quantumcorespacealchemyst
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Benzene from NaOH and Sodium benzoate, in ethanol or methanol. low temperature
I am looking for information on whether the reaction
NaOH + NaC7H6O2 = C6H6 + Na2CO3 can be accomplished with less heating, by using a liquid medium to contact them and dissolve them.
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blogfast25
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Quote: Originally posted by quantumcorespacealchemyst  | I am looking for information on whether the reaction
NaOH + NaC7H6O2 = C6H6 + Na2CO3 can be accomplished with less heating, by using a liquid medium to contact them and dissolve them.
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In short: no.
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quantumcorespacealchemyst
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alright. how though, i want to understand the mechanics please.
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BromicAcid
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Decarboxylations generally take place at elevated temperatures. I once attempted the decarboxylation of benzoic acid in DMSO which itself functions
as a decarboxylation catalyst. However even up to 150C there was no effect.
I would be doubtful of any reaction happening up to the boiling point of EtOH, at least anything noticeable. The fact that the boiling points of EtOH
and Benzene are only about 2C apart does put up a bit of a separation issue. But it seems simple enough, give it a try and report back.
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quantumcorespacealchemyst
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i see. i have attempted the NaOH + Sodium benzoate (dry powders, mixed, dry distillation) and the reaction doesn't seem to have reached a high enough
temperature to allow reaction. i am realizing now the flask is sealed at the neck with PTFE tape and if i reheat later, hot enough, the tape may
decompose.
[Edited on 16-4-2015 by quantumcorespacealchemyst]
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UC235
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Can we keep this garbage in beginnings, please. The decarboxylation necessarily proceeds through a phenyl anion, which is extremely unstable. As a
result, the activation energy is very high and requires high temperatures to proceed at a meaningful rate. The NaOH is present to function as a proton
source that won't evaporate at several hundred Celsius.
IIRC, sodium benzoate in the presence of water in a sealed tube produces benzene almost quantitatively, but this occurs at extremely high temps (and
by necessity, pressure).
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Bert
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Thread Moved
15-4-2015 at 21:14 |
vmelkon
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I don't recommend doing this in glassware but perhaps you don't care about that particular flask.
As for the heat, I assume you are using a hot plate. I recommend a propane torch.
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quantumcorespacealchemyst
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cracked the flask on subsequent retry using only hotplate.
used propane torch on paint thinner can rigged up with bent copper tube.
idk if it was the cool temps outside; slow finicky, poor set up anyway due to gorilla glue bond done wrong and can losing heat.
interesting red liquid obtained as impurity, solidified
better method desired
separated impurity is puzzling and troubling as it seemingly is in the collected benzene.
what about electrochemically?
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blogfast25
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Distil to get rid of the red impurity.
http://www.sciencemadness.org/talk/viewthread.php?tid=325
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aga
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Having once made a small quantity of benzene, what do you use as a bottle to store it in ?
My 15ml escaped overnight, leaving an empty glass vial.
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quantumcorespacealchemyst
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PTFE sheeting cut to fit smooth in/under cap of amber glass bottle.
i store it at 13-22°C (temp range so far noted this year from winter to now). i see if a circle crease forms on the PTFE after setting it into the
cap and tightening the bottle to see if it is even and smooth.
i also have broken a cap or two by overtightening and popping off the top circle from the grip part. mostly it seems better to preseat the PTFE in
the cap and screw the bottle in, checking for the right crease/fit after unscrewing, to set it.
setting the PTFE on the bottle is somewhat like setting it halfway in the cap and many times it stretches and breaks through the sheet when tightening
the cap/bottle.
if using a cap that had the original spacer removed, a replacement may need to be used so the PTFE makes a good seal. i use the crease formation to
gauge if there is enough compression between the cap bottom and bottle rim (and enough hugging from the spacer to form a good mold ). if the
backing/spacer behind the PTFE has some give the PTFE seems to mold alright. usually theres always a decent spacer. sometimes i had to replace one
because i thought it had a food product or something that was uncleanable.
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