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Author: Subject: MeHQ from benzoquinone
Jackson
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[*] posted on 19-2-2019 at 12:20
MeHQ from benzoquinone


Hi, I am looking to synthesize 4-Methoxyphenol from benzoquinone. My question is, Can hydroquinone be replaced with benzoquinone in the reaction? The reaction would be an acidic benzoquinone solution in methanol reacting in a free radical reaction. Would this work at all? I would be able to get hydroquinone, but seeing as I already have benzoquinone, it would be preferable.
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Schleimsäure
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[*] posted on 20-2-2019 at 10:33


In wikipedia it is stated:

4-Methoxyphenol is produced from p-benzoquinone and methanol via a free radical reaction.

However the given sources on that statement only show a start from hydroquinone. In one of these routes p-benzoquinone is used as a catalyst.

See also here:
http://www.sciencemadness.org/talk/viewthread.php?tid=9835

So, my guess as a layman, is no. The double bonds of the oxygens are quite different than the OH-groups of the dihydroxybenzenes.
Somebody more knowledgable than me probably can explain the mechanism.


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Jackson
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[*] posted on 20-2-2019 at 11:07


Yeah, in that thread, the reaction mechanism looks like benzoquinone is the actual thing undergoing the reaction, and it is needed to start the reaction, because the reaction converts hydroquinone to benzoquinone.

C8C6EA38-B478-4B03-80F0-A81279013C8D.gif - 4kB

PS: could other alcohols be used for this purpose like ethanol to get 4-ethoxy phenol instead?

[Edited on 2/20/2019 by Jackson]
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[*] posted on 20-2-2019 at 11:12


Quote: Originally posted by Jackson  


PS: could other alcohols be used for this purpose like ethanol to get 4-ethoxy phenol instead?

[Edited on 2/20/2019 by Jackson]


Probably
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[*] posted on 20-2-2019 at 11:31


Okay, guess I’ll just have to try it and report back
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[*] posted on 24-2-2019 at 13:37


Okay, I have tried it with isopropanol and Benzoquinone.

I added about a gram of Benzoquinone to a beaker and then added 91% percent isopropanol until it all dissolved. Then I added about five ml of 96% sulfuric acid. This was mixed for 24 hours. It was ten neutralized with sodium bicarbonate, which yielded a white precipitate. This was filtered out, and an attempted recrystalization from naphtha was attempted. It didn’t really dissolve so I tried heating. It didn’t dissolve but it did have a melting point within a couple degrees of the theoretical melting point. I think it might be the sodium salt of 4-isopropoxyphenol. I put it into the freezer and it froze into a white chunk on the bottom of the flask. I took it out and put it onto some filter paper to dry.
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[*] posted on 26-2-2019 at 04:08


Quote: Originally posted by Jackson  
It was ten neutralized with sodium bicarbonate, which yielded a white precipitate. This was filtered out, and an attempted recrystalization from naphtha was attempted. It didn’t really dissolve so I tried heating.

Sodium sulfate decahydrate is not soluble in naphtha or similar organic solvents.




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