Detachable prefixes

The systematic name consists of the prefix deoxy- , preceded by the locant and followed by the stem name with such configurational prefixes as necessary to describe the configuration(s) at the asymmetric centres present in the deoxy compound. Configurational prefixes are cited in order commencing at the end farthest from C-l. Deoxy is regarded as a detachable prefix, i.e. it is placed in alphabetical order with any substituent prefixes. 

Note. The treatment of anhydro (see 2-Carb-26), dehydro (see 2-Carb-17.3) and deoxy as detachable prefixes follows long-standing practice in carbohydrate chemistry, but is in conflict with [14] (p. 12). 

The compounds are named by use of a combination Df deoxy- and amino- prefixes. When the complete name of the derivative includes other prefixes, deoxy- takes its place in the alphabetical order of detachable prefixes. 

Note. It is common practice in carbohydrate names to regard thio as detachable, and therefore alphabetized with any other prefixes. 

An intramolecular ether (commonly called an intramolecular anhydride), formally arising by elimination of water from two hydroxy groups of a single molecule of a monosaccharide (aldose or ketose) or monosaccharide derivative, is named by attaching the (detachable) prefix anhydro- preceded by a pair of locants identifying the two hydroxy groups involved. 

Note. Detachable prefixes are cited in alphabetical order along with any substituent prefixes. Examples ... 

The (non-detachable) prefix carba- signifies replacement of a heteroatom by carbon in general natural product nomenclature [26], and may be applied to replacement of the hemiacetal ring oxygen in carbohydrates if there is a desire to stress homomorphic relationships. If the original heteroatom is unnumbered, the new carbon atom is assigned the locant of the non-anomeric adjacent skeletal atom, with suffix a . 

Alphabetical order for citation of detachable prefixes. Prefixes are used to name substituents, as discussed above. Such prefixes are called detachable prefixes. There is a further class of prefix described as non-detachable. An example is cyclo-, as in cyclohexyl, which is different in stoichiometry from the unmodified hexyl. Non-detachable prefixes are used to modify permanently the name of a parent hydride and thus to create a new parent hydride (see also section 4.5.3.4, p. 78). 

When constructing a name, detachable prefixes are cited in front of the name of the parent hydride in alphabetical order. The names are alphabetised by considering the first letter of each name m in methyl, b in butyl, d in 1,2-dimethylpropyl. In retained names, the first non-italicised letter is considered i in isobutyl, n in neopentyl, but b in tert-huiy. ... 

The assembly of the components to construct a full name starts by attaching the names of the detachable prefixes in alphabetical order to the name of the parent hydride. Then, and only then, necessary multiplicative prefixes are introduced, without changing the alphabetical order obtained previously. Finally, locants are inserted. 

In some names with more than one detachable prefix, a set of locants can be attributed in more than one way, as with the locants 3 and 5 in the following example. In such a case, the lowest locant is allocated to the substituent cited first. 

The numbering of monocyclic hydrocarbons is not fixed, as any carbon atom may receive the locant 1 . Non-detachable prefixes have priority for lowest locants, and if this is indicated hydrogen it must receive the locant 1 . The importance of the presence of an indicated hydrogen is evident in substituted rings. 

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. 

Replacement nomenclature is used to name heteromonocycles that contain more than ten atoms. In developing a replacement name, carbon atoms are regarded as exchanged for heteroatoms. The non-detachable prefixes (Table 4.8) are used to indicate the exchange. Cycloalkane or annulene names are the bases for transformation into the name of a heterocycle. 

The non-detachable prefixes bicyclo-, tricyclo-, etc. and spiro- characterise the bridged and the spiro systems. Numbers in square brackets give necessary information about the lengths and positions of the bridges in these polycyclic systems. 

When a system does not have a retained name or a name that can be composed systematically as above, and when ortho- and ortho-peri- x% on are possible, it is named using fusion nomenclature, i.e. by combining the names of the two or more systems that are fused. One system is adjudged to be the senior according to criteria described elsewhere and is taken as a parent hydride, and the other is denoted in the name by a non-detachable prefix. The junction of the two systems is indicated in a specific manner. Instead of numerical locants, italic letters a , 6 , c , etc. are used to identify bonds in the parent hydride. The final letter o and normal locants are characteristic of the prefix. The examples below illustrate the fusion operation and the resulting fusion name. 

In one method, the non-detachable prefixes hydro- and dehydro- (in the case of mancudes only) can be used to indicate the addition or subtraction of one hydrogen atom. As even numbers of hydrogen atoms are involved when a carbon-carbon single bond becomes a double or triple bond, the multiplicative prefixes di-, tetra-, etc., as well as the appropriate locants, are used. The prefix dehydro- is always used to indicate the subtraction of hydrogen atoms from saturated heterocycles having Hantzsch-Widman names. 

If a choice has to be made, lowest locants are assigned first to heteroatoms in cycles, then to positions of unsaturation and, finally, to substituents cited as detachable prefixes. 

Steroids are compounds possessing the tetracyclic skeleton of cyclopenta[a]phenan-threne (1) or a skeleton derived therefrom by one or more bond scissions or ring expansions or contractions. Natural steroids have trivial names. The nomenclature of steroids is not based on these trivial names, but on a few stereoparent hydrides that are common to many compounds. Substitutive nomenclature is used to designate characteristic groups and unsaturation. Structural modifications are expressed by appropriate non-detachable prefixes. 

Non-detachable prefixes are used to indicate modifications afiecting rings homo-(enlarging), seco- (opening) and nor- (contracting). Locants are supplied as necessary to indicate the positions of modification. 

Prefixes are of two kinds, detachable and nondetachable. Nondetach-able prefixes, such as bicyclo, spiro, benzo, aza, ethano, are integral parts of the parent name and should not be separated from it. Their use has been described already. Detachable prefixes almost invariably refer to substituents and appear in alphabetical order before the parent name. Hydro and subtractive prefixes (e.g., demethyl) have sometimes been treated as nondetachable, appearing immediately before any other nondetachable prefixes, but it is preferable to treat them as detachable except when they do not have associated locants. This exception arises in particular when the name of a fully hydrogenated cyclic molecule is derived from a fully unsaturated parent name, e.g., 2-iodoperhydro-1-azanaphthalene (or 2-iododecahydro-l-azanaphthalene), 2-nitrotetra-hydrofuran. 

The use of alphabetical order for detachable prefixes is of some importance even when problems of indexing are ignored, since in some... 

Note Hydro and dehydro prefixes, if treated as detachable (see Rule C-16.11), are considered along with prefixes for substituents when this criterion is applied. 

See Chapter 2 of Fox and Powell for the detailed application of the following lUPAC conventions in organic names spelling, italics, punctuation, enclosing marks, locants, and detachable and non-detachable prefixes. 

Photograph the explants before fixation (the translucent zone cannot be seen after fixation). To avoid detachment of the tissues from the filters, prefix the explants in ice-cold methanol on the grids as follows Remove the culture medium by sucking, and pipet methanol gently on the tissues. Leave for 5 min, and transfer filters by watchmaker forceps to Eppendorf tubes for subsequent treatments (see Notes 8 and 9). Typical explants are shown in Fig. 3. 

Deoxy prefixes with a frontal locant are considered as detachable, therefore ordered alphabetically and used indiscriminately both for trivially and for systematically named sugars. In assigning the pertinent configurational descriptors, interposed CH2 (and also CO) groups are again disregarded. 

All prefixes encoding explicit statements about the structure of a pertinent acyclic or cyclic parent system are incorporated into the stem terms, i. e. treated as non-detachable parts of a name. 

In contrast, all substitutive prefixes (Tables 6,8) are treated as detachable and ordered alphabetically. 

Hydro and subtractive prefixes could traditionally be treated as non-detachable or detachable (Chem. Abstr., Beilstein) according to a very recent lUPAC proposal they are generally to be classified as non-detach-able. 

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