9. Alkenes and Alkynes

What is the major product of the reaction?

What is the major product of the reaction?

What is the major product of the reaction?

When 2-bromo-3-phenylbutane is treated with sodium methoxide, two alkenes result (by E2 elimination). The Zaitsev product predominates.

a. Draw the reaction, showing the major and minor products.

Predict the elimination products of the following reactions. When two alkenes are possible, predict which one will be the major product. Explain your answers, showing the degree of substitution of each double bond in the products.

a. 2-bromopentane + NaOCH₃

b. 3-bromo-3-methylpentane + NaOMe (Me = methyl,CH₃)

c. 2-bromo-3-ethylpentane + NaOH

What is the major elimination product obtained from the reaction of each of the following alkyl halides with hydroxide ion?

a.

b.

For each of the following alkyl halides, indicate the stereoisomer that would be obtained in greatest yield in an E2 reaction.

a. 3-bromo-2,2,3-trimethylpentane

For each of the following alkyl halides, indicate the stereoisomer that would be obtained in greatest yield in an E2 reaction.

b. 4-bromo-2,2,3,3-tetramethylpentane

a. What is the major product obtained when each of the following compounds undergoes an E2 reaction with methoxide ion? Show the configuration of the product.

b. Does the product obtained depend on whether you start with the R or S enantiomer of the reactant?

1.

Draw the elimination products for each of the following E2 reactions; if the products can exist as stereoisomers, indicate which stereoisomers are obtained.

c. (2R,3S)-2-chloro-3-methylpentane + high concentration of CH₃O^-

When 2-bromo-2,3-dimethylbutane reacts with a strong base, two alkenes (2,3-dimethyl-1-butene and 2,3-dimethyl-2-butene) are formed.

a. Which of the bases (A, B, C, or D) would form the highest percentage of the 1-alkene?

b. Which would give the highest percentage of the 2-alkene?

What is the major elimination product obtained from the reaction of each of the following alkyl halides with hydroxide ion?

c.