A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry (IUPAC). The primary function of chemical nomenclature is to ensure that a spoken or written chemical name leaves no ambiguity concerning which chemical compound the name refers to: each chemical name should refer to a single substance.
- 3.1: Prelude to Organic Nomenclature
- Organic chemists, regardless of what languages they speak, can communicate with one another about their chemical work simply by writing equations and structural formulas. For more rapid and efficient communication we need to have names for compounds that would contain enough information so we could generate the proper structures from them, and conversely, if we know the structures then the system would have simple enough rules that we could construct universally recognized and accepted names.
- 3.2: Alkanes
- The most definitive set of organic nomenclature rules currently in use were evolved through several international conferences and are known as the International Union of Pure and Applied Chemistry Rules (IUPAC rules). We first shall describe this system for naming the hydrocarbons known as alkanes - the so-called saturated paraffin hydrocarbons that have no double or triple bonds, or rings.
- 3.3: Cycloalkanes
- The cycloalkanes with one ring and are named by adding the prefix cyclo- to the name of the corresponding continuous-chain alkane having the same number of carbon atoms as the ring. Substituents are assigned numbers consistent with their position in such a way as to give the lowest numbers possible for the substituent positions. The substituent groups derived from cycloalkanes by removing one hydrogen are named by replacing the ending -ane of the hydrocarbon with -yl to give cycloalkyl.
- 3.4: Alkenes, Cycloalkenes, and Alkadienes
- The open-chain hydrocarbons with one double bond are called alkenes. The carbon-carbon double bond often is called an "olefinic linkage" and the alkenes designated as olefins (oil-formers). The IUPAC system for naming alkenes, the longest continuous chain containing the double bond is given the name of the corresponding alkane with the ending -ane changed to -ene. This chain then is numbered so that the position of the first carbon of the double bond is indicated by the lowest possible number.
- 3.5: Alkynes
- A number of hydrocarbons, called alkynes or acetylenes, have triple bonds between carbon atoms. The IUPAC system for naming alkynes employs the ending -yne instead of the -ane used for naming of the corresponding saturated hydrocarbon. Hydrocarbons with more than one triple bond are called alkadiynes, alkatriynes, and so on, according to the number of triple bonds Hydrocarbons with both double and triple bonds are called alkenynes (not alkynenes).
- 3.6: Arenes
- The so-called aromatic hydrocarbons, or arenes, are cyclic unsaturated compounds that have such strikingly different chemical properties from conjugated alkenes (polyenes) that it is convenient to consider them as a separate class of hydrocarbon. The simplest member is benzene, which frequently is represented as a cyclic conjugated molecule of three single and three double carbon-carbon bonds. The hydrocarbon group from benzene itself is called a phenyl group.
- 3.E: Organic Nomenclature (Exercises)
- These are the homework exercises to accompany Chapter 3 of the Textmap for Basic Principles of Organic Chemistry (Roberts and Caserio).
Thumbnail: A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry (IUPAC).
Contributors and Attributions
John D. Robert and Marjorie C. Caserio (1977) Basic Principles of Organic Chemistry, second edition. W. A. Benjamin, Inc. , Menlo Park, CA. ISBN 0-8053-8329-8. This content is copyrighted under the following conditions, "You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format."