Textbook Question
Do the equilibria of the following acid–base reactions lie to the right or the left? (The pKa of H2O2 is 11.6.)
HOOH + HO− ⇌ HOO− + H2O
RC☰CH + HOO− ⇌ RC☰C− + HOOH
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Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis
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. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblem 49c
Bruice 8th EditionCh. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblem 49cChapter 8, Problem 49c
What stereoisomers are obtained when 2-butyne undergoes each of the following reaction sequences?
c. 1. Cl2/CH2Cl2 2. Br2/CH2Cl2
Verified step by step guidance1
Step 1: Understand the starting material and the reaction conditions. The starting material is 2-butyne, which is an alkyne with a triple bond between the second and third carbons. The reaction involves two halogenation steps: first with Cl2 in CH2Cl2, and then with Br2 in CH2Cl2.
Step 2: Analyze the first reaction (Cl2/CH2Cl2). When 2-butyne reacts with Cl2 in an inert solvent like CH2Cl2, the triple bond undergoes electrophilic addition. The first equivalent of Cl2 adds across the triple bond, forming a trans-dichloroalkene as the major product due to anti-addition.
Step 3: Consider the second reaction (Br2/CH2Cl2). The trans-dichloroalkene formed in the first step reacts with Br2 in CH2Cl2. This reaction is also an electrophilic addition, where Br2 adds across the double bond. The addition occurs in an anti-fashion, leading to the formation of a tetrahalogenated product.
Step 4: Determine the stereochemistry of the final product. Since both halogenation steps proceed via anti-addition, the final product will have specific stereochemistry. The relative positions of the chlorine and bromine atoms on the carbon chain will depend on the anti-addition mechanism.
Step 5: Summarize the stereoisomers. The final product will be a tetrahalogenated compound with two chlorines and two bromines. The stereoisomers will depend on the anti-addition in both steps, leading to a specific arrangement of the halogen atoms on the carbon chain.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Stereoisomerism
Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of those atoms. This can lead to different physical and chemical properties. In the case of alkenes and alkynes, stereoisomers can include cis-trans isomers and enantiomers, which are crucial for understanding the outcomes of reactions involving these compounds.
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Determining when molecules are stereoisomers.
Electrophilic Addition Reactions
Electrophilic addition reactions are a type of reaction where an electrophile reacts with a nucleophile, resulting in the addition of atoms or groups across a double or triple bond. In the context of 2-butyne reacting with Cl2 and Br2, these reactions lead to the formation of vicinal dihalides, which can exhibit stereoisomerism depending on the orientation of the added halogen atoms.
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05:39Features of Addition Mechanisms.
Halogenation of Alkynes
Halogenation of alkynes involves the addition of halogen molecules (like Cl2 or Br2) to the carbon-carbon triple bond, resulting in the formation of alkenes or alkanes with halogen substituents. The stereochemistry of the resulting products can vary based on the reaction conditions and the order of halogen addition, leading to different stereoisomers, which is essential for predicting the outcomes of the given reaction sequence.
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Related Practice
Textbook Question
What stereoisomers are obtained when 2-butyne undergoes each of the following reaction sequences?
a. 1. H2/Lindlar catalyst 2. Br2/CH2Cl2
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Textbook Question
Show how the following compounds can be synthesized starting with ethyne:
b. trans-3-heptene
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Textbook Question
Show how each of the following compounds can be prepared using the given starting material, any needed inorganic reagents, and any organic compound that has no more than four carbons:
a.
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Textbook Question
Show how the following compounds can be synthesized starting with ethyne:
a. cis-2-octene
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Textbook Question
What is each compound's systematic name?
c.
d.
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