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/sci/ - Science & Math

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5846422 No.5846422 [Reply] [Original]

Any chemfags around?

I've spent the past 3 hours researching it, but everything I come across just glazes over the answer -

Why do weak acids catalyze condensation polymerization? (specifically, step-growth)

The reaction I'm looking at involves glycol and phthalic anhydride catalyzed by sodium acetate. I think I understand the overall mechanism - it seems like the anhydride ring breaks, releasing an O, and the alcohol binds to the broken ring, releasing 2H. I just don't see how the addition of sodium acetate affects this at all.

My first hunch was that it acetate ions pulled H off of water molecules to form acetic acid, driving the reaction forward. Not sure if this fully explains it, though.

Wikipedia mentions that the acetate is protonated, which leads to a further reaction between the acid and the alcohol to form an ester and water - this seems like it would shift the equilibrium towards the reactants, though.

Any thoughts, ideas, or research recommendations?