Make a model of chair cyclohexane corresponding to the leftmost model in Fig. 7.4. Raise carbon-4 so that carbons 2–5 lie in a common plane. This is the half-chair conformation of cyclohexane, and it is the transition state for the interconversion of the chair and twist-boat conformations. (Notice the position of this conformation on the energy diagram of Fig. 7.6.) Give two reasons why the half-chair conformation is less stable than the chair or twist-boat conformation.

Transcribed Image Text:

Raise carbon-4 and its two hydrogens with the left hand. FIGURE 7.4 5 chair Hold carbon-1 1 with the right hand so that it does not move. Hold carbon-4 with the left hand so that it does not move. 5 6 3 2 boat (unstable) chair Lower carbon-1 and its two hydrogens with the right hand.