Sciencemadness Discussion Board

SN1, competition reaction of substrate and product to react with base? - Word Problem Help

JefferyH - 12-5-2014 at 10:35

I'm looking at a worksheet right now and this word problem I can't quite seem to figure out.


Quote:
An enolate in the form of its (monohydrate) sodium salt of an active methylene compound (pKa 9) is added to a mixture containing an alkyl bromide. These two substrates can react in an SN1 reaction to form a product that can further react with a base (Sodium Hydroxide) to undergo a dealkylation reaction which results in neutralization of the base. The pKa of the product before dealkylation is roughly 10 pKa. The dealkylation is favored and irreversible.

What will be the major composition of the ending reaction mixture?

Assume this reaction finishes in under 30 minutes.


I would assume that the intermediate acid would neutralize the base far more quickly than it can react with ending product to dealkylate it. BUT I am unsure of whether or not the final product before dealkylation can react with an enolate that is already in the solution, and steal its base away to undergo dealkylation, since they contain similar pKa's. It seems the enolate is mostly deprotonated, meaning it would be relatively neutral as a base, I think.

Perhaps this is a matter of the equilibrium of the enolate? Perhaps the dealkylated product is dependent upon how far to the right of the equilibrium the enolate is? Maybe the more stable the enolate the less dealkylated product there will be?


[Edited on 12-5-2014 by JefferyH]