Organic Structures - Organic Chemistry Concepts: An EFL Approach - page 3

be separated into aromatic or aliphatic types. All aromatic compounds have
special bonding arrangement within a ring. You will see details of this aromatic
bonding in later chapters. The word “aliphatic” then refers to all non-aromatic
examples. Aliphatic hydrocarbons can be either saturated or unsaturated . Sat-
urated compounds have no multiple bonds. Unsaturated compounds have at
least one multiple bond.

FIGURE 1.1
Primary classifications of hydrocarbon compounds.

Organic chemistry uses a number of special words that are not used
in other branches of chemistry. Do not worry about this. These words
will become familiar as you use them again and again. However, it is
important to note that these words have specific meanings, and you
must use them correctly.

Other common definitions that help with classifications are shown in Figure 1.2 .
These are:

acyclic - structures that do not have a ring in them;

n

carbocyclic - a ring that is made of only carbon atoms;

n

heterocyclic - a ring that has at least one non-carbon atom in it.

n

Functional groups are an important way to classify organic compounds. Func-
tional groups are fixed arrangements of atoms within a compound. These groups
are mainly responsible for the physical and chemical properties of a compound.
They are formed when carbon-hydrogen bonds in saturated hydrocarbons are
replaced to give either multiple bonds or bonds to heteroatoms.