# How do you name this compound?

May 27, 2018

The name is ($E$)-3-carboxypenta-1,3-diene.

#### Explanation:

The "new" (2013) IUPAC rules give chain length priority over functional groups.

The longest chain contains five carbon atoms, so the base name is
penta-1,3-diene.

There is a $\text{COOH}$ group on $\text{C3}$, so the name becomes
3-carboxypenta-1,3-diene.

Finally, the $\text{C3=C4}$ double bond has the E" configuration because the highest-priority groups (carboxy and methyl) are on opposite sides of the bond.

The IUPAC name is ($E$)-3-carboxypenta-1,3-diene.