Rank the following from most reactive to least reactive in an E2 reaction:

Which reactant in each of the following pairs undergoes an elimination reaction more rapidly? Explain your choice.

a.

b.

Explain why only a substitution product and no elimination product is obtained when the following ­compound reacts with sodium methoxide:

For each of the following compounds, draw the product that forms in an E2 reaction and indicate its configuration:

b. (1S,2R)-1-bromo-1,2-diphenylpropane

Why do cis-1-bromo-2-ethylcyclohexane and trans-1-bromo-2-ethylcyclohexane form different major products when they undergo an E2 reaction?

Which isomer reacts more rapidly in an E2 reaction: cis-1-bromo-4-tert-butylcyclohexane or trans-1-bromo-4-tert-butylcyclohexane? Explain your answer.

A chemist allows some pure (2S,3R)-3-bromo-2,3-diphenylpentane to react with a solution of sodium ethoxide (NaOCH₂CH₃) in ethanol. The products are two alkenes: A (cis-trans mixture) and B, a single pure isomer. Under the same conditions, the reaction of (2S,3S)-3-bromo-2,3-diphenylpentane gives two alkenes, A (cis-trans mixture) and C. Upon catalytic hydrogenation, all three of these alkenes (A, B, and C) give 2,3-diphenylpentane. Determine the structures of A, B, and C; give equations for their formation; and explain the stereospecificity of these reactions.

Predict the elimination products of the following reactions, and label the major products.

b. trans-1-bromo-2-methylcyclohexane + NaOCH₃ in CH₃OH

Predict the elimination products of the following reactions, and label the major products.

a. cis-1-bromo-2-methylcyclohexane + NaOCH₃ in CH₃OH