How can you identify enantiomers?

Question

Nolan Allen · Accepted Answer

How do you distinguish your left hand from your right hand?

I live in the UK right now, and because of the channel tunnel, there are times when you use a right hand drive on left hand lanes, and vice versa when car and trucks come from the continent to Britain. Mistakes often occur with experienced drivers. It is all too easy to do. Now, this may seem intuitively obvious, but if someone else was approaching you, you might think twice before identifying his left hand, which is of course on the side of your right hand. Anyway, I can offer you one tip with regard to stereoisomers. Given a model (which you must build!) of a chiral centre that is correct, say #CR_1R_2R_3R_4#. Say that this is correct (and you must satisfy yourself of this!). The interchange of any 2 groups, #R_1# for #R_2#, #R_2# for #R_4#, (I stress any two!) results in the enantiomer. By this reasoning, if we interchange again (of course this may be the original two groups, but not necessarily) we get back the original isomer. However, keep in mind that you are shooting yourself in the foot if you don't use models. You also need to practice how to depict these models on a printed page. Good luck.

Ava Andrews · Answer

undefined Enantiomers are non-superimposable mirror images of each other. They have the same physical properties except for their interaction with plane-polarized light (optical activity). Enantiomers rotate plane-polarized light in opposite directions. This property can be observed using a polarimeter. Additionally, enantiomers have opposite configurations at chiral centers, which can be identified through methods such as X-ray crystallography or NMR spectroscopy.