Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: curiouscat on May 27, 2013, 08:22:24 AM
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I'm investigating an industrial reaction where by reacting with H2O2 + HCl (with heating) one makes .
In terms of byproducts which may I expect? My expectations (partially based on literature searches ) are and and .
But is there anything else that might be major competition? Am I missing any?
Any strategies to minimize these undesired by products.
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I am surprised that aromatic substitution occurs, but I don't know that it does not. The reactions I might expect are further oxidation of the products, the ketone and perhaps the ester. If the ester forms and continued heating under hydrolytic conditions would give phenol. Phenol would be chlorinated or otherwise oxidized. I don't know any of these will occur, just speculation.
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I'm with orgopete, I'd say that over-oxidation is a likely culprit. Benzoic acid?
Not surprised about the aromatic substitution, I think I've seen chlorides + peroxide as a green-chemical chlorinating reagent before. I think with a copper catalyst? Maybe could reduce this if you made sure everything's clean of transition metals.
One other thing; peroxides make radicals, radicals polymerize styrene, or at least cause anti-Markovnikov addition.
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I'm with orgopete, I'd say that over-oxidation is a likely culprit. Benzoic acid?
On further investigation, it seems benzaldehyde was one significant byproduct especially when something goes wrong.
Not surprised about the aromatic substitution, I think I've seen chlorides + peroxide as a green-chemical chlorinating reagent before. I think with a copper catalyst? Maybe could reduce this if you made sure everything's clean of transition metals.
Thanks. I'll see what I can do. Our plan was test batches in a Glass Lined Reactor.
One other thing; peroxides make radicals, radicals polymerize styrene, or at least cause anti-Markovnikov addition.
Yes, especially at 100 C preventing Styrene from polymerizing is going to be challenging.
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Would adding an inhibitor like tert butyl catechol make sense to reduce the undesired self-polymerization?
Or would that be likely to inhibit my desired reaction too? Is the inhibitor action a free radical scavenger? Or....?
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I think that BHT or whatever would probably react with your peroxide directly. I definitely remember running an oxidation of hydroquinone in peroxide at like 70°C...but that was with iodine catalyst. So I guess my answer is, yes, it makes sense to try, but it may not stand up to the peroxide.
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I think that BHT or whatever would probably react with your peroxide directly. I definitely remember running an oxidation of hydroquinone in peroxide at like 70°C...but that was with iodine catalyst. So I guess my answer is, yes, it makes sense to try, but it may not stand up to the peroxide.
Thanks. It's a tricky problem.
Normally styrene is stored below 30 C to avoid polymerization. Especially above 65 C the risk of highly exothermic runaway polymerization is high. And my desired halohydrin formation (based on most patents) is carried from 80 - 100 C.
So essentially I'm operating much above the self-polymerization kickoff temperature.