Ch. 14 - Ethers, Epoxides, and Thioethers
Wade9th EditionOrganic ChemistryISBN: 9780135213728
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 14, Problem 22
Propose mechanisms for the epoxidation and ring-opening steps of the epoxidation and hydrolysis of trans-but-2-ene shown above. Predict the product of the same reaction with cis-but-2-ene.
Verified step by step guidance1
Step 1: Epoxidation of trans-but-2-ene occurs via reaction with a peracid (e.g., CH₃C(=O)OOH). The peracid transfers an oxygen atom to the double bond of trans-but-2-ene, forming an epoxide. The reaction proceeds through a concerted mechanism where the π-electrons of the double bond attack the electrophilic oxygen of the peracid, while the O-O bond of the peracid breaks and the proton is transferred to the carbonyl oxygen.
Step 2: The epoxide formed from trans-but-2-ene is a three-membered cyclic ether. This intermediate is highly strained and reactive, making it susceptible to ring-opening reactions under acidic conditions.
Step 3: In the ring-opening step, the epoxide reacts with water in the presence of an acid catalyst (H⁺). The acid protonates the oxygen atom of the epoxide, increasing its electrophilicity. Water then attacks one of the carbon atoms of the epoxide, leading to the formation of a diol. The attack occurs in an anti fashion, resulting in the trans addition of hydroxyl groups.
Step 4: For trans-but-2-ene, the product of the reaction is meso-butane-2,3-diol. This is because the anti addition of hydroxyl groups to the trans epoxide leads to a molecule with internal symmetry (meso compound).
Step 5: If cis-but-2-ene undergoes the same reaction, the epoxidation and subsequent ring-opening would result in a racemic mixture of enantiomers (R,R and S,S butane-2,3-diol). This is due to the anti addition of hydroxyl groups to the cis epoxide, which does not have internal symmetry.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
12mWas this helpful?
0