Work-up (chemistry)

• quenching a reaction to deactivate any unreacted reagents
• cooling the reaction mixture or adding an antisolvent to induce precipitation, and collecting or removing the solids by filtration, decantation, or centrifugation
• removal of solvents by evaporation
• separating the reaction mixture into organic and aqueous layers by liquid-liquid extraction
• purification by chromatography, distillation or recrystallization

• The reaction mixture containing the Grignard reagent is allowed to warm to room temperature in a water bath to allow excess dry ice to evaporate
• Any remaining Grignard reagent is quenched by the addition of water
• Dilute hydrochloric acid is added to the reaction mixture to protonate the benzoate salts, as well as to dissolve the magnesium salts. White solids of impure benzoic acid are obtained.
• The benzoic acid is decanted to remove the aqueous solution of impurities, more water is added, and the mixture is brought to a boil with more water added to give a homogeneous solution.
• The solution is allowed to cool slowly to room temperature, then in an ice bath to recrystallize benzoic acid.
• The recrystallized benzoic acid crystals are collected on a Buchner funnel and are allowed to air-dry to give pure benzoic acid.