10. Addition Reactions

Which stereoisomer of 3-hexene forms (3S,4S)-4-bromo-3-hexanol and (3R,4R)-4-bromo-3-hexanol when it reacts with Br₂ and H₂O?

Predict the major product(s) for each reaction. Include stereochemistry where appropriate.

c. cis-but-2-ene + Cl₂/H₂O

d. trans-but-2-ene + Cl₂/H₂O

Predict the major product(s) for each reaction. Include stereochemistry where appropriate.

a. 1-methylcyclohexene + Cl₂/H₂O

b. 2-methylbut-2-ene + Br₂/H₂O

Propose a mechanism for the addition of bromine water to cyclopentene, being careful to show why the trans product results and how both enantiomers are formed.

Show how you would make the following compounds from a suitable cyclic alkene.

(d)

Show how you would accomplish the following synthetic conversions.

a. 3-methylpent-2-ene → 2-chloro-3-methylpentan-3-ol

Problem-Solving Hint: The opening of a halonium ion is driven by its electrophilic nature. The weak nucleophile attacks the carbon bearing more positive charge.

Predict the product of formula C₇H₁₃BrO from the reaction of this same unsaturated alcohol with bromine. Propose a mechanism to support your prediction.

Suggest an alkene that could be used to make each of the following halohydrins.

(a)

Predict the product(s) of each of the following reactions, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.

(a)

Provide arrow-pushing mechanisms for Assessments 9.10(b) and 9.10(c) that rationalize the regioselective and stereospecific formation of each halohydrin.

(b)

(c)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iii) Br₂, H₂O

(d)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iv) Cl₂, CH₃OH

(d)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iv) Cl₂, CH₃OH

(h)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iii) Br₂, H₂O

(k)