Practical investigations
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I am currently carrying out my practical investigation on the "preparation of aspirin" and I was wondering, other than recrystallisation, what other methods are there to increase the yield and purity of the final product?
Igloo writes ...
I am assuming that your question refers to the yield and purity once the crude product has been isolated from the reaction mixture.
Recrystallisation is the only conventional technique available, though, by trial and error, you might well find a solvent - other than hot water – from which aspirin can be isolated. Ordinary water works because aspirin is a poor solvent at room temperature but a very good one at high temperatures, e.g. 80°C. However this is not to say that a mixture of water with another solvent might not give better results or perhaps the use of another solvent altogether.
In general, there may well be other preparative techniques, e.g. the use of ethanoyl chloride with salicylic acid, which might well give better yields overall.
Always carry out a risk assessment and check with your teacher before starting any practical work.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 16 March 2007
