[xozebx]

The mechanism for a Dess-Martin oxidation is clearly indicated on the webpage below, but the first step (the displacement of the acetate) has no curved arrows. Can anyone help me as to what the arrows would look like for the first step?

The only thing which comes to mind is that a lone pair on the -OH attacks the I, kicking out an acetate ion, which then grabs the H remaining on the O now bonded to the I to stabilize all the charges. I don't see much of a driving force for this, though.

http://www.organic-chemistry.org/namedreactions/dess-martin-oxidation.shtm

[Squirmy]

Think about an SN1 reaction. Is there a driving force for carbocation formation?

For multi-step mechanisms, all you need is an equilibrium amount of the intermediates and a favorable step at the end to pull it all through.