Hi Everyone,
I need some suggestions on some easy non-instrumental methods for separation of enantiomers of a compound with two chiral centers just next to each other. Basically I have a mixture of RS, SR, SS and RR isomers of my compound. And my limitation is that I cannot do Chiral HPLC.
Please help with some information.
Let me see if I understand. You would like us to suggest to you a method to resolve apart two pairs of enantiomers which reside on two separate centers, for four possible enantiomers (Two isomers, each with two enantiomers), but we can not use any instrumental methods, we can not use chiral HPLC and perhaps most importantly of all, you have not told us what the compound is. Oh, and you asked for the suggestions to be easy too. You wrote: "Please help with some information." OK. Exactly! Please make this request to your teacher.
Hello! First you need to separate the diastereomers, by mean of flash or dry-flash column chromatography, or sometimes it can be done by crystallization i.e. sometimes diastereomers solubility is sufficiently different. Each diastereomer is pair of enantiomers. Than your enantiomers can be chemically transferred in to diastereomers and than separated again by afore mentioned methods. There is no simpler way to do this. This is the classic approach
Provide information about your compound structure. Then only we can give the answer
Tell us more about structure, we have separated by SFC (pyrethrin derivatives) but said earlier you might be able to separate by Column (Prep TLC for smaller amounts).
You can separate diastereomers with Flash Chromatography but if you need to separate enantiomers you need something chiral to separate them, either chiral chromatography or perform a kinetic resolution to end up with one of the enantiomers.