Locants derived radicals

A special nomenclature exists for assemblies of identical cyclic units linked by single or double bonds in such a way that no new rings are created. Names are derived by combining the appropriate multiplying prefix (bi-, ter-, quater-, etc.) and either (a) the name of the cyclic unit or (b) that of the derived radical, with locants, primed where necessary, before the name indicating the positions of linkages, e.g., 53 and 54. 

Radicals from Ring Systems. Univalent substituent groups derived from polycyclic hydrocarbons are named by changing the final e of the hydrocarbon name to -yl. The carbon atoms having free valences are given locants as low as possible consistent with the fixed numbering of the... 

Metallocene derivatives may be named by either standard organic suffix (functional)7 or prefix nomenclature. Substituents are given the lowest numerical locants in the usual manner on the equivalent cyclopentadienyl rings of the ocene entity. The first ring is numbered 1 to 5 and the second ring is numbered V to 5. In metallocenes composed of multiple ocene groupings the cyclopentadienyl rings are further numbered 1" to 5", V" to 5", etc. The radical names -ocenyl, -ocenediyl, -ocenetriyl, etc. are used. For examples see Table 25. 

When a name applies equally to two or more isomeric condensed parent ring systems with the maximum number of non-cumulative double bonds and when the name can be made specific by indicating the position of one or more hydrogen atoms in the structure, this is accomplished by modifying the name with a locant, followed by italic capital H for each of these hydrogen atoms. Such symbols ordinarily precede the name. The said atom or atoms are called indicated hydrogen . The same principle is applied to radicals and compounds derived from these systems. 

Locants of substituents of symmetrically substituted derivatives of symmetrical amines are distinguished by primes or else the names of the complete substituted radicals are enclosed in parentheses. Unsymmetrically substituted derivatives are named similarly or as A-substituted products of a primary amine (after choosing the most senior of the radicals to be the parent amine). For example,... 

The principal groups lead to the endings -diacetic acid and -di(ethylamine) , respectively, in these two cases. The central unit —Y— is cited as the bivalent radical, p-phenylene- for -C6H4- and oxy- for O. Locants are added and the full names become p-phenylenediacetic acid and 2,2 -oxydi(ethyl-amine). The parentheses in the latter name serve te remove possible confusion with a derivative of diethylamine. 

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