Separation by Solvent Extraction
To separate a mixture consisting of a carboxylic acid and a neutral compound by using
solvent extraction techniques.
Frequently, organic chemists must separate an organic compound from a mixture of compounds, often derived from natural sources or products of synthetic reactions. One technique used to separate the mixture compounds is called extraction. Extraction is a process that selectively dissolves one or more of the mixture components into an appropriate solvent. The solution of these dissolved compounds is often referred to as the extract. Extraction processes include removal of soluble compounds from a solid matrix, such as
in the brewing of coffee or tea, or in decaffeinating coffee with liquid carbon dioxide. In the organic chemistry laboratory, however, extraction almost always refers to the transfer of compounds from one liquid solvent to another. A compound can be separated from impurities in a solution by extracting the compound
from the original (or first) solvent into a second solvent. For the process to be selective, the compound must be more soluble in the second solvent than in the first solvent, and the impurities must be insoluble in the second solvent. Additionally, the two selected solvents must be immiscible, or not soluble in one another, so that they produce two separate solvent layers. After dissolving the mixture in the first solvent, the solution is added to a second solvent. The two layers are vigorously mixed to maximize the surface area between them. This mixing facilitates the transfer of a dissolved compound from one solvent layer to another. Once the transfer process is complete, the layers are again allowed to form, as shown in Figure 1. ...