Cambridge O Level Chemistry · Syllabus 5070 · Organic Chemistry
Ester
What is Ester?
An organic compound formed when a carboxylic acid reacts with an alcohol using an acid catalyst, containing the -COO- ester linkage, and named with the alkyl group from the alcohol first followed by the alkanoate stem from the acid.
This definition is part of the Organic Chemistry chapter in Cambridge O Level Chemistry.
Common mistakes with Ester
- “Ethanol plus methanoic acid gives ethyl methanoic acid.” why it fails An ester name never keeps the word “acid”, and the two halves are easy to swap. correct Alkyl from the alcohol first, alkanoate from the acid second: ethanol gives “ethyl”, methanoic acid gives “methanoate”, so the ester is ethyl methanoate. Taught in 11.2.
- 4. “Ethanol plus methanoic acid gives ethyl methanoic acid.” defect The word “acid” retained in an ester name. why An ester is not an acid; it has no acidic hydrogen. The acid's ending becomes -oate. repair Delete “ic acid” and write “ate”: ethyl methanoate. transfer Name the ester from butan-1-ol and propanoic acid, then say which parent gave each word.
Questions students ask about Ester
How do you name and draw an ester from an alcohol and a carboxylic acid?
Take the alkyl name from the alcohol first, then the alkanoate name from the acid second, and never keep the word "acid" in the ester name. Ethanol and methanoic acid give ethyl methanoate, formed with an acid catalyst and containing the -COO- ester linkage, with water as the other product.
Reviewed by Academiq Edu Instructor PanelLast reviewed Syllabus 2026-2028