Hantzsch-Widman names table

Table 3 Stem Suffixes for Hantzsch-Widman Names ...

The lUPAC recommendations regarding the Hantzsch-Widman names are not intended to supersede the commonly used traditional, trivial names listed in Table 1. 

For single rings (i.e. mononuclear systems) up to ten atoms in size, there is no question but that Hantzsch-Widman names are overwhelmingly the most widely used, and specialists can be presumed to recognize them readily. However, when one of the trivial names of Table 1 can be used, it prevails almost exclusively. Thiophene will be immediately understood by specialists and most nonspecialists, whereas thiole will distract the reader s attention from the chemistry while he considers the writer s intention is the Hantzsch-Widman system indeed being used, or is it a typographical error Chemical Abstracts also uses these trivial names in its indexes. 

Table 1 Stem suffixes for Hantzsch-Widman names...

The common, accepted names of most of the important monocyclic parents are given in Table 2.2, along with the systematic names from the Hantzsch-Widman naming system. The latter names are derived from the following four rules ... 

Systematic names of the Hantzsch-Widman type, as well as fusion names, imply unsaturation to the extent of the maximum number of noncumulative double bonds. Suitable suffixes (Table 3) serve to identify the fully saturated derivatives. Partially unsaturated rings may be designated by hydro prefixes with locants and an even-numbered multiplier, such as 2,3-dihydro , applied to a fully unsaturated name, or by dehydro prefixes applied to the saturated name, e.g. (116). 

The extended Hantzsch-Widman system is used to name monocycles of saturated and mancude rings with between three and ten members, inclusive. The names are composed of two parts non-detachable prefix(es), indicating the heteroatom and a stem indicating the size of the ring. Names of prefixes (called a prefixes) are listed in Table 4.8 and names of stems in Table 4.9. 

Table 4.9 Name stems used in Hantzsch-Widman nomenclature.

The modified element name sila indicates replacement in the carbon skeleton, and similar treatment can be applied to other element names. The parent hydride names of Table 5.2 may all be adapted in this way and used in the same fashion as in the oxa-aza nomenclature of organic chemistry. In inorganic chemistry, a major use is in names of cyclic derivatives that have heteroelement atoms replacing carbon atoms in structures. It may be possible to name such species by Hantzsch-Widman procedures (see p. 77), and these should always be used when applicable. 

This method is useful when dealing with simple heterocycles, but it can become clumsy with more complex ones. An alternative is the Hantzsch-Widman system, which uses the same prefixes, but adds a stem name designed to indicate not only the ring size but also the state of unsaturation or saturation (note when the stem name begins with a vowel the last letter, a, of the prefix is dropped). The stem names for rings containing up to 10 atoms are shown in Table 1.1. 

Table 1.1 Hantzsch-Widman stem names for heterocycles with 3-10 ring atoms...

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