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Show the mechanism for the generation of the acylium ion if an acid anhydride is used instead of an acyl chloride for the source of the acylium ion.
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Ch. 18 - Reactions of Benzene and Substituted Benzenes
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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TOC.tableOfContents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding31
- 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. 18 - Reactions of Benzene and Substituted BenzenesProblema 5e,f
Bruice 8th EditionCh. 18 - Reactions of Benzene and Substituted BenzenesProblema 5e,fCapitolo 18, Problema 5e,f
What is the major product of a Friedel–Crafts alkylation using the following alkyl chlorides?
e. (CH3)2CHCH2Cl
f. CH2=CHCH2Cl
Guida verificata passo dopo passo1
Step 1: Understand the Friedel–Crafts alkylation reaction. This reaction involves the use of an alkyl halide (R-Cl) and a Lewis acid catalyst, such as AlCl₃, to introduce an alkyl group onto an aromatic ring. The reaction proceeds via the generation of a carbocation intermediate.
Step 2: Analyze the alkyl halides provided. For (CH₃)₂CHCH₂Cl (structure ii), the alkyl chloride can form a secondary carbocation after the loss of Cl⁻. For CH₂=CHCH₂Cl (structure i), the allylic carbocation formed is stabilized by resonance due to the adjacent double bond.
Step 3: Consider carbocation stability. In Friedel–Crafts alkylation, the stability of the carbocation intermediate is crucial. Secondary carbocations (as in ii) are relatively stable, while allylic carbocations (as in i) are even more stable due to resonance stabilization.
Step 4: Predict the major product for each case. For (CH₃)₂CHCH₂Cl, the secondary carbocation will lead to the introduction of an isopropyl group onto the aromatic ring. For CH₂=CHCH₂Cl, the allylic carbocation will lead to the introduction of a propenyl group onto the aromatic ring.
Step 5: Consider regioselectivity and steric effects. The aromatic ring will preferentially react at positions that minimize steric hindrance and maximize electronic stabilization. Typically, the ortho and para positions relative to existing substituents are favored unless steric hindrance is significant.
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Friedel-Crafts Alkylation
Friedel-Crafts alkylation is a reaction that introduces an alkyl group into an aromatic ring using an alkyl halide and a Lewis acid catalyst, typically aluminum chloride. This electrophilic aromatic substitution reaction allows for the formation of new carbon-carbon bonds, enhancing the complexity of aromatic compounds. The choice of alkyl halide can influence the regioselectivity and stability of the product.
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06:30
Friedel-Crafts Alkylation
Carbocation Stability
In Friedel-Crafts alkylation, the formation of a carbocation intermediate is crucial. The stability of this carbocation significantly affects the reaction outcome. Tertiary carbocations are more stable than secondary or primary ones due to hyperconjugation and inductive effects, leading to a higher likelihood of substitution at the aromatic ring. Understanding carbocation stability helps predict the major product of the reaction.
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05:58Determining Carbocation Stability
Regioselectivity
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others. In the context of Friedel-Crafts alkylation, the position where the alkyl group attaches to the aromatic ring can vary based on the stability of the carbocation and the substituents already present on the ring. Recognizing the factors that influence regioselectivity is essential for predicting the major product in reactions involving different alkyl halides.
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05:09Heck Reaction
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