Base Catalyzed Transesterification

[member232]

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For a base-catalyzed transesterifcation reaction, an OR" group will attack the carbonyl of the ester, forming a tetrahedral intermediate with the substituents O- , OR', OR", and R. The OR' group will be kicked off as the carbonyl reforms.

My question is, how is the OR' group kicked off in the form of -OR' ? Shouldn't a good leaving group be created, so that for example, HOR would be able to leave and allow the reformation of the carbonyl?

How is - OR' the product, and not HOR' ? (I know that in order to have HOR' you would need a work-up and a proton source, but I'm just confused as to how you can get OR' to leave the tetrahedral intermediate without protonating it)

Thanks in advance!

 

[N1st]

Traditionally you do transesterifications by heating with an acid catalyst for this reason.

But since you specify it is basic conditions, things will be deprotonated.