Textbook Question
Which of the double bonds in zingiberene, the compound responsible for the aroma of ginger, is most reactive in an electrophilic addition reaction with HBr?
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Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of BenzeneProblem 28b
Bruice 8th EditionCh. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of BenzeneProblem 28bChapter 9, Problem 28b
What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction?
b. 
Verified step by step guidance1
Step 1: Analyze the structure of the starting compound. The molecule contains two double bonds, which are conjugated (alternating single and double bonds). This conjugation can influence the reactivity of the molecule.
Step 2: Identify the reagent used in the reaction. HBr (hydrobromic acid) is a strong acid and provides a source of Br⁻ ions. The reaction will proceed via electrophilic addition to one of the double bonds.
Step 3: Determine the regioselectivity of the reaction. According to Markovnikov's rule, the hydrogen atom from HBr will add to the carbon of the double bond that has more hydrogens, while the bromine atom will add to the carbon with fewer hydrogens.
Step 4: Consider the reaction mechanism. The reaction proceeds through the formation of a carbocation intermediate. The stability of the carbocation will determine which double bond reacts. A more stable carbocation (e.g., tertiary > secondary > primary) will be favored.
Step 5: Predict the product. After the addition of HBr to the most reactive double bond, the bromine atom will be attached to the carbon with fewer hydrogens, and the hydrogen atom will be attached to the carbon with more hydrogens. The remaining double bond will stay intact.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrohalogenation
Hydrohalogenation is a chemical reaction where an alkene reacts with a hydrogen halide (like HBr) to form an alkyl halide. The reaction typically follows Markovnikov's rule, where the hydrogen atom from the hydrogen halide adds to the carbon with the most hydrogen substituents, leading to the more stable carbocation intermediate. This process is crucial for understanding how alkenes can be transformed into more functionalized products.
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General properties of hydrohalogenation.
Markovnikov's Rule
Markovnikov's rule states that in the addition of HX (where X is a halogen) to an asymmetric alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This results in the formation of the more stable carbocation intermediate, which influences the final product distribution. Understanding this rule is essential for predicting the outcome of hydrohalogenation reactions.
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Carbocation Stability
Carbocation stability is a key concept in organic chemistry that refers to the relative stability of positively charged carbon species. Carbocations are stabilized by alkyl groups through hyperconjugation and inductive effects, with tertiary carbocations being the most stable, followed by secondary and primary. The stability of the carbocation formed during hydrohalogenation directly affects the regioselectivity of the reaction and the final product.
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Related Practice
Textbook Question
What is the major product obtained from the addition of HBr to the following compound?
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Textbook Question
What products would be obtained from the reaction of 1,3,5-hexatriene with one equivalent of HBr? Disregard stereoisomers.
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Textbook Question
What is the major product of each of the following reactions, assuming that one equivalent of each reagent is used in each reaction?
b.
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Textbook Question
What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction?
c.
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Textbook Question
What is the major product of each of the following reactions, assuming that one equivalent of each reagent is used in each reaction?
c.
1752
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