Organic Compounds with Functional Groups
Structure, Nomenclature, and Chemical Properties of Organic Compounds Containing Functional Groups

Functional Groups
  • A functional group is a specific group of atoms in a molecule that is responsible for the atom's characteristic chemical reactions.
  • Complex organic compounds are divided up into functional groups that act as families.
  • Functional groups contain at least one atom that is not C or H, usually O or N or a halogen.
  • R is used to represent a carbon/hydrogen chain. R' is used to represent a chain that may be different on the same molecule.
  • They are small structural units within molecules at which most of the chemical reaction's occur.
  • Functional groups distinguish organic compounds from other compounds. For example, there are many different kinds of organic compounds, namely alcohols and carboxylic acids. Their functional groups are the alcohol group and the carboxylic group respectively which differentiates them from other types of organic compounds.
  • A functional group is also known as a functional moiety.

Functional group: An atom or group of atoms which give the compound distinctive chemical properties [e.g. -Cl, -OH, >C=C<, -CO2H]. Thus all organic compounds except saturated hydrocarbons have one or more functional groups. The functional group
determines the class of compound. In nomen
clature the functional group may be identified by a prefix, a suffix, or by the class of compound.

NOTE: the double bonds in the following table should be over the carbons; there was a formatting problem.
Important Families of Organic Compounds
only single bonds
double bonds between two carbons
C = C
triple bonds between two carbons
C = C
R - O - H
R - O - R'
R - C - H
R - C - R'
Carboxylic Acids
R - C - O - H
R - C - O - R'

Overall Nomenclature
  • The nomenclature of these types of complex organic compounds are based upon the number of carbon atoms.
  • These are some common prefixes for the most seen organic compounds:
    • meth-, (1);
    • eth-, (2);
    • prop-, (3);
    • but-, (4);
    • pent-, (5);
    • hex-, (6);
    • hept-, (7):
    • oct-, (8);
    • non-, (9);
    • dec-, (10);
    • alk-, (11)
  • Examples where this naming system is used are shown below.
  • In addition, the ending -ane stands for no unsaturation (no double or triple bonds).

Basic Principles of Naming
  1. Identify the functional group.
    1. Identify the position of the functional group in the chain.
    2. Number the carbon atoms in the parent chain. The functional group should end up the least number possible (as there are two ways of numbering—right to left and left to right). The number (in Arabic numerals, i.e. 1, 2, 3....) is written before the name of the functional group suffix (such as -ol, -one, -al, etc.). If the group is a group that can only exist at the end of any given chain (such as the carboxylic acid and aldehyde groups), it need not be numbered.
  2. Identify the side-chains and number them. Side chains are the carbon chains that are not in the parent chain, but are branched off from it.
  3. Identify the remaining functional groups, if any, and name them by the name of their ions (Such as hydroxy for -OH, oxy for =O , oxyalkane for O-R, etc.).
  4. Identify double/triple bonds. Number them with the number of the carbon atom at the head of the bond (i.e the carbon atom with the lesser number that it is attached to). For example a double bond between carbon atoms 3 and 4 is numbered as 3-ene. Multiple bonds of one type (double/triple) are named with a prefix (di-, tri-, etc.). If both types of bonds exist, then use "ene" before "yne" e.g. "6 13 diene 19 yne" If all bonds are single, use "ane" without any numbers or prefixes.
  5. Arrange everything like this: Group of side chains and secondary functional groups with numbers made in step 3 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers.
    Wherever it says "with numbers", it is understood that between the word and the numbers, you use the prefix(di-, tri-)
  6. Add punctuation:
    1. Put commas between numbers (2 5 5 becomes 2,5,5)
    2. Put a hyphen between a number and a letter (2 5 5 trimethylhexane becomes 2,5,5-trimethylhexane)
    3. Successive words are merged into one word (trimethyl hexane becomes trimethylhexane)

  • Alcohols are organic compounds in which a hydrogen has been replaced with a hydroxyl group (OH).
  • The OH makes alcohols polar and able to form hydrogen bonds, which means that alcohols are more soluble in water than most organic compounds.
  • The suffix "-ol" is used.
Alcohol - Formula
Methanol - CH3OH
Ethanol - C2H5OH
Propanol - C3H7OH


Organic Acids/ Carboxylic Acids
  • Organic acids are organic compounds in which a hydrogen has been replaced with a carboxyl group (COOH).
  • In some ways, a carboxylic acids is a combination of an aldehyde and an alcohol.
  • The ending is always "oic" acid.
  • No number is needed because the group is at the end.
Organic Acid - Formula
Methanoic Acid - HCOOH
Ethanoic (Acetic) Acid - CH3COOH
Propanoic Acid - C2H5COOH

organic acid
organic acid

  • Halides are organic compounds in which one or more hydrogens have been replaced with a halide (F, Cl, Br, I).
  • They are named with fluoro-, chloro-, bromo-, iodo-, etc., depending on the halogen.
Halide - Formula
Chloromethane - CH3Cl
Chloroethane - C2H5Cl
Chloropropane - C3H7Cl


  • In an amine, a hydrogen atom has been replaced by an amino group (NH2).
Amine - Formula
aminomethane (Methyl amine) - CH3NH2
aminoethane (Ethyl amine) - C2H5NH2
aminopropane (Propyl amine) - C3H7NH2

primary amine
primary amine

  • An aldehyde contains a carbonyl group (C=O) connected to at least one hydrogen atom.
  • The ending for an aldehyde is "-al."
  • No number is needed because the group is at the end.
Aldehyde - Formula
Methanal (Formaldehyde) - HCHO
Ethanal - CH3CHO
Propanal - C2H5CHO


  • A ketone is similar to an aldehyde in that it also contains a carbonyl group (C=O), but in a ketone, the carbon in the carbonyl group is not connected to any hydrogen atoms.
  • The suffix for a ketone is "-one."
  • No number is needed because the group is at the end.
Ketone - Formula
Propanone - C3H6O
Butanone - C4H8O
Pentanone - C5H10O


  • In an ether, an oxygen atom serves as a link in a hydrocarbon chain.
  • The name of an ether is determined by the lengths of the chains on either side of oxygen.
  • Last word in the name is "ether"
Ether - Formula
Methoxymethane (Dimethyl ether) - CH3OCH3
Methoxyethane (Methyl ethyl ether) - CH3OC2H5
Methoxybutane (Methyl butyl ether) - CH3OC4H9
Ethoxypropane (Ethyl propyl ether) - C2H5OC3H7


  • An ester group (COO) serves as a link in a hydrocarbon chain.
  • It is formed in a reaction between an alcohol and an organic acid, and its name is derived from the reactants.
  • The name of the group after the "O" comes first.
  • Second word always ends in "oate."
Ester - Formula
Methyl methanoate - HCOOCH3
Methyl ethanoate - CH3COOCH3
Methyl propanoate - C2H5COOCH3
Ethyl methanoate - HCOOC2H5
Propyl methanoate - HCOOC3H7


Some Practice Examples

  1. Name this structure:

Answer: 2-chlorobutane

The 2 is because the Cl is bonded to the compound at the 2nd intersection from the left. (Notice that from the right it would have been 3, but it needs to be the smallest number).
The chloro is because the chlorine is the side chain and this makes it a halide.
The butane is because "but-" is the prefix for 4. Since there are 4 carbons in this compound, then this prefix is applicable. (There are carbons at the 2 intersections of the links of the compound.)

2. Name this structure (Ignore the reactants!) :
Answer : 2,3-dibromopentane

Since the numbers indicate at what points of the compound there are side chains, the 2 indicates that the Br is bonded to the C at the second intersection from the left, and the 3 indicates that both the CH3 and the Br are bonded to another C at the third intersection from the left.
The dibromo- is because there are 2 (di-) bromides, making this compound a halide.
The pentane is because there are 5 carbon atoms in the main link/chain of the compound.