jack-sparrow
Hazard to Others
Posts: 130
Registered: 30-11-2005
Location: Ask Big Brother
Member Is Offline
Mood: ahoy!
|
|
4-hydroxybenzoic acid synthesis
Hi, I am looking for a good method to synthesize 4-hydroxybenzoic acid.
 Thanx
|
|
|
solo
International Hazard
Posts: 3967
Registered: 9-12-2002
Location: Estados Unidos de La Republica Mexicana
Member Is Offline
Mood: ....getting old and drowning in a sea of knowledge
|
|
You might try looking this up......solo
Selective synthesis of 4-hydroxybenzoic acid with -cyclodextrin as catalyst
Makoto Komiyama *, Hidefumi Hirai
Die Makromolekulare Chemie, Rapid Communications
Volume 2, Issue 11 , Pages 661 - 662,2003
[Edited on 13-4-2006 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
|
|
|
caribou
Harmless
Posts: 29
Registered: 21-2-2006
Member Is Offline
Mood: No Mood
|
|
See also http://www.orgsyn.org/orgsyn/prep.asp?prep=cv2p0341 and references cited therein.
|
|
|
jack-sparrow
Hazard to Others
Posts: 130
Registered: 30-11-2005
Location: Ask Big Brother
Member Is Offline
Mood: ahoy!
|
|
thank you Solo, I will try to get a hand on this paper.
Thank you caribou but I already tried that synthesis.
|
|
|
jack-sparrow
Hazard to Others
Posts: 130
Registered: 30-11-2005
Location: Ask Big Brother
Member Is Offline
Mood: ahoy!
|
|
Hi, I am still struggling to get a good protocol for this prep. If possible, something that gives the para isomer selectively. I plan to do the
reaction on 100 g scale so I dont want to get messed up in the separation of 2 and 4 hydroxybenzoic isomers.
Thank you
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
Check the ' Phenol from Paractemol (Acetominophen) ' thread in Reagents and Apparatus . There I mention the conversion of o-hydroxybenzoic acid
(salicylic) to the para isomer by heating the potassium salt. It is detailed in some old o-chem book or other, don't remember which right now.
You're going to have to do o/p isomer separation at some stage, or just buy the target material. Nothing gives really clean production. In the case
of the o => p acid-K salt, it's prett good conversion. I think that steam distillation can be used to remove the ortho isomer (reuse it); while the
difference isn't as great as with the nitro-phenols it's still there. Crystallisation of the less volatile gives the param, the mother liquor can be
evaporated and recycled.
It helps to run the reaction in a sealed tube, under a couple of atmospheres of CO2 pressure; decarboxylation to phenol is the competing reaction.
If you can get bulk Parabens, you have an ester of the acid.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
