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Downloaded by PENNSYLVANIA STATE UNIV on June 21, 2012 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0126.ch007
Hetero-Acyclic Systems
Chapter 6 details the principles of replacement nomenclature and their application to organic heterocyclic systems. Originally developed and used exclusively for naming cyclic compounds, the replacement concept has since been extended to acyclic compounds, chiefly because it provides relatively simple systematic names for complex structures—i.e., for straight chains containing more than two hetero atoms. However, in the broadest sense a hetero-acyclic system is any chain, branched or unbranched, containing atoms of at least two different elements. Treatment of organic hetero chains by replacement nomenclature is the subject of this chapter. Application of the replacement method to inorganic chains is illustrated for silicon compounds in Chapter 38. Recommended Nomenclature Practice In replacement nomenclature, straight-chain organic hetero-acyclic systems are named analogously to heterocyclic systems (see Chapter 6) using the prefixes shown in Table 6.1. The hetero chain always terminates with carbon. CH OCH CH OCH OCH CH 3
2
2
2
2
CH SCH OCH CH NHCH 3
2
2
2
2,5,7-Trioxanonane
3
4-Oxa-2-thia-7-azaoctane
3
Lowest possible numbers are assigned first to the hetero atoms and then to atoms bearing double or triple bonds as described in Chapter 2. CH SCH CH OCH NHCH=CH 3
2
2
2
2
5-Oxa-2-thia-7-azanon-8-ene
In naming branched-chain organic hetero-acyclic systems the parent chain is selected by applying the following criteria in the order of listing: (1) The longest straight chain containing the maximum number of hetero atoms. (2) The longest straight chain containing the maximum number of the species o f hetero atom standing highest i n Table 6.1. (3) The longest straight chain carrying the maximum number of double and triple bonds. 65 In Nomenclature of Organic Compounds; Fletcher, J., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
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NOMENCLATURE OF ORGANIC COMPOUNDS
^CH OCH CH OCH CH OCH
