Cis Trans vs. E/Z

[wormboge]

Does cis/trans require one substituent on each carbon to be hydrogen? Does E/Z require another atom to be bonded to whatever atom is bonded to the carbons sharing the double bond?

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[Saisri_PharmStdnt]

Does cis/trans require one substituent on each carbon to be hydrogen? Does E/Z require another atom to be bonded to whatever atom is bonded to the carbons sharing the double bond?

CIS/TRANS question: I'm not 100% certain, but I don't think so.
E/Z question: E/Z has to do with ranking the highest priority substituents.

I found a couple of tutorial pages that may be helpful (listed in no particular order)

• Cis Trans and E Z Geometric Isomers Organic Chemistry Tutorial -
• How to Use E/Z Nomenclature with Alkenes That Have Nonidentical Groups - dummies
• Organic Chemistry: Alkenes: Cis/Trans & E/Z

 

[CommyO]

They're pretty much interchangable

 

[PlsLetMeIn21]

I learned that cis/trans was casual naming and could refer to whatever substituents you cared about while E/Z was more formal and you had to consider the priorities on each carbon. If you consider 2-chloro-2-butene, the two methyl groups can be cis, but because Cl has higher priority than CH3 in IUPAC rules, the formal name would be E.

 

[whitecoater]

cis/trans is for naming geometric isomer with similar groups across the double bonds.

E/Z is for naming geometric isomer with dissimilar groups across the double bonds.