Introduction Into Esters
INTRODUCING ESTERS
This page explains what esters are and looks at their simple physical properties such as solubility and boiling points. It includes an introduction to more complicated naturally-occurring esters like animal and vegetable fats and oils.
What are esters?
Esters are derived from carboxylic acids. A carboxylic acid contains the -COOH group, and in an ester the hydrogen in this group is replaced by a hydrocarbon group of some kind. This could be an alkyl group like methyl or ethyl, or one containing a benzene ring like phenyl.
A common ester - ethyl ethanoate
The most commonly discussed ester is ethyl ethanoate. In this case, the hydrogen in the -COOH group has been replaced by an ethyl group. The formula for ethyl ethanoate is:
Notice that the ester is named the opposite way around from the way the formula is written. The "ethanoate" bit comes from ethanoic acid. The "ethyl" bit comes from the ethyl group on the end.
Note: In my experience, students starting organic chemistry get more confused about writing names and formulae for esters than for almost anything else - particularly when it comes to less frequently met esters like the ones coming up next. Take time and care to make sure you understand!
A few more esters
In each case, be sure that you can see how the names and formulae relate to each other.
Notice that the acid is named by counting up the total number of carbon atoms in the chain - including the one in the -COOH group. So, for example, CH3CH2COOH is propanoic acid, and CH3CH2COO is the propanoate group.
Note: You can find more about naming acids and esters by following this link to a different part of this site.
Use the BACK button on your browser to return to this page.
Fats and oils
Differences between fats and oils
Animal and vegetable fats and oils are just big complicated esters. The difference between a fat (like butter) and an oil (like sunflower oil) is simply in the
This page explains what esters are and looks at their simple physical properties such as solubility and boiling points. It includes an introduction to more complicated naturally-occurring esters like animal and vegetable fats and oils.
What are esters?
Esters are derived from carboxylic acids. A carboxylic acid contains the -COOH group, and in an ester the hydrogen in this group is replaced by a hydrocarbon group of some kind. This could be an alkyl group like methyl or ethyl, or one containing a benzene ring like phenyl.
A common ester - ethyl ethanoate
The most commonly discussed ester is ethyl ethanoate. In this case, the hydrogen in the -COOH group has been replaced by an ethyl group. The formula for ethyl ethanoate is:
Notice that the ester is named the opposite way around from the way the formula is written. The "ethanoate" bit comes from ethanoic acid. The "ethyl" bit comes from the ethyl group on the end.
Note: In my experience, students starting organic chemistry get more confused about writing names and formulae for esters than for almost anything else - particularly when it comes to less frequently met esters like the ones coming up next. Take time and care to make sure you understand!
A few more esters
In each case, be sure that you can see how the names and formulae relate to each other.
Notice that the acid is named by counting up the total number of carbon atoms in the chain - including the one in the -COOH group. So, for example, CH3CH2COOH is propanoic acid, and CH3CH2COO is the propanoate group.
Note: You can find more about naming acids and esters by following this link to a different part of this site.
Use the BACK button on your browser to return to this page.
Fats and oils
Differences between fats and oils
Animal and vegetable fats and oils are just big complicated esters. The difference between a fat (like butter) and an oil (like sunflower oil) is simply in the