Cycloalkanes

An example would be 2-methylpentane, which is a pentane molecule with a methyl group at the second carbon molecule. Halogens can be added like fluoro, chloro, bromo, and iodo- for the halogen side-groups. When these are added, the compound is called an alkyl halide. C2H5Cl can be ethyl chloride or chloroethane. It means the same thing. Of course, side groups can contain halogens, too, such as trichloromethyl (CCl3-) and bromomethyl (BrCH2).

CYCLOALKANES

These involve at least one carbon ring associated with it. The simplest one is a single unsubstituted carbon ring with the general formula of the ring being CnH2n because carbon is bonded to itself with a single bond in a ring. The simplest one is cyclopropane, which contains 3 carbons in a “triangular ring” that has six hydrogen atoms associated with it. These are named like the alkanes, with cyclobutane, cyclopentane, and cyclohexane named for the number of carbon atoms added to the ring.

The rules are similar:

• Name the ring first unless the ring is itself a substituent group on a larger alkane.

• Start the numbering with the first substituted carbon atom.

• Go around the ring so that the next substituted group has the lowest possible number.

• If there are a lot of substituted groups, list them in alphabetical order.

• More than one ring involves a polycyclic compound, which can be bicyclic, tricyclic, etcetera.

• Rings can be separated, have one common carbon atom, one common bond, or two common atoms.

Spiro rings have one common atom; fused rings have a common bond, and bridged rings have two common atoms. If no carbon atoms are in common, this is called an isolated ring system. Figure 65 shows some of the cycloalkanes: