Soxhlet Extraction (Lab 4)

Question 1

What is Soxhlet extraction?

Answer 1

An extraction technique used to extract a compound from a solid material.

The analytes dissolve in a solvent that reaches them as temp raises, and the solvent now carrying analytes then condenses into the reservoir.

1) sample is packed in thimble
2) solvent is being heated underneath, on an RBF
3) vapors of solvent raise to the thimble containing the material to be extracted
4) vapors containing the analytes and solvent raise to the condenser and are liquified
5) once liquid reaches overflow level in the thimble, the solvent-analyte solution moves through the siphon and back to the distillation flask.
6) the solvent then evaporates again (leaving the solutes behind) to reach the thimble and repeat the process until extraction is completed.

Question 2

How come once the liquid reaches overflow in the thimble, only the solvent and desired compound go through but not the rest of the compounds?

Answer 2

This selective extraction occurs because the desired compound is more soluble in the solvent and has a higher affinity for it compared to other compounds present in the solid material. As a result, the desired compound is preferentially extracted and collected in the receiving flask while the other compounds remain largely in the solid material.

(Because the rest of the compounds are in the thimble and are solid and not soluble in the solvent, so they can’t leave the thimble. )

Question 3

Why do we use TBME instead of diethyl ether?

Answer 3

Tert-butyl methyl ether (TBME) is often preferred over diethyl ether in Soxhlet extraction for several reasons:

1. Higher boiling point: TBME has a higher boiling point than diethyl ether, which allows for more efficient extraction at higher temperatures without evaporating too quickly.
2. Lower flammability: TBME is less flammable compared to diethyl ether, making it safer to work with, especially in industrial settings where flammability can be a concern.
3. Less prone to peroxide formation: Diethyl ether can form explosive peroxides upon exposure to air and light, which poses a safety risk. TBME is less prone to peroxide formation, reducing the risk of unexpected explosions.
4. Greater solubility: TBME often exhibits greater solubility for a wider range of compounds compared to diethyl ether, allowing for more efficient extraction of target compounds.

Question 4

Why do we use TBME over dichloromethane?

Answer 4

TBME is preferred over dichloromethane in Soxhlet extraction due to its lower toxicity, reduced environmental impact, ease of disposal, and potential compatibility with a wider range of compounds.

Question 5

Curcumin comes in two forms. What are they? Which ones more stable?

Answer 5

Keto and enol. Enol is more stable, but they still are present similar amount of time

Question 6

Solvents, what makes them polar?

Answer 6

The functional groups. That’s why hydrocarbons are non polar and diethyl ether and dichloromethane are polar