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Hydroboration Oxidation Reaction
Transcript of Hydroboration Oxidation Reaction
Hydroboration Oxidation reaction
A hydroboration-oxidation reaction is an anti-Markovnikov reaction. The hydroxyl group attaches to the less-substituted carbon. The resulting stereochemistry is “syn” meaning the C-H and C-B bonds are formed on the same side of the molecule.
Week 1 Observations
1-octene was added to the round bottom flask through the septum. 1-octene was a clear solution. The reaction was then cooled. Upon the addition of Bh3THF to the round bottom flask there was a small layer of separation that formed between the two compounds. The 1-octene was the upper layer of the solution. The reaction was then removed from the ice bath and allowed to warm to room temperature for 45 minutes while being stirred continuously. Once the compounds reacted the septum was removed and 8 drops of water were added to the reaction. The reaction then started bubbling. The bubbles were the result of the rest of the boron in solution being used by the water. After the reaction was completed there were still two distinct layers of clear solution.
Week 2 Observations
1.2 mL NaOH was added to the reaction flask. The reaction then gained a milky appearance and was off white. Second, 1.2 mL H2O2 was added to the flask. This caused the reaction to bubble and heated the reaction flask. Once the reaction was completed 2 layers had formed; a clear lower layer and a cloudy and bubbly upper layer. The reaction then proceeded to cool as the H2O2 was consumed. The reaction was then left to reflux for an hour. The reaction bubbled slightly while refluxing. After the reflux was complete, 2 distinct layers had formed, both were clear. The top layer was the organic layer. Once the reaction had cooled after reflux then 2 mL of diethyl ether was added. The diethyl ether added to the organic layer and remained clear. The organic and inorganic layers were then separated and left for extraction.
The reaction was found by Herbert C. Brown in the 1950’s. He earned the Nobel Prize in Chemistry in 1979 regarding his efforts regarding the hydroboration reaction. He initially used diborane in the reaction to discover that diborane reacts with ketones and aldehydes, which were hydrolyzed with water to produce alcohols. Diboranes were then considered too rare and he then proceeded to try many different types of boron compounds. One of his coworkers, Dr. B. C. Subba Rao discovered that the borohydride added hydrogen and boron to the carbon-carbon double bond in ethyl oleate and that it could then be oxidized to form an alcohol. The reaction converts alkenes into anti-Markovnikov alcohols.
Uses of 1-octanol:
It is also being examined for its uses in controlling tremors and other neurological tremors. Ethyl alcohol is also useable but it requires higher doses
Step 1: Hydroboration of the alkene
Step 2: The Anti-Markovnikov addition of Boron
Step 3: Hydrogen peroxide donates a pair of electrons
Step 4: rearrangement of the R group to an adjacent oxygen that results in the removal of a hydroxide ion