Textbook Question
Show how Wittig reactions might be used to synthesize the following compounds. In each case, start with an alkyl halide and a ketone or an aldehyde.
(a) Ph–CH=C(CH3)2
(b) Ph–C(CH3)=CH2
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Ch. 18 - Ketones and Aldehydes
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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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 18, Problem 34b
Predict the major products of the following reactions.
(b) 
Verified step by step guidance1
Step 1: Analyze the reactants and reagents. The starting compound is a cyclohexane ring with an aldehyde (-CHO) group and a hydroxyl (-OH) group attached. The reagent is potassium dichromate (K₂Cr₂O₇) in sulfuric acid (H₂SO₄), which is a strong oxidizing agent.
Step 2: Understand the oxidation process. Potassium dichromate in acidic conditions can oxidize primary alcohols to carboxylic acids and aldehydes to carboxylic acids. Secondary alcohols are oxidized to ketones.
Step 3: Identify the functional groups susceptible to oxidation. In this molecule, the aldehyde group (-CHO) and the hydroxyl group (-OH) are both susceptible to oxidation under these conditions.
Step 4: Predict the oxidation of the aldehyde group. The aldehyde (-CHO) will be oxidized to a carboxylic acid (-COOH) because strong oxidizing agents like K₂Cr₂O₇/H₂SO₄ can fully oxidize aldehydes.
Step 5: Predict the oxidation of the hydroxyl group. The hydroxyl (-OH) group is a primary alcohol and will also be oxidized to a carboxylic acid (-COOH) under these conditions. The final product will have two carboxylic acid groups on the cyclohexane ring.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reaction Mechanisms
Understanding reaction mechanisms is crucial in organic chemistry as they describe the step-by-step process by which reactants transform into products. This includes identifying intermediates, transition states, and the movement of electrons. Familiarity with mechanisms helps predict the outcome of reactions and the stability of products formed.
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Functional Groups
Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Recognizing functional groups allows chemists to predict reactivity and the types of products that can be formed in a reaction. Common functional groups include alcohols, carboxylic acids, and amines, each influencing the reaction pathway.
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Regioselectivity and Stereochemistry
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others, while stereochemistry deals with the spatial arrangement of atoms in molecules. Understanding these concepts is essential for predicting the major products of reactions, as they determine which isomers are formed and their three-dimensional orientation, impacting their chemical properties.
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Related Practice
Textbook Question
Propose a mechanism for both parts of the Wolff–Kishner reduction of cyclohexanone: the formation of the hydrazone, and then the base-catalyzed reduction with evolution of nitrogen gas.
910
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Textbook Question
Predict the major products of the following reactions.
(a)
1027
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Textbook Question
Predict the major products of the following reactions.
(d)
806
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Textbook Question
Predict the major products of the following reactions.
(c)
1162
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Textbook Question
Show how Wittig reactions might be used to synthesize the following compounds. In each case, start with an alkyl halide and a ketone or an aldehyde.
(c) Ph–CH=CH–CH=CH–Ph
(d)
1879
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