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Topic: hydroboration-oxidation alkenes  (Read 1601 times)

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Offline xshadow

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hydroboration-oxidation alkenes
« on: May 21, 2016, 03:56:37 PM »
HI!!

I don't understand this step of the reaction:

B(RO)3 + OH- ---> [B(RO)3OH ]-  (2)
[B(RO)3OH ]-  ---> B(RO)2OH + RO-   (this repeated other 2 times)
 

My question is: why OH- can substitute , one by one , the three RO group??

OH- is a better "leaving group" than RO- ... why can't OH- in in the intermediate (2) exit again???
 Thanks
« Last Edit: May 21, 2016, 05:28:02 PM by xshadow »
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Offline Dan

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Re: hydroboration-oxidation alkenes
« Reply #1 on: May 22, 2016, 05:38:44 AM »
Quote from: xshadow on May 21, 2016, 03:56:37 PM
why can't OH- in in the intermediate (2) exit again???

It can. All these reactions are reversible.

The situation is similar to Fisher esterification. Think about Le Chatelier.
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Offline xshadow

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Re: hydroboration-oxidation alkenes
« Reply #2 on: May 22, 2016, 11:34:31 AM »
Quote from: Dan on May 22, 2016, 05:38:44 AM
Quote from: xshadow on May 21, 2016, 03:56:37 PM
why can't OH- in in the intermediate (2) exit again???

It can. All these reactions are reversible.

The situation is similar to Fisher esterification. Think about Le Chatelier.
ah,ok , thanks!

...because my textbook when exlpains  its mechanism   doesn't say that all these reactions are reversible (no Keq value)
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