organic compounds have a carbon backbone and an isomer

In a Newman projection, the ethane molecule is viewed along the C–C axis, with the carbon that is in front shown as a vertex and the carbon that is in back shown as a circle. Differences between the conformations of ethane are depicted especially clearly in drawings called Newman projections, such as those shown in part (a) in Figure 24.4 'Eclipsed and Staggered Conformations of Ethane'. The simplest alkane to have a conformational isomer is ethane. Because rotation about the bond does not affect the overlap of the bonding orbitals, there is no electronic energy barrier to rotation. Overlapping sp 3 hybrid orbitals on adjacent carbon atoms form a cylindrically symmetrical σ bond. Differences in three-dimensional structure resulting from rotation about a σ bond are called differences in conformation, and each different arrangement is called a conformational isomer (or conformer) Isomers whose three-dimensional structures differ because of rotation about a σ bond.įigure 24.3 Carbon–Carbon Bonding in Alkanes Consequently, many different arrangements of the atoms are possible, each corresponding to different degrees of rotation.

Because rotation about the carbon–carbon single bond can occur without changing the overlap of the sp 3 hybrid orbitals, there is no significant electronic energy barrier to rotation. Each sp 3 hybrid orbital is cylindrically symmetrical (all cross-sections are circles), resulting in a carbon–carbon single bond that is also cylindrically symmetrical about the C–C axis. The C–C single bonds in ethane, propane, and other alkanes are formed by the overlap of an sp 3 hybrid orbital on one carbon atom with an sp 3 hybrid orbital on another carbon atom, forming a σ bond ( Figure 24.3 'Carbon–Carbon Bonding in Alkanes').

Organic compounds have a carbon backbone and an isomer