90 total
By the end of these notes, you should be able to:
An ester is a type of organic compound that contains a special group of atoms called the ester linkage, written as –COO–. Esters are found everywhere in real life — they are responsible for the sweet, fruity smells in many fruits and are used in perfumes and food flavourings.
Esters are made when an alcohol reacts with an acid (or an acid derivative). In this section, we look at one specific way to make esters: by reacting an alcohol with something called an acyl chloride.
An acyl chloride (also called an acid chloride) is a very reactive organic compound. It has the general formula RCOCl, where:
Think of an acyl chloride as a carboxylic acid that has had its –OH replaced by a –Cl. This makes it far more reactive than a regular carboxylic acid.
The most common acyl chloride you need to know is ethanoyl chloride, with the formula CH₃COCl.
When an alcohol reacts with an acyl chloride, two products are formed:
This reaction happens at room temperature and is very fast — it does not need heat or a catalyst. That makes it much quicker than making esters from carboxylic acids.
The general word equation is:
Alcohol + Acyl chloride → Ester + Hydrogen chloride
The syllabus asks you to know this specific example in detail.
Reactants:
Products:
The chemical equation:
CH₃COCl + CH₃CH₂OH → CH₃COOCH₂CH₃ + HCl
In words:
Ethanoyl chloride + Ethanol → Ethyl ethanoate + Hydrogen chloride
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