Recently I have been trying to determine the absolute configuration of a chiral molecule using crystallization methods.It is either difficult to get good crystals even by changing solvent systems or the space group comes out to be centrosymmetric, if at all it crystallizes.Hence it could not be solved. Derivatization methods have not helped either as the attempted reactions do not lead to any new spot in TLC.The compound is oily and enantioselectivity could not be improved by attempted crystallization using a mixture of solvents.
The classic method for determining absolute configuration is degradation to a smaller molecule of known configuration.If you give us the structure of your molecule we might be able to make suggestions.
Completely in agreement with the previous answers. There are several methods, but none generally applicable. You should provide at least a constitutional formula of your compound.
I think there only one thing you can do, is trying again and again to get good single crystal from the compound or its derivatization.
Another method you can determine the abs. config. by comparing the calculated and observed CD/VCD spectra. This method has been used successfully in my group last year in the total synthesis of Hickdentin A (you can find it in 10.1021/jacs.6b10237).
Hope my answer could have you. Good
Dear Arnab
There are several possibilities. You can find some of them in this review: Chem. Rev. 2004, 104, 17-117.
Dear Arnab Biswas, kindly let us know what are solvent systems used for re-crystallization. If you are able to view the appearance of colored precipitate/mass at any stages during the process of re-crystallization, then it is better to wash the compound with either n-Hexane/Ether under negative temperature and get the solid. Further can try for obtaining crystals from that by re-crystallization again.
- Badges
- Science topic