University:
Swansea University
Course:
CH302 | Organic Chemistry
Academic year:

2021
Views:

307

Pages:

10
Author:

Charlee Buchanan

PRACTICE: PRACTICE: PRACTICE: When 2-bromo-2-methylbutane is treated with a base, a mixture of 2-methyl-2-butene and 2-methyl-1-butene is produced. When potassium hydroxide is the base, 2-methyl-1-butene accounts for 45% of the mixture. But when potassium tert-butoxide is the base, 2-methyl-1-butene accounts for 70% of the mixture. What would you predict for the percent of 2-methyl-1-butene in the mixture if potassium propoxide were the base? a) less than 45% b) 45% c) between 45% and 70% d) more than 70% PRACTICE: Which reaction would proceed the fastest? PRACTICE: PRACTICE: What would be the major product of the dehydrohalogenation of 3-chloropentane by KOH? PRACTICE: PRACTICE: What would be the major product of dehydrohalogenation of 2-chloropentane by potassium hydroxide? PRACTICE: PRACTICE: In the dehydration of 2-bromo-2-methylbutane with potassium hydroxide, which hydrogen atom is preferentially abstracted? PRACTICE: 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 alkyl bromide. -, is a good nucleophile and it would attack the carbocation to form an 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. PRACTICE: Which carbocation would not be likely to undergo rearrangement? PRACTICE: Which alcohol is dehydrated fastest in concentrated H PRACTICE: What reagent could accomplish this reaction? 2SO4? PRACTICE: Consider this prototypical nuclephilic substitution shown in the box. The effect of doubling the volume of solvent would be to multiply the reaction rate by a factor of a) 1/4 b) 1/2 c) 2 d) 4 PRACTICE: If this alcohol is dehydrated, which alkene is likely to be formed in the largest quantity? PRACTICE: What would be the first step in the dehydration of cyclohexanol in sulfuric acid? a) loss of - OH b) loss of H+ by the alcohol c) formation of a sulfite ester d) protonation of the alcohol PRACTICE: A bimolecular nuclephilic substitution (SN2) is a) a two-step process in which a bond is broken, then a new bond is formed, and there is inversion of configuration. b) a two-step process in which a bond is broken, then a new bond is formed, and there is retention of configuration. c) a one-step process with inversion of configuration. d) a one-step process with retention of configuration.