How do you indicate cis vs trans on double bonds?

How do you know whether a double bond is cis or trans in a stereoisomer? And if it is one, how do you change to another?

Cis double bonds have large groups on the same side. So if you have a cis double bond, the two groups would both be on top or both be on the bottom. In trans, the large groups are on opposite sides. So one is on top and one is on bottom. To switch from one stereoisomer to the other, just flip the R groups on one side of the double bond.

This entry was posted on Monday, October 12th, 2009 at 5:26 pm and is filed under trans. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

One Response to “How do you indicate cis vs trans on double bonds?”

Andrew on October 12th, 2009 at 10:36 pm

Cis double bonds have large groups on the same side. So if you have a cis double bond, the two groups would both be on top or both be on the bottom. In trans, the large groups are on opposite sides. So one is on top and one is on bottom. To switch from one stereoisomer to the other, just flip the R groups on one side of the double bond.
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