Sciencemadness Discussion Board

Synthesis of para hydroxy benzoic acid

Zock4 - 20-9-2016 at 10:42

Hello guys
I plan to synthesize para hydroxy benzoic acid. The wikipedia page says that it is as easy as heating potassium salicylate and potassium carbonate to about 240 degrees C and then add acid. But how long do I need to heat it and how do I clean the PHB from the salicylic acid ?
Tips are very welcome.

Greetings

Maroboduus - 20-9-2016 at 11:39

Try clicking on the reference for that reaction at the bottom of the wikipedia page. It is linked to the write-up for that procedure.
Looks like an interesting site that link is on. I'll have to check it out further.

EDIT: I'd put an air condenser on that flask to catch the phenol. never know when a little phenol might come in handy.

[Edited on 20-9-2016 by Maroboduus]

arkoma - 20-9-2016 at 12:20

@Maroboduus--I NEVER think about those links. Thanx, and it does indeed look like an interesting procedure and is definitely within the reach of amateurs

Maroboduus - 20-9-2016 at 14:57

Well, most of them are either dead or useless (at least the links to books), but it's easy to check and sometimes you hit pay-dirt!
I'll forgo any reference to glory-holes lest my gold mining metaphor be misinterpreted.

I too found it interesting. Mostly because I'm drawing a complete blank on what the reaction mechanism is.
I obviously need to review my O-chem texts. It's been a long time.