Textbook Question
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (iii) Na0 , NH3 (liquid), ―33°C . 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 44c(v)
Mullins 1st EditionCh. 10 - Alkynes: Electrophilic Addition and Redox ReactionsProblem 44c(v)Chapter 9, Problem 44c(v)
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (v) HCl (2 equiv.). If you expect two products, show both.
(c) 
Verified step by step guidance1
Identify the structure of the alkyne provided in the problem. Alkynes are hydrocarbons containing a carbon-carbon triple bond (C≡C). Determine whether the alkyne is terminal (triple bond at the end of the chain) or internal (triple bond within the chain).
Understand the reaction conditions: HCl (2 equivalents). This indicates that the alkyne will undergo two successive electrophilic addition reactions with HCl, where the π-bonds of the triple bond will react with HCl molecules.
In the first step, the π-electrons of the triple bond attack the hydrogen atom of HCl, forming a carbocation intermediate. Use Markovnikov's rule to determine the regioselectivity of the addition: the hydrogen atom will add to the carbon of the triple bond that already has more hydrogens, and the chlorine atom will add to the other carbon.
In the second step, the remaining π-bond of the double bond (formed after the first addition) reacts with another molecule of HCl. Again, apply Markovnikov's rule to determine the placement of the second chlorine atom. This results in a geminal dihalide (both chlorine atoms attached to the same carbon).
If the alkyne is symmetrical, only one product will form. If the alkyne is asymmetrical, two regioisomeric products may form depending on the placement of the substituents around the triple bond. Draw the final product(s) based on the structure of the starting alkyne and the reaction mechanism described.
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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 can undergo various reactions, including addition reactions. The presence of the triple bond makes them more reactive than alkenes and alkanes, allowing them to react with halogens, hydrogen, and acids.
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Electrophilic Addition
Electrophilic addition is a reaction mechanism where an electrophile reacts with a nucleophile, leading to the formation of a more saturated product. In the case of alkynes reacting with HCl, the triple bond acts as a nucleophile, attacking the electrophilic hydrogen in HCl, resulting in the addition of hydrogen and chloride across the triple bond.
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Markovnikov's Rule
Markovnikov's Rule states that when HX (where X is a halogen) adds to an alkene or alkyne, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This rule helps predict the major product in reactions involving unsymmetrical reagents, leading to the formation of more stable carbocations during the reaction.
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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.]
(a)
1083
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Textbook Question
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)
988
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Textbook Question
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (vii) 1. BH3 2. H2O2, NaOH. If you expect two products, show both.
(c)
1048
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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)
788
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Textbook Question
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (vi) H2SO4, HgSO4, H2O. If you expect two products, show both.
(c)
1121
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