Conformational Analysis and Cycloalkanes

These flashcards cover key concepts and details regarding conformational analysis of ethane and butane, as well as the structure and strain of cycloalkanes and their derivatives.

What is the main focus of ethane conformational analysis?

Understanding the free rotation around the sigma bond and its implications for molecular structure.

What are the two primary conformations of ethane?

Staggered and eclipsed.

What is the dihedral angle for staggered (gauche) conformation?

60 degrees.

What are Newman projections used for?

To represent the conformation of molecules and visualize interactions between atoms.

What is the potential energy associated with: A) Staggered, B) Eclipsed conformations of ethane?

A) Staggered has lower potential energy, about 0 kcal/mol. B) Eclipsed has higher potential energy, reaching about 2.9 kcal/mol.

What is the main difference in strain between the staggered and eclipsed conformations of butane?

Eclipsed conformations exhibit steric hindrance/van der Waals strain, while staggered conformations do not.

List the types of strain associated with cyclohexane conformations.

Angle strain, torsional strain, and steric strain.

What is the stability comparison between cis and trans-1,2-dimethylcyclohexanes?

Trans is more stable than cis due to less steric strain.

What are the naming rules for spiro compounds?

Spiro/# of unique carbons in smaller ring/# of unique carbons in larger ring/alkane name based on total number of carbons.

What are the characteristics of cyclopropane regarding strain?

It has suboptimal orbital overlap and torsional strain, with all adjacent pairs of bonds eclipsed.