Isolation of organic compounds from mixtures by solvent extraction.

EXPERIMENTAL PROCEDURE: 1. 2.07 g of the mixture of naphthalene and benzoic acid was weighed accurately on a balance. The mixture was then dissolved in 40 ml dichloromethane and the solution was poured into a separatory funnel. 2. 20 ml of aqueous sodium bicarbonate solution was added to the dichloromethane. A stopper was placed on the separatory funnel and was shaken and pressure was frequently released. The 2 liquids separated into clear layers and the lower layer (dichloromethane layer) was tapped …

…melting point. 6. The bicarbonate extract was acidified with concentrated HCl. A piece of litmus paper showed that it was acidic. 7. The benzoic acid was extracted by shaking it with25ml portions of dichloromethane. The organic extracts were collected in a pre-weighed Erlenmeyer flask and evaporated on the steam bath. The mass of Benzoic acid produced was determined. RESULTS (i) Naphthalene: 0.85g; Benzoic acid: 0.71g (ii) The melting point of Naphthalene: 80-89º c