Author Topic: 2,5-dihydroxybenzaldehyde from hydroquinone  (Read 627 times)

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bottleneck

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2,5-dihydroxybenzaldehyde from hydroquinone
« on: March 13, 2003, 02:20:00 PM »
German patent:

Patent DE105798



No yields are mentioned, but it claims hydroquinone does indeed give 2,5-dihydroxybenzyl alcohol when condensed with hydroquinone. Simultaneous oxidation gives 2,5-dihydroxybenzaldehyde ("gentisic aldehyde")

As mentioned in aromatic.aldehyde.synthesis.pdf on Rhodium.ws, these benzyl alcohols can be oxidized in situ. In the above patent, the oxidation seemes to happen by formation of esters of a sulfonic acid and subsequent elimination. The yields of these reactions are noted to be "as high as 85% but averaring only 40-50%."

It would be great if one could just isolate the benzyl alcohol so one could use the DMSO-method of BzOH->BzO mentioned on rhodium.ws. Does anyone know if the alkanol moiety of benzyl alcohols deactivates the aromatic ring to electrophilic attack?

Edit:  No yields are mentioned, but it claims hydroquinone does indeed give 2,5-dihydroxybenzyl alcohol when condensed with FORMALDEHYDE. Simultaneous oxidation gives 2,5-dihydroxybenzaldehyde ("gentisic aldehyde")

Rhodium

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deactivating substituents
« Reply #1 on: March 13, 2003, 09:31:00 PM »
hydroquinone does indeed give 2,5-dihydroxybenzyl alcohol when condensed with hydroquinone.

Review that sentence.

I believe that -CH2OH substituents are slightly deactivating, but not as bad as -CHO substituents are.

bottleneck

  • Guest
Thanks for the information.
« Reply #2 on: March 14, 2003, 01:33:00 PM »
Oh! I meant condesed with formaldehyde :) Jeez.  :-[

Thanks for the information.