds that contain the group, RCO- :
X
These molecules are derivatives of carboxylic acids.
X Acid derivative Example Name
-OR
ester
-Cl acyl chloride
(can also be fluoride,
bromide or iodide)
-OCOR
acid anhydride
-NH2
amide
-NHR
N-substituted
amide
, 2
Esters
Esters are quite common naturally occurring molecules that are largely responsible for the fragrance of
flowers. These esters can be extracted and blended with essential oils to make perfumes.
Most esters have a fruity smell.
Esters can be used as a in PVC for instance and as solvents and in food flavourings.
An example of an ester is ethyl ethanoate.
Instead of an –OH (in a carboxylic acid) there is an –OC2H5. This is why we can call it an acid derivative.
Notice that the ester is named the opposite way around from the way the formula is written.
Physical properties of esters
Boiling Point
Esters are polar molecules and the strongest force between their molecules is permanent dipole-dipole.
Explain why the boiling point of butanoic acid is higher than that of ethyl ethanoate.
, 3
Solubility
Esters can form hydrogen bonds with water and the very short chain ones are soluble.
Draw a diagram showing the hydrogen bonding between an ethyl ethanoate and two water molecules.
Formation of esters (RP10 - preparation of an organic liquid)
Esters are made when carboxylic acids are heated with alcohols in the presence of concentrated sulfuric
acid catalyst. For example, an equation for the formation of ethyl propanoate is shown below:
Write equations using displayed formulae for the following esterification reactions and name the ester
produced:
Methanol and propanoic acid
Ethanol and methanoic acid
