10. Addition Reactions

Halohydrin formation is a stereospecific reaction. Identify the products of halohydrin formation of the following diastereomeric alkenes to demonstrate this stereospecificity.

In light of your answer to Assessment 9.47, predict the product of the following reactions we have seen previously where an alcohol is substituted for water.

(c)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iii) Br₂, H₂O ; (iv) Cl₂, CH₃OH;

(l)

Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iii) Br₂, H₂O ; (iv) Cl₂, CH₃OH

(f)

Retrosynthetic analysis is the process of working backward to develop the synthesis of a new compound. In Chapter 10, we begin developing multistep syntheses in this manner. For now, try to work backward a single step by suggesting an alkene and a reagent that would give products (a)–(i). [Your answers should not include alkenes that undergo rearrangement to give the desired products.]

(i)

What will be the major product obtained from the reaction of Br₂ with 1-butene if the reaction is carried out in

c. ethyl alcohol?

d. methyl alcohol?

1-Methylcyclohexene forms two products when it reacts with bromine in methanol.

a. Draw the mechanism for the formation of the products.

b. Describe their stereochemical relationship—that is, are they enantiomers or diastereomers?

Using any alkene and any other reagents, how would you prepare the following compounds?

d.

What will be the major product obtained from the reaction of Br₂ with 1-butene if the reaction is carried out in

a. dichloromethane?

b. water?

Each of the following reactions has two nucleophiles that could add to the intermediate formed by the reaction of the alkene with an electrophile. What is the major product of each reaction?

a.

What is the major product of the reaction of 2-methyl-2-butene with each of the following reagents?

j. Br₂/CH₃OH

A graduate student attempted to form the iodohydrin of the alkene shown below. Her analysis of the products showed a good yield of an unexpected product. Propose a mechanism to explain the formation of this product.

Using 1,2-dimethylcyclohexene as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.) If a chiral product is shown, assume that it is part of a racemic mixture.

(g)

Show how you would synthesize each compound using methylenecyclohexane as your starting material.

(h)

The solutions to Solved Problem 8-5 showed only how one enantiomer of the product is formed. For each product, show how an equally probable reaction forms the other enantiomer.