Question

What is the difference between hexanes and cyclohexanes?

Answer 1

Hexanes are aliphatic, a straight (or branched) chain; cyclohexane is alicyclic, it features a carbocyclic ring.

Explanation:

The general formula of hexanes is `C_6H_14`, the carbon chain is saturated (i.e. its formula is `C_6H_14`; `C_nH_(2n+2)`). Cyclohexane has a formula of `C_6H_12`, 2 less hydrogens than the saturated formula, and thus has `1^@` of unsaturation.

Of course the extra `C-C` bond in cyclohexane (which must be present to effect ring closure) has reduced the hydrogen count of the molecule.

It goes without saying (does it? then why am I saying it!) that these are different molecules, with different chemical and physical properties. The melting point of cyclohexanes is unusually high, presumably because the rings can pack together in the solid state effectively.