Functional groups
The central –OH is an alcohol group.
It is not counted as a fourth ordinary carboxylic-acid proton.
Molecular compound · hydroxytricarboxylic acid
Citric acid
C₆H₈O₇
Citric acid is C₆H₈O₇. It contains three carboxylic acid groups and one alcohol group, so three carboxyl protons can be removed stepwise.
Food distinction: citrus juice is a mixture containing citric acid, not pure citric acid.
Essentials
Three –COOH groups control ordinary acid behavior.
A condensed structural formula is more informative than C₆H₈O₇ alone because it exposes the functional groups.
Detail
The full 2D structure fixes connectivity.
Citric acid has a three-carbon backbone with three carboxyl groups and one central hydroxyl group.
2D ≠ rigidly flat
The skeletal drawing is a connectivity map.
Single bonds allow conformational motion in three dimensions.
Understand
Citric acid deprotonates stepwise to citrate.
Each step removes one carboxyl proton; which species dominate depends on pH.
Citrate
Multiple oxygen donor sites let citrate bind metal ions.
This makes citrate chemically richer than a one-site acid.
Reference identifiers
Names and identifiers that pin down the chemical identity.
| Formula | C₆H₈O₇ |
|---|---|
| CAS Registry Number | 77-92-9 |
| PubChem CID | 311 |
Advanced
Push past the first model without losing the simple picture.
Why triprotic?
Three carboxylic acid groups provide three readily ionizable protons.
Is citrate rigid?
No. It has defined connectivity but can adopt different conformations and coordination modes.
Is citric acid the same as lemon juice?
No. Juice is a multicomponent mixture.
Constituent elements