How do I estimate the optical roation of an (S)-enantiomer if I know the optical rotation to the (R)-enantiomer?
For instance, for limonene, after conducting an experiment, I got that the optical rotation for the (R)-enantiomer was 10, would the (S) be -10?
Any help would be great.
Yes, the R and S forms are the negative of each other.
If your rotations are Sepcific Rotations (do a Google search for the definition] then DrBob is correct. If your R and S samples are of different concentrations or the path length is different, then you would need to calculate the expected rotation.
To estimate the optical rotation of an (S)-enantiomer if you know the optical rotation of the (R)-enantiomer, you can use a simple rule called the "opposite enantiomer rule." According to this rule, the optical rotation of the (S)-enantiomer will be the negative value of the optical rotation of the (R)-enantiomer.
In your example, if you found that the optical rotation of the (R)-limonene enantiomer is +10, the estimated optical rotation of the (S)-limonene enantiomer would be -10. This is because the opposite enantiomer rule states that the (S)-enantiomer will have the opposite sign of optical rotation compared to the (R)-enantiomer.
It is important to note that this rule holds true for enantiomers that are pure enantiomeric compounds (mirror images of each other with no other stereoisomers present). Also, keep in mind that this rule is an estimation, and the actual value may slightly differ due to experimental conditions and impurities.
To determine the exact optical rotation values for enantiomers, other methods such as polarimetry or spectroscopy can be used. These methods can provide more accurate measurements, especially if the specific optical rotation values of the enantiomers are required.