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The material in these tutorials are intended to aid in your understanding of basic organic nomenclature. The pages are subdivided into topics based on the different functional groups present in organic molecules. Each section consists of a brief introduction, including examples, and a number of interactive on-line quizzes to test your understanding of the material. As a student it is your responsibility to determine when you have a sufficient understanding of the material.
Organic nomenclature is based on the priority of the different functional groups in the molecule. If you are not familiar with the different functional groups you need to study them first.
These pages make use of Jmol to display molecules. If you are not familiar with Jmol check this short help page.
IUPAC Rules of Nomenclature
The International Union of Pure and Applied Chemists (IUPAC) has devised a system of rules which act as a guide in naming organic molecules. A standardized system for naming organic compounds was needed due the the vast number of structures possible with hydrocarbons. Although the IUPAC system of nomenclature has been in place since the 1930's, it still provides several alternative methods for naming organic compounds. In addition, there are a number of compounds which are still referred to by their common names. This complicates organic nomenclature to some degree as several names may be possible for any single compound. The important point of organic nomenclature is that the name(s) are unique to that single compound and should be unambiguous, i.e. the name reflects the structure of the molecule.
Since every organic molecule contains carbon (and usually hydrogen) atoms, the names of these to elements do not appear in the name of the compound. Instead IUPAC uses the longest continuous chain of carbon atoms to determine the basic root name (or parent hydride) of the compound. The root name is then modified due to the presence of different functional groups which replace hydrogen or carbon atoms in the parent hydride.
There are a number of different ways to modify the root name to indicate the functional groups present.
Note: some complex molecules are named by a combination of the methods.
- Substitutive nomenclature is the most common. In this case the highest priority function group modifies the suffix of the root name, while all other groups, or substituents, are added as prefixes to the root name.
- Function group (or class) nomenclature names the compound based on the highest priority functional group, i.e. the compound is named as an alcohol, ketone, alkyl halide, etc.
- Additive nomenclature is used to indicate the addition of an atom (usually hydrogen) or group not implicit in the compound's root name.
- Conjunctive nomenclature is used to combine assemblies of functionalized parent systems implying the loss of the appropriate number of hydrogen atoms from each (i.e. cyclohexanecarboxylic acid).
- Replacement nomenclature is used to indicate when an atom, usually carbon, is replaced by another atom.
- Subtractive nomenclature is used to indicate the loss of an atom (usually hydrogen) or group implicit in the compound root name.
- In addition there are a number of compounds whose common name have been adopted into IUPAC nomenclature.
This site will focus primarily on the substitutive and functional class nomenclature but includes examples of all systems including cases where the name is generated by a combination of methods.
The following list of functional groups will contain an introduction to the nomenclature of that functional group, including examples. At the end of each section is a on-line quiz designed to test your new knowledge of the subject.
All tutorials can be accessed through this link: Tutorials. Note: if you can not seem to get the correct answer, enter a question mark (?) in the text box and you will get the correct answer returned.
- A basic example to start
- Functional Groups
- Alkanes
- Alkenes and Alkynes
- Ethers, Crown Ethers, Epoxides and Sulfides
- Amines
- Thiols
- Alcohols
- Ketones
- Aldehydes
- Nitriles
- Carboxylic Acids
- Aromatics
- Stereochemistry
- E/Z nomenclature
- R/S nomenclature
- List of Common Substituents
- An image map summary of organic nomenclature
- Test your new knowledge of nomenclature by naming these compounds
- Test your new knowledge of nomenclature by drawing the structure of these compounds
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