Here's one way to prepare cholesteryl benzoate crystals:
Step 1 Dissolve 1.0 g of cholesterol in 3 cm3 of pyridine in a conical flask.
Step 2 Add 0.40 cm3 of benzoyl chloride.
Step 3 Heat the mixture on a steam bath for about 10 minutes.
Step 4 Cool the mixture, and add 15 cm3 of methanol.
Step 5 Collect the solid cholesteryl benzoate by suction filtration. Rinse the flask and the crude crystals with a little cold methanol.
Step 6 Recrystallize the cholesteryl benzoate using ethyl ethanoate as the solvent.
The methanol is said to be added to react with the benzoyl chloride. Why is this required?
Usually, in a preparation such as that of 1-bromobutane, some substance such as sodium carbonate is added in order to allow for separation of the aqueous substances from the organic layer. That makes sense. However, in the case of the above preparation, by adding methanol the substances within the conical flask go from benzoyl chloride, pyridine and cholesteryl benzoate to HCl, pyridine, methyl benzoate and cholesteryl benzoate. What's the point? Either way, both mixtures are going to eventually be separated from the cholesteryl benzoate by suction filtration.