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Why is Aldehyde more stable, thus more acidic and also is more reactive at the same time?
Aldehyde vs Ketone
- Thread starter Ultimeaciax
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Aldehydes have carbonyl groups at the end of a chain. This means that the carbon also has a hydrogen attached to it. The oxygen is very electronegative, so it "sucks" electron density away from the carbon hydrogen bond. This weakens the carbon hydrogen bond, making them acidic.
Ketones have carbonyl groups in the middle of the chain. There is NO hydrogen attached to the carbon (of the carbonyl). Thus, when the electronegative oxygen draws electron density away from the carbon, the charge is drawen away over the 2 carbon-carbon bonds. These carbons might have hydrogens on them, but the electron density decrease is now spread out over many more carbon hydrogen bonds...making them not as weak and thus less acidic.
Aldehydes' functional group is at the end of the chain making them more accessible for a reaction (such as a nucleophlic attack) as there are less electrons repelling the "attacker" (nucleophile) away.
Ketones have two carbon chain, which mean more electron repelling, less chance of reaction to occur at given temperature.
Ketones have carbonyl groups in the middle of the chain. There is NO hydrogen attached to the carbon (of the carbonyl). Thus, when the electronegative oxygen draws electron density away from the carbon, the charge is drawen away over the 2 carbon-carbon bonds. These carbons might have hydrogens on them, but the electron density decrease is now spread out over many more carbon hydrogen bonds...making them not as weak and thus less acidic.
Aldehydes' functional group is at the end of the chain making them more accessible for a reaction (such as a nucleophlic attack) as there are less electrons repelling the "attacker" (nucleophile) away.
Ketones have two carbon chain, which mean more electron repelling, less chance of reaction to occur at given temperature.
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Thread moved. These types of questions belong in Study Q&A forum.
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Thanks for the response h9i9j9. Very informative. However, with your description, wouldn't that make ketone a more stable compound compared to aldehyde?
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In which context are you refering to "aldehydes are more stable than ketones".
From a nucleophilic substitution perspective, I'm pretty sure an aldehyde is more reactive and thus less stable than a ketone of similar molar mass (due to sterics).
However, aldehydes might be easier reducted, which mean that they are more reactive and less stable than a ketone.
In orgo, context matters.
From a nucleophilic substitution perspective, I'm pretty sure an aldehyde is more reactive and thus less stable than a ketone of similar molar mass (due to sterics).
However, aldehydes might be easier reducted, which mean that they are more reactive and less stable than a ketone.
In orgo, context matters.
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Well I'm studying off EK Orgo now and currently on Aldo Condensation, they stated that aldehyde is more stable, more acidic and also more reactive. So, I guess in a nucleophilic addition, aldehydge is more stable and yet more reactive compared to ketone? This is why I was confused.
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I think aldehydes are more reactive than ketones if it is the electropile.
Btw, how can something be more reactive and more stable? (examples of these are relatively rare...and probably go beyond the scope needed for the mcat.) If you're interested, I think the halogens are the exception to this rule....however, I'm pretty sure aldehydes are not....
Btw, how can something be more reactive and more stable? (examples of these are relatively rare...and probably go beyond the scope needed for the mcat.) If you're interested, I think the halogens are the exception to this rule....however, I'm pretty sure aldehydes are not....
