Q: Which reagent combination is used in oxymercuration-demercuration to achieve Markovnikov hydration of an alkene without carbocation rearrangement?

$$\text{Hg(OAc)}_2, \text{H}_2\text{O}$$ \, \text{followed by} \, \text{NaBH}_4$

Q: Why is THF used in hydroboration reactions with diborane ($$\text{B}_2\text{H}_6$$)?

THF stabilizes the borane ($$\text{BH}_3) $$species, preventing its dimerization

Q: Which of the following best describes the regiochemistry of hydroboration-oxidation of alkenes?

Anti-Markovnikov addition of $$\text{OH}$$

Q: What is the role of $$\text{NaBH}_4 in $$the oxymercuration-demercuration reaction?

$$\text{NaBH}_4$$ replaces the mercury group with hydrogen, yielding the alcohol

Q: Which reagent is commonly used for epoxidation of alkenes?

$$\text{mCPBA} ($$meta-chloroperbenzoic acid)

Q: What is the stereochemical outcome when an epoxide is opened by water under acidic conditions?

Anti addition of $$\text{OH}$$ groups

Q: Which reagent combination produces a cis-1,2-diol from an alkene?

$$\text{OsO}_4$$ and $$\text{H}_2\text{O}_2$$

Q: What is the main difference between oxidative cleavage with $$\text{KMnO}_4$$ and ozonolysis?

$$\text{KMnO}_4$$ oxidizes aldehydes to carboxylic acids, ozonolysis does not

Question 1

Which reagent combination is used in oxymercuration-demercuration to achieve Markovnikov hydration of an alkene without carbocation rearrangement?

Accepted Answer

$$	ext{Hg(OAc)}_2, 	ext{H}_2	ext{O}$$ \, 	ext{followed by} \, 	ext{NaBH}_4$

Question 2

What is the stereochemical outcome of the addition step in oxymercuration of alkenes?

Accepted Answer

Anti addition of water across the double bond

Question 3

Which product is formed when 1-methylcyclopentene undergoes hydroboration-oxidation?

Accepted Answer

2-methylcyclopentanol (anti-Markovnikov alcohol)

Question 4

Why is THF used in hydroboration reactions with diborane ($$	ext{B}_2	ext{H}_6$$)?

Accepted Answer

THF stabilizes the borane ($$	ext{BH}_3) $$species, preventing its dimerization

Question 5

Which of the following best describes the regiochemistry of hydroboration-oxidation of alkenes?

Accepted Answer

Anti-Markovnikov addition of $$	ext{OH}$$

Question 6

What is the role of $$	ext{NaBH}_4 in $$the oxymercuration-demercuration reaction?

Accepted Answer

$$	ext{NaBH}_4$$ replaces the mercury group with hydrogen, yielding the alcohol

Question 7

Which reagent is commonly used for epoxidation of alkenes?

Accepted Answer

$$	ext{mCPBA} ($$meta-chloroperbenzoic acid)

Question 8

What is the stereochemical outcome when an epoxide is opened by water under acidic conditions?

Accepted Answer

Anti addition of $$	ext{OH}$$ groups

Question 9

Which reagent combination produces a cis-1,2-diol from an alkene?

Accepted Answer

$$	ext{OsO}_4$$ and $$	ext{H}_2	ext{O}_2$$

Question 10

What is the main difference between oxidative cleavage with $$	ext{KMnO}_4$$ and ozonolysis?

Accepted Answer

$$	ext{KMnO}_4$$ oxidizes aldehydes to carboxylic acids, ozonolysis does not

Question 11

Which catalyst is used for syn hydrogenation of alkenes to alkanes?

Accepted Answer

$$	ext{Pt} or$$ $$	ext{RhCl(PPh}_3)_3 ($$Wilkinson's catalyst)

Question 12

A student wants to convert 3,3-dimethylbut-1-ene to 3,3-dimethylbutan-2-ol. Which method should they use to avoid carbocation rearrangement?

Accepted Answer

Oxymercuration-demercuration

Question 13

Which step in hydroboration-oxidation determines the stereochemistry of the alcohol product?

Accepted Answer

Addition of $$	ext{BH}_3 to $$the alkene (syn addition)

Question 14

Which of the following is NOT a possible outcome of warm, concentrated $$	ext{KMnO}_4$$ oxidation of an alkene?

Accepted Answer

Formation of cis-1,2-diols

Question 15

What is the product of ozonolysis of cyclopentene followed by reduction with dimethyl sulfide?

Accepted Answer

Glutaraldehyde

Question 16

Which mechanism best explains the anti addition observed in the opening of an epoxide ring with water?

Accepted Answer

Stepwise nucleophilic attack at the less substituted carbon, followed by proton transfer

Question 17

Which of the following reactions would be most appropriate to synthesize a cis-1,2-diol from an alkene in a laboratory setting?

Accepted Answer

Hydroxylation with $$	ext{OsO}_4$$ and $$	ext{H}_2	ext{O}_2$$

Question 18

Which of the following statements about the mercurinium ion intermediate in oxymercuration is correct?

Accepted Answer

It is a three-membered ring with mercury, preventing rearrangement

Question 19

In the hydroboration-oxidation mechanism, what is the role of hydroperoxide ($$	ext{H}_2	ext{O}_2$$)?

Accepted Answer

It oxidizes the boron atom, allowing migration of the alkyl group to oxygen

Alkene Reactivity: Controlled Hydration, Dihydroxylation, and Oxidative Cleavage

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