Comments on: Hydrates, Hemiacetals, and Acetals

By: James Ashenhurst

James Ashenhurst — Thu, 18 Aug 2022 18:10:35 +0000

In reply to advait. Strong acid is probably protonating the phenol. Don't think phenol forms acetals.

By: James Ashenhurst

James Ashenhurst — Thu, 18 Aug 2022 18:10:03 +0000

In reply to PRAGALATHAN V S. Yes, the phenol oxygen can add to formaldehyde to give a hemiacetal-like structure.

By: PRAGALATHAN V S

PRAGALATHAN V S — Sat, 21 May 2022 10:21:06 +0000

Can phenol and formaldehyde give hemiacetal in basic conditions?

By: Raj Mano

Raj Mano — Thu, 12 May 2022 20:30:21 +0000

I think the spiroketal (Note 8) is formed from the starting ketodiol that should have one CH2- less (totally 9 carbons).

By: James

James — Sat, 10 Jul 2021 15:34:29 +0000

Can hemiacetals and acetals be hydrolysed in alkaline medium?

By: Lakshay Sharma

Lakshay Sharma — Wed, 31 Mar 2021 18:18:15 +0000

In question – 0402 can it be this way
First the Oxygen atom attack the H+ in the medium an leave as an alcohol leaving an sp2 hybrid carbocation species.
Then the ethan-1,2-diol attack that carbon resulting the oxygen to take the pi electrons of the double bonds and become negative which later can form an -OH group due to H+ in the medium
The carbon is still positively charged then gets an intramolecular attack from the other carbonyl oxygen atom
This will give us a product will give a product having a 6 atom heterogenous ring(as it will have an oxygen atom) and the ring will have an hemi-acetal group.
I would be really grateful if you tell me where am I wrong an point out my mistakes
Thank you!!
P.S- I assume in my solution there are too many intermediates in the reaction mechanism which can result in making it less favorable or due to hinderance
If there is more to it please let me know

By: James Ashenhurst

James Ashenhurst — Thu, 25 Feb 2021 16:28:39 +0000

In reply to Madeline DeLosa.

Would need to see the specific example, but generally, if a 5- or 6- membered ring can be formed, you can assume that will happen first.
For example, sugars like glucose have an aldehyde at C-1 and alcohols at the other 5 carbons, and they tend to spend most of their time (99%) as the cyclic hemiacetal. See here:
https://www.masterorganicchemistry.com/2017/07/13/pyranoses-and-furanoses-ring-chain-tautomerism-in-sugars/

By: Madeline DeLosa

Madeline DeLosa — Tue, 23 Feb 2021 23:51:21 +0000

If you have an OH on a carbonyl compound and add alcohol to it in acidic conditions, does it make a difference which OH attacks first? In other words, will the inter or intramolecular reaction proceed first?
Thank you!

By: advait

advait — Tue, 19 Jan 2021 10:34:40 +0000

in reaction of acetone with phenol in presence of conc H2SO4 ,electrophilic addition occurs and acetal do not form why ?

By: Dheeraj

Dheeraj — Sat, 03 Oct 2020 10:32:58 +0000

Can you explain how acetals or hemiacetals get converted to aldehyde in acidic medium.