[windom626]

Im just trying to get this right, so i draw the trans-1,3-di-tert-butylcyclohexane in a chair conformation, and i counted the energies of steric strains, correct me if im wrong, are there 4, 1,3 diaxial interactions? Which would give us a total of 45,6 kJ/mol to keep this structure stable, and in the twist-boat conformation there are only 3 of those interactions? And that's why it is more stable? Am i geting this correct?

[rolnor]

This is a very good example were you can do some molecular modeling. I don know if you are right though, very possible. I have used ”PC-Model” from Serena Software, very useful in cases like this.

[hollytara]

t-butyl in axial position is very disfavored by energy.  When you have trans 1,3 - both chairs have 1 axial and 1 equatorial, so both chairs are disfavored.  Twist boat can minimize the unfavorable interactions from the t-butyls and this makes it more favorable in this case.