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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: PKa on July 21, 2018, 12:39:49 PM

Title: prediction of optical rotation
Post by: PKa on July 21, 2018, 12:39:49 PM
HI I am new to this forum and am looking to get some answers from chiral chemistry experts.
I am curious to know if one can predict the optical rotation of a compound if we know the optical rotation of individual components that are part of the molecule. for example, can we predict or use a formula to predict the optical rotation of Boc-Cys-Ala-OMe if we know the optical rotations of Boc-Cys-OH and H-Ala-OMe?
As far as I know, it is not possible to predict the optical rotation of any compound unless it is a reported compound with a known specific rotation. I would appreciate any leads or links to read more on he topic.
Title: Re: prediction of optical rotation
Post by: phth on July 26, 2018, 01:59:45 AM
It can be done with DFT, but it is complicated.  Do you forget about the S-cis/S-trans isomerism that only exists between Cys-Ala not Cys+Ala
Title: Re: prediction of optical rotation
Post by: PKa on July 26, 2018, 10:11:59 PM
Thanks for the reply. I do not remember having read anywhere about this kind of calculation . Yes S-cis and S-trans would make it little more complicated. It would be interesting to find out that somebody had already done this kind of study.