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(vi)
Mullins 1st EditionCh. 10 - Alkynes: Electrophilic Addition and Redox ReactionsProblem 44c(vi)Chapter 9, Problem 44c(vi)
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) 
Verified step by step guidance1
Identify the alkyne structure provided in the problem. Determine whether it is a terminal alkyne (triple bond at the end of the chain) or an internal alkyne (triple bond within the chain). This distinction is important for predicting the product.
Understand the reaction conditions: H₂SO₄ (sulfuric acid), HgSO₄ (mercuric sulfate), and H₂O (water). These conditions promote the hydration of alkynes, leading to the formation of a ketone via the Markovnikov addition of water across the triple bond.
Apply the mechanism: The alkyne reacts with H₂O in the presence of H₂SO₄ and HgSO₄. First, the alkyne is protonated to form a carbocation intermediate. The Hg²⁺ ion stabilizes the carbocation, and water adds to the more substituted carbon (Markovnikov addition).
Recognize the enol intermediate: The addition of water forms an enol (a compound with a hydroxyl group attached to a carbon-carbon double bond). This enol is unstable and undergoes tautomerization to form a ketone. Tautomerization involves the migration of a proton and the rearrangement of the double bond.
If the alkyne is symmetrical, a single ketone product will form. If the alkyne is asymmetrical, two possible ketone products may form due to the different substituents on either side of the triple bond. Analyze the structure of the alkyne to determine whether one or two products are expected.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Alkyne Hydration
Alkyne hydration is a chemical reaction where an alkyne reacts with water in the presence of an acid catalyst, typically sulfuric acid (H₂SO₄) and a mercury(II) salt (HgSO₄). This process leads to the formation of an enol, which can tautomerize to a more stable ketone. Understanding this reaction is crucial for predicting the products formed when alkynes are treated under these conditions.
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Markovnikov's Rule
Markovnikov's Rule states that in the addition of HX (where X is a halogen or OH) to an alkene or alkyne, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This principle helps predict the regioselectivity of the reaction, guiding the formation of the major product when alkynes undergo hydration.
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Tautomerization
Tautomerization is a chemical process where a compound exists in two interconvertible forms, typically involving the relocation of a proton and a shift of a double bond. In the context of alkyne hydration, the initial enol product can convert to a ketone through tautomerization, which is often the more stable and predominant form. Recognizing this process is essential for identifying all possible products of 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)
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Textbook Question
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)
1078
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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)
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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
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (iv) HBr (1 equiv.). If you expect two products, show both.
(c)
1087
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