Extraction

what happens when there is some ethyl acetate in base?

base cannot precipitate

how do you get rid of ethyl acetate in base?

blow air into the flask that holds the unknown base

extraction

separates on solubility between each component of mixture, separate + isolate individual compounds from a mixture

what does extraction must need

you must have a solvent

two types of extraction

liquid/solid extraction and liquid/liquid extraction

liquid/solid extraction

have solid mixture, add solvent to mixture + extract out compound interested in (extract caffeine from coffee/tea)

in liquid/liquid extraction

the solid is already dissolved in one solvent

u will have:

- original solvent

- extraction solvent

original solvent

initial liquid containing your target compound and impurities (ethyl acetate)

extraction solvent

immiscible liquid added to pull the target compound out of the original solvent through varying solubility

extraction rules

1. So + Sx must be immiscible

2. Sx cannot irreversibly react w/compound trying to extract

3. specificity

4. Sx needs to be easily removed

So + Sx must be immiscible why?

if you have solid mixture in a solvent and you have a second solvent that mixes with it, they will not form two distinct layers and so you won't be able to separate the layers

- separating these two solvents will not separate the solid

Sx cannot irreversibly react w/compound trying to extract why?

you will create a new compound and create more problems to solve

specificity

want extraction solvent to be as specific to compound you are trying to separate out

why specificity?

the more separation techniques performed, the lower the overall yield, you will never recover 100% yield

- want to minimize number of separation techniques to maximize the overall yield

Sx needs to be easily removed why?

not interested in Sx, so want to get rid off it easily

- solid dissolved in liquid --> separate by simple distillation

- want solvent with low boiling point to get rid of it easily

problem with liquid/liquid extraction

rule number 1: So + Sx cannot mix

why is this a problem?

if compound A is soluble in So + Sx does not mix, high likely outcome that compound A will not be soluble in Sx, but we need it to be exclusively soluble in Sx

conditions that affect solubility

temperature, pH, pressure, ionic strength (high salt/low salt)

which conditions will affect solubility in the lab

temperature and ionic strength

does volume affect solubility?

plays a role in solubility, but does not change solubility

do not change pressure in lab bc?

bc we are usually never dealing with closed systems + it is dangerous

dont change temperature?

bc we have liquid/liquid extraction in closed system + physically handling it, not very safe to do that

how does pH affect solubility?

benzyilic acid is soluble in ether + insoluble in water

- but if extract with NaOH can convert benzylic acid into salt that is insoluble in ether + soluble in water

- reverse rxn by neutralizing NaOH with HCl + convert back to benzylic acid, no longer soluble in water, precipitates

why do we shake funnel?

to speed up process and maximize SA contact

if you shake not hard?

not enough SA contact + don't mix well enough, don't get good transfer

if shake too hard?

introduce air into system + emulsions can form (can cause two immisible liquids to blend)

ethyl acetate high/low VP?

high

shaking funnel can cause?

high pressure in funnel bc closed system, thus you have to vent by turning funnal upside down + opening stop cock to let air/pressure out (can explode if no vent!)

water more/less dense than ethyl acetate?

more dense, so will be on bottom + go out of funnel first

put HCl on ice why?

bc adding SA to SB is exothermic reaction

- want to control rxn by cooling it down

check if solution is acidic beforehand bc?

this way you know you are working with HCl

turn vacuum on before pouring liquid?

want good tight seal between paper and funnel

- get paper wet to get even tighter seal

how to get rid of water in ethyl acetate, since it is soluble in EA?

add sodium sulfate to suck water up (hygroscopic solid)

if sodium sulfate clumps means?

still have water in solution, add more sodium sulfate

too much cotton what happens?

will not only stop sodium sulfate but will also stop EA

decant

another way to get rid of water

- carefully pour liquid out of flask to prevent sodlum sulfate from leaving

for distillation, water in on (bottom/top) water out on (bottom/top)

bottom, top

water in on bottom bc?

fills the condensor completely at lower pressure + makes distillation go quicker

theory of extraction

mixture of compounds w/ different polarities, compounds will migrate into solvent that matches polarity of compoundch

changing pH of solution

mixture can become ions by protonation w/acid or deprotonation w/base

ions more/less soluble in aq solutions, so move into aq/organic layer

more, aq

neutral organic compounds is/is not soluble in aq solution, so move into aq/organic layer

is not, organic