krfkeith
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Chlorobenzene from Benzoic Acid?
So I've been looking for ways to get to chlorobenzene without first making benzene and then chlorinating it. Benzoic acid is fairly easy to come by,
and not nearly as scary as benzene proper.
Now supposedly, benzoic acid can be chlorinated by an aqueous solution of sodium hypochlorite, so bleach. Obviously, since we're trying to make
chlorobenzene, the ortho, meta, or para isomer shouldn't matter. Upon further research, I found that benzoic acid can apparently be reacted with
calcium oxide to make benzene. So, would this reaction also work with chlorinated benzoic acid?
To review, what I'm trying to do is:
C6H5COOH + NaClO (aq) --> C6H5COOHCl + Na2O
C6H5COOHCl + CaO --> C6H5Cl + CaCO3 (?)
Am I totally off base here? On the right track?
Any help is greatly appreciated! Thanks!
[Edited on 24-5-2013 by krfkeith]
[Edited on 24-5-2013 by krfkeith]
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ParadoxChem126
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Here is one way to make chlorobenzene from benzoic acid:
React the benzoic acid with methanol and an acid catalyst to make methyl benzoate. Then react the methyl benzoate with ammonia to make benzamide. Use
bleach and sodium hydroxide to do a Hoffman degredation on the benzamide, forming aniline. React the aniline with nitrous acid (sodium nitrite +
sulfuric acid) to form the benzenediazonium ion. Now react the benzenediazonium with copper chloride to make chlorobenzene.
Technically, benzoyl chloride works better than methyl benzoate, but the thionyl chloride needed to make it from benzoic acid is harder to find than
methanol.
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Nicodem
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Thread Moved
24-5-2013 at 09:17 |
vmelkon
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Quote: Originally posted by krfkeith  |
C6H5COOH + NaClO (aq) --> C6H5COOHCl + Na2O
[Edited on 24-5-2013 by krfkeith]
[Edited on 24-5-2013 by krfkeith] |
Your product doesn't make any sense
C6H5COOHCl
(The chlorine is binding to what atom?)
and also the equation isn't balanced and also you aren't going to get sodium oxide in a aqueuas solution, you get sodium hydroxide instead.
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Boffis
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A paper was posted on another thread about decarboxylation of various benzoic acids including p and m chlorobenzoic acids and they were found to be
fairly resistant to decarboxylation. So while it may be possible it may require very aggressive condition such as calcining the Na salt but as
discussed elsewhere on this forum the production of benzene via this route is not simple and the presence of an extra chlorine increases the risk of
side reactions. Indeed in the paper attached two of the acids generated unidentified carbonyl (benzophenone derivative?) compounds.
So Paradoxchem's suggestion looks like a better route even if much more complex. It may be possible to simplify it using boric acid catalysed amide
formation without going through the acid chloride or the ester. Incidently both analine salts and chlorobenzene crop up on ebay from time to time,
have you had a look recently?
Attachment: Decarboxylation of benzoic acid derivatives & synthesis of Cheng-Hsai Wang.pdf (1.3MB)
This file has been downloaded 1194 times
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bbartlog
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The conditions in the above-referenced paper are pretty mild for this reaction... DSMO boils at 189C. So I wouldn't give up on the decarboxylation
just because it didn't work there.
And paradoxchem's suggestion is ludicrous; 8 or 9 chemicals (not counting solvents you might need at various points) and five steps to get to a
relatively simple compound? Proceeding via benzene would be better than that.
The less you bet, the more you lose when you win.
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S.C. Wack
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I've posted that aniline can be made by the Schmidt reaction or nitromethane and polyphosphoric acid. But if benzene is bad then NaN3 and CH3NO2 (and
aniline) probably are too, and not particularly cost effective.
So good luck with that. Might want to follow beaten paths.
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krfkeith
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I think that I'm just going to go ahead and go through benzene. It isn't that bad after all, as long as you're not stupid.
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ParadoxChem126
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| Quote: Originally posted by bbartlog |
And paradoxchem's suggestion is ludicrous; 8 or 9 chemicals (not counting solvents you might need at various points) and five steps to get to a
relatively simple compound? Proceeding via benzene would be better than that.
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I was trying to give a way to make chlorobenzene without making benzene first, like the author wanted. Also, the author probably wanted to explore
organic chemistry, and my method explored many reactions. Also, the chemicals needed in my method are relatively easy to obtain.
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krfkeith
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Paradoxchem, I appreciated your reply! Thansk!
I had another idea though, what about demethylation of chlorotoluene?
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Random
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| Quote: Originally posted by S.C. Wack | I've posted that aniline can be made by the Schmidt reaction or nitromethane and polyphosphoric acid. But if benzene is bad then NaN3 and CH3NO2 (and
aniline) probably are too, and not particularly cost effective.
So good luck with that. Might want to follow beaten paths. |
Aniline out of nitromethane? Could you elaborate?
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ParadoxChem126
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How do you plan to do that?
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halogen
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http://onlinelibrary.wiley.com/doi/10.1002/chin.200533074/ab...
chlorodecarboxylation, I remember thinking 'you can do that?'
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bbartlog
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This is a variant of the Kochi reaction which is itself considered a variation of the Hunsdiecker decarboxylation.
The less you bet, the more you lose when you win.
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clearly_not_atara
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I'm a little surprised that the simple method didn't get more attention, here. Chlorination of sodium benzoate by sodium hypochlorite in aqueous
solution is about as easy as it gets. I can't imagine chlorinating benzene, which is not water-soluble, with chlorine, a gas, could possibly be
easier, particularly since you then need Lewis acids. The negative charge on benzoate activates it towards chlorination. See e.g.:
https://www.nature.com/articles/131028d0
Wang's paper attached above by Boffis is a method specifically tuned to the electron-deficient carboxylic acids. Indeed, the various toluic
acids gave no yield in this method, while 3-nitrophthalic acid gives a product. Meta-chlorobenzoic acid is not really that electron-deficient, so it
is not surprising that the decarboxylation doesn't take. However, p-chlorobenzoic acid and o-chorobenzoic acid are successfully decarboxylated by
heating in resorcinol:
https://www.journal.csj.jp/doi/pdf/10.1246/bcsj.33.1154
m-chlorobenzoic acid was successfully decarboxylated in high yield by the "standard" method of heating with CuCO3 in quinoline to 250 C, while
2,4-dichlorobenzoic acid required the use of the stronger catalyst Ag2CO3:
https://pubs.acs.org/doi/pdf/10.1021/ac60032a017
Furthermore, a YouTube video I don't feel like watching claims the decarboxylation of sodium chlorobenzoates by simple heating:
https://www.youtube.com/watch?v=2FgNxFey_2U
In fact, even OP's original goal of avoiding any benzene production can be satisfied with a selective decarboxylation in DMSO at 120 C with catalytic
Ag2CO3 (granted expensive / low yield):
https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10....
I fail to see how a method involving a Sandmeyer reaction (exothermic, foamy) could possibly be preferred. Since chlorobenzene is safer than
chloroform, while having similar properties, I think these methods should not be ignored.
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Jenks
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That's a great suggestion. Dichlorination may be an issue so be careful about the amount of bleach added, limiting it to one molar equivalent of
chlorine or slightly over. I like the decarboxylation using copper carbonate - I did not know that was a decarboxylation catalyst - but the solvents
proposed in this thread (resorcinol, quinoline) are crazy. Maybe the decarboxylation would work neat, without solvent, carefully controlling the
temperature and distilling off the chlorobenzene as it forms, as is done with sodium benzoate -> benzene.
Incidentally, I happened to make copper carbonate recently, as my wife who teaches high school was needing a demo. A pre-1983 penny was mostly
dissolved in slightly diluted nitric acid and the copper nitrate was precipitated as the (approximate) copper carbonate using washing soda (sodium
carbonate).
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DraconicAcid
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| Quote: Originally posted by vmelkon | | Quote: Originally posted by krfkeith |
C6H5COOH + NaClO (aq) --> C6H5COOHCl + Na2O
[Edited on 24-5-2013 by krfkeith]
[Edited on 24-5-2013 by krfkeith] |
Your product doesn't make any sense
C6H5COOHCl
(The chlorine is binding to what atom?)
and also the equation isn't balanced and also you aren't going to get sodium oxide in a aqueuas solution, you get sodium hydroxide instead.
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Clearly, the OP means C6H5CO2H + OCl- --> ClC6H4CO2- + H2O
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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SWIM
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| Quote: Originally posted by Jenks | | That's a great suggestion. Dichlorination may be an issue so be careful about the amount of bleach added, limiting it to one molar equivalent of
chlorine or slightly over. I like the decarboxylation using copper carbonate - I did not know that was a decarboxylation catalyst - but the solvents
proposed in this thread (resorcinol, quinoline) are crazy. Maybe the decarboxylation would work neat, without solvent, carefully controlling the
temperature and distilling off the chlorobenzene as it forms, as is done with sodium benzoate -> benzene. |
Benzoate to benzene is generally done by dry distilling with soda-lime.
I get the feeling that doing this might be pretty hard on that chloro group. Especially since its a very high temperature reaction.
Might be
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clearly_not_atara
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There is no hydrolysis of the aryl chloride; however, the carbanion intermediate C6H4Cl- can lose chloride to form a benzyne under simple salt
pyrolysis:
pubs.acs.org/doi/full/10.1021/jp071241x
So lower-temperature catalytic methods are better.
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