Lab Notes 2

Question 1

What is the purpose of liquid-liquid extraction?

Answer 1

technique to separate a desired organic product from a reaction mixture or to isolate an organic substance from its natural source

Question 2

How is liquid-liquid extraction used in this experiment?

Answer 2

separate BEZOIC ACID (weak acid), ETHYL-4-AMINOBENZOATE (weak organic base), & 9-FLUORENONE (neutral organic compound)

Question 3

Once isolated, what is done to organic compounds?

Answer 3

crystallize and check purity with MP

Question 4

What does the mixture of compounds contain?

Answer 4

an organic and aqueous layer after shaking and standing

Question 5

The desired substance is more soluble in

Answer 5

IMMISCIBLE SOLVENT than starting solution

Question 6

inorganic compounds dissolve in — and organic compounds dissolve in —

Answer 6

aqueous phase, organic solvent

Question 7

What is the distribution coefficient equation? What does it mean?

Answer 7

K(D) = [A]org/[A]aq=S(org)/S(aq)

ratio of solubility/conc of amount of a certain solute dissolved in the two solutes at equilibrium

Question 8

Why do we need K(D)?

Answer 8

many organic compounds (aldehydes, alcohols, amines, and esters) are partially soluble in water, aqueous layer, but also in organic = competition between two liquids for solute

Question 9

K(D) < 1?

Answer 9

solute prefers aqueous solvent

Question 10

K(D) > 1?

Answer 10

solute prefers organic solvent

Question 11

What is solubility measured in?

Answer 11

g/mL

Question 12

performing several extractions with smaller volumes of solvent is more – than –

Answer 12

efficient than performing a single extraction

Question 13

for a good extraction, the solvent must be…

Answer 13

1. not react irreversibly
2. immiscible with original solution
3. readily dissolve substance to be extracted
4. extract only desired substance
5. easily separate from solute after extraction

diethyl ether

Question 14

what is the purpose of a separatory funnel?

Answer 14

separate two inniscible liquids

comes with stopper for mixing and stopcock for drainage

Question 15

what is the purpose of the bulge at the top of a separatory funnel?

Answer 15

minimize contamination of the top layer and bottom layer

Question 16

what is an emulsion?

Answer 16

suspension of insoluble droplets of one solvent in the other (oil and vinegar in salad dressing)

Question 17

if you extract the base first, what is in the ether layer? aqueous layer? what reagent?

Answer 17

1. HCL to ether solution
2. either layer has 9-flurenone and benzoic acid
3. aqueous layer has ethyl 4-aminobenzoate
4. add NaOH to aqueous later to extract benzoic acid (9-flureonone in ether layer)