Sigma Bond Rotation

As we’ve learned before, single bonds have the ability to freely rotate, meaning that we have to get used to seeing multiple arrangements of single bonds and understanding that they are all the same thing. 

These multiple arrangements are known as conformers.

Problem: Determine if the following pair of molecules is isomers or conformers?

3m

Notice that the only difference between these was one rotation?

This next one is tricky because it has two rotations in it. See if you can identify them.

Problem: Determine if the following pair of molecules is isomers or conformers?

4m

Remember: If double bonds are switching configuration, that’s an isomer. If single bonds are rotating, that a conformer. 

Problem: Determine if the following pair of molecules is isomers or conformers?

2m

One more, hopefully these are getting a little easier!

Problem: Determine if the following pair of molecules is isomers or conformers?

3m

We’ll be rotating double bonds all the time in this course, so I’m hoping by now you are more comfortable recognizing that multiple rotations really equal to the same thing.