When do you use cis and trans?
Is it only when there is a double bond or can a triple bonded molecule have cis/trans?
Also, why is this molecule a trans?
Thanks!
When to use -cis and -trans?
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Re: When to use -cis and -trans?
Cis and trans are used to designate the orientation around a double bond (or, around a plane sometimes). A triple bond cannot be designated cis/trans because a triple bond is linear - there are only two substituents around a triple bond and those are both linear since the triple bond itself is linear. In comparison, a double bond can have 4 substituents around it. The cis/trans designation indicates the orientation of the two groups with the highest priority.
For that molecule, the CH2CH3 and the triple bond substituent are higher in priority than the Cl & F (see priority rules). Since they're on opposite sides of the bond, the orientation of the groups around the bond is trans.
For that molecule, the CH2CH3 and the triple bond substituent are higher in priority than the Cl & F (see priority rules). Since they're on opposite sides of the bond, the orientation of the groups around the bond is trans.
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Re: When to use -cis and -trans?
Chem_Mod wrote:Cis and trans are used to designate the orientation around a double bond (or, around a plane sometimes). A triple bond cannot be designated cis/trans because a triple bond is linear - there are only two substituents around a triple bond and those are both linear since the triple bond itself is linear. In comparison, a double bond can have 4 substituents around it. The cis/trans designation indicates the orientation of the two groups with the highest priority.
For that molecule, the CH2CH3 and the triple bond substituent are higher in priority than the Cl & F (see priority rules). Since they're on opposite sides of the bond, the orientation of the groups around the bond is trans.
Just to clarify, the priority rules for E/Z are completely different than cis/trans. Please see the post I made regarding cis/trans and E/Z for details. The "groups of interest" for cis/trans will follow the parent chain. For E/Z, it will follow the priority rules.
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