Ch. 9 - Alkenes and AlkynesSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Solution: Why would the concentrated hydrobromic acid be an inappropriate catalyst for the dehydration of alcohols? a) HBr is too weakly acidic to protonate the alcohol. b) The conjugate base, Br - , is a good nucleophile and it would attack the carbocation to form an alkyl bromide.  c) HBr is strongly acidic, so the water molecule would not be a good leaving group after protonation of the alcohol. d) HBr would be more likely to promote rearrangement of the carbocation intermediate. 

Problem

Why would the concentrated hydrobromic acid be an inappropriate catalyst for the dehydration of alcohols?

a) HBr is too weakly acidic to protonate the alcohol.

b) The conjugate base, Br - , is a good nucleophile and it would attack the carbocation to form an alkyl bromide. 

c) HBr is strongly acidic, so the water molecule would not be a good leaving group after protonation of the alcohol.

d) HBr would be more likely to promote rearrangement of the carbocation intermediate.