Geometric

Isomers

Sarah Gilbert

two isomers for 2-butene

• Cis-: “on the near side of”

• Trans-: “across, beyond, transverse”

• These are almost the same the only difference is whether the fourth carbon added goes on the same side as the third or not.

• Chemical formula is C4H8

• Average molar mass 56.11 g/mol

Cis-2-butene• Same line

formula as trans-2-butene

Trans-2-butene

Extra Fact

• This is the most simple alkeneshowing cis/trans isomerism, meaning it exists as two geometric isomers.

• They are very difficult to separate by distillation due to their close boiling points

Summary

• Double bonds can not rotate due to the strength of their bonds, but single bonds can because they have less connection.

• Even though these two isomers have the same formula they are very different structures with different names.