Textbook Question
Predict the major products of the following reactions.
a. propene + BH3⋅THF
b. the product from part (a) + H2O2/OH−
10. Addition Reactions
Hydroboration
Problem 61b(vi)
Textbook Question
Predict the product(s) that would result when the alkenes shown here are allowed to react under the following conditions: (vi) 1. BH3 2. H2O2, NaOH
(b) 
Verified step by step guidance1
Step 1: Recognize the reaction type. The given conditions (1. BH₃, 2. H₂O₂, NaOH) indicate hydroboration-oxidation, which is a method for converting alkenes into alcohols.
Step 2: Understand the regioselectivity of hydroboration-oxidation. This reaction follows anti-Markovnikov addition, meaning the hydroxyl group (-OH) will attach to the less substituted carbon of the double bond.
Step 3: Consider the stereochemistry. Hydroboration-oxidation proceeds with syn addition, meaning the hydrogen and hydroxyl group will add to the same face of the alkene.
Step 4: Identify the structure of the starting alkene. Analyze the position of the double bond and determine which carbon is less substituted to predict where the hydroxyl group will attach.
Step 5: Draw the product. After determining the regioselectivity and stereochemistry, sketch the resulting alcohol, ensuring the hydroxyl group is on the less substituted carbon and both groups are added syn to each other.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydroboration-Oxidation
Hydroboration-oxidation is a two-step reaction process used to convert alkenes into alcohols. In the first step, borane (BH₃) adds across the double bond of the alkene, resulting in a trialkylborane intermediate. The second step involves oxidation with hydrogen peroxide (H₂O₂) in the presence of a base (NaOH), which converts the boron atom into a hydroxyl group, yielding an alcohol.
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General properties of hydroboration-oxidation.
Regioselectivity
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In hydroboration, the addition of borane occurs in a syn fashion, favoring the formation of the less substituted alcohol due to the mechanism's anti-Markovnikov nature, where the hydroxyl group ends up on the less substituted carbon of the alkene.
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Stereochemistry
Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the hydroboration-oxidation reaction, the syn addition of borane leads to specific stereochemical outcomes, which can influence the properties and reactivity of the resulting alcohol. Understanding stereochemistry is crucial for predicting the 3D orientation of the product.
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