the alpha hydrogen

[inaccensa]

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So i understand that the carbonyl group is electron withdrawing. Lets assume acetone. Now the hydrogens of both the methyl group attached to the carbonyl are considered alpha correct? Secondly, for the hydrogen, the carbonyl is electron withdrawing and so is the carbon of the methyl group. So the hydrogens are essentially have lets say a partial positive charge. But why do we keep refeering to the hydrogens as acidic, isn't the carbon of the methyl acidic, since it easily gives up the hydrogen?

 

[549]

Yes, both groups are hydrogens will be alpha. Also, hydrogens with a partial positive charge and that are easily lost to electron-rich groups are considered acidic protons. Think of HCl. You wouldn't call the Cl acidic just because it gives up the proton. The hydrogen is acidic, as is the entire HCl molecule.

 

[Hemichordate]

So the more electron withdrawing the carbonyl group, the more acidic the protons?

Also, does having an acidic proton on one side increase the acidity of an alpha hydrogen on the other side (of the carbonyl)?

 

[Omni]

So the more electron withdrawing the carbonyl group, the more acidic the protons?

Also, does having an acidic proton on one side increase the acidity of an alpha hydrogen on the other side (of the carbonyl)?

Electron withdrawing groups will make it more acidic because it will help stabilize the charge. If on one methyl group you have CH3 and the other is CH2Cl, the latter will be more acidic due to the Cl. Since it is electron withdrawing, it will pull the negative charge from the less electronegative carbon and put it on its self, which prefers to have that.

If, on the other hand, you had CH3 vs CH2CH3, the former will be more acidic. This is because the CH3 is an electron donating group, and as a result, in the ethyl group, the CH3 will be pushing its negative charge on an all ready negative atom.