Here’s a few wrong ways to draw a chair flip : This being organic chemistry, there’s plenty of ways to screw this up. Three Ways NOT To Properly Do A Cyclohexane Chair Flip Note how on C-1, “axial up” becomes “equatorial up”. These two conformations can be converted to each other using a chair flip. The Chair Flip Of 1-Methylcyclohexane, Revisited This brings us back to 1-methylcyclohexane. What do you see?ĭuring this chair flip, all the axial groups become equatorial… and all the equatorial groups become axial! Pay close attention to the axial groups and the equatorial groups. In this video, watch how this model of a cyclohexane chair is first converted into a boat, and then into a new cyclohexane chair. The Chair Flip Converts All Axial Groups To Equatorial Ones, And Vice VersaĪhh! You see – it’s not QUITE the same. That’s like converting a dollar bill into four quarters and then exchanging them back into a dollar bill. Your first thought might be – that’s pretty useless! Who cares if we just start with a cyclohexane chair and convert it into another cyclohexane chair. Now, if we take the “original” head rest (on the left) and pull it down, so that it makes a new “foot rest”, we have the following. Step 2: Pull Down The Opposite Head Rest To Make A New Foot Rest Now, if we take the “foot rest” of cyclohexane, and rotate several of the bonds, we are able to obtain a structure which looks like it has two “head rests”. Step 1: Bring Up A “Footrest” of The Chair To Make A”Boat” Hammock Looked at from one perspective, we see the chair with its “head rest” on the left and “foot rest” on the right. Here’s a molecular model of cyclohexane, showing all the axial hydrogens (white) and equatorial hydrogens (red). When we first introduced the cyclohexane chair, we mentioned that it was the lowest energy conformation of cyclohexane – but not the only conformation.
#Cyclohexane in chemdoodle series
The point of this post is to describe how these two conformations can be converted into each other, through a series of bond rotations we call a “chair flip”. However, unlike, say, conformations in linear alkanes, which involve rotations about single bonds, it might not be immediately obvious how the chair on the left can be converted to the chair on the right. Same connectivity, different shape – this is a definition of “conformational isomers” if ever there was one. How Do These Conformations Interconvert? Through A Cyclohexane “Chair Flip” hold on!Ĭan you see how this is a different situation? We could put the methyl group on an axial carbon or an equatorial carbon… and these are not superimposable on each other, unlike the “flat” drawing above.Ģ. Now let’s draw the cyclohexane chair version. No matter how you rotate it, or flip it – it’s all superimposable versions of the same thing. Let’s take a really simple substituted version of cyclohexane – 1-methylcyclohexane, for example.įrom the “dash wedge” diagram, there is only one way to depict 1-methylcyclohexane. This brings up an interesting thought experiment. In a recent post, an aerial tour of the cyclohexane chair, we showed that there are two different positions a substituent can occupy on a cyclohexane chair – axial (straight up and down, relative to the ring) and equatorial (off to the side of the ring). The Two Chair Conformations Of 1-Methyl Cyclohexane
#Cyclohexane in chemdoodle how to
All about how to draw the product of a cyclohexane chair flip – and also, three ways not to!
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