Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Exploring on September 29, 2011, 04:02:56 PM
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a bit of help.. who is more electrophilic, the carbon (of the carbonyle group obviously) of the benzaldehyde or de carbon of the O=C=O , that is CO2 molecule?
I a finding lots of problems about comparing which is more/less electrophilic/nucleophilic.
thank you very much for your *delete me*!
Edit: All caps removed. This is your first warning, if you type in all caps again you will be temporarily banned. Dan
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All caps titles are highly electrophilic and have been known to react explosively with good Lewis bases.
*ahem* I'll show myself out...
Anyway, it depends on the reaction. CO2 is a stronger Lewis acid than benzaldehyde, so in that sense it is more electrophilic.
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sorry for the caps :-[,
and thnsk for the answer. As fas as I understand carbon dioxide is a weak electrophile... and when comparing aldehydes and ketones, aldehydes are more reactive.
In the presence of the same electrophile, if i have a solution of benzaldehye and I bubble CO2 , i presume I´llhave a mixture of the two reaction products.. CO2+E and E+BzCHO, or it totally depends on the E (electrophile?)?
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sorry for the caps :-[,
and thnsk for the answer. As fas as I understand carbon dioxide is a weak electrophile... and when comparing aldehydes and ketones, aldehydes are more reactive.
In the presence of the same electrophile, if i have a solution of benzaldehye and I bubble CO2 , i presume I´llhave a mixture of the two reaction products.. CO2+E and E+BzCHO, or it totally depends on the E (electrophile?)?
Examine the charges generated when an electrophile is attacked by both types of carbonyl, which cation is more stabilized?
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I think it totally depends on the nucleophile.
if your Nu have protons available to have a proton transfer fron the Nu to the O-
you either can hace a carboxilic acid or a Nu=C-Ar
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Practically speaking, it is easier to do a reaction with benzaldehyde as the electrophile. So for instance if you were bubbling CO2 through a solution of benzaldehyde in ether, and added in a Grignard reagent, you would get mostly the secondary alcohol and not the carboxylic acid. That's largely just because of the low solubility of CO2, though; if you instead added a mixture of dry ice and benzaldehyde, I think you would largely get the carboxylic acid. I'd have to try it to be sure, though; the dry ice would be solid so it would be complicated by that.
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I think it totally depends on the nucleophile.
if your Nu have protons available to have a proton transfer fron the Nu to the O-
you either can hace a carboxilic acid or a Nu=C-Ar
When the pi electrons of the C=O attack the electrophile you end up with a C+-O- as a reaction intermediate. Which of the two structures can assist in stabilizing the C+ in a more efficient fashion?