Distillation

Distillation separates and purifies liquid compounds on the basis of differences in volatility (boiling point), and remains the method of choice for...

Distillation separates and purifies liquid compounds on the basis of differences in volatility (boiling point), and remains the method of choice for purifying volatile liquid intermediates, removing high-boiling non-volatile impurities, and recovering and recycling reaction solvents at both laboratory and manufacturing scale. Simple distillation is adequate where the boiling point difference between the target compound and its impurities is substantial, while fractional distillation, employing a packed or plated fractionating column that provides repeated vaporisation-condensation equilibration, is required to resolve compounds of more closely similar boiling point; vacuum distillation, performed under reduced pressure to lower the effective boiling point, is routinely applied to purify thermally sensitive compounds that would decompose at their atmospheric-pressure boiling point.