Where does the O-O-H come from in this hydroboration-oxidation mechanism?

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In summary, the conversation discusses the confusion about the source of O-O-H in the 3rd step of a reaction. The H2O is not used until the last step and the H2O2 has already been used, so it's believed that the other O comes from NaOH when it dissociates into Na+ and OH-. However, this would result in too many electrons. The conversation then clarifies that there is actually more H2O2 available and that the reaction arrow only shows what is being used, not the quantities.
  • #1
Lo.Lee.Ta.
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I cannot for the life of me figure out where the O-O-H comes from that got added in the
3rd step! :confused:

Here's image of the reaction mechanism:

boricacid.jpg


The H2O is not used until the last step and the H2O2 has already been used (except for the H+), so the other O that adds to the OH- to form O-O-H must be coming from the NaOH when it dissociates into Na+ and OH-...
But this would not make sense because we would have an OH- and an O- adding together, and that would be too many electrons! :confused:

Thank you so much! :)
 
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  • #2
There is more of H2O2 from where it came from.
 
  • #3
Oh! Okay! I thought that there could only be one molecule of H2O and H2O2 and NaOH because that is what is shown on the reaction arrow.
But, I guess, that only shows what is being used...not the quantities of each...

Thank you! :)
 

1. What is hydroboration-oxidation and why is it important in chemistry?

Hydroboration-oxidation is a two-step reaction in organic chemistry that involves the addition of a boron atom and an oxygen atom to a carbon-carbon double bond. This reaction is important because it allows for the conversion of alkenes into alcohols, which are important functional groups in many organic compounds.

2. Where does the "O-O-H" group come from in the hydroboration-oxidation mechanism?

The "O-O-H" group comes from the oxidation step of the reaction, where the boron atom is replaced with a hydroxyl group (OH). This hydroxyl group is responsible for the formation of the alcohol product.

3. How does the hydroboration-oxidation mechanism work?

The first step in the mechanism is the addition of boron to the alkene, forming a trialkylborane intermediate. In the second step, the intermediate is oxidized with hydrogen peroxide or an alkyl peroxide to replace the boron atom with an OH group, resulting in the formation of the alcohol product.

4. What are the benefits of using hydroboration-oxidation over other methods for synthesizing alcohols?

One of the main benefits of hydroboration-oxidation is that it is a regioselective reaction, meaning it selectively adds the OH group to the less substituted carbon in the alkene. This allows for the synthesis of specific alcohol products. Additionally, the reaction is mild and does not require harsh conditions, making it a relatively safe and efficient method for alcohol synthesis.

5. Are there any limitations to using hydroboration-oxidation in organic synthesis?

While hydroboration-oxidation is a useful method for synthesizing alcohols, it does have some limitations. It is not effective for synthesizing tertiary alcohols or alcohols with bulky substituents. Additionally, the reaction may not work well for certain types of alkenes, such as those with electron-withdrawing groups.

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