The Slow Evaporation Method

This is the most successful method we have used for more than 100 compounds (more than 90% of the time)! The next method being slow cooling (from high temperature to Room Temperature or Low temperature, slowly).

The Method: The compound can be dissolved in a single solvent or mixture of two solvents and left for Slow Evaporation. It can be done either under atmospheric conditions or under inert atmosphere. The best containers to use are (in the order): centrifuge tube, NMR tube, test tube, round bottom flask, conical flask and beaker. Do not use too big container for the volume of solution you are handling.

The Solvents:

Check the Polarities in the Solvent Properties Table.

Some Details for two solvent method: Dissolve the compound in the solvent that can dissolve. The volume depends on the amount of compound you are using. About 1-5 ml per 0.1 g may be a good starting point. Then add the other solvent slowly with good mixing. When you are reaching near the critical mixture, some precipitation will form and take a longer time to dissolve. If it does not dissolve, try the following:

The Crystallization:

Created by A.Chandrasekaran