How Do We Name Alkanes

Ideally, every organic compound should have a name from which its structural formula can be drawn. For this purpose, chemists have adopted a set of rules established by an organization called the International Union of Pure and Applied Chemistry (lUPAC). 

The lUPAC name of an alkane with an unbranched chain of carbon atoms consists of two parts (1) a prefix that indicates the number of carbon atoms in the chain and (2) the ending -ane to show that the compound is a saturated hydrocarbon. Table 3.2 gives the prefixes used to show the presence of 1 to 20 carbon atoms. 

The first four prefixes listed in Table 3.2 were chosen by the lUPAC because they were well established in the language of organic chemistry. In fact, they were well established even before there were hints of the structural theory underlying the discipline. For example, the prefix but- appears in the name butyric acid, a compound of four carbon atoms formed by the air oxidation of butter fat (Latin butyrum, butter). Prefixes to show five or more carbons are derived from Greek or Latin numbers. (See Table 3.1 for the names, molecular formulas, and condensed structural formulas for the first 20 alkanes with unbranched chains.) 

The lUPAC name of an alkane with a branched chain consists of a parent name that indicates the longest chain of carbon atoms in the compound and substituent names that 

Prefixes Used in the lUPAC System to Show the Presence of 1 to 20 Carbons in an Unbranched Chain 

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So far the only branched alkanes that we ve named have methyl groups attached to the mam chain What about groups other than CH3 What do we call these groups and how do we name alkanes that contain them d... 

The information in Table 2-5 enables us to name the first 20 straight-chain alkanes. How do we go about naming branched systems A set of lUPAC rules makes this a relatively simple task, as long as they are followed carefully and in sequence. 

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