When to Use Z and E?

[Michael_Johanis_2K]

Is there a rule (at least for Chem 14B) that tells me when I need to put Z or E in front of a compound? I know how to determine whether I should use Z or E, but I am not quite sure when I should even have one of these letters in front of my compound's name.

[Monica Habashy 3A]

You use them when you notice the trends in the way they are ordered in terms of priority.

[Katrina_Galian 1J]

We use Z and E when we're working with alkenes that need to be categorized as either cis or trans. Particularly when none of the 4 groups attached to the 2 carbons match. For example, on page 103 of the course reader, Z-1-Bromo-2-Chloropropene is named so due to the fact that none of the groups attached to the carbons match.

[EmmaShahabi1L]

Additionally, some times the classification of the Z and the E can be interchanged with a cis or a trans. So it's somewhat arbitrary, similar to the use of a common name instead of the IUPAC method.

[Chem_Mod]

Please be careful about what Emma said. They SOMETIMES can be interchanged, but they are fundamentally different naming systems. Often times, they will give different answers. Please be sure to learn both E/Z and cis/trans naming rules. They are not the same and should not be regarded as interchangeable.