Question

A sample of 4-toluic acid is contaminated with a small amount of sand & toluene. Using active extraction (changing the polarity by addition of certain chemicals) & a gravity filtration to remove a component, describe how you would obtain pure 4-toluic acid in its solid form from this mixture. Note that use of an organic solvent like ether should be used initially, & then any other procedures, including use of a separatory funnel is required.

Answer 1

4-toulic acid and toluene are ether soluble and sand is ether insoluble.

To the mixture, add ether. 4-toulic acid and toluene will dissolve in ether. Sand will remain insoluble which is separated by filteration.

4-toulic acid is much more polar than toluene. When hexane is added to mixture containing 4-toulic acid and toluene, the polarity of solvent system will decrease. In this less polar solvent, 4-toulic acid wll remain soluble and toluene will not dissolve. Two layers will be obtained. One will be toluene and other will be 4-toulic acid dissolved in mixture of hexane and ether. These two layers can be separated by using a separatory funnel. The solvents present in the layer containing 4-toulic acid are removed by evaporation/simple distillation and solid 4-toulic acid is obtained.