Chad's Enol rxn...CONFUSED!

[Cofo]

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Or...does the conjugate base of the acid TsO^- ...deprotonate the H from OH...causing the O^- to become double bonded to the carbon again, forming a carbonyl carbon? IDK.....can someone help?

 

[FROGGBUSTER]

The electrons on the -OH actually get kicked down when the carbon of the alkene attacks the Br-Br. This form a C=O-H+, and then OTs- de-protonates it.

You should look up mechanisms for this if you have a textbook. Chad just gives you the quick and dirty on this stuff.

 

[AlbinoPolarBear]

Starting from the keto form, the carbonyl oxygen gets protonated by the TsOH, making it a positively charged carbonyl oxygen.

The conjugate base, TsO-, will then deprotonate an alpha hydrogen, making a double bond, and kicking the carbonyl pi bond to the positively charged oxygen (the oxygen will now be neutral).

This creates the enol form, from which it can react.

The enol oxygen will then regain the carbonyl double bond, therefore kicking the enol double bond, making it a nucleophile to attack the Br2 molecule.

The TsO- in the solution will deprotonate the carbonyl oxygen to make it neutral again.

 

[Cofo]

The electrons on the -OH actually get kicked down when the carbon of the alkene attacks the Br-Br. This form a C=O-H+, and then OTs- de-protonates it.

You should look up mechanisms for this if you have a textbook. Chad just gives you the quick and dirty on this stuff.

Thanks Frog and Albino. I understand it now...haha...I kinda sold my textbook a few weeks ago 👎 dumb move.