Esterification
Acid plus alcohol gives ester plus water.
A sweet smell
Perfumes and flavourings often smell sweet. Many of them contain a kind of compound called an ester. An ester is made from an acid and an alcohol.
What else do you think forms along with the ester?
What this lesson covers
The idea
An acid reacts with an alcohol in the presence of an acid catalyst to form an ester and water; this is an esterification reaction, and esters are generally sweet-smelling substances.
A sweet smell
Perfumes and flavourings often smell sweet. Many of them contain a kind of compound called an ester. An ester is made from an acid and an alcohol.
What else do you think forms along with the ester?
- Water
- Hydrogen gas
- Carbon dioxide
Making an ester
Press Next step. A teacher does this in the lab.
Acid + alcohol
The acid and the alcohol join to make the ester, and water is also formed. The reaction needs an acid catalyst.
An acid reacts with an alcohol in the presence of an acid catalyst to form an ester and water. This is an esterification reaction, and esters are generally sweet-smelling substances.
- Acid | + Alcohol | Gives
- ethanoic acid | ethanol | ester + water
Notes
An acid reacts with an alcohol in the presence of an acid catalyst to form an ester and water: an esterification reaction. Esters are generally sweet-smelling.
Check yourself
What forms when an acid reacts with an alcohol in the presence of an acid catalyst?
What is the smell of esters generally?
What are esters used for?
Ethanoic acid has 2 carbon atoms and ethanol has 2 carbon atoms. How many carbon atoms does the ester formed from them have?
Answer: 4
2 + 2 = 4 carbon atoms: the ester is CH₃COOCH₂CH₃, C₄H₈O₂.
- A salt and hydrogen. A salt and hydrogen form when a metal reacts with an acid. Here an ester and water form.
- An alkene and water. An alkene forms when ethanol is dehydrated with hot concentrated sulphuric acid.
- An ester and water — correct. Yes!
- Sweet — correct. Yes!
- Sour like vinegar. Vinegar is a solution of acetic acid. Esters are generally sweet-smelling.
- Like burning. Esters are generally sweet-smelling substances.
- Making soap by themselves. Esters are converted to soap-making ingredients by sodium hydroxide in saponification, but their uses named here are perfumes and flavouring.
- Making perfumes and as flavouring agents — correct. Yes!
- Oxidising alcohols. Oxidising agents such as alkaline potassium permanganate do this. Esters are used in perfumes and as flavouring agents.