Organic Chemistry: Ethers and Epoxides – Quiz and Solutions
Question 1: What is the Name of the Following Compound?
Answer Options:
- a. 3-isopropoxy-1-cyclopentene
- b. 3-tert-butoxy-1-cyclopentene
- c. 4-propoxy-1-cyclopentene
- d. 4-isopropoxy-1-cyclopentene
Correct Answer:
d. 4-isopropoxy-1-cyclopentene
Feedback:
The correct name is **4-isopropoxy-1-cyclopentene**. The non-cyclic substituent on the oxygen atom in this ether is an isopropyl group, and it is located at the 4-position of the cyclopentane ring.
Question 2: What is the Name of the Following Compound?
Answer Options:
- a. phenol
- b. anisole
- c. aniline
- d. toluene
Correct Answer:
b. anisole
Feedback:
The correct name is **anisole**. Phenol is Ph-OH, where Ph is a phenyl group (-C6H5). Anisole is a methoxybenzene.
Question 3: Which of the Following Statements is Not True?
Answer Options:
- a. Diethyl ether can be prepared by the acid-catalyzed dehydration of ethanol.
- b. Pentane has a higher boiling point than diethyl ether.
- c. Ethers have a higher dipole moment than alkanes.
- d. The oxygen atom of an ether is sp3 hybridized.
Correct Answer:
b. Pentane has a higher boiling point than diethyl ether.
Feedback:
This statement is not true. Diethyl ether has a higher boiling point than pentane due to stronger intermolecular forces (dipole-dipole interactions) compared to pentane (only van der Waals forces).
Question 4: Which of the Following Syntheses Could be Performed in One Step Under Acidic Conditions?
Answer Options:
- a. diphenyl ether from phenol
- b. diethyl ether from ethanol
- c. diisopropyl ether from isopropanol
- d. di(tert-butyl) ether from tert-butyl alcohol
Correct Answer:
b. diethyl ether from ethanol
Feedback:
Diethyl ether can be synthesized from ethanol in one step under acidic conditions via an acid-catalyzed dehydration reaction.
Question 5: Which of the Following Reactions Provides Anisole in High Yield?
Answer Options:
- a. bromobenzene + sodium methoxide
- b. sodium phenoxide + bromomethane
- c. phenol + sodium methoxide
- d. bromobenzene + bromomethane
Correct Answer:
b. sodium phenoxide + bromomethane
Feedback:
This reaction is an example of the Williamson ether synthesis. Sodium phenoxide reacts with bromomethane in an SN2 reaction to produce anisole.
Question 6: Which of the Following Ethers Cannot be Prepared by a Williamson Ether Synthesis?
Answer Options:
- a. anisole
- b. isopropyl ethyl ether
- c. tert-butyl methyl ether
- d. tert-butyl phenyl ether
Correct Answer:
d. tert-butyl phenyl ether
Feedback:
tert-Butyl phenyl ether cannot be prepared by a Williamson ether synthesis because the tert-butyl group is too sterically hindered to undergo an SN2 reaction.
Question 7: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **2**
- b. **1**
- c. **3**
- d. **4**
Correct Answer:
c. **3**
Feedback:
Alkoxymercuration-demercuration of an alkene results in the Markovnikov addition of an alcohol to form an ether. Compound **3** is the Markovnikov product of this reaction.
Question 8: What are the Major Products Obtained Upon Treatment of Anisole, PhOCH3, with Excess HBr?
Answer Options:
- a. phenol and bromomethane
- b. bromobenzene and methanol
- c. phenol and methanol
- d. bromobenzene and bromomethane
Correct Answer:
a. phenol and bromomethane
Feedback:
Treatment of anisole with excess HBr results in the cleavage of the ether bond, yielding phenol and bromomethane.
Question 9: What are the Major Products Obtained Upon Treatment of tert-Butyl 1-Propyl Ether with Trifluoroacetic Acid?
Answer Options:
- a. methylpropene and propene
- b. tert-butyl alcohol and 1-propanol
- c. methylpropene and 1-propanol
- d. tert-butyl alcohol and propene
Correct Answer:
c. methylpropene and 1-propanol
Feedback:
Treatment of tert-butyl 1-propyl ether with trifluoroacetic acid leads to the formation of methylpropene (via E1 elimination) and 1-propanol.
Question 10: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **1**
- b. **4**
- c. **3**
- d. **2**
Correct Answer:
c. **3**
Feedback:
This reaction is a Claisen rearrangement. The allylic phenyl ether undergoes a [3,3]-sigmatropic rearrangement to form an ortho-allylphenol (compound **3**).
Question 11: What is the Correct Assignment of the Names of the Following Cyclic Ethers?
Answer Options:
- a. **1** = anisole; **2** = epoxybutane; **3** = 1,4-dioxane
- b. **1** = aniline; **2** = 1,4-dioxane; **3** = tetrahydrofuran
- c. **1** = tetrahydrofuran; **2** = 1,4-dioxane; **3** = anisole
- d. **1** = ethylene oxide; **2** = tetrahydrofuran; **3** = 1,4-dioxane
Correct Answer:
d. **1** = ethylene oxide; **2** = tetrahydrofuran; **3** = 1,4-dioxane
Feedback:
The correct names are: **1** – ethylene oxide, **2** – tetrahydrofuran, and **3** – 1,4-dioxane.
Question 12: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. both **2** and **3**
- b. only **3**
- c. only **1**
- d. only **2**
Correct Answer:
b. only **3**
Feedback:
The reaction of an alkene with a peroxyacid (like MCPBA) results in the formation of an epoxide. The stereochemistry of the alkene is retained in the epoxide product. Therefore, the correct answer is **3**.
Question 13: What is the Major Organic Product Obtained from the Following Sequence of Reactions?
Answer Options:
- a. **4**
- b. **2**
- c. **1**
- d. **3**
Correct Answer:
a. **4**
Feedback:
The reaction of an alkene with Br2/H2O forms a bromohydrin. Treatment of the bromohydrin with a base leads to an intramolecular SN2 reaction, forming the epoxide product **4**.
Question 14: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **4**
- b. **2**
- c. **1**
- d. **3**
Correct Answer:
c. **1**
Feedback:
The reaction of an epoxide with aqueous acid results in ring-opening and the formation of a 1,2-diol (also known as a glycol). The correct product is **1**.
Question 15: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **3**
- b. **1**
- c. **2**
- d. **4**
Correct Answer:
a. **3**
Feedback:
The reaction of an epoxide with HCl results in ring-opening and the formation of a chlorohydrin. In this case, the chloride attacks the less substituted carbon of the epoxide, leading to product **3**.
Question 16: What is the Major Organic Product Obtained from the Following Sequence of Reactions?
Answer Options:
- a. **1**
- b. **4**
- c. **2**
- d. **3**
Correct Answer:
a. **1**
Feedback:
The reaction of an alkene with a peroxyacid (like mCPBA) forms an epoxide. Subsequent reaction with a Grignard reagent results in nucleophilic attack at the less substituted carbon of the epoxide, leading to product **1** after an aqueous workup.
Question 17: What Would be the Best Choice of Reagent(s) to Perform the Following Transformation?
Answer Options:
- a. O3; followed by Zn
- b. peroxyacid
- c. OsO4; followed by NaHSO3
- d. H2O, H2SO4
Correct Answer:
b. peroxyacid
Feedback:
Peroxyacids (like mCPBA) are commonly used to convert alkenes to epoxides.
Question 18: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **1**
- b. **4**
- c. **2**
- d. **3**
Correct Answer:
a. **1**
Feedback:
The reaction of an epoxide with a strong nucleophile like methoxide results in ring-opening. The methoxide attacks the less substituted carbon of the epoxide, leading to product **1**.
Question 19: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **4**
- b. **2**
- c. **3**
- d. **1**
Correct Answer:
b. **2**
Feedback:
The reaction of a primary alkyl halide with thiourea followed by hydrolysis with aqueous base yields a thiol. The correct product is **2**.
Question 20: What is the Major Organic Product Obtained from the Following Reaction?
Answer Options:
- a. **3**
- b. **4**
- c. **1**
- d. **2**
Correct Answer:
a. **3**
Feedback:
The reaction of a thiol with a base followed by reaction with an alkyl halide yields a sulfide (also known as a thioether). The correct product is **3**.