Some Common Group Tables

Organic molecules are classified according to the functional groups they contain, where a functional group is defined as a combination of atoms that behave as a unit. Most functional groups are distinguished by the heteroatoms they contain, and some common groups are listed in Table 12.1. 

Table 5.7 Estimate of the electronegativities of some common groups...

INTRODUCTION TO CHEMICAL NOMENCLATURE Table 4. Some common groups... 

The Chains and Averages of Polymers Table 1.3 Name, Abbreviation, and R Group for Some Common Amino Acids ... 

Odor perception and description are highly subjective in nature. Nevertheless, there is a generally agreed-upon odor vocabulary that is used to characterize individual ingredients and finished fragrances. Table 1 shows some commonly used odor descriptors grouped into five general classifications. 

Quaternary ammonium compounds are usually named as the substituted ammonium salt. The anion is Hsted last (3). Substituent names can be either common (stearyl) or lUPAC (octadecyl). If the long chain in the compound is from a natural mixture, the chain is named after that mixture, eg, taHowalkyL Prefixes such as di- and tri- are used if an alkyl group is repeated. Complex compounds usually have the substituents Hsted in alphabetical order. Some common quaternary ammonium compounds and their appHcations in patent Hterature are Hsted in Table 1. 

Cluster emission is an exotic decay that has some commonalities with a-decay. In a-decay, two protons and two neutrons that are moving in separate orbits within the nucleus come together and leak out of the nucleus as a single particle. Cluster emission occurs when other groups of nucleons form a single particle and leak out. Several of the observed decays are shown in Table 10. The emitted clusters include C, Ne, Mg, and Si. The... 

Table 3. Relative Permeability of the Heartwood of Some Common Species, Decreasing from Group 1 to Group 4...

Table 3.1 Structures of Some Common Functional Groups...

The polarity patterns of some common functional groups are shown in Table 5.1. Carbon is always positively polarized except when bonded to a metal. 

Table 1.1. Approximate pAT Values from Some Compounds with Carbanion Stabilizing Groups and Some Common Bases3...

Taking into account that Bq parameters represent the coefficient of an operator related to the spherical harmonic ykq then the ranges of k and q are limited to a maximum of 27 parameters (26 independent) Bq with k = 2,4,6 and q = 0,1,. .., k. The B°k values are real and the rest are complex. Due to the invariance of the CF Hamiltonian under the operations of the symmetry groups, the number of parameters is also limited by the point symmetry of the lanthanide site. Notice that for some groups, the number of parameters will depend on the choice of axes. In Table 2.1, the effect of site symmetry is illustrated for some common ion site symmetries. 

It should now be apparent how the species A1( A2, Bv and B2 arise. Character tables have been worked out and are tabulated for all the common point groups. Presenting all the tables here would go beyond the scope of the discussion of symmetry and group theory as used in this book. However, tables for some common point groups are shown in Appendix B. 

Table 11.3. Some common organic functional groups, showing the family name, the prefix or suffix usedfor naming the group, the drawn structure, and the written formula. 

Table VIII lists some commonly used activating groups. That most widely in use is dicyclohexylcarbodiimide (DCC), often in conjunction with additives such as A -hydroxysuccinimide (HONSu) or HOBt. These convert the O-acyl isourea intermediate 12 into the N-acyl derivative 13 (Scheme 14), which is less prone to racemization under the experimental conditions. But it must be emphasized that all such chemical methods involve some racemization of asymmetric centers, and the trick is to reduce this to an absolute minimum.

The adsorptive effects of the polar adsorbents are often due to the presence of hydroxyl groups and the formation of hydrogen bonds with the solute molecules. The strength of these bonds and hence the degree of adsorption increases as the polarity of the solute molecule increases. In order to separate the solute from the adsorbent it is necessary to use a solvent in which the solute will dissolve and which also has the ability to displace the solute from the adsorbent. Solvents that are too polar will overwhelm the adsorptive effects and result in the simultaneous elution of all the components of a mixture. Table 3.3 lists various classes of compounds and some common solvents in order of polarity. 

Some research groups have investigated effects of substituents less common in organic chemistry. Quin and co-workers (127,128) determined a-SCSs of tri-and tetravalent phosphorus substituents in n-alkyl and cyclohexyl derivatives (Tables 5 and 6). The difference between -PH2 and -P(CH3)2 effects is easily explained by 3-SCS(CH3) (about 10 ppm for each methyl) this approach, however, is not satisfactory for P(OCH3)2 and PC12, since it would suggest a-SCS values of ca. 16 (found 21.4) and ca. 22 (found 32.5), respectively, for those two substituents. A stereochemical dependence similar to that of X = CH3 and OH seems to exist only for the primary phosphine (X = PH2) and the compounds with tetravalent phosphorus substituents, whereas the a-SCS values of the tri-valent functions are quite similar in many cases, regardless of their stereochemical position. 

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