Textbook Question
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (ii) H2, Pd/C, Pb(OAc)2 , CaCO3 (Lindlar's catalyst). If you expect two products, show both.
(c)
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Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
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Mullins 1st EditionCh. 10 - Alkynes: Electrophilic Addition and Redox ReactionsProblem 44f(ix)
Mullins 1st EditionCh. 10 - Alkynes: Electrophilic Addition and Redox ReactionsProblem 44f(ix)Chapter 9, Problem 44f(ix)
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (ix) Br2 (2 equiv.). If you expect two products, show both.
(f) 
Verified step by step guidance1
Step 1: Analyze the structure of the alkyne provided in the image. The molecule contains a terminal alkyne group (-C≡CH) attached to a complex cyclic structure with a nitrogen atom and a ketone functional group.
Step 2: Understand the reaction conditions. The treatment with Br₂ (2 equivalents) indicates that the alkyne will undergo halogenation. In this reaction, bromine molecules will add across the triple bond of the alkyne.
Step 3: Predict the first addition of Br₂. The triple bond will react with one equivalent of Br₂, resulting in the formation of a dibromoalkene intermediate. The bromine atoms will add anti to each other due to the mechanism of halogenation.
Step 4: Predict the second addition of Br₂. The dibromoalkene intermediate will react with the second equivalent of Br₂, leading to the formation of a tetrabromoalkane. The bromine atoms will add across the double bond, resulting in a saturated carbon chain with four bromine atoms.
Step 5: Consider stereochemistry and regioselectivity. Since the alkyne is terminal, the addition of bromine will occur without regioselectivity concerns. The stereochemistry of the final product will depend on the anti-addition mechanism during each step of halogenation.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Alkynes
Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. They are unsaturated compounds and are characterized by the general formula CnH2n-2. The presence of the triple bond significantly influences their reactivity, making them more reactive than alkenes and alkanes. Understanding the structure and reactivity of alkynes is crucial for predicting the products of chemical reactions involving these compounds.
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Alkyne Hydration
Electrophilic Addition Reactions
Electrophilic addition reactions are a key type of reaction for unsaturated hydrocarbons, including alkynes. In these reactions, an electrophile reacts with the nucleophilic π bond of the alkyne, leading to the formation of new σ bonds. When treated with bromine (Br₂), for example, alkynes can undergo addition to form dibrominated products. Recognizing the mechanism of these reactions is essential for predicting the products formed under specific conditions.
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Regioselectivity
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In the case of alkynes reacting with bromine, the addition can occur at different positions, leading to different products. Understanding regioselectivity helps in predicting which isomer will be formed based on the stability of intermediates and the nature of the reactants involved.
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Related Practice
Textbook Question
Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]
(c)
1
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Textbook Question
Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]
(a)
1
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Textbook Question
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (i) H2 , Pd/C; If you expect two products, show both.
(c)
5
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Textbook Question
Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]
(b)
1
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Textbook Question
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (viii) Cl2 (1 equiv.). If you expect two products, show both.
(c)
1
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