Ethers and Epoxides: Reactions, Properties, and Synthesis Mechanisms

Ethers and Epoxides: Reactions, Properties, and Applications

1. Boiling Point Difference: Ethanol vs. Dimethyl Ether

Question: Which provides the best explanation for the large boiling point difference between ethanol (b.p. 78 °C) and dimethyl ether (b.p. -25 °C)?

Correct Answer: The difference in hydrogen bonding (H-bonding).

Note: The molecular weight of both ethanol and dimethyl ether is 46. The significant difference in boiling points is due to ethanol's ability to form strong intermolecular hydrogen bonds, which dimethyl ether cannot.

2. Utility of Crown Ethers

Question: Crown ethers are especially useful for:

Correct Answer: Complexing with metal cations.

3. Product of Cyclohexene and Peroxybenzoic Acid

Question: What is the product of the reaction of cyclohexene with peroxybenzoic acid?

Your Answer: Cyclohexene oxide (Correct).

4. Common Fragment in Ether Mass Spectra

Question: Which fragment is most commonly generated in the mass spectra of ethers?

Correct Answer: An oxonium ion.

5. Williamson Ether Synthesis Product

Question: What organic product(s) would result from the reaction of sodium phenoxide with propyl bromide?

Your Answer: Propyl phenyl ether (Correct).

6. Function of NaBH₄ in Alkoxymercuration

Question: In ether synthesis by alkoxymercuration-demercuration, what is the function of the NaBH₄?

Correct Answer: To convert C-HgOAc to C-H (reduction step).

7. Products of Methyl Phenyl Ether Reaction with HBr

Question: What are the products of the reaction of methyl phenyl ether with HBr?

Correct Answer: Phenol and methyl bromide.

8. Definition of Autoxidation

Question: The spontaneous oxidation of a chemical through contact with atmospheric oxygen is known as:

Your Answer: Autoxidation (Correct).

9. Reagent for Norepinephrine to Epinephrine Conversion

Question: In the adrenal glands, which reagent converts norepinephrine into epinephrine (adrenaline)?

Correct Answer: S-adenosylmethionine (SAM).

10. Use of meta-Chloroperoxybenzoic Acid (mCPBA)

Question: meta-Chloroperoxybenzoic acid is useful for converting:

Correct Answer: Alkenes into epoxides (Epoxidation).

11. Reactivity of Epoxides vs. Dialkyl Ethers

Question: Epoxides are considerably more reactive than dialkyl ethers. What factor is responsible for the greater reactivity of epoxides?

Correct Answer: The strain energy of the epoxide's three-membered ring.

12. C-O Bond Cleavage in Epoxides by Bases

Question: Bases will react with epoxides to produce C-O bond cleavage, but alkyl and aryl ethers do not. Which of the following best explains this difference?

Correct Answer: Ring strain in the epoxides.

13. Commonality in Oxirane Ring Opening Mechanisms

Question: What do the opening of an oxirane ring by: 1) a bromonium ion in bromohydrin formation, 2) a mercurinium ion in oxymercuration, and 3) an alcohol in an acid-catalyzed reaction all have in common?

Correct Answer: Nucleophilic attack occurs at the more electrophilic ring carbon.

14. Hardener Compound in Epoxy Glue

Question: What class of compound is most commonly used as a hardener in an epoxy glue?

Correct Answer: A polyamine.

15. Application of Specific Organic Structure

Question: What consumer product utilizes the following organic structure? (Structure implies a diglycidyl ether of bisphenol A precursor.)

Correct Answer: Epoxy glues.

Note: The structure is a member of the class of epoxides (used in epoxy resins).