Nomenclature cyclic

Although epoxides are always considered to have their oxygen atom as part of a three membered ring the prefix epoxy in the lUPAC system of nomenclature can be used to denote a cyclic ether of vanous sizes Thus... 

Frosts circle (Section 11 19) A mnemonic that gives the Huckel TT MOs for cyclic conjugated molecules and 10ns Functional class nomenclature (Section 4 2) Type of lUPAC nomenclature in which compounds are named according to functional group families The last word in the name... 

Organic ring systems are named by replacement nomenclature. Three- to ten-membered mono-cyclic ring systems containing uncharged boron atoms may be named by the specialist nomenclature for heterocyclic systems. Organic derivatives are named as outlined for substitutive nomenclature. The complexity of boron nomenclature precludes additional details the text by Rigaudy and Klesney should be consulted. 

Cyclic ethers are named either as heterocyclic compounds or by specialist rules of heterocyclic nomenclature. Radicofunctional names are formed by citing the names of the radicals R and R followed by the word ether. Thus methoxyethane becomes ethyl methyl ether and ethoxyethane becomes diethyl ether. 

Anions derived from cyclic imides may, of course, be named by the foregoing principles, but it is often desirable to name them so as to emphasize their functional character. To do so, the -imide name is changed to -imidide . Such anions are obviously mesomeric, but for nomenclature purposes they are considered to be derived from the more stable tautomer, the imide form, as shown in (201). 

It is often the case that chemists involved or familiar with ethylene oxide (oxiran) chemistry refer to these cyclic oligomers as EO-4, EO-6 and EO-7 respectively. Such designations are informal if not colloquial but, like any name, are useful if they correctly convey an idea. The difficulty with these informalities, indeed with the crown nomenclature system is that it cannot adequately deal with complicated structures or even isomers of simple ones. 

Pedersen prepared a series of macrocyclic polyethers, cyclic compounds containing four or more oxygens in a ring of 12 or more atoms. He called these compounds crown ethers, because their molecular- models resemble crowns. Systematic nomenclature of crown ethers is somewhat cumbersome, and so Pedersen devised a shorthand description whereby the word crown is preceded by the total number of atoms in the ring and is followed by the number of oxygen atoms. 

There is some evidence that Cs + can be formed by cyclic voltammetry of Cs+[OTeF5] in pure MeCN at the extremely high oxidizing potential of 3 V, and that Cs + might be stabilized by 18-crown-6 and cryptand (see pp. 96 and 97 for nomenclature). However, the isolation of pure compounds containing Cs + has so far not been reported. 

Cyclazines are conjugated cyclic molecules in which planarity is secured by three covalent bonds to a central nitrogen atom. They differ in the size of the individual ring units. In the nomenclature of cyclazines, the name is preceded by the number of jt-centers between the points of attachment to the nitrogen which are arranged by increasing number and put in brackets, e.g. [3.3.3]cyclazine (1) and [2.3.4]cyclazine (2). 

Carb-O. Historical development of carbohydrate nomenclature 0.1. Early approaches 0.2. The contribution of Emil Fischer 0.3. Cyclic forms 0.4. Nomenclature commissions 2-Carb-l. Definitions and conventions... 

The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules. 

Cyclic acetals formed by the reaction of saccharides or saccharide derivatives with aldehydes or ketones are named in accordance with 2-Carb-24.1, bivalent substituent names (formed by general organic nomenclature principles) being used as prefixes. In indicating more than one cyclic acetal grouping of the same kind, the appropriate pairs of locants are separated typographically when the exact placement of the acetal groups is known. 

Acetals, nomenclature, 123-124 cyclic, nomenclature, 121-122 Acid degradation, monosaccharides, 457-459 Acid hydrolysis... 

Haworth representation, cyclic monosaccharides, 61-63 Hemiacetal groups disaccharides with, 149-150 without, 148-149 nomenclature, 122-123 oligosaccharides with, 153-154 without, 151-153... 

Replacement nomenclature relating the cyclic ether to the corresponding... 

Because of space limitations, only meso- and macrocycles possessing heteroatoms and/or subheterocyclic rings are reviewed in general, lactones, lactams, and cyclic imides have been excluded. In view of the delayed availability of some articles appearing in previous years, several have been incorporated. The introduction of a systematic nomenclature of catenanes, rotaxanes, and derived assemblies has recently appeared <00JPC437> this should have appeared two decades ago, but is still timely in futuristic point of view. 

Cyclic peptides are analyzed less frequently then the linear ones but their sequencing and nomenclature are much more complicated. There is no generally accepted nomenclature scheme but we describe here the one proposed by Ngoka and Gross [4]. It takes account of Roepstorff-Fohlmann s and Biemann s conventions but introduces amendments to address cyclic peptide fragmentation. 

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