Extraction involves dissolving a compound or compounds either from a solid into a solvent or from a solution into another solvent. Extraction is a method used to purify a substance by removing the impurities that was added to it. A solvent- solvent extraction is a type of extraction that is most commonly done by using two substances that are typically insoluble with each other. An acid-base extraction is a solvent-solvent extraction, in almost every case one of the solvents is water or an aqueous solution and a requirement of a solvent-solvent extraction is that the mixture of the two solvents will separate into two layers. The upper layer is that which is less dense, while the lower layer is the denser of the two. The organic solvent must also be volatile so it can be easily removed by evaporation at the end. Extractions are extremely useful for isolating and purifying amines, carboxylic acids, phenols as well as some neutral compounds. All three of these functional groups can be interconverted from non-ionic organic-soluble forms to water-soluble ionic forms by changing the pH levels. In the experiment done in this lab, a mixture of and a neutral compound and either an acid or base impurity will be separated by an acid-base extraction. The unknown compound will then be purified by recrystallization and identified by melting points.
The solubility of the basic component was manipulated to show that the basic compound was ether insoluble and water soluble. The extraction experiment with HCl shows that the impurity in the mixture was basic; therefore the basic compound must have been 4-chloroaniline.This was determined because once the aqueous layer was drained into the test tube and NaOH was added precipitation formed. The precipitation occurred because when base was added to the aqueous solution that contains the salt of a deprotonated organic base, the organic base is then re-protonated. When this happens it is...