Nomenclature Cahn-Ingold-Prelog system

CE CGE CHOL CIP CPG CTAB CZE dA, dG, dC DBU DEAE DMF DMT DNP DOPE DOTMA EDTA EM EOF ESI-MS Fmoc FPE ICAM-1 Capillary electrophoresis Capillary gel electrophoresis Cholesterol Cahn-Ingold-Prelog nomenclature system for absolute configuration Controlled pore glass Hexadecyltrimethylammonium bromide Capillary zone electrophoresis Deoxyadenosine, deoxyguanosine, deoxycytosine l,8-Diazabicyc o[5.4.0]undec-7-en Diethylaminoethyl- Dimethylformamide Bis(4-methoxyphenyl)phenylmethyl-, (syn. Dimethoxytrityl-) 2,4-DinitrophenyI- Dioleylphosphatidylethanolamine N-[l-(2,3-dioleyloxy)propyl]-N, N, N-trimethylammonium chloride Ethylenediamine tetra-acetic acid Electrophoretic mobility Electro-osmotic flow Electrospray ionization mass spectrometry 9-Fluorenylmethoxycarbonyl-Fluid phase endocytosis Intracellular Adhesion Molecule-1... 

Over the years, several nomenclature systems have been developed to characterize the relationship between enantiomers. The system based on optical activity and the classification of enantiomers as dextrorotatory [d or (+)] or levorotatory [1 or (—)] already has been described. However, this system of nomenclature is of limited applicability because the sign of rotation, (+) or (—), does not predict the absolute configuration or the relative spatial arrangement of atoms in the enantiomers. In an attempt to designate the precise configurations about carbon centers of asymmetry, the Cahn-Ingold-Prelog RjS system have been developed and adopted as the most commonly used nomenclature system for isomers. 

Derivatives and Isomers of Alkenes Nomenclature The Cahn-Ingold-Prelog Priority System Relative Stability of Alkenes Heats of Formation Double Bonds in Rings Physical Properties of Alkenes Alkynes Structure and Bonding... 

FIGURE 1.1 Chemical and stereochemical nature of amino acids. Substituents in (a) and (b) are on opposite sides of the plane N-Ca-C, the bold bond being above the plane. Interchange of any two substituents in (a) changes the configuration. For the Cahn-Ingold-Prelog system of nomenclature, the order of preference NH2 > COOH > R2 relative to H is anticlockwise in (a) = (S) and clockwise in (c) = (R). 

In response to this nomenclature dilemma, the Cahn-Ingold-Prelog (IUPAC, International Union of Pure and Applied Chemistry) system of nomenclature was developed and is now the standard mediod to specify the relative configuration of chiral centers in molecules. Each chiral center will have two possible mirror-image configurations, which are designated as eidter R or S. 

To deal with this problem, we use the E-Z system of nomenclature (pun intended) for cis-trans isomers, which is patterned after the Cahn-Ingold-Prelog convention for asymmetric carbon atoms (Section 5-3). It assigns a unique configuration of either E or Z to any double bond capable of geometric isomerism. 

Cahn-Ingold-Prelog system of nomenclature (Section 5.6) The system of designating a stereogenic center as either Rot S according to the arrangement of the four groups attached to the center. 

In the stereochemical nomenclature of coordination compounds, the procedure for assigning priority numbers to the ligating atoms of a mononuclear coordination system is based upon the standard sequence rules developed for chiral carbon compounds (the Cahn, Ingold, Prelog or CIP rules6, see Section IR-9.3.3.2). 

The first proposed nomenclature suggested that isomers should be called cis when W and Y are on the same side of the double bond and trans when they are on the opposite side (Fig. 1.2), provided W X and Y Z. However, this nomenclature was limited to the particular case where W and Y are identical. The more recent nomenclature of Cahn-Ingold-Prelog, based on the German Zusammen (Z) and Entgegen (E) notation, was extended to systems where W and Y are different substituents (Fig. 1.2). There is no direct relation between the two nomenclatures since they depend on the nature of substituents and so the Z isomer is not necessarily cis. Moreover, the order of priority is determined by the atomic number of each atom connected to the C=C double bond [1]. Although the E/Z nomenclature may also be applied to compounds B/B and C/C, these are considered as conformational isomers, whereas compounds A/A are configurational isomers. 

Better answers Part of my goal in this edition has been to add more explanatory material to clarify how to arrive at the answer. The possibility of more than one answer to a problem has been noted. The IUPAC Nomenclature appendix has been expanded to include bicyclics, heteroatom replacements, and the Cahn-Ingold-Prelog system of stereochemical designation. 

Three chemists, R. S. Cahn (England), C. K. Ingold (England), and V. Prelog (Switzerland), devised a system of nomenclature that, when added to the lUPAC system, solves both of these problems. This system, called the i ,5-systeffl or the Cahn—Ingold-Prelog system, is part of the lUPAC rules. 

The Fischer nomenclature for these two series of compounds, D for (1) and L for (2), which was based on their chemical correlation to the two enantiomers of glyceraldehyde, has been largely superseded by the Cahn-Ingold-Prelog system. 

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