Dissociation in Basic Solution

[deleted92121]

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This question has been racking my brain non-stop.

I am asked to determine which species dissociates to phenyl acetate for a reaction carried out in a basic solution. All the choices are esters themselves. I am given no additional information. I figure using a basic aqueous solution is obvious but WTF?!

Any ideas on how to solve the problem would be grand.

Thanks.

 

[lkthlttr]

This question has been racking my brain non-stop.

I am asked to determine which species dissociates to phenyl acetate for a reaction carried out in a basic solution. All the choices are esters themselves. I am given no additional information. I figure using a basic aqueous solution is obvious but WTF?!

Any ideas on how to solve the problem would be grand.

Thanks.

This makes no sense to me as written. Could you rephrase? Or post the exact question if possible?

 

[deleted92121]

This makes no sense to me as written. Could you rephrase? Or post the exact question if possible?

Exact question phrasing:

"For the reaction carried out in basic solution, which one of the following species dissociates to ethyl acetate"?

I have included a link to the exact question. This is a question in my O-Chem workbook provided by my professor and I am lost as can be.

http://www.cramster.com/answers-jun...ion-carried-basic-solution_1346917.aspx?rec=0

 

[lkthlttr]

Exact question phrasing:

"For the reaction carried out in basic solution, which one of the following species dissociates to ethyl acetate"?

I have included a link to the exact question. This is a question in my O-Chem workbook provided by my professor and I am lost as can be.

http://www.cramster.com/answers-jun...ion-carried-basic-solution_1346917.aspx?rec=0

Ah, that is much clearer! Ok this question is asking which of these 5 compounds will break down in basic solution to give you phenyl acetate. You can fairly assume that in basic solution, that the first step will be deprotonation of the most acidic proton. In each case there is a hydroxyl group, and removal of the proton from this group will be the first step. Then those electrons will form a pi bond with the adjacent carbon (to make a carbonyl) and cause the substituent which is the best leaving group to leave. Then you need to decide which of these resulting compounds is phenyl acetate. The answer then should be clear: number 4 is the only compound which will form phenyl acetate under basic conditions.

 

[deleted92121]

Ah, that is much clearer! Ok this question is asking which of these 5 compounds will break down in basic solution to give you phenyl acetate. You can fairly assume that in basic solution, that the first step will be deprotonation of the most acidic proton. In each case there is a hydroxyl group, and removal of the proton from this group will be the first step. Then those electrons will form a pi bond with the adjacent carbon (to make a carbonyl) and cause the substituent which is the best leaving group to leave. Then you need to decide which of these resulting compounds is phenyl acetate. The answer then should be clear: number 4 is the only compound which will form phenyl acetate under basic conditions.

That was my initial thought but I just could not seem to make it work. Thank you so much for your help.

DU

 

[MedPR]

Doesn't 3 dissociate into phenyl acetate as well?

 

[lkthlttr]

No, for number three the best leaving group would be the (-)OPh because the only other alternative would be (-)CH3 and that is not a good leaving group at all. So after workup you'd get acetone and phenol.