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Here we have the separating funnel and stopper.The first thing to do is checking that the stopcock is tight
Rotate the stopcock to make sure that it is not too loose
by now you should have set up the ring support on the retort stand
place the separating funnel into the ring and make sure that the tip of it sits inside the receiver conical flask
this important because you need drain out your solution and need not hold on to the conical flask so before you started to do extraction
it'll be good to put a few drops of water inside the separating funnel
you are certain that this funnel is not leaking because the menicus of the water then have just been poured in stay at the same level
pour away the water into the drainage system in your fumehood
remember the you only discard aqueous solution to this drain
Use a glass funnel to channel the liquid in
transfer the methylene chloride into the separating funnel
using a measuring cylinder, measure out the volume of sodium bicarbonate you need for this extraction
the volume used for extraction process is not that critical. here we are using ~12 ml
of the bicarbonate solution
carefully transfer the bicarbonate solution into the same separating funnel
when the last drop
has gone down
swing the funnel slightly
if we see carefully though we're having a colorless solution but actually on a closer look we've 2 separate layers of transparent colorless liquid
that do not mix because at the bottom we have the denser CH2Cl2
and at the top, the less dense bicarbonate solution
now remove the separating funnel from the ring support and apply the stopper
holding the funnel as shown, invert it and vent it into the fumehood as you rotate the stopcock
since organic solvents have low boiling point, some of these org. solvents are converted to gas during shaking
we have to vent it to release the pressure once again you got to vent it INTO the fumehood for safety reasons
after venting, rotate the stopcock to close it. shake the whole flask to mix the 2 phases
and vent it again
do it for a few times
remove the stopper
now hold the separating funnel by the neck and swirl it, allowing the phases to settle
so that you can see a perfect interface, put the final back into the ring support
see the horizon line separating the organic and aqueous layer
notice the 2 phases are separated. now let's swirl it one more time
the system has settled down. you see two distinct layers. At the bottom is CH2Cl2
because of its high Mr/Vol ratio. the top is water - which is less dense
let's start to drain the layers
at the beginning you can turn the stopcock a bit more to allow a greater volume of the liquid to flow down . it will be swifter that way
when you observed that the interface is reaching the stopcock, rotate it
so that we can slow down the liquid flow
control with your fingers
we still see some organic layer near the stopcock
so use our fingers and rotate carefully to allow a small aperture for the last drop to come down
control and stop
so we have the organic part drain out to the bottom
it is a colourless solution and there is no visible water around
make sure that there are no water molecules at all... we are very happy with the current situation
for the top layer, we pour it out into a erlenmeyer flask from the top. this is how we ensure that the 2 layers do not mix again
the bottom layer comes out from the bottom
top layer out from the top
simple as that ... in most circumstances we need to do multiply extraction so that the compound we want separates cleanly
remind yourself that the bottom layer is the organic layer
so transfer the layer back into the separating funnel
you always have to use a glass funnel while transferring
make sure everything goes in
transfer another portion of your clear aq. bicarbonate solution into the measuring cylinder
and pour it, again via a glass funnel, into the same separating funnel
for the stopper back close to shake it
again
layer to settle down quickly
once more
rotate and swirl the flask
so that you are not mixing the two together
watch it ... !
eyes on the meniscus
rotate to allow an aperture for liquid to run down
drop by drop dripping down
and..
watch it!
here it comes!
STOP
here you go
the top layer
is the aqueous layer
so we combine with a previous portion of the aqueous layer
put the funnel back
into the ring support
and then we'll continue to do it one more time
this is the last extraction
for the last extraction we use to clean and dry conical flask to receive the liquid
so once more we drain the bottom layer
swirl it when the meniscus is reaching the stop ***
give it a few seconds for it to settle... sometimes you may need to give it a couple of minutes so ...hold your patience
drop by drop
eyeball the meniscus
eyes on it
ah-hah!
here you go
now we have the organic layer
make sure there is no visible water
we combine with the previous 2 portions
combine them into one entity
and also here in this conical flask there should be a clear solution without any droplets of organic layer
here is the aqueous layer
and the organic layer
may still contain some water
it is not visible... you can't see it.. that is why we need to add some drying agent
typically is sodium sulphate
here we have have the chemical anhydrous sodium sulphate - super hygroscopic !
pour some drying agents
use a spatula to transfer the powder
transfer carefully
add bit by bit
into the conical flask
be careful we add the sodium sulphate to the ORGANIC LAYER not aqueous layer
swirl to allow even mixing
you see that some of the sodium sulphate sticks to the bottom ... it aggregate together because it absorbs the water
look carefully!! it forms small lumps
it means that this solution still contain some water inside
so you'll only stop adding when the sodium sulphate remains as a powder form in the liquid
top up more! swirl
we see the solid at the base can move around, they are not restricted to the bottom
what does that tell you... it is getting dryer .. the sodium sulphate is absorbing almost all the moisture from the organic layer
become clear
so the solid more freely
it's completely dry
no complaints.. let it settle down for few minutes
now we can proceeded to filtration
you should by now know how to fold a fluted filter paper.. if you haven't, go and watch it! it is a very nicely made video :)
Look at how beautifully made this fluted paper (Dr. Hoang --> #skills #pro #practice)
transfer the suspensions
through the filter paper
the fluted filter paper increases the surface area, allowing more liquid to flow down the funnel via gravity.
Leaving a slight gap between the funnel and the conical flask to prevent a vacuum (slow flow rate)
we use a bit more methylene chloride to wash out everyone dissolved compound #leavenomanbehind
no sunctions, only gravity
patience...!
derp
derp
this is good
absolutely dry, transparent liquid
now we need to dry the solvent to retrieve our target compound *watch the video - #rotavap
in this photo you see that there is still some water globules in the methylene chloride ...it is not entirely dried yet
after we have added a spoonful of anhydrous sodium sulfate
see the suspension, not good enough! #abysmal
slightly better, still wet
the conical flask the < shows that the mechanical it is to Woo went
Left is bad ------------------Right is Great!