Functional Groups

Structure & Reactivity

Appendix

Quick Reference:  Functional Groups and Names

The most commonly encountered groups of atoms in organic and biological
chemistry are called functional groups.  It is useful to be able to
recognise these groups, to know what they are called, and to know how to name
specific compounds that contain these groups.

For example, compounds that contain the C=C group are called alkenes. 
Compounds that contain a C=O group, in which the carbon is attached to two other
carbons, are called ketones.  Alkenes generally have names that end in the
suffix “ene”, such as pentene, octene, or 2-methyl-2-hexene.  Ketones have
names that end in “one”, such as propanone or butanone.

The table below summarizes a number of these functional groups.

The specific  names of organic compounds contain suffixes that tell us
about the main functional groups present.  The middle part of the name, or
base name, tells us about the number of carbons in the main chain of the
compound.

The table below outlines how to tell the number of carbons in a main chain or
in a group attached to the main chain.

So, a ten-carbon chain containing a C=O group at the end is called decanal. 
It is an aldehyde, because, being at the end of the chain, the carbonyl carbon
is attached to one carbon and one hydrogen.  An eight-carbon chain with a
C=O group on the third carbon is called 3-octanone.  A six-carbon chain
attached to an oxygen atom, which is in turn attached to a five-carbon chain,
might be called hexyl pentyl ether, provided there are no other complicating
features in the structure.

Problem FG10.1.

Use the quick reference to provide names for the following compounds.

Problem FG10.2.

Use the quick reference to provide structures for the following names.

a) ethyl propyl ether           
b) 4-heptanone

c)  1-chlorohexane               
d)  (E)-3-nonene

e)  2,3,3-trimethylhexane        f) 
hexyl propanoate

g) butanal                            
h)  2-heptanol

i) N-ethyldecylamine          
j)  N-pentylbutanamide

k)   pentyl hexanoate            
l)  ethyl pentyl ether

m)  4-bromononane           
n)  1-octyne

There are a number of variations on these groups that are encountered often
enough that they have commonly used names of their own.  For example, a
3-carbon group that is attached to another chain via the middle carbon, rather
than via the first, is called an isopropyl group.

There are a couple of common carbonyl-containing groups, shown below.

This site is written and maintained by Chris P. Schaller, Ph.D., College of Saint Benedict / Saint John’s
University (with contributions from other authors as noted).  It is freely
available for educational use.

Send corrections to [email protected]

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