Basic Organic Nomenclature

An Introduction

Dave Woodcock,
Associate Professor Emeritus UBC (Okanagan)
©1996,2000, 2008

8. Heterocyclics
(ii) Systematic Approach

Index


If you have been unable to find a name for your ring system from amongst the common names accepted by IUPAC, this page introduces the IUPAC approach to naming heterocyclic systems with from 3 to 10 atoms in a ring which contains oxygen, sulfur and/or nitrogen.

This systematic approach requires that the heteroatoms in the ring be named using prefixes which are followed by a ring-size root and a suffix indicating whether or not it contains the maximum number of double bonds. The number of different possibilities to look through make this a non-trivial exercise!


1. Heteroatom prefixes and order of priority.

The following table is in decreasing order of priority:

Heteroatom (valence)Prefix
O (II)
oxa
S (II)
thia
N (III)
aza

Note that the final a of these prefixes is omitted before a vowel.


2. The suffix

Number of
Atoms in Ring
(Root Source)
With N in RingNo N in Ring
With
double
No
double
With
double
No
double
3
tri
irine
iridine
irene
irane
4*
tetra
ete
etidine
ete
etane
5*
ole
olidine
ole
olane
6
ine
**
in
ane
7
hept
epine
**
epin
epane
8
oct
ocine
**
ocin
ocane
9
non
onine
**
onin
onane
10
dec
ecine
**
ecin
ecane

* See table below

** use perhydro- + name with double bonds

*Names for compounds with 4 or 5 ring members and 1 (one) double bond).

Ring Members
With N
No N
4
etine
itene
5
oline
olene


Some Examples

oxirane
aziridine
thirane
oxetane
1,2-diazetidine
(R)-2-propylthietane
1,3-dioxolane
1,3-oxathiolane
1,3-oxazole
1,4-dioxane
1,3-oxathiane
1,3,5-triazine
Review Heterocyclics with common names.

Next Page: Comprehensive Self-study Questions


Index

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