FireLion3
Hazard to Others
Posts: 218
Registered: 11-1-2014
Member Is Offline
Mood: No Mood
|
|
Benzene from Sodium Benzoate - Dry distillation required? Why?
I was looking at these preps and they all talk about dry distilling benzene from Sodium Benzoate and Hydroxide, but why is a dry distllation required?
Both Sodium Benzoate and Sodium Hydroxide is soluble in water, and benzene is hardly soluble in water. Benzene is less than 1% soluble in water, so
why can this all not be run in a single reaction flask and then phase separated?
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by FireLion3  | | I was looking at these preps and they all talk about dry distilling benzene from Sodium Benzoate and Hydroxide, but why is a dry distllation required?
Both Sodium Benzoate and Sodium Hydroxide is soluble in water, and benzene is hardly soluble in water. Benzene is less than 1% soluble in water, so
why can this all not be run in a single reaction flask and then phase separated? |
It [the decarboxylation] only gets going at temperatures well above the BP of water. Also, I'm not sure a solution of the base, as opposed to molten
base, is alkaline enough to effectuate the decarboxylation.
[Edited on 14-7-2014 by blogfast25]
|
|
|
UnintentionalChaos
International Hazard
Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline
Mood: Nucleophilic
|
|
| Quote: Originally posted by FireLion3 | | I was looking at these preps and they all talk about dry distilling benzene from Sodium Benzoate and Hydroxide, but why is a dry distllation required?
Both Sodium Benzoate and Sodium Hydroxide is soluble in water, and benzene is hardly soluble in water. Benzene is less than 1% soluble in water, so
why can this all not be run in a single reaction flask and then phase separated? |
The reaction doesn't start until several hundred degrees C. The hydroxide is there to serve as a high-temp proton donor. Sodium benzoate in water in a
sealed tube also produces benzene effectively, but you are at the require temps and enormous pressure.
Attachment: 48_2_New York_10-03_0616.pdf (116kB)
This file has been downloaded 448 times
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
|
|
|
FireLion3
Hazard to Others
Posts: 218
Registered: 11-1-2014
Member Is Offline
Mood: No Mood
|
|
That makes sense. I was hoping to make reasonable quantities of Benzene from Benzoate without having to do a dry distillation, but having to distill
would make the process unreasonable to perform. I can purchase Benzene, but the price per liter is so much higher than the Benzoate route.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
The process is not 'unreasonable to perform'. It takes a fairly simple DIY apparatus and some good safety precautions. See higher up in the relevant
sticky thread in 'Organics'.
[Edited on 14-7-2014 by blogfast25]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
