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E/Z and cis/trans alkenes template

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(Z)- and (E)-but-2-ene, the trisubstituted 3-methylpent-2-ene, and 2-bromobut-2-ene, where trans-methyl groups are (Z): E/Z by CIP priorities against cis/trans.

What the template shows

Rank the two groups on each alkene carbon: higher priorities on the same side is Z, opposite is E
Alkene stereoisomers
But-2-ene
Each alkene carbon carries CH₃ and H: cis = Z, trans = E
(Z)-but-2-ene
cis: CH₃ groups on the same side
(E)-but-2-ene
trans: CH₃ groups on opposite sides
A trisubstituted alkene
cis/trans has no meaning; E/Z still works
(E)-3-methylpent-2-ene
C3: CH₂CH₃ > CH₃; C2: CH₃ > H; the two winners are opposite
(Z)-3-methylpent-2-ene
the two higher-priority groups on the same side
When the names disagree
E/Z follows priorities, not the carbon chain
(Z)-2-bromobut-2-ene
chain CH₃ groups trans, yet Z: Br outranks CH₃ on C2
(E)-2-bromobut-2-ene
chain CH₃ groups cis, yet E
Z (zusammen, together): the higher-priority group on each carbon on the same side. E (entgegen, opposite): on opposite sides.
Priorities on each carbon are assigned separately with the CIP rules, exactly as for a stereocentre.
cis/trans only describes two like groups (or the main chain); for tri- and tetrasubstituted alkenes use E/Z.
An alkene carbon with two identical groups (C=CH₂, C=C(CH₃)₂) has no E/Z isomers.

Drawn with 30 atoms, 4 shapes – every one editable in MolDraw.

Sources

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Frequently asked questions

Is the E/Z and cis/trans alkenes template free?

You can preview the E/Z and cis/trans alkenes template here and open and edit it in MolDraw for free. Downloading or exporting it is part of MolDraw Pro, together with the other premium templates.

Can I edit the E/Z and cis/trans alkenes template?

Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it.

Is the chemistry checked?

Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page.

Are the R/S labels in the stereochemistry templates checked?

Yes. Every R/S and E/Z descriptor is computed with RDKit from the drawn structure, so the labels match the wedges and dashes.