Alkanes IUPAC nomenclature

Thomson Click Organic Interactive to use an online palette to draw alkane structures based on IUPAC nomenclature. 

IUPAC Nomenclature of Alkanes, Alkyl Halides, and Alcohols... 

An alkyl group lacks one of the hydrogens of an alkane. A methyl group (CH3—) is an alkyl group derived from methane (CH4). Unbranched alkyl groups in which the point of attachment is at the end of the chain are named in IUPAC nomenclature by replacing the -one endings of Table 2.2 by -yl. 

An additional feature of IUPAC nomenclature that concerns the direction of numbering is the first point of difference rule. Consider the two directions in which the following alkane may be numbered ... 

A single alkane may have several different names a name may be a common name, or it may be a systematic name developed by a well-defined set of rules. The most widely used system is IUPAC nomenclature. Table 2.6 summarizes the rules for alkanes and cycloalkanes. Table 2.7 gives the rules for naming alkyl groups. 

Summary of IUPAC Nomenclature of Alkanes and Cycloalkanes (Continued)... 

Substitutive IUPAC nomenclature names epoxides as epoxy derivatives of alkanes. According to this system, ethylene oxide becomes epoxyethane, and propylene oxide becomes 1,2-epoxypropane. The prefix epoxy- always immediately precedes the alkane ending it is not listed in alphabetical order like other substituents. 

Ethers are named, in substitutive IUPAC nomenclature, as alkoxy derivatives of alkanes. 

Recall from Section 6.18 that epoxides may be named as -epoxy derivatives of alkanes in substitutive IUPAC nomenclature. 

Section 16.1 Ethers are compounds that contain a C—O—C linkage. In substitutive IUPAC nomenclature, they are named as alkoxy derivatives of alkanes. In functional class IUPAC nomenclature, we name each alkyl group as a separate word (in alphabetical order) followed by the word ether. 

Sulfides are sulfur analogs of ethers they contain the C—S—C functional group. They are named as alkylthio derivatives of alkanes in substitutive IUPAC nomenclature. The functional class IUPAC names of sulfides are derived in the same manner as those of ethers, but the concluding word is sulfide. 

IUPAC nomenclature names ethers as alkoxy alkanes, alkoxy alkenes, or alkoxy alkynes. The group in the chain that has the greatest number of carbon atoms is designated the parent compound. In the case of aromatic ethers, the benzene ring is the parent compound. 

A systematic method for naming alkanes (and other organic compounds) that is simple to use and minimizes memorization was developed by the International Union of Pure and Applied Chemistry and is called the IUPAC nomenclature. To make it easier for the chemists of that time to learn, it incorporated common nomenclature wherever possible. 

There are two ways of naming alkyl halides. The systematic (IUPAC) nomenclature treats an alkyl halide as an alkane with a halo- substituent Fluorine is fluoro-, chlorine is chloro-, bromine is bromo-, and iodine is iodo-. The result is a systematic haloalkane name, as in 1-chlorobutane or 2-bromopropane. Common or trivial names are constructed by naming the alkyl group and then the halide, as in isopropyl bromide. This is the origin of the term alkyl halide. Common names are useful only for simple alkyl halides, such as the following ... 

The IUPAC nomenclature for amines is similar to that for alcohols. The longest continuous chain of carbon atoms determines the root name. The -e ending in the alkane name is changed to -amine, and a number shows the position of the amino group along the chain. Other substituents on the carbon chain are given numbers, and the prefix N- is used for each substituent on nitrogen. 

The IUPAC nomenclature for carboxylic acids uses the name of the alkane that corresponds to the longest continuous chain of carbon atoms. The final -e in the alkane name is replaced by the suffix -ok acid. The chain is numbered, starting with the carboxyl... 

As we cover new functional groups in later chapters, the applicable IUPAC rules of nomenclature will be given. In addition, Appendix A at the back of this book gives an overall view of organic nomenclature and shows how compounds that contain more than one functional group are named. For the present, let s see how to name branched-chain alkanes and learn some general naming rules that are applicable to all compounds. 

Alkanes are a class of saturated hydrocarbons with the general formula C H2n. -2- They contain no functional groups, are relatively inert, and can be either straight-chain (normal) or branched. Alkanes are named by a series of IUPAC rules of nomenclature. Compounds that have the same chemical formula but different structures are called isomers. More specifically, compounds such as butane and isobutane, which differ in their connections between atoms, are called constitutional isomers. 

We can present and illustrate the most important of the IUPAC rules for alkane nomenclature by naming the five C6H14 isomers. By definition (Table 2.2), the unbranched C6H14 isomer is hexane. 

Tabular summaries of the IUPAC rules for alkane and alkyl group nomenclature appear on pages 96-98. 

Diols are almost always given substitutive IUPAC names. As the name of the product in the example indicates, the substitutive nomenclature of diols is similar to that of alcohols. The suffix -diol replaces -ol, and two locants, one for each hydroxyl group, are required. Note that the final -e of the parent alkane name is retained when the suffix begins with a consonant (-diol), but dropped when the suffix begins with a vowel (-ol). 

B is correct. The following IUPAC rules of nomenclature must be used to name an alkane ... 

The five IUPAC rules previously outlined in the Nomenclature section for aldehydes also apply to ketones, with one exception After dropping the -e ending of the alkane name, you add -one for ketones (rather than -al, which designates aldehydes). 

We have been using the common nomenclature of ethers, which is sometimes called the alkyl alkyl ether system. The IUPAC system, generally used with more complicated ethers, is sometimes called the alkoxy alkane system. Common names are almost always used for simple ethers. 

Several additional examples of alkane nomenclature are given in Figure 4.1. Sampl Problem 4.2 Give the IUPAC name for the following compound. 

IUPAC rules allow for two systems of nomenclature, depending on the complexity of the acid molecule. Carboxylic acids that are derived from open-chain alkanes are systematically named by replacing the terminal -e of the corresponding alkane name with -oic acid.The carboxyl carbon atom is numbered Cl in this system. 

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