9. Alkenes and Alkynes

Predict the major product(s) of the following elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(c)

What is the major product formed when the following compounds undergo an E1 reaction?

b.

Predict the major product(s) of the following elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(e) 

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

a. (1S,2S)-1-bromo-1,2-diphenylpropane

When (1-bromoethyl)cyclohexane is heated in methanol for an extended period of time, five products result: two ethers and three alkenes. Predict which of the three alkenes is the major elimination product.

Predict the products of E1 elimination of the following compounds. Label the major products.

(a)

When using sulfuric acid, but in the absence of other nucleophiles like water or bromide ion, less stable alkenes can be isomerized to their more stable isomer. Provide a mechanism for these acid-catalyzed isomerization reactions. [This is one illustration of the principle of microscopic reversibility.]

(b)

For each of the following reactions, draw the major elimination product; if the product can exist as stereoisomers, indicate which stereoisomer is obtained in greater yield.

e. 3-bromo-3-methylpentane + high concentration of CH₃CH₂O⁻

f. 3-bromo-3-methylpentane + CH₃CH2OH

Which alkyl halide in each pair is more reactive in an E2 reaction with hydroxide ion?

c.

d.

What products will be obtained from the E2 reaction of the following alkyl halides?

c.

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

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

What is the major elimination product obtained from an E2 reaction of each of the following alkyl halides with hydroxide ion?

f.