FireLion3
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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?
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blogfast25
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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]
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UnintentionalChaos
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| 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.
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FireLion3
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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.
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blogfast25
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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]
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