Organic Extraction Methods

Podcast

Play an AI-generated podcast conversation about this lesson

Separating and purifying organic substances.

The difference in solubility of an organic substance in two different immiscible solutions.

To ensure that all of the substance is withdrawn from the original solvent.

The distribution or partition coefficient (KD). Signup and view all the answers

Immiscibility, favorable KD, non-reactive, low boiling point, and easy separation from solute. Signup and view all the answers

Because it is a common solvent and doesn't react with most organic compounds. Signup and view all the answers

Non-polar or slightly polar organic liquids. Signup and view all the answers

Because it is extensively used as an extracting solvent due to its favorable properties. Signup and view all the answers

It increases the polar property of the solution, resulting in a decrease in the solubility of the non-polar compound. Signup and view all the answers

Pentane, hexane, tetra chloromethane, chloroform, benzene, and toluene. Signup and view all the answers

To allow for thorough mixing and contact between the aqueous and organic layers. Signup and view all the answers

It changes color. Signup and view all the answers

To release excess pressure. Signup and view all the answers

By titrating the aqueous layer with sodium thiosulfate. Signup and view all the answers

It allows for the calculation of the percentage extraction (E%). Signup and view all the answers

It helps to increase the solubility of iodine in water. Signup and view all the answers

Extraction is a crucial method for separating and purifying organic substances from natural products like seeds and leaves of plants.
It relies on the difference in solubility of an organic substance in two immiscible solutions, such as water and chloroform.

The process involves finding a solvent (b) that can dissolve the substance (x) and does not mix with the original solvent (a).
The solute is distributed between the two unmixed liquid layers according to the distributive law.
The upper layer is the liquid of lower density, and the lower layer is the liquid of higher density.
Multiple extractions may be necessary to ensure all substance (x) is withdrawn from solvent (a).
The ratio of the concentrations of solute in the two solvents is known as the distribution or partition coefficient (KD).

An extracting solvent should be immiscible, have a favorable KD, not react with other solvents, have a low boiling point, and be easily separated from the solute.

Ether is a commonly used extracting solvent, slightly soluble in water, and its efficiency can be improved by adding a small amount of an ionizable salt to the water layer.
Other low-boiling organic solvents used in this experiment include pentane, hexane, tetra chloromethane, chloroform, benzene, and toluene.

Mix 0.05g of iodine and 1.5g of potassium iodide in a beaker with 50ml water, then add 7.5ml of chloroform.
Shake the mixture well and release excess pressure before allowing the layers to separate.
Note the dissolution of iodine in the organic layer through the color change of the organic layer.
Separate the lower layer (chloroform) slowly, and calculate the E% extraction by titrating the aqueous layer using sodium thiosulfate.