Optical isomerism is a type of stereoisomerism. This page describes what stereoisomers are and how you recognize the possibility of optical isomers in a molecule.

You are watching: Which of the following compounds can exist as optical isomers (enantiomers)? check all that apply.

Origin that Optical Isomers

The examples of necessary optical isomers save a carbon atom joined to four different groups. These two models each have the same teams joined to the main carbon atom, yet still regulate to it is in different:


Obviously as they space drawn, the orange and blue teams are no aligned the exact same way. Could you obtain them come align by rotating among the molecules? The next diagram shows what happens if you turn molecule B.


They still room not the same - and also there is no way that you can rotate castle so that they look specifically the same. These are isomers of each other. They are described as gift non-superimposable in the sense that (if you imagine molecule B gift turned into a ghostly version of itself) you couldn"t slide one molecule specifically over the various other one. Something would constantly be pointing in the dorn direction.

What wake up if 2 of the groups attached to the central carbon atom room the same? The following diagram mirrors this possibility.


The 2 models room aligned precisely as before, but the orange team has been replaced by one more pink one. Rotating molecule B this time shows that it is precisely the same as molecule A. You only get optical isomers if all four groups attached to the central carbon are different.


Chiral and also achiral molecules

The essential difference in between the two examples we"ve looked at lies in the the opposite of the molecules. If there are two groups the exact same attached to the main carbon atom, the molecule has a airplane of symmetry. If friend imagine slicing v the molecule, the left-hand side is specific reflection the the right-hand side.

Where over there are 4 groups attached, there is no symmetry everywhere in the molecule


Example 1: Isobutanol

The asymmetric carbon atom in a link (the one v four various groups attached) is often displayed by a star.


It"s extremely vital to attract the isomers correctly. Attract one of them using conventional bond notation to display the 3-dimensional arrangement approximately the asymmetric carbon atom. Then attract the winter to display the examiner that you recognize what you space doing, and also then the winter image.

api/deki/files/16172/lacticchir.GIF?revision=1&size=bestfit&width=96&height=68" />

The 2 enantiomers are:


It is vital this time to attract the COOH group backwards in the mirror image. If girlfriend don"t over there is a an excellent chance of friend joining the on to the main carbon wrongly.

api/deki/files/16164/ringskel2.gif?revision=1" />

In this case, whatever is as before, other than that if girlfriend trace around the ring clockwise and also counter-clockwise from the carbon at the bottom the the ring, over there is an the same pattern in both directions. You can think of the bottom carbon being attached to a hydrogen, one -OH group, and two similar hydrocarbon groups. It as such is not a chiral center.

The other thing which is an extremely noticeable about this molecule is the there is a airplane of symmetry through the carbon atom we room interested in. If girlfriend chopped that in half through this carbon, one side of the molecule would certainly be an exact reflection that the other. In the first ring molecule above, that is no the case.

See more: What Is Composed Of Rows And Columns That Represent An Entity? ?

If you have the right to see a aircraft of symmetry v the carbon atom it will certainly not it is in a chiral center. If over there is not a airplane of symmetry, it will certainly be a chiral center.