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enter image description here

This reaction was on prepchem.com and I want to know whether it could work. Most of their reactions are well sourced but this is rather scant (and can't find the patent referenced). It is possible that it is actually the ether that is relocated, but I can't deduce a mechanism for either reaction despite a lot of searching through papers on all sorts of boron reactions.

There are all sorts of ways that boric acid can complex with oxygen, so I feel like it might just be real, so if there is some boronic dark magic I would love to know.

Someone did claim they could explain it and said:

The OH of the phenol adds into the BOH3, You make BOH4, Which is an ionic, That anion is unstable so it’ll release a OH-, Which then nucleophilic attacks para, Electrons move and you eliminate BOH3, Then you rearomatize

They also drew an image that I linked below but it looks like the boric acid just gains an OH- from somewhere to make tetrahydroxyborate, and the phenolic oxygen somehow loses an electron? IDK it just looks like a + charge symbol next to it? Really confusing exchange.

https://i.sstatic.net/AqzcQ.png

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  • $\begingroup$ I can see the phenol- boric acid cationic complex forming, similar to phenol-BF3, and losing water to give a neutral species, but I cannot see it losing hydroxide ion which in any case would be mopped up by the boric acid present in the reaction mixture. $\endgroup$
    – Waylander
    Commented Feb 24, 2023 at 11:03
  • $\begingroup$ Drop the first 0 in the reference and search for US patent 4013727 (seven digits, not eight). You should be able to see the original patent. $\endgroup$
    – Oscar Lanzi
    Commented Feb 24, 2023 at 13:16

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Prepchem.com apparently misinterpreted what was in the patent.

The abstract of the patent reads:

A process for preparing hydroxyphenyl ethers by oxidizing phenyl ethers with hydrogen peroxide in the presence of a ketone or with a ketone peroxide.

This has nothing to do with rearrangement. Instead we start with a phenyl ether, in this case anisole, and then the oxidation using a peroxide compound (as referenced in the abstract) plus boric acid (mentioned in the body of the patent) yields a mixture of hydroxyl-bearing products. Since the reaction with the peroxide is essentially an electrophilic aromatic substitution and the ether function is activating and ortho/para- directing, we would expect to get a mixture of ortho and para products. Neither product would be expected to rearrange to the other; they both come from the parent ether.

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  • $\begingroup$ Thanks for that! They must have started using an automated system to scrape these, not even close. Certainly an interesting reaction, but several other reactions produce a similar mix of products and I was looking for a way to convert the unused ortho product into the para. Glad to learn about the inaccurate patent number too since I think I have come across similar erroneous numbers before and might be able to use them after all. $\endgroup$
    – TWiz
    Commented Jun 12, 2023 at 19:20

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