Cycloalkane nomenclature

Cycloalkanes are alkanes that contain a ring of three or more carbons. They are frequently encountered in organic chemistry and are characterized by the molecular formula C H2 . Some examples include  

As you can see, cycloalkanes are named, under the lUPAC system, by adding the prefix cyclo- to the name of the unbranched alkane with the same number of carbons as 

When the ring contains fewer carbon atoms than an alkyl group attached to it, the compound is named as an alkane, and the ring is treated as a cycloalkyl substituent  

SAMPLE SOLUTION (a) The molecule has a tert-butyl group bonded to a nine-membered cycloalkane. It is tert-butylcyclononane. Alternatively, the tert-butyl group could be named systematically as a 1,1-dimethylethyl group, and the compound would then be named (1,1-dimethylethyl)cyclononane. (Parentheses are used when necessary to avoid ambiguity. In this case the parentheses alert the reader that the locants 1,1 refer to substituents on the alkyl group and not to ring positions.) 

An additional feature of lUPAC 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  

When deciding on the proper direction, a point of difference occurs when one order gives a lower locant than another. Thus, although 2 is the first locant in both numbering schemes, the tie is broken at the second locant, and the rule favors 2,2,6,6,7, which has 2 as its second locant, whereas 3 is the second locant in 2,3,3,7,7. Notice that locants are not added together, but examined one by one. 

Finally, when equal locants are generated from two different numbering directions, choose the direction that gives the lower number to the substituent that appears first in the name. (Remember, substituents are listed alphabetically.) 

Tabular summaries of the lUPAC rules for alkane and alkyl group nomenclature appear in Tables 2.5 and 2.6 on pages 93-94. 

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Skeletal isomerism of alkanes and stereochemistry of cycloalkanes Nomenclature of alkanes and cycloalkanes Preparation of alkanes... 

Cycloalkane Nomenclature 75 Sources of Alkanes and Cycloalkanes 76 Physical Properties of Alkanes and Cycloalkanes 77... 

Cycloalkane nomenclature is derived from that of the straight-chain alkanes. 

The heterocycloalkanes can be named using cycloalkane nomenclature. The prefix aza- for nitrogen, oxa- for oxygen, thia- for sulfur, and so forth, indicates the heteroatom. Other systematic and common names abound in the literature, particularly for the aromatic heterocycles. 

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