As a general term, a substance's said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another. Solvents 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… (More on Anhydrous)