Textbook Question
Provide the alcohol that would be used to make the bromoalkanes shown using PBr₃.
(c)
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Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination
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. 13 - Alcohols, Ethers and Related Compounds: Substitution and EliminationProblem 38
Mullins 1st EditionCh. 13 - Alcohols, Ethers and Related Compounds: Substitution and EliminationProblem 38Chapter 12, Problem 38
When HCl was used for the attempted dehydration reaction shown, a reaction occurred, but none of the desired product was formed. Suggest the identity of the actual product obtained.
Verified step by step guidance1
Step 1: Begin by analyzing the dehydration reaction. Dehydration reactions typically involve the removal of a water molecule from an alcohol to form an alkene. In this case, HCl is used as the acid catalyst, which can protonate the alcohol group.
Step 2: Consider the mechanism of the reaction. When HCl is added, the hydroxyl group (-OH) of the alcohol is protonated to form a good leaving group, water (H₂O). This step is crucial for the formation of a carbocation intermediate.
Step 3: Evaluate the stability of the carbocation intermediate formed after the departure of water. Carbocation stability is influenced by factors such as hyperconjugation and resonance. If the carbocation can rearrange to a more stable form, it will do so.
Step 4: Recognize that HCl introduces chloride ions (Cl⁻) into the reaction mixture. These chloride ions can act as nucleophiles and attack the carbocation, leading to the formation of a substitution product (an alkyl chloride) instead of the desired alkene.
Step 5: Conclude that the actual product obtained is likely an alkyl chloride, formed via nucleophilic attack by Cl⁻ on the carbocation intermediate. This substitution reaction competes with the intended elimination reaction, preventing the formation of the desired alkene.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Dehydration Reactions
Dehydration reactions involve the removal of a water molecule from a compound, typically resulting in the formation of a double bond or a cyclic structure. In organic chemistry, these reactions are crucial for synthesizing alkenes from alcohols. Understanding the mechanism and conditions under which dehydration occurs is essential for predicting the products formed.
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General Reaction of Dehydration with POCl3
Acid-Catalyzed Reactions
Acid-catalyzed reactions utilize acids, such as HCl, to facilitate the transformation of reactants into products. In dehydration reactions, the acid protonates the alcohol, making it a better leaving group. This concept is vital for understanding how the presence of an acid can influence the reaction pathway and the products formed, including potential side reactions.
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Carbocation Stability
Carbocation stability is a key factor in determining the outcome of many organic reactions, including dehydration. Carbocations are positively charged carbon species that can rearrange or react further based on their stability, which is influenced by factors such as alkyl substitution and resonance. Recognizing the stability of potential carbocations helps predict the actual products formed in reactions, especially when the desired product is not obtained.
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Related Practice
Textbook Question
Predict the major product of the following elimination reactions.
(b)
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Textbook Question
Predict the major product of the following elimination reactions.
(a)
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Textbook Question
Provide the alcohol that would be used to make the bromoalkanes shown using PBr₃.
(b)
894
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Textbook Question
Besides PBr3. and SOCl2 , there are other ways of synthesizing haloalkanes. One such way is shown. Provide an arrow-pushing mechanism that rationalizes formation of the chloroalkane. [Hint: Dimethyl sulfide is a good nucleophile and Cl₂ is an electrophile. Start by reacting those two together.]
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Textbook Question
Predict which side of the equilibrium is favored by ∆H, ∆G, and ∆S.
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