Question

Which is more stable 2-bromo cyclohexene or 3-bromo cyclohexene?

Answer 1

Molecules will try to adopt the most stable conformation that minimizes strain. For

cyclohexane, C6H12, this would be the chair conformation. Let’s see why.

If cyclohexane was planar, its structure would look like the picture to the left. All the

carbons in cyclohexane are sp3

hybridized, so the ideal bond angle for a tetrahedral

atom would be 109.5 degrees. However, the planarity of the ring would force the

carbons to have bond angles of 120 degrees, which makes it unstable. There would

also be torsional strain, as all 12 carbon-hydrogen bonds would be fully eclipsed.

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