[lrisNil]

The treatment of acetal A with aqueous acid initially produces unstable compound B, which has a band in its IR spectrum at ~1730 cm–1. However, this compound is only stable at very low temperatures. At room temperature, it reacts to form compound C. The IR spectrum of compound C is does NOT have a band between 1600–1800 cm–1.

Suggest reasonable structures for compounds B and C , and use arrows to show the detailed mechanism for the formation of B from A and for the formation of C from B.

Any help appreciated, thank you.

[billnotgatez]

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[OrgXemProf]

1. What do you know about the reaction of acetals with aqueous acid?

2. You may recall that in aqueous solution the open-chain form of glucose is in equilibrium with various hemiacetal structures.

Hope the foregoing proves useful.

[chr147]

I've been doing some work on this question and could use a bit of assistance. I've realized that the acid conditions will remove the protecting group, leaving a ketone. Im thinking that the OH group attached to the molecule will result in an intramolecular reaction, rather than the diol reacting with the carbonyl. Would this be correct logic?

[lrisNil]

When it say "aqueous acid" does that just mean HCl?

So I think I should attack the HCl with the lone pairs on the OH, so that results in OH+ (H2O?!) and Cl-

is that correct, I'm confused..! 

[chr147]

HCl and water, or H3O+

No i think it removes the protecting group instead, thats gonna bring back a carbonyl group.