Answer to Question #164784 in Organic Chemistry for Zara

Question

Why is less caffeine actually isolated than is suggested by the calculation? 

Answer 1

Caffeine is water soluble but so are some tannins and gallic acid which is formed in the process of boiling tea leaves. The latter two components can be converted to their calcium salts which are insoluble in water. The caffeine can then be extracted from the water by methylene chloride in almost pure form.