How To Draw The Mirror Image Of A Molecule

Chirality and Enantiomers

Earlier talking about the enantiomers, let'south go over the concept of mirror images and especially when information technology pertains to organic molecules.

Any object has a mirror image. No tricks or magic here – just put a mirror in front of anything and you'll see its mirror paradigm:

The key here is that some objects are not the same equally their mirror images. The simplest case is our hands. They may look identical, but you won't be able to swap them without having the fingers on different positions or orientations.

Another example would exist the glasses shown above. They are the same as their mirror paradigm only if we supercede one of the lenses with a dark lens, the mirror image is now unlike – you lot cannot replace the glasses with the mirror prototype. It does non repeat the object in space considering the position of the lenses is different.

In chemistry, the word for describing mirror prototype beingness identical or unlike is "Superimposable".

If the object and its mirror image are the same, they are superimposable, if these two are not the same and so they are not-superimposable images. Any object that is non-superimposable to its mirror image is said to be Chiral.

The same goes for molecules: Chiral molecules are not superimposable on their mirror prototype. Achiral molecules are superimposable to their mirror images which indicates that the mirror image is the same chemical compound.

Stereogenic Middle – Origin of Chirality

Nigh often, the origin of chirality in organic molecules is the presence of an asymmetric carbon. This is a carbon with four unlike groups (atoms) also referred to as a stereogenic center or a chiral(aty) center.

If nosotros draw the mirror image of this molecule, nosotros volition meet that it is not-superimposable to it. And here is one new definition to learn:

If 2 molecules are nonsuperimposable mirror images, they are called Enantiomers.

Enantiomers are types of stereoisomers since all the atoms are connected the same but they have a different 3D orientation.

A lilliputian scheme as a reminder about constitutional isomers and stereoisomers. It also mentions the diastereomers, but you can ignore those for at present if you take not covered them in your class:

Getting back to the asymmetric carbon and chirality – A molecule tin have more than than one chirality heart and if you need to identify those, remember that you are looking for a carbon (fifty-fifty though it is not restricted to carbons only) with four dissimilar groups.

For example, these are the chirality centers in each of the post-obit molecules:

To recognize the chiral center, look for the wedge and nuance bonds as usually these are the ones indicating a chiral center.

One important affair to think, a carbon with a double bond cannot be a chiral center every bit it does not have four different groups. Yes, it has four bonds but that is the standard valency of the carbon. It must have iv different group s, therefore information technology must have a tetrahedral geometry.

How to Depict Enantiomers

In full general, the easiest way to draw the enantiomer of a given molecule is to merely redraw the compound, replacing all dashes with wedges and all wedges with dashes.

This is not a universal solution though because the wedge and nuance representation is relative and depends on the direction we are looking from. To know for sure if two molecules are enantiomers, the Cahn-Ingold-Prelog system (R and Due south) is used.

Another way of cartoon the enantiomer of a given molecule, is to put an imaginary mirror and depict everything reflected and this will also give you the enantiomer:

However, attention! – You should not practise both: you should not draw the mirror reflection and change the wedges and dashes together with it, since yous volition finish up having the same molecule:

You should either keep the molecule as it is and change every wedge to a dash or you lot can identify a mirror prototype anywhere (on the side, on the tiptop, below, in front or behind) next to the molecule and depict its reflection.

Do the post-obit issues and bank check the next mail service on the R and Southward configuration, to double check your answers.

For each of the following pairs of compounds, make up one's mind the relationship betwixt the ii compounds: Are they enantiomers or the aforementioned compound drawn differently? If yous hesitate, determine the absolute configuration of chiral centers (if any:R or S).

answer

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Solution

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By joining Chemistry Steps, you will proceeds instant access to the answers and solutions for all the Exercise Issues including over 20 hours of problem-solving videos, Multiple-Choice Quizzes, Puzzles, and t he powerful set of Organic Chemistry 1 and 2 Summary Study Guides.