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What are esters?

Esters have characteristic smells, and are often used in flavourings and perfumes.

For example:

propyl ethanoate smells of pears

butyl butanoate smells of pineapple

methyl butanoate smells of apple.

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Esters

Esters contain this group of atoms:

Esters are made from the reaction of a carboxylic acid with an alcohol:

...which is written as –COO–.

carboxylic acid + alcohol ester + water

+ +

+ +CH3CH2COOH CH3OH H2OCH3CH2COOCH3

propanoic acid methanol methyl propanoate water+ +

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Naming esters

Esters are named after the alcohol and the carboxylic acid from which they are made. The alcohol gives the first part of the name, and the carboxylic acid gives the second. Esters always end in “–anoate”.

ethanoic acid methanol

methyl ethanoate

For example:

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Matching carboxylic acids to their esters

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Practising naming esters