Random
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Benzoic acid to benzaldehyde or benzyl alcohol
Is there a way to make benzaldehyde or benzyl alcohol from benzoic acid? Which other compounds I can synthesize with benzoic acid?
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DJF90
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Yes, but the reagents used are typically more expensive than the products. If you have access to a Parr hydrogenator then perhaps you could
catalytically reduce them. Another option may be electroreduction.
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aliced25
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Hydrogenation, etc. all seem to lead to the cyclohexyl derivatives, the only reagents that will do the job are the hydrides.
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Nicodem
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Thread Moved
5-9-2010 at 08:31 |
Nicodem
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http://www.sciencemadness.org/talk/viewthread.php?tid=2223&a...
And by the way, please open referenceless threads only in the Beginnings section...
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DJF90
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Conditions can be tailored to give the desired product. For complete hydrogenation of the ring a Rhodium/Al2O3, PtO2 (1-3atm, RT) or Raney Nickel
(70-100atm, 70-100*C) catalyst is used. Catalysts based on the oxides of copper, chromium and zinc (e.g. copper chromite) are especially suited to the
hydrogenation of carbon-oxygen bonds, but require high pressures and temperatures to do so (100-300*C, 140-350atm). Benzene rings resist hyrogenation
under these conditions and yields of the alcohol are high to quantitative.
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Random
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It seems hard to do, maybe I could try electro reduction, by the way are there any chemicals I can synthesize out of benzoic acid easily?
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rrkss
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You can make benzoate esters. Look up the fischer esterification reaction.
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Nicodem
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Random, how about UTFSE!
https://www.sciencemadness.org/whisper/viewthread.php?tid=14...
https://www.sciencemadness.org/whisper/viewthread.php?tid=13...
https://www.sciencemadness.org/whisper/viewthread.php?tid=34...
https://www.sciencemadness.org/whisper/viewthread.php?tid=32...
https://www.sciencemadness.org/whisper/viewthread.php?tid=42...
ref. 1-3 in http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0391
etc., etc., ...
Don't you find it a bit absurd to ask which other compounds you can synthesize with benzoic acid, without even bothering describing what
equipment and chemicals you have, and what is your level of experience and knowledge about preparative chemistry? The number of
compounds derivable from benzoic acid is limitless. So instead of randomly posting questions, open topics instead. After all, threads are supposed to
be for topics, while questions can be asked in short questions thread or some other thread on the topic.
Quote: Originally posted by Random  | | It seems hard to do, maybe I could try electro reduction, by the way are there any chemicals I can synthesize out of benzoic acid easily?
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And what is the reference for the electroreduction of benzoic acid?
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zed
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Of course, you can make Benzoic acid into Benzaldehyde. Easier ways to make Benzaldehyde though.
The procedure is called the Rosenmund reduction. And, sometimes it works, though there have been many reported failures.
You simply convert the Benzoic acid into Benzoyl Chloride, then you "sort of" hydrogenate it, by bubbling Hydrogen through a solution containing your
Benzoyl Chloride, and a goodly amount of Palladium on Barium Sulfate catalyst.
http://en.wikipedia.org/wiki/Rosenmund_reduction
[Edited on 7-9-2010 by zed]
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Satan
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http://www.chemistry.or.jp/journals/bcsj/J-STAGE/6801/pdf/68...
http://www.patsnap.com/patents/view/EP0348094A1.html
[Edited on 7-9-2010 by Satan]
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Nicodem
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It is also possible to electroreduce benzoic acids to benzaldehydes if this is being extracted as it forms: J. Org. Chem., 37, 1513–1516.
DOI: 10.1021/jo00975a010
A more general and seminal paper on the electroreduction of carboxylic acids is Chem. Ber., 37 (1904) 3187-3191. DOI:
10.1002/cber.190403703116
Another non-hydride reagent that can reduce carboxylic acids (either to aldehydes or alcohols, depending on the method) is sodium amalgam. These two
describe the reduction to substituted benzaldehydes:
Chem. Ber., 55 (1922) 2664-2674. DOI: 10.1002/cber.19220550839 (reduction stopping at the aldehyde stage appears to be specific for p- and
o-hydroxybenzoic acids)
J. Am. Chem. Soc., 68 (1946) 2502–2504. DOI: 10.1021/ja01216a020 (indicates the addition of toluidine to form a shif base protects the
substrate from further reduction)
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DJF90
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Also don't forget (as I did) the Bouveault-Blanc reduction of esters using Na/EtOH.
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S.C. Wack
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I'd love to see him working with sodium too. Much more fun than Zn(BH4)2 or I/NaBH4.
More on that electroreduction.
DE177490
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Tautomer
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The .docx file posted here has been deleted.
[Edited on 14-7-2017 by Bert]
[Edited on 14-7-2017 by Bert]
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wayne_m
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ZnO as a catalyst
This paper shows ZnO or ZrO to be good catalysts for direct conversion at ~360C in hydrogen gas.
http://chemistry.mdma.ch/hiveboard/picproxie_docs/000208702-...
I am going to try this as soon as I make some ZnO.
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Loptr
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Does it have to be a .docx file? I don't trust what could be lurking behind the scenes as a macro or exploit....
"Question everything generally thought to be obvious." - Dieter Rams
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Loptr
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So how are you planning to contain the hydrogen gas at that temperature? Could you explain a little more about your setup? The ZnO is the easy part...
"Question everything generally thought to be obvious." - Dieter Rams
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wayne_m
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I figured I would use a 3 necked RBF, with a gas adapter in one neck to feed hydrogen into the system. The center neck would feed to a glass tube with
a nichrome wire to keep it at the right temperature (insulated with vermiculite, which is a setup I've used before) and a thermometer probe to monitor
it.
If the setup works, I'll use a still-head with a plug, so I can add more benzoic acid as necessary.
The catalyst tube would be fairly narrow, to allow heating of the vapor to be effected, and have a porous plug of catalyst sponge about halfway along
its length. It would feed into a condenser that would be kept well above the boiling point of benzaldehyde but allow the condensed benzoic acid to
return to the boiling flask through the third neck. The boiling points are 70 degrees apart, so that should be relatively easy.
The benzaldehyde and water would then go to another condenser and land in the receiving flask.
The hydrogen would be produced in a separate apparatus which would serve as the pressure relief. The boiling/condensation apparatus would be a closed
system, with the only vent being the hydrogen inlet. Water pressure from a hoffman type apparatus would maintain a small amount of pressure and serve
as an over-pressure valve. The article says that it is all done at atmospheric pressure, so this should be good enough.
Hydrogen is consumed in the process, so it would need a constant feed.
I have a variable-voltage power supply to handle heating and gas production.
I don't know when I'll have the free time to set up this system, but I did throw together a simple experiment this evening without the hydrogen, and I
did manage to get a couple ccs of liquid that smelled like almonds and phenol. I'm sure I had the catalyst way out of proportion, and contaminated
with some copper from a previous experiment I mixed in that mortar (hence the phenol smell) and the temperature control was non-existent. I also
managed to drop the setup (always remember to tighten your clamps!) and get some of the catalyst into the boiling flask. Plus, my hot plate had some
oil on it from making soap a few days ago, so I got a nice acrolein smell permeating the room.
Just another day in paradise.
The paper mentions reducing the acid all the way to benzene. Even if this doesn't work out, maybe it will be good for that. Heck, even if it does
work, I'll try it for that! I have lots of benzoic acid. (Well, I have lots of sodium benzoate and HCl, which amounts to the same thing.) It sure
beats the sodium benzoate/NaOH in a paint can method!
Incidentally, I'm making the ZnO from a process I read about recently, precipitating it from zinc sulfate with aqueous ammonia. It's supposed to
produce ~30 nm particles. I dropped some zinc into a beaker of sulfuric acid yesterday, and I'm just waiting for it to finish reacting.
https://www.rroij.com/open-access/a-simple-method-for-prepar...
[Edited on 15-7-2017 by wayne_m]
[Edited on 15-7-2017 by wayne_m]
[Edited on 15-7-2017 by wayne_m]
[Edited on 15-7-2017 by wayne_m]
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wayne_m
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The interesting bit about this setup has been figuring out how to recycle any benzoic acid in a closed system.
I don't figure that one pass would get a very high conversion, although I'm doubtful that my flow rate would be very high.
I may have to rethink it and use a heating vessel that can keep it under pressure, so I can adjust my flow rate.
Then I could just use an addition funnel as a collector for the condensed acid. Keeping everything hot will be the new challenge. After the acid level
boils down, close the feed cock, open the funnel cock, and let it flow back into the boiling flask. As it flows, it will drop the temperature and stop
the boiling until it heats up again. I'd have to keep feeding hydrogen enough to purge the system so I don't end up with a bunch of toluene in the
product.
Then I would just have to vent the benzaldehyde collection flask with a pressure regulating valve. I'd lose some hydrogen, but I'd have more control
over flow rate.
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Booze
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| Quote: Originally posted by Random | | It seems hard to do, maybe I could try electro reduction, by the way are there any chemicals I can synthesize out of benzoic acid easily?
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Of course! You can decarboxylate it to phenol (you can do this in a simple distillation setup without the condenser, or use one with hot water, but I
recommend the first one). I'm sure there are many more, but that is the only one I've done recently.
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Booze
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| Quote: Originally posted by Nicodem | Random, how about UTFSE!
https://www.sciencemadness.org/whisper/viewthread.php?tid=14...
https://www.sciencemadness.org/whisper/viewthread.php?tid=13...
https://www.sciencemadness.org/whisper/viewthread.php?tid=34...
https://www.sciencemadness.org/whisper/viewthread.php?tid=32...
https://www.sciencemadness.org/whisper/viewthread.php?tid=42...
ref. 1-3 in http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0391
etc., etc., ...
Don't you find it a bit absurd to ask which other compounds you can synthesize with benzoic acid, without even bothering describing what
equipment and chemicals you have, and what is your level of experience and knowledge about preparative chemistry? The number of
compounds derivable from benzoic acid is limitless. So instead of randomly posting questions, open topics instead. After all, threads are supposed to
be for topics, while questions can be asked in short questions thread or some other thread on the topic.
| Quote: Originally posted by Random | | It seems hard to do, maybe I could try electro reduction, by the way are there any chemicals I can synthesize out of benzoic acid easily?
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And what is the reference for the electroreduction of benzoic acid? |
Can I ask why references are so vastly necessary?
[Edited on 20-7-2017 by Booze]
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Loptr
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It's that whole "standing on the shoulders of giants" thing. Why reinvent the wheel when you can pick up where they left off..
"Question everything generally thought to be obvious." - Dieter Rams
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