Principal group

Substitutive Nomenclature. The first step is to determine the kind of characteristic (functional) group for use as the principal group of the parent compound. A characteristic group is a recognized combination of atoms that confers characteristic chemical properties on the molecule in which it occurs. Carbon-to-carbon unsaturation and heteroatoms in rings are considered nonfunctional for nomenclature purposes. 

Listed in order of decreasing priority for citation as principal group or parent name. 

If the characteristic group occurs in more than one cyclic system, that system is chosen as parent which (a) carries the largest number of the principal group or, failing to reach a decision, (b) is the senior ring system. 

If the characteristic group occurs both in a chain and in a cyclic system, the parent is that portion in which the principal group occurs in largest number. If the numbers are the same, that portion is chosen which is considered to be the most important or is the senior ring system. 

The side chain is considered to extend only from the principal group to the cyclic component. Any other chain members are named as substituents, with appropriate prefixes placed before the name of the cyclic component. 

Acyl Halides. Acyl halides, in which the hydroxyl portion of a carboxyl group is replaced by a halogen, are named by placing the name of the corresponding halide after that of the acyl radical. When another group is present that has priority for citation as principal group or when the acyl halide is attached to a side chain, the prefix haloformyl- is used as, for example, in fiuoro-formyl-. 

An aldehyde group is denoted by the prefix formyl- when it is attached to a nitrogen atom in a ring system or when a group having priority for citation as principal group is present and part of a cyclic system. 

When another principal group has precedence and oxygen is linking two identical parent compounds, the prefix oxy- may be used, as with 2,2 -oxydiethanol for HOCH2CH2OCH2CH2OH. 

Hydroxylamines and Oximes. For RNH—OH compounds, prefix the name of the radical R to hydroxylamine. If another substituent has priority as principal group, attach the prefix... 

For oximes, the word oxime is placed after the name of the aldehyde or ketone. If the carbonyl group is not the principal group, use the prefix hydroxyimino-. Compounds with the group Z = N—OR are named by a prefix alkyloxyimino- as oxime O-ethers or as O-substituted oximes. Compounds with the group r C=N(0)R are named by adding A-oxide after the name of the alkylideneaminc compound. For amine oxides, add the word oxide after the name of the base, with locants. For example, C5H5N—O is named pyridine A-oxide or pyridine 1-oxide. 

When another group having higher priority for citation as principal group is also present, the ketonic oxygen may be expressed by the prefix 0x0-, or one can use the name of the carbonyl-containing radical, as, for example, acyl radicals and oxo-substituted radicals. Examples are... 

Ester groups in R —CO—OR compounds are named (1) by the prefix alkoxycarbonyl- or aryloxycarbonyl- for —CO—OR when the radical R contains a substituent with priority for citation as principal group or (2) by the prefix acyloxy- for R —CO—O— when the radical R contains a substituent with priority for citation as principal group. Examples are... 

Organosulfur Halides. When sulfur is directly linked only to an organic radical and to a halogen atom, the radical name is attached to the word sulfur and the name(s) and number of the halide(s) are stated as a separate word. Alternatively, the name can be formed from R—SOH, a sulfenic acid whose radical prefix is sulfenyl-. For example, CH3CH2—S — Br would be named either ethylsulfur monobromide or ethanesulfenyl bromide. When another principal group is present, a composite prefix is formed from the number and substitutive name(s) of the halogen atoms in front of the syllable thio. For example, BrS—COOH is (bromothio)formic acid. 

Animal aquaculture is concentrated on finfish, moUuscs, and cmstaceans. Sponges, echinoderms, tunicates, turtles, frogs, and alligators are being cultured, but production is insignificant in comparison with the three principal groups. Common and scientific names of many of the species of the finfish, moUuscs, and cmstaceans currently under culture are presented in Table 2. Included are examples of bait, recreational, and food animals. 

Soft magnetic materials are characterized by high permeabiUty and low coercivity. There are sis principal groups of commercially important soft magnetic materials iron and low carbon steels, iron—siUcon alloys, iron—aluminum and iron—aluminum—silicon alloys, nickel—iron alloys, iron-cobalt alloys, and ferrites. In addition, iron-boron-based amorphous soft magnetic alloys are commercially available. Some have properties similar to the best grades of the permalloys whereas others exhibit core losses substantially below those of the oriented siUcon steels. Table 1 summarizes the properties of some of these materials. 

This is also known as the SIC Code and is assigned for tax and financial purposes. Because the classification can determine if a faciHty falls under certain regulations, it is important to ensure that the classification is correct. The SIC Code consists of four digits, the first two of which show the principal group. Eor chemicals and aUied products, this group is 28. Table 3 Hsts the Industry Group Numbers under this major group. 

Region Principal Group 24 (Lumber and wood products) Principal Group 26 (Paper and aUied products) Principal Group 28 (Chemicals and aUied products) Total... 

Cycloadditions resulting in ring-fused systems may be classified in two principal groups intramolecular and intermolecular cycloadditions. As the synthesis of the requisite precursor for an intramolecular cycloaddition is often more involved, more emphasis has been placed on those of an intermolecular nature. 

Table 7 lists some of the commonest substituent groups and the corresponding prefixes and/or suffixes, in order of priority for selection as principal group. Some examples of their use are given in (148)-(152). 

A large number of chiral crowns have been prepared by numerous groups. The reader is directed to the tables at the end of this chapter to obtain an overview of these structures. It would not be useful to try to recount the synthetic approaches used in the preparation of all of these compounds we have chosen rather to subdivide this mass of compounds into three principal groups. The groups are (1) Cram s chiral binaphthyl systems (2) chiral crowns based on the tartaric acid unit and (3) crowns incorporating sugar subunits. These are discussed in turn, below. 

Principal groups are listed in order of decreasing priority subordinate groups have no priori tv order. 

The arguments which have been advanced to support mechanisms of product formation involving ionic intermediates can be classified into two principal groups. 

Note 2. To maintain integrity of carbohydrate names, it is sometimes helpful to overstep the strict order of principal group preference specified in general organic nomenclature [13,14]. For example, a carboxymethyl-substituted sugar can be named as such, rather than as an acetic acid derivative (see 2-Carb-31.2). 

Kinetic studies indicated that external H interacted with the renal brush border Na /H exchanger (resistant-type) at a single site with apparent pKa 7.3-7.5. Because the imidazolium ring of histidine is the principal group that is titratable in this... 

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