Paracetamol Hydrolysis question (4-aminophenol)

[Athiril]

Not after a parodinal formula.

I was wondering, how many mol to how many mol it takes for paracetamol to convert to 4-aminophenol, using potassium hydroxide.

edit: and the resulting amount of 4-aminophenol.

[gainer]

It takes 151.17 grams of paracetamol (Tylenol) to make 109.13 grams of 4-aminophenol.

[Athiril]

The important part is how much potassium hydroxide does that take? Is it 1 mol to 1 mol?

If you get less 4-aminophenol than the weight of paracetamol and hydroxide together.. what are the byproducts?

[Alan Johnson]

If you use paracetamol (insoluble) to make p-aminophenol (insoluble) how do you know the reaction has gone to completion and the result is not a mixture of the two?To get round this I make the aminophenolate which is soluble.I use sodium not potassium but the equation can be converted by replacing Na=23 by K=39.The by-products are sodium acetate and water.

C8H9NO2......+.....2NaOH...........->...C6H6NaNO....+C2H3NaO2.....+H2O
Paracetamol..Sodium Hydroxide....->.Sodium Aminophenolate...+...+..
151.17..................80...............->....131.12.......

[Kirk Keyes]

You probably want an excess of NaOH there too to drive the reaction and keep the pH up for the hydrolysis...

[Athiril]

I wanted to come back to this.. what about hydrolysis with HCl?

I want to prepare the dry chemical form.

[Gerald C Koch]

I wanted to come back to this.. what about hydrolysis with HCl?

I want to prepare the dry chemical form.

Do you wish to prepare p-aminophenol or to just prepare a pure form of acetaminophen without the binder?

If it is the former then sulfuric acid would be a better choice since the mixture must be refluxed for about an hour and HCl will produce acid fumes while sulfuric acid will not.

[Athiril]

I find it hard to get H2SO4 here, but now I live a suburb of a capital city I'll give it another go.

I want to prepare dry aminophenol.

Paracetamol without the binder I can do... filter with methylated spirits and dry that methylated spirits of, real pain in the arse to then mortal and pestle it into powder, but it works, but it degrades with reasonably logn exposure to air, the powder itself will discolor over time.

Although I did keep it out on a piece of paper rather than a jar or container.

Wouldn't hyrdolysis with HCl make the aminophenol-hydrochloride form?

[Athiril]

I was just thinking I should be able to do the hydrolysis of paracetamol with NaOH, then precipitate it with HCl, filter and wash with water.. but then what form do I end up with?

[Gerald C Koch]

The hydrolysis works better in acid solution. The mixture must be kept close to the boiling point for about an hour and hydrochloric acid generates some very nasty fumes under these conditions. When the hydrolysis is completed the acid is neutralized with sodium carbonate and pap free base precipitates. This can be converted to the HCl if desired. Add a small amount of sodium sulfite to the carbonate solution to prevent oxidation. I would suggest using a 1M solution of sulfuric acid.

For sulfuric acid can you obtain battery acid as this is dilute sulfuric acid? Should be available in auto parts stores.