Anhydrous - Solvents

Solvents

See also: Air-free technique#Associated preparations

In many cases, the presence of water can prevent a reaction from happening, or form undesirable products. To prevent this, anhydrous solvents must be used when performing certain reactions. Examples of reactions requiring the use of anhydrous solvents are the Grignard reaction and the Wurtz reaction.

Solvents are commonly rendered anhydrous by boiling them in the presence of a hygroscopic substance; metallic sodium is one of the most common metals used. Other methods include the addition of molecular sieves or alkali bases such as potassium hydroxide or barium oxide. Column solvent purification devices (generally referred to as Grubb's columns) recently became available, reducing the hazards (water reactive substances, heat) from the classical dehydrating methods.