Conformations of cycloalkanes

While the conformation of cycloalkanes has been discussed in detail later, it will be worth while to see how the ring strain in such compounds is calculated as this will give us a broad picture about their relative stability. 

We also discuss the conformations of cycloalkanes, especially cyclohexane, in detail because of their importance to the chemistry of many kinds of naturally occurring organic compounds. Some attention also will be paid to polycyclic compounds, substances with more than one ring, and to cyclo-alkenes and cycloalkynes. 

Draw the conformations of cycloalkanes, compare their energies, and predict the most stable conformations. 

Besides torsional strain and steric strain, the conformations of cycloalkanes are also affected by angle strain. 

Space. Such noobonding steric interactions are particularly important in determining the minimum-eneigy conformations of cycloalkanes with medium-size rings (C7-Cni-... 

Figure 1 Increase of the number of known conformations of cycloalkanes with increasing size.

Limited rotation around the carbon-carbon single bonds of cycloalkanes also results in a variety of conformations of cycloalkanes. In cyclohexane the chair conformation is the most energetically favored. Another conformation is the boat conformation. 

What are the conformations of cycloalkanes Cyclopropane, with only three carbon atoms, is necessarily planar (because three points determine a plane). The C—C—C angle is only 60° (the carbons form an equilateral triangle), much less than the usual sp tetrahedral angle of 109.5°. The hydrogens lie above and below the carbon plane, and hydrogens on adjacent carbons are eclipsed. 

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