We begin our study of compounds with a range of functional groups other than hydrocarbons and consider the nomenclature of organic compounds of oxygen, nitrogen, and halogens. Many of the principles you have learned in connection with naming hydrocarbons will have direct application to these compounds. We will use systematic nomenclature to obtain first-choice names, but we also will indicate common usage, at least parenthetically.
- 7.1: General Approaches to Naming Organic Compounds
- There are two aspects to consider: how to derive the name from the structure, and how to derive the structure from the name.
- 7.2: Alcohols and Phenols- ROH, ArOH
- The IUPAC nomenclature system for alcohols and phenols, involves adding the suffix -ol for \(OH\) to the name of the parent hydrocarbon. Notice that alkane \(+\) -ol becomes alkanol, with the e omitted.
- 7.3: Ethers, ROR'
- The substituent name for the \(RO-\) function is alkoxy, and it is correct to name \(R-O-R'\) compounds as alkoxy derivatives of hydrocarbons. In the common nomenclature for ethers, each of the \(R\) groups in \(R-O-R'\) is named as a separate word, except when the groups are identical, in which case the prefix di or bis may be used (di is used for simple groups, bis for substituted groups).
- 7.4: Aldehydes
- The suffix -al is appended to the name of the hydrocarbon corresponding to the longest carbon chain that includes the aldehyde carbon. Remember that alkane + -al becomes alkanal with the e omitted, and because the al function is necessarily at C1, the -1- is redundant and is omitted.
- 7.5: Ketones, RCOR'
- The IUPAC system employs the suffix -one added to the prefix identifying the longest carbon chain of \(RCOR'\) that includes the carbonyl group. The chain is numbered to give the carbonyl group. The chain is numbered to give the carbonyl group the lowest possible number.
- 7.6: Carboxylic Acids
- By the IUPAC system, the suffix -oic is added to the prefix identifying the hydrocarbon chain that includes the carboxyl carbon. Situations arise when it is necessary to consider the parent as a one-carbon chain. In such circumstances, \(RCO_2H\) becomes a substituted carboxylic acid. This variation is met most frequently when \(R\) is a cycloalkyl or aryl group.
- 7.7: Acyl Groups, RCO-
- An acyl group and in specific cases in named by adding the suffix -oyl to the appropriate hydrocarbon prefix. That is, alkane- ++ -oyl becomes alkanoyl. Acyl groups also may be called alkanecarbonyl or cycloalkanecarbonyl groups.
- 7.8: Amines
- Primary amines, having only one substituent on nitrogen, are named with the substituent as a prefix. More systematic nomenclature appends -amine to the longest chain, as for alcohols. Secondary and tertiary amines, which have two and three substituents on nitrogen, commonly are named as N-substituted amines. As for substituted amides, N is included to indicate that the substituent is on the nitrogen atom unless there is no ambiguity as to where the substituent is located.
- 7.9: Nitriles, RCN
- Compounds with the ≡N function are named by adding the suffix nitrile to the main-chain hydrocarbon that includes the carbon linked to the nitrile (≡N) function. The chain is numbered so the CN carbon is C1.
- 7.10: The Use of Greek Letters to Denote Substituent Positions
- In the older literature, considerable use is made of the Greek letters α, β, γ, and so on, to designate successive positions along a hydrocarbon chain. The carbon directly attached to the principal function group is denoted as α, the second carbon is β, and so on down the chain. Because the usage is widespread, cognizance of the system is important, but systematic naming and numbering systems should be used whenever possible.
- 7.11: Single- or Multiple-Word Names
- A troublesome point in naming chemical compounds concerns the rules governing when a compound is to be written as a single word (as methylamine) or as two or more words (as methyl chloride). To solve this problem, you must determine whether the principle or parent function is an element or a compounds in its own right; if it is either one, then the name is written as a single word.
- 7.E: Other Compounds than Hydrocarbons (Exercises)
- These are the homework exercises to accompany Chapter 7 of the Textmap for Basic Principles of Organic Chemistry (Roberts and Caserio).
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."