Structural Isomers

One kind of isomerism occurs when the atoms are connected in different ways. For example, three different structures can be drawn for the hydrocarbon C₅H₁₂, which differ in the carbon skeleton of the molecules, as shown in Figure 1.1. The first of these structural isomers, pentane, has 2 methyl groups (- CH₃) and 3 methylene groups (-CH₂-); the second, 2-methylbutane, has 3 methyl groups, methylene, and a CH unit; and the third, 2,2-dimethyl-propane, has 4 methyl groups and a single C atom to which these are bonded..

Figure 1.1. Structural isomers of C₅H₁₂.