Home > Organic Chemistry > Drawing Cyclohexanes in Boat and Chair Conformations

How do you number chair conformations?

Answer 1

Unambiguously…?

And so you got a chair conformation....three substituents AXIAL and three substituents EQUATORIAL on each FACE of the chair...

Now of course, if the chair is substituted by other functional groups, the normal rules of organic precedence apply...

Clearly, the ipso carbon, whatever the substituent will be #C1#...

For #"cis"-1,4-Bu^tC_6H_10CH_3# here the carbon that is substituted by #Bu^t# is #C1#...and clearly #C-Me# is #C4# on the given scheme....and we would anticipate, reasonably, that #Bu^t# would be disposed EQUATORIALLY....as indicated on the given diagram...

And if you cannot see this on paper, I urge you to make a model...

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Answer 2

Santiago Alfonso

Chair conformations in cyclohexane can be numbered by assigning the lowest number to the substituent with the highest priority according to the Cahn-Ingold-Prelog rules (priority is determined by the atomic number of the substituent's attached atoms). Once the highest priority substituent is assigned the lowest number, the other substituents are numbered sequentially around the ring, following either a clockwise or counterclockwise direction. The numbering should be done in a way that minimizes the total sum of the substituent numbers.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.