Cyclohexane chairs - How in the world is a 120 degree rotation possible?

[sabdul]

Hello.

I was under the impression that the chair-chair inteconversion or ring flip is the simple flipping of the ends of the chairs converting the axial substituents to equatorial and vice versa. This is how I usually get the different conformations. But my organic chem prof said that you can rotate the chair 120 degrees twice and for the 3 120 degree drawings flip them to get 6 total conformations. This was done for the molecule 1,2-bromo-4-methylcyclohexane where the two bromine groups are cis to one another but trans to the methyl group. Can someone please explain this to me?

Thanks.

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[PiBond]

For MCAT purposes, I wouldn't dwell on your professor's words too much. Just know that chairs are constantly flipping back and forth and that they prefer to have the largest groups in the equitorial position due to unfavorable diaxial interactions.