In TBR Orgo II book it says that hemiketals and hemiacetals can only be formed under basic conditions and not acidic conditions. Can someone please explain this statement to me? We never learned something so absolute in Orgo and when I do google searches I find plenty of examples of acid catalyzed hemiacetal formation. Thanks.
Hemiacetal and Hemiketal
- Thread starter BradyC
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They can be acid catalyzed. Remember that books aren't always 100% right.
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Are you sure it wasn't the acetal or ketal forms they were referring to? Both hemiketal and hemiacetal forms can be produced under either acid or base catalyzed conditions. I think it's the ketal or acetal forms that can be formed only in the presence of strong acid because the hydroxide ion would have to be protonated twice to be a good leaving group and that would require a positive charge which never happens in the presence of a base catalyzed reaction.
I'm a bit rusty on this topic so you might want to get a second opinion.
I'm a bit rusty on this topic so you might want to get a second opinion.
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Many organic reactions can be acid or base catalyzed. Some professors prefer to teach only one method for a variety of reactions due to time constraints in the semester; however, remember that they can occur!
Base catalyzed for your reference below:
Base catalyzed hemiacetal formation (attack of aldehyde by alkoxide, followed by deprotanation of alcohol)
You may not have seen this in your class
Base catalyzed for your reference below:
Base catalyzed hemiacetal formation (attack of aldehyde by alkoxide, followed by deprotanation of alcohol)
You may not have seen this in your class
