Question 1

Which reagent is commonly used to convert an alkene into an epoxide, as shown in the synthesis of cyclohexene oxide from cyclohexene?

Accepted Answer

$$m-$$CPBA (meta-chloroperoxybenzoic acid)

Question 2

What is the product and its name when propene is treated with a peracid ($$[O]$$)?

Accepted Answer

Propylene oxide

Question 3

Why does propylene oxide react with aqueous $$NaOH to $$give a diol, while tetrahydrofuran does not react under the same conditions?

Accepted Answer

Epoxides are more reactive due to ring strain, making them more susceptible to nucleophilic attack.

Question 4

Which of the following best explains the increased reactivity of epoxides compared to other ethers?

Accepted Answer

Epoxides have significant ring strain due to their three-membered ring structure.

Question 5

When a bromoalcohol (bromohydrin) is treated with $$K_2CO_3$$, what type of reaction occurs to form an epoxide?

Accepted Answer

An intramolecular $$S_N2$$ reaction

Question 6

Which of the following epoxides contains a stereogenic (chiral) carbon center?

Accepted Answer

The epoxide with a hydroxyl group attached to one of the ring carbons

Question 7

What effect does acid ($$H_2SO_4) $$have on the C-O bonds of an epoxide?

Accepted Answer

It protonates the oxygen, making the C-O bonds easier to break with nucleophiles.

Question 8

Which reaction will be faster: ring opening of an epoxide with $$H_2O or $$with $$NaOH/H_2O$$? Why?

Accepted Answer

With $$NaOH/H_2O$$, because the hydroxide ion is a stronger nucleophile than water.

Question 9

What is the product when styrene is treated with a peracid ($$[O]$$)?

Accepted Answer

Styrene oxide

Question 10

Which of the following best describes the mechanism for the formation of an epoxide from a bromohydrin and $$K_2CO_3$$?

Accepted Answer

The base deprotonates the alcohol, which then attacks the adjacent carbon bearing the bromine, displacing the bromide ion.

Question 11

Which of the following is the correct product when alpha-pinene is treated with a peracid ($$[O]$$)?

Accepted Answer

Alpha-pinene oxide

Question 12

In the Corey-Chaykovsky reaction, what is the role of the sulfur ylide ($$CH_2S(CH_3$)_2^+$$)?

Accepted Answer

It acts as a nucleophile, adding to the carbonyl carbon to form an epoxide.

Question 13

Which of the following statements about the reactivity of epoxides is true?

Accepted Answer

Epoxides are more reactive than ethers due to ring strain.

Question 14

What is the major product when cyclopentene is treated with a peracid ($$[O]$$)?

Accepted Answer

Cyclopentene oxide

Question 15

Which of the following best explains why acid-catalyzed ring opening of epoxides occurs more readily than base-catalyzed ring opening?

Accepted Answer

Protonation of the epoxide oxygen increases the electrophilicity of the carbons, making them more susceptible to nucleophilic attack.

Question 16

Which of the following is a correct statement about the stereochemistry of epoxide formation from alkenes?

Accepted Answer

The reaction is stereospecific: cis-alkenes give cis-epoxides, and trans-alkenes give trans-epoxides.

Question 17

Which of the following is the correct mechanism for the transformation of a vicinal bromohydrin to an epoxide using $$K_2CO_3$$?

Accepted Answer

Deprotonation of the alcohol followed by intramolecular $$S_N2$$ displacement of bromide.

Question 18

Which of the following best describes the product of the reaction between a ketone and a sulfur ylide ($$CH_2S(CH_3$)_2^+) in $$the Corey-Chaykovsky reaction?

Accepted Answer

An epoxide

Question 19

Which of the following is a correct statement about the ring-opening reaction of epoxides with nucleophiles?

Accepted Answer

The nucleophile attacks the less substituted carbon in basic conditions.

Epoxide Chemistry: Synthesis, Reactivity, and Mechanisms

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