[DannyBoi]

Hi,

I'm having trouble doing the arrow pushing for this question:




For A, I push one of the two electron pairs on the hydroxy group to an H in H3O and then let the H3O turn to water, but I don't understand how to move the methyl group to the adjacent carbon? Any clarification is appreciated

[MissPhosgene]

For b, can you do alkyl shifts?

[DannyBoi]

Hi again MissPhosgene!

We've not discussed such a concept so I don't think it's an option for this question.

[MissPhosgene]

Oh! Ha, I actually meant a not b. It's really similar to a hydride shift, except an alkyl group moves.

http://science.uvu.edu/ochem/index.php/alphabetical/a-b/12-akyl-shift/

If you google alkyl shift, a bunch of stuff comes up.

[discodermolide]

Hi,

I'm having trouble doing the arrow pushing for this question:




For A, I push one of the two electron pairs on the hydroxy group to an H in H3O and then let the H3O turn to water, but I don't understand how to move the methyl group to the adjacent carbon? Any clarification is appreciated

Try forming a cyclopropyl carbonium ion, which then migrates the methyl group to the adjacent carbon atom

[voidSetup]

I think usually if there is an alkyl/hydride shift you need a carbocation intermediate first. So how could that form once the hydroxy group is protonated?

[discodermolide]

I think usually if there is an alkyl/hydride shift you need a carbocation intermediate first. So how could that form once the hydroxy group is protonated?

a non-classical carbonium ion is formed, causing the elimination of water.

[spirochete]

I think usually if there is an alkyl/hydride shift you need a carbocation intermediate first. So how could that form once the hydroxy group is protonated?

a non-classical carbonium ion is formed, causing the elimination of water.

Please don't confuse the poor kid!  With the questions he's asking we don't need to invoke any fancy non classical conbonium ions, even if they do form.  At the very least we can rationalize everything fine with classical (normal carbocations.

To answer OP's question:  Protonation of a hydroxy group means that water can by pushed out of the molecule as a good leaving group.  Now you have a carbocation that can do all kinds of fun things that you know how to push arrows for.  Just draw hydride or alkyl group shifts, then do an E1 mechanism to give you all those products.