and then the nucleophile, which is actually neutral in charge, just polar, then adds to the carbocation and ejects a proton of it's own to sustain neutrality?
this would be the case for the acid catalyzed addition of
water to an alkene, but likely a water molecule removes the proton.
The nucleophile couldn't contain a negative ion, because the protons in solution would combine with it, wouldn't they?
a nucleophile can have a negative charge even in a strongly acidic solution, but not in this particular reaction.
But if the nucleophile is attracted to positive charges, why doesn't it react with the readily available protons in the system, forming NuH2+,
maybe it does. maybe it gets protonated and deprotonated
a thousand times a second. but when the deprotonated form
comes in contact with the carbocation and sticks, the next
step of the reaction can take place (this actually happens
very fast compared to the formation of the carbocation).
The rates of some acid catalyzed reactions are very pH
dependent, like an amine with a ketone.
As hypo says, there is an equilibrium factor. As foxy says,
reaction diagrams are usually not literal depictions.
They also almost never represent all the reactions that
are taking place.
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