What is a functional group in organic chemistry

Functional groups

In this article we will show you what functional groups look like and what their role is in chemistry.

Have a look at our Video in order to understand the content of this article even faster.

Functional groups simply explained

A functional group is especially important in organic chemistry. You can think of them as a distinctive group of atoms that can change the properties and responsiveness of a molecule. But in most cases it has a different one Electronegativity of the H or C atoms and can influence the distribution of electrons.

This electron distribution and the resulting intermolecular forces can be the physical material properties of the molecule. For example, they change the solubility or the Boiling point and melting point.

The functional groups can also chemical properties change. This can be, for example, the Reaction speed or the Responsiveness of a molecule. You can control these chemical properties yourself through numerous reactions and the resulting changes in the functional groups.

All chemical compounds that have the same functional group become so-called Substance groups summarized. For example, you probably already have something from Alkanes , Alkenes , Alcohols or aldehydes.

Functional group classification

Using the example groups of substances, you can memorize an important division for the functional groups. Depending on the type of atoms involved, you can do it in groups with heteroatoms and groups without heteroatoms subdivide.

Heteroatoms are often the elements oxygen (), Nitrogen (), Sulfur (), Phosphorus () and / or halogens. The hydroxy group () of the alcohols belongs to the groups with heteroatoms.

The groups without heteroatoms mostly consist of double bonds () as with the alkenes, triple bonds () as with the alkynes or the Aromatics .

However, these functional groups without heteroatoms are often not viewed as “full-fledged” and only viewed as structural components. Nevertheless, the groups without heteroatoms show a special reaction behavior, which is why you can also count them among the functional groups.

Functional group overview

In this table we present you the main representative of the functional groups including their associated substance groups:

Substance groupFunctional groupSemi-structural formula
aldehydeAldehyde groupR-COH
alcoholHydroxyl groupRAW
AmineAmino groupR-NH2
Carboxylic acidCarboxy groupR-COOH
Carboxylic acid esterEster groupR.1-COO-R2
EtherEther groupR.1-O-R2
Halogenated hydrocarbonsHalide-F
-Br
-Cl
-I
KetoneKeto groupR.1-CO-R2
NitrileNitrile / cyano group-C≡N
Peroxycarboxylic acidPeroxycarboxyl groupR-COOOH
phenolHydroxyl groupRAW
ThiolThiol / mercato groupR-SH

Functional groups in chemistry

In the following we will go into more detail on four examples of organic substance groups and their functional groups. Among other things, you will see an example of the substances and how the functional group of them properties influenced.

Functional group alcohol