Practice Problem: E2 on Cyclic Systems and Cyclohexane Chairs

The video tutorial explains the E2 elimination reactions of two stereo isomers with a bromo and TERT butyl group. It highlights the difference in reaction speed between the cis and trans isomers due to their chair conformations and thermodynamic stability. The cis isomer reacts faster because its favorable conformation allows for easier proton extraction, while the trans isomer's unfavorable conformation slows the reaction. The tutorial emphasizes the importance of anti-periplanar arrangement and the role of steric hindrance in determining reaction dynamics.

What is the main difference between the cis and trans isomers in the context of the reaction discussed?

• The cis isomer does not react at all.

• Both isomers react at the same rate.

• The trans isomer has a faster reaction rate.

• The cis isomer has a faster reaction rate.

In an E2 elimination reaction, what is the necessary spatial relationship between the leaving group and the beta proton?

• They must be anti-periplanar.

• They must be syn-periplanar.

• They must be axial.

• They must be equatorial.

Why is the chair conformation important in E2 elimination reactions involving cyclohexane?

• It changes the molecular weight of the compound.

• It ensures the correct spatial arrangement for the reaction.

• It affects the solubility of the compound.

• It determines the color of the compound.

What role does the tert-butyl group play in the stability of the molecule?

• It provides steric hindrance, favoring equatorial positioning.

• It increases the molecule's solubility.

• It makes the molecule more acidic.

• It decreases the molecule's reactivity.

Why is the reaction slower for the trans isomer compared to the cis isomer?

• The trans isomer is more soluble.

• The trans isomer has a more favorable chair conformation.

• The trans isomer has a higher molecular weight.

• The trans isomer's chair conformation is energetically unfavorable.