Question

In the work-up procedure, Castor Oil, limonene, Pd/C catalyst, and hydrogenated Castor Oil must be separated. What solvent or process removes unreacted limonene?

Filtration?

Dissolving with methylene chloride?

Evaporation?

Dissolving with hexanes?

Answer 1

dissolving or solvent extraction with the methylene chloride is the best method for extraction of unreacted limonene. Since castor oil and limonene have similar solubility characteristics therefore it is very viable to use saltwater and dichloromethane solution to extract limonene in the dichloromethane since this would decrease the limonene's capacity to go into the aqueous phase and will eventually be maximum in concentration in the methylene chloride.

evaporation cannot be done although it is possible, since it would be a very energy intensive process to evaporate limonene from the reaction mixture.