Simple question, a bit confused..

[whoknows87]

So I came across a question that is asking what is the absolute configuration of (+) Carvone and (-) Carvone respectively ? I thought + means clockwise = R and (-) = Counter = S so I chose R,S and the book said wrong it's S and R what did I miss here? did I just misread the question

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[shaboobly]

R and S have nothing to do with how the molecule rotates ppl. its just the orientation around a chiral center given by cahn ingold prelog rules

 

[whoknows87]

all of the options included R and S

 

[Singhp03]

R and S have nothing to do with how the molecule rotates ppl. its just the orientation around a chiral center given by cahn ingold prelog rules

bingo, +/- anotations are D(dextro)/L(levo) respectively. You would have to find abs. config of both compounds the old fashion way.

note: dextro mean 'right' and levo mean 'left'

 

[shaboobly]

all of the options included R and S

they prob gave you a structure showing the stereochemistry and want you to determine the absolute configuration around each chiral center. as stated above me, dextro is the groups go clockwise and levo is groups go counter clockwise.

groups with a higher atomic number are a higher priority.

 

[whoknows87]

thats what I thought but why would EK give me all the answers as R and S, but on a previous question the book answer was the (+) in the name indicates that the molecule rotates clockwise

on a separate question the answer key states (d) is the same as (+) both rotate light clockwise

I hope you see why I am confused

 

[shaboobly]

thats what I thought but why would EK give me all the answers as R and S, but on a previous question the book answer was the (+) in the name indicates that the molecule rotates clockwise

on a separate question the answer key states (d) is the same as (+) both rotate light clockwise

I hope you see why I am confused

i dont see how you can be confused because the two are not related. a meso compound does not rotate ppl but still has an absolute configuration around a chiral center.

 

[Singhp03]

thats what I thought but why would EK give me all the answers as R and S, but on a previous question the book answer was the (+) in the name indicates that the molecule rotates clockwise

on a separate question the answer key states (d) is the same as (+) both rotate light clockwise

I hope you see why I am confused

it can be very confusing bc the language is so similar, but u need to know that optic rotation is different than abs. config. Reread the answer from the book, they might have been talking about the molecule rotating LIGHT clockwise

Wiki says it best: It is not possible to determine whether a given chiral molecule will be levorotatory or dextrorotatory directly from its configuration, except via detailed computer modeling.[3] In particular, both "R" and "S" stereocenters have the ability to be dextrorotatory or laevorotatory.