What is extraction in organic chemistry?
A process to selectively dissolve one or more compounds from a mixture into an appropriate solvent.
What is the extract?
The solution containing the compound(s) dissolved from the original mixture after extraction.
What does immiscible mean?
Two liquids that do not mix and form separate layers
What is washing in extraction?
Removing impurities from a solvent layer by transferring them to another immiscible solvent.
Difference between microscale and macroscale extraction?
Microscale uses small tubes/pipets; macroscale uses separatory funnels. Both rely on the same solubility principles.
Criteria for choosing solvents for extraction
1) Immiscible with each other
How to identify density layers in separatory funnel?
Water is usually the bottom layer unless a dense solvent like dichloromethane is used.
What is an emulsion and common mistake?
Small droplets of one liquid in another; often mistaken as a third layer. Can be resolved with salt
What is salting out?
Adding salts to aqueous layer to decrease solubility of an organic compound
How to assess the extent of an acid-base reaction?
Compare pKa values; stronger acids react with weaker bases to completion.
What is pKa?
The negative logarithm of an acid’s Ka; smaller pKa = stronger acid.
How much acetanilide is used in Lab 4?
0.25–0.35 g
How much p-toluic acid and p-tert-butylphenol?
0.4–0.6 g each
What volume of tert-butyl methyl ether is used?
25 mL
What is done after combining all solids in the ether?
Place the solution into a 125 mL separatory funnel.
How much NaHCO3 is first added to the ether layer?
10 mL
Why do you vent a separatory funnel?
To release CO2 gas generated during reaction and prevent pressure buildup.
How do you confirm water layer identity?
Introduce 1–2 drops of water; if it mixes
What happens if you open the stopcock while the stopper is in?
Creates a vacuum; bottom layer may not drain properly.
How many times is the 10 mL NaHCO3 extraction repeated?
Two more times (3 total).
Why add 5 mL water after NaHCO3 extractions?
To recover any remaining soluble acid in the aqueous layer.
How much NaOH is added to the ether layer?
10 mL
What is done after NaOH extractions?
Add 5 mL water
How is p-toluic acid precipitated?
Add HCl dropwise to the NaHCO3 extract until acidic (pH < 3).
