Destroyer Ochem 2014 question

[dentalduck15]

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I need some help on number 31 regarding the reaction sequence. I see that the first reagentwill oxidize the OH substituent to a double bonded oxygen. the second reagent will remove a methyl from the ketone. What I do not understand is the intermediate that forms between the second and the last reagent, it looks like choice b, where is does the oxygen come from, and why does it have a neg.charge.
Thanks y'all.

 

[dawg289]

I don't know the question, but it sounds like you are referring to the haloform reaction. In the haloform reaction, Cl2, Br2, I2 and excess OH- converts a methyl ketone (R-CO-CH3) to a carboxylate (R-COO-). The mechanism will give an explanation as to why there is a negative charge, but it is not necessary to know for the exam. Just know the reagents, starting reactant and final product.

 

[dentalduck15]

Alright, thanks. I just want to make sure that I am not missing anything.