How can I draw cis-2-octene according to IUPAC?
When trying to draw compounds according to IUPAC nomenclature, you have to break down the name into its individual components. The six factors that determine the name of a compound are
- Functional group
- Parent chain;
I won't go into the rules for each one of these factors because it would make for a very long answer. So, let's analyze the name of the compound.
Compound names that end in
Now for the first part of the name, cis-2. The 2 is used to designate the first atom that forms the aforementioned double bond. This implies that the double bond will be placed between carbon 2 and carbon 3 on the parent chain.
Cis just means that you have two identical groups on the same side of the double bond. In this case, cis will refer to the two hydrogen atoms attached to the carbons that form the double bond.
Now to put all this together. Start by drawing the parent chain, octane.
Remember that the double bond is placed between carbon 2 and carbon 3, so you'll have
Now for the tricky part. The compound drawn above is actually trans-2-octene, because the two hydrogens are attached to different sides of the double bond. This is how it would look with these hydrogens attached
Since the cis stereoisomer must have the two hydrogen atoms on the same side of the bond, the actual bond line notation fir cis-2-octene will be