[Discosucks]

Hi guys

We have been asked to design and carry out the synthetic synthesis of paracetamol , with the aim of ending up with 10g of product .

I have found a number of methods and I'v decided to go with the nitration of phenol to make 4-nitrophenol and then the reduction of a nitro group to an amine to make 4-aminophenol and finally recating this with acetic anhydride to make paracetamol

(http://www.ausetute.com.au/paracetamol.html)

Its been a while sense we done any theory or synthesis and I am totally drawing a blank with it comes to working out the start amount of Phenol to end up with 10g of paracetamol .

I know this is such a rookie question but My head is seriously scrambled trying to work out what approach to take .

( im not looking for calculations , i will them once i know what direction to take )

[Borek]

How many moles of paracetamol will be produced per mole of phenol used?

[Discosucks]

0.0066 / 0.0106 = 0.62325 moles I think?

[AWK]

0.0066 / 0.0106

Where these numbers are in your first post?

[Borek]

0.0066 / 0.0106 = 0.62325 moles I think?

What are these numbers?

This is a simple stoichiometry. Stoichiometry is typically based on the reaction equation, so you can write series of reaction equations to do calculations. Or, you can just follow some part of the molecule that doesn't change to get the molar ratio between reactants and products.

[Discosucks]

Ok i'v had a sleep on it haha .

So because they both phenol and the product have a benzene ring , and this means the reaction will be 1:1 ?

Ie 10g of phenol = 10g of paracetamol ?

[Discosucks]

If this wasnt the case im thinking i would have to work backwards from the weight in g of paracetamol i want with the chemical equations?

?g 4-aminophenol = 10g paracetamol

?g 4-nitrophenol = ?g 4-aminophenol

?g phenol = ?g 4-nitrophenol


And im thinking i would do this with balanced equations ?

[Borek]

So because they both phenol and the product have a benzene ring , and this means the reaction will be 1:1 ?

Yes.

Ie 10g of phenol = 10g of paracetamol ?

No.

Have you ever heard about a mole?

[AWK]

?g phenol = ?g 4-nitrophenol

This reaction is very troublesome. Its yield is low.

Overall yield of all reactions starting from phenol may be ~20-30 %

[Discosucks]

So because they both phenol and the product have a benzene ring , and this means the reaction will be 1:1 ?

Yes.

Ie 10g of phenol = 10g of paracetamol ?

No.

Have you ever heard about a mole?

Yes sorry . 1 mole of phenol will give 1 mole of paracetamol.

I need to to convert them both to moles and then work how many moles in phenol will give 10g of product.

I'm actually trying to dig out my first year chemistry notes . I know this is really basic but its been ages sense we did it lol

[Discosucks]

?g phenol = ?g 4-nitrophenol

This reaction is very troublesome. Its yield is low.

Overall yield of all reactions starting from phenol may be ~20-30 %

Really ? That's not good .

Is there a method you would recommend instead?

Thanks 

[AWK]

search google patents

[Discosucks]

Hi again guys .

I got my text book out and got the amounts sorted in the end 

One question .

In the end the lecture said we were to do the synthesis in one step .

So We did the reaction of 4 aminophenol + Ethanoic anhydride = paracetamol .

I used this procedure and adapted it to suit

(http://www.rsc.org/learn-chemistry/content/filerepository/CMP/00/000/047/Paracetamol_web.pdf   on page 14 )    .

The procedure we used told us to do the reaction at room temperature , how ever the other groups in my class were using procedures that stated the reaction should be done under re flux ?

To me the end product looks a lot different from the 4 aminophenol and I'm hopeful that it has worked , its currently drying and we will be testing the end product ( mp and hplc ) in the analytical class next week.

Just wondering if anyone can shed some light on the room temp vs reflux situation?

[AWK]

Hot water easily hydrolyses an ethanoic anhydride if it is added to hot solution. Look at RSC paper how fast is reaction of acetamide formation.

[Discosucks]

so what we did was right?

Was there any need for the others to bother with reflux then?