bluamine
Hazard to Others
Posts: 197
Registered: 17-8-2015
Member Is Offline
Mood: No Mood
|
|
Benzene to benzaldehyde conversion
Hi everyone!
I'm studying this reaction that realizes the equation below:
C6H6 +CO + HCl ----CuCl/anh. AlCl3----> C6H5CHO
Now the question is how much pressure is needed to a achive this conversion, and can it be done in the lab?
[Edited on 6-7-2022 by bluamine]
|
|
|
Metacelsus
International Hazard
Posts: 2539
Registered: 26-12-2012
Location: Boston, MA
Member Is Offline
Mood: Double, double, toil and trouble
|
|
This is known as the Gattermann–Koch reaction and can be done at atmospheric pressure. See the attached paper.
But be careful, working with CO sounds like a good way to kill yourself. And benzene isn't very nice either.
Attachment: dilke1949.pdf (817kB)
This file has been downloaded 323 times
|
|
|
bluamine
Hazard to Others
Posts: 197
Registered: 17-8-2015
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Metacelsus  | This is known as the Gattermann–Koch reaction and can be done at atmospheric pressure. See the attached paper.
But be careful, working with CO sounds like a good way to kill yourself. And benzene isn't very nice either.
|
Oh thank you!! I'll check it out
Well yes carbon monoxide is very toxic and benzene is carcinogenic so it must be done outside or in a fumehood, and gloves with mask must be worn.
By the way is there any good way to produce carbon monoxide in the lab other than calcium carbonate/zinc metal reaction?
I had the intention to do this reaction under atmospheric pressure until I've found some claims about doing it under high pressure
[Edited on 8-7-2022 by bluamine]
|
|
|
Keras
National Hazard
Posts: 895
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
| Quote: Originally posted by bluamine |
By the way is there any good way to produce carbon monoxide in the lab other than calcium carbonate/zinc metal reaction?
[Edited on 8-7-2022 by bluamine] |
I wasn’t even aware that gave rise to CO. You can try dehydrating formic acid with concentrated sulphuric acid (or phosphorus pentoxide?):
HCOOH → H₂O + CO. That actually works (with sulphuric acid), as demonstrated by a Chemplayer’s video (that I replicated).
|
|
|
bluamine
Hazard to Others
Posts: 197
Registered: 17-8-2015
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Keras |
I wasn’t even aware that gave rise to CO. You can try dehydrating formic acid with concentrated sulphuric acid (or phosphorus pentoxide?):
HCOOH → H₂O + CO. That actually works (with sulphuric acid), as demonstrated by a Chemplayer’s video (that I replicated).
|
I just don't have any source for formic acid actually but I'm looking forward
It would be interesting though
[Edited on 9-7-2022 by bluamine]
|
|
|
Keras
National Hazard
Posts: 895
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
| Quote: Originally posted by bluamine |
I just don't have any source for formic acid actually but I'm looking forward
It would be interesting though
|
Apparently, that works with oxalic acid, too, which is much more OTC (source: Wikipedia page on CO)
|
|
|
Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
Zn + CO2 = CO + ZnO
ZnC2O4 = CO + CO2 + ZnO 350-500
CaC2O4*H2O, hydrate gone after 170*C
decomposes into CaCO3 + CO at 475*C
further decomposes at 755*C to CaO + CO2
formates does not surprisingly form CO on decomposition and the products depends on if its zinc, lead, lithium formate etc
infact, - sodium formate may be of use
It was shown that after melting at 253°C, sodium formate slowly decomposes by hydrogen loss to Na2CO3, CO and Na2C2O4 at 330°C.
|
|
|
Bonee
Harmless
Posts: 29
Registered: 20-12-2010
Member Is Offline
Mood: No Mood
|
|
Why would you want to work with very carcinogenic benzene? its easy peasy with PTC oxidation of benzyl alcohol with hypochlorite
|
|
|
PellePeloton
Harmless
Posts: 2
Registered: 21-6-2022
Member Is Offline
|
|
| Quote: Originally posted by Bonee | | Why would you want to work with very carcinogenic benzene? its easy peasy with PTC oxidation of benzyl alcohol with hypochlorite
|
Many things are relative. Put in perspective, benzene is not THAT carcinogenic.
Proof? There is still about 1% of benzene in unleaded gasoline (plus 4% other aromatics). So every time someone fills the tank, he sloshes around with
about 500 ml of benzene. No hood, no mask, no big problem.
In a lab, work in a hood.
|
|
|
Texium
Administrator
Posts: 4579
Registered: 11-1-2014
Location: Salt Lake City
Member Is Online
Mood: PhD candidate!
|
|
| Quote: Originally posted by PellePeloton | | Proof? There is still about 1% of benzene in unleaded gasoline (plus 4% other aromatics). So every time someone fills the tank, he sloshes around with
about 500 ml of benzene. No hood, no mask, no big problem. |
And we all know that it's completely harmless to
inhale gasoline fumes /s.
|
|
|
Triflic Acid
Hazard to Others
Posts: 486
Registered: 27-9-2020
Member Is Offline
Mood: Slowly Oxidizing into Oblivion
|
|
If it were really that bad it would be banned. I'm not saying it's safe, but it's not the liquid cyanide it's portrayed as. It's like asbestos. Don't
be stupid and try to drink it, and you're fine.
There wasn't a fire, we just had an uncontrolled rapid oxidation event at the power plant.
|
|
|
Keras
National Hazard
Posts: 895
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
I think like most carcinogenic substances, the major risk comes from daily, or repeated exposure at relatively low, non-alarming levels. IIRC, benzene
in itself is not carcinogenic. But enzymes in the liver oxidise it, and those oxidised products are liable to attack DNA, denature enzymes and cause
other disorders. The same thing happen with paracetamol – the molecule is benign, but one of its metabolites is not. The body attempts to render the
product more soluble by oxidising it, which makes it more polar, but in this it also makes it quite deleterious.
What is surprising, though, is that toluene is not suspected of being even remotely carcinogenic, albeit differing from benzene by only a single
methyl group.
|
|
|
myr
Harmless
Posts: 48
Registered: 18-7-2018
Member Is Offline
|
|
| Quote: Originally posted by Keras | I think like most carcinogenic substances, the major risk comes from daily, or repeated exposure at relatively low, non-alarming levels. IIRC, benzene
in itself is not carcinogenic. But enzymes in the liver oxidise it, and those oxidised products are liable to attack DNA, denature enzymes and cause
other disorders. The same thing happen with paracetamol – the molecule is benign, but one of its metabolites is not. The body attempts to render the
product more soluble by oxidising it, which makes it more polar, but in this it also makes it quite deleterious.
What is surprising, though, is that toluene is not suspected of being even remotely carcinogenic, albeit differing from benzene by only a single
methyl group.
|
My understanding is that it is oxidized directly to benzoic acid, which is then eliminated: the methyl is preferentially attacked, so none of the
reactive aromatic oxidation products are formed
|
|
|
Keras
National Hazard
Posts: 895
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
| Quote: Originally posted by myr |
My understanding is that it is oxidized directly to benzoic acid, which is then eliminated: the methyl is preferentially attacked, so none of the
reactive aromatic oxidation products are formed |
Makes sense. Also, benzoic acid (and other molecules of the same ilk) is metabolised to hippuric acid by reaction with glycine.
|
|
|
bluamine
Hazard to Others
Posts: 197
Registered: 17-8-2015
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Keras | What is surprising, though, is that toluene is not suspected of being even remotely carcinogenic, albeit differing from benzene by only a single
methyl group.
|
What's more surprising is that its derivative TNT is suspected to be carcenogenic
|
|
|
draculic acid69
International Hazard
Posts: 1371
Registered: 2-8-2018
Member Is Offline
|
|
| Quote: Originally posted by bluamine | | Quote: Originally posted by Keras | What is surprising, though, is that toluene is not suspected of being even remotely carcinogenic, albeit differing from benzene by only a single
methyl group.
|
What's more surprising is that its derivative TNT is suspected to be carcenogenic |
Yeah carcinogenic isn't the main problem with tnt.
In fact I'd say it's a minor concern.
|
|
|
Keras
National Hazard
Posts: 895
Registered: 20-8-2018
Location: (48, 2)
Member Is Offline
|
|
I would argue not. –NO₂ containing molecules are now suspected to be carcinogenic, proof being the recent classification of nitrites salts as such
by the EU.
That being said, yeah, I’m not expected to drink or eat TNT anytime soon, so that’s a minor issue to me. :p
|
|
|
unionised
International Hazard
Posts: 5126
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
I'd have thought the easy way to get CO was from CO2 and C; pass the gas over hot charcoal.
It's Friday. Like many other people I will be drinking alcohol this evening, even though it's a known carcinogen.
|
|
|
teodor
National Hazard
Posts: 876
Registered: 28-6-2019
Location: Heerenveen
Member Is Offline
|
|
Depression leads to cancer. Do all experiments in a good mood and don't lose interest in chemistry and Nature. CO is far more dangerous than benzene.
Buy CO detector and place it somewhere in your room, it can alarm you with a loud sound in case of danger. If you like accurate work do everything in
a fume hood a turn it on if you can smell C6H6. If you cannot you are perfectly right with safety.
|
|
|
zed
International Hazard
Posts: 2283
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline
Mood: Semi-repentant Sith Lord
|
|
Lots of better ways to make Benzaldehyde. Oxidation of Benzyl Alcohol or Chlorination of Toluene, are both superior to utilizing CO and HCl.
Though to be fair, Chlorination of Toluene, followed by hydrolysis... produces some very unpleasant intermediates.
|
|
|
Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
i was looking into reactions of ethylbenzene and xylene, xylene can be oxidized into toluic acid which can then be reduced to toluene
toluene may then be oxidized partly into benzaldehyde
there was something about ethylbenzene, acetophenone? i lost track of it but that was also useful
many paint removers contain a mix of xylenes and ethylbenzene so its decently OTC
as for oxidation agents im not sure how to go about it, you might be looking at hot H2CrO4 with the solvent dropped into it carefully, mixing up maybe
3:1 chromic acid and solvent and then heating can make it blow up, very annoying mess.
Na2S2O8 - persulfate maybe, manganate?
lead dioxide can form ozone without falling apart, this could be utilized with a perchlorate solution
|
|
|
bluamine
Hazard to Others
Posts: 197
Registered: 17-8-2015
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Keras |
That being said, yeah, I’m not expected to drink or eat TNT anytime soon, so that’s a minor issue to me. :p |
I'm wondering if it has a similar odor/taste of something common so you may have it in your food but have any ide 
[Edited on 22-7-2022 by bluamine]
|
|
|
bluamine
Hazard to Others
Posts: 197
Registered: 17-8-2015
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by zed | | Lots of better ways to make Benzaldehyde. Oxidation of Benzyl Alcohol or Chlorination of Toluene, are both superior to utilizing CO and HCl.
Though to be fair, Chlorination of Toluene, followed by hydrolysis... produces some very unpleasant intermediates. |
I guess that reaction is like chlorination of methane, give a lot of byproducts...
|
|
|
Texium
|
Thread Moved
28-2-2023 at 07:43 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
