Ester
The ester has the structure R-COO-R' — it can be thought of as a carboxylic acid where the hydroxyl's hydrogen was swapped for an alkyl group. Many short-chain esters have a characteristic fruity smell.
General formula
R–COO–R'
Naming rule
Name = [acid radical]-oate + [alcohol radical]-yl. For example, ethyl ethanoate comes from ethanoic acid + ethanol.
How to name it with IUPAC
Use this sequence to move from the structure to the systematic name:
- Separate the acid-derived part from the group attached to oxygen.
- Name the acid part as -oate first, then the alkyl group after “of”.
- CH₃COOCH₂CH₃ = ethyl ethanoate: ethanoate + ethyl.
CH₃COOCH₂CH₃ = ethyl ethanoate: ethanoate + ethyl.
Examples
| Name | Formula |
|---|---|
| Methyl methanoate | HCOOCH₃ |
| Ethyl ethanoate | CH₃COOC₂H₅ |
| Methyl ethanoate | CH₃COOCH₃ |
Visual examples
See how the functional group appears inside the chain. Compare the drawings with the formulas in the table to practice visual recognition.
Chemical reading
An ester has carbonyl and oxygen in one group but no O–H bond, so it accepts but does not donate hydrogen bonds.
Properties and applications
Esters occur in flavors, fragrances, solvents, plasticizers, and fats; fruity odor is common but not diagnostic.
- Esterification joins acid and alcohol, while hydrolysis breaks the ester. CH₃COOCH₂CH₃ is ethyl ethanoate.
- Compare polarity, chain size, and hydrogen bonding before predicting physical properties.