February 1, 2023

Synthesis of acetaminophen from 4-aminophenol and acetic anhydride.

Okay so what we’ll need to do is set up a hot plate on the jack and again the idea of the jack is that we could lower any time we need to remove the reaction mixture from in this case our water bath all right so we’re gonna um i filled it the stainless steel bowl with water and what we’re going to do is heat the water around the boiling temperature and we’re

Going to gently stir the reaction make sure once we place it on our 50 milliliter flask we’ll go ahead and clamp it right there and let it sit within the water balance all right so i’m going to take a minute to go away for amino phenol and while we do that we’ll go ahead um and turn on the hot plate for amino phenol is one of our two sorting material all right

So we’re gonna go ahead and weigh around three grams i’m going to use the white paper okay so the experiment calls for using acidic and hydride as one of our two be asians so i’m gonna do is i’m gonna use a transfer pipette a disposable transfer pipet to measure out 3.5 milliliters of acidic anhydride you know what i’m gonna do is go ahead and pour that all

Right and we’re going to dissolve the reaction mixture and water we need eight milliliter of deonized water i could get use the same graduated cylinder since i’m adding water to the same reaction mixture and what you have and the fume hood is the bottle of di water go ahead and fill it to about eight milliliters and if you were in a lab touching the flask the

Flask is actually warm to the touch which tells you the reaction is what exothermic or endothermic if heat is being released reaction is exothermic right so now what we’ll need to do is put it um in the hot water bath by really clamping it on the clamp and we’re gonna add this to a bar to gently stir it okay so now we can take the flask and clamp it and what you

Want to do at this point is to definitely lower the jack so you’re away from the hot water as far as possible and again that clamp is going to hold it right at the neck of the flask and then what you do is you lift the jack back up notice the color of the reaction mixture all right again what we have here is eight milliliter of di water our solvent and then we

Have our two starting material acidic and hydride and four amino phenol think about the mechanism think about what is this you know the limiting reactant okay so now once upon sit in the hot water bath for about about five minutes i’m gonna go ahead and turn off the heat source as well as lower the track basically removing it from the heat source notice the

Stir bar is still on so it turns it off right now so what i’ll do is i’ll take another stir bar and i’ll use that and just a regular server and i’ll use that to remove the stir bar that’s in solution and here we are okay now that we’ve allowed it to cool for some time i’m gonna take it out and and i’ll go ahead and place it on the bench top and then once it

Reaches room temperature i’ll go ahead and put it on the ice bath all right if you take a look you can already see the formation of the crystals right or the product once it reaches room temperature we’ll place it right on the ice stuff okay so keep in mind the reaction is or the formation of the crystals or the products is at equilibrium so you want to make

Sure you allow it to form the product slowly so now that it has reached room temperature we’re gonna go ahead and take the flask and place it all right so we’re going to go ahead and set up the suction filtration we’ll need the three arm or the side arm flask and then i’ll have the two pieces for the blusher finally i’ll need to remember to hold the flask when

You insert the fake rubber tv right and you’re gonna pre-weigh and filter paper or you can also pre-weigh the top part of the buchner puddle along with the filter paper but this time i only weighed the filter paper itself and then we’ll go ahead and clamp it right into the vacuum okay by washing the product with two three milliliter portions of cold di water

We ensure that any remaining acidic anhydride that hasn’t been reacted gets washed away as well all right we’re allowing the crude product to air dry under a vacuum and then we’ll measure the weight of the crude product okay so before we crystallizing the cruise product which has a slightly um a tint of a pink color what we’ll do is um place some of the crude

Product in a capillary melting point tube so that later we can characterize it and all we need to do is really gently tap the capillary tube into the product until it fills about two to three millimeters and then we’ll place it in this hollow tube to allow the product to move from one end of the capillary tube to the other we’re going to be using 50 methanol

In water as our rv crystallization solvent we can go ahead and heat it up okay so now it’s time to recrystallize the crude product so what i’ll do is take the cruise product and place it in a 50 milliliter erlenmeyer flask we’re going to use a minimum amount of hot recrystallization solvent it’ll take about three milliliter of the recrystallization solvent

Per one gram of the crude product for this specific experiment right but it could vary slightly so it’s important to keep that in mind so now we’re going to allow it to cool down on the benchtop okay so now that we’ve flooded on ice for some time take a look we do have the rv crystallized product okay so next we’ll be vacuum filtering the product and washing

It with a few brushes of cold diy water okay so now that we have our recrystallized product we’ll allow it to air dry under a vacuum for about 15 minutes okay so for our tlc um solids what we’re going to use is ethyl acetate two drops of concentrated ammonium hydroxide and it’s actually in a dropper so one two then we’ll place the solvent in a beaker and you

Can swirl it to mix and place the glass up on top notice this is a concentrated solution of ammonium hydroxide so you would need to take care not to breathe it in i’ve placed a few crystals of the recrystallized acetaminophen in acetone and i will use that to spot the product you

Transcribed from video
Synthesis of acetaminophen By Alaa Hashim