In order to draw chemical structures I use ChemBioDraw Ultra.
As an exercise I've to draw the most stable conformation.
I expect a twist-boat like structure (instead of usual chair conformation for substituted dioxanes)
Is there a freeware or an easy computer online tool to check if my propose (right side picture) is correct?
When I go to >Edit > Get 3D Model the program gives me a small picture with a 3D-Model:
By double-clicking this small image it opens ChemBio3DUltra and I can rotate this molecule:
@Martin: Is this correct (I've expected a twisted cyclic ring)?
@Martin I draw the structure at right with i-Bu and H exchanged in Chemdraw and do >Edit > Get 3D Model
The reason why I first thought it should be twist boat like was that one C-O is pointing up and the other pointing down. May be someone knows why people gives this stereoinformation inside the cyclic ring?
As I've drawn it as a twist boat I get exactly the same with ChemBioDraw. Is there a way to calculate by how many kcal/mol the first one is more stable then the second one with ChemBioDraw?
What's interesting: I searched for a structure in which the twist-boat conformation is the most favorable one and found one:
However, when there are two large substituents in the cis-1,4 arrangement on a cyclohexane ring, neither of which will go easily into an axial position, then it appears that the twist-boat conformation (Section 12-3A) is most favorable [http://authors.library.caltech.edu/25034/13/BPOCchapter12.pdf, page 458]
(The A-value of a tert-Butyl is in the range of 5 kcal/mol which is around the value of the energy difference between cyclohexane in twist-boat and chair conformation. I've drawn cis-1,4-di-tert-butyl-cyclohexane with ChemDraw and used >Edit>Get 3D Model and ChemBioDraw gave me the structure which is NOT the energetical most suitable one! Why?