TBR Passage about Stereoisomers?

[CloverBale]

Which of the following statements are valid for the isomers of carvone and limonene?

I. Both limonene and carvone have four possible stereoiosmers each.

But the answer explains that both carvone and limonene have one chiral center, so they will each have two possible stereoiosmers (enantiomers). Making statement I valid.


Am I missing something here?

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[aldol16]

Carvone and limonene do only have two enantiomers each - otherwise, (+)- and (-)-carvone wouldn't be a thing.

 

[sazerac]

I. Both limonene and carvone have four possible stereoiosmers each.

Am I missing something here?

Are you missing the word "each"?

 

[CloverBale]

I thought the amount of stereoisomers for a molecule with n chiral centers was 2^n?

Are you missing the word "each"?

 

[sazerac]

But the answer explains that both carvone and limonene have one chiral center, ...


Am I missing something here?

Are you missing the word "one"?

 

[manohman]

Was a little confused about this for a different reason.

Couldnt you have other stereoisomers (diastereomersg because you have the double bond? In the diagram its trans but couldnt it also be cis? So 2 x 2 possible stereoisomers?

 

[aldol16]

Couldnt you have other stereoisomers (diastereomersg because you have the double bond? In the diagram its trans but couldnt it also be cis? So 2 x 2 possible stereoisomers?

In order for cis or trans double bonds to occur, what must be true about the substituents?

 

[manohman]

In order for cis or trans double bonds to occur, what must be true about the substituents?

They have to be different on each side of the alkene so if you switch any two on one side you go from cis to trans.

Even though its in a ring couldnt you switch substituents still? Would just be a somewhat strained structure?

 

[aldol16]

They have to be different on each side of the alkene so if you switch any two on one side you go from cis to trans.

Even though its in a ring couldnt you switch substituents still? Would just be a somewhat strained structure?

So with limonene, where's only one double bond in which the four substituents are different and that's in the cyclohexene ring. Try drawing out the cis and trans versions of that particular alkene. You'll find that one is too distorted to exist. Cyclohexane rings like to remain in the extended (not distorted) form. Cyclooctene is the one that can twist around and exist in cis and trans forms. Trans cyclooctene is actually the lightest of the trans cyclic hydrocarbons that can exist stably at room temperature.