Homologous series functional groups

Homologous series Functional group and condensed structural formula Suffix in name of compound General formula Structure of the functional group... 

Chemistry is primarily concerned not with the properties of single molecules but with periodic trends, homologous series, functional groups, and the like. 

Table 10.5 shows some of the different functional groups present in several homologous series. These groups are attached to, or part of, the hydrocarbon backbone or skeleton of the molecules in the series. They give the molecules the distinctive properties of the particular... 

Usually not favorable for separation of components that show similar Hquid-phase behavior, ie, steroisomers, homologous series, iso-notmA—neo isomers components to be separated must have some different functional group for MSA to affect Hquid-phase behavior differently. 

For a more detailed description or modeling of the surfactant properties of the alkanesulfonates it is necessary to use individual, well-defined compounds typical of the technical mixtures. Recently, new data were obtained from a series of individual homologous alkanesulfonates in which the positions of the functional group and the cations vary [38]. 

Activation volumes may be used to elucidate the mechanisms of classes of reactions involving the same functional groups, and changes in activation volumes can be used to characterize the point at which a change in reaction mechanism takes place in a series of homologous reactions. 

FIGURE 1. The relationships between the methyl deviation, 5(CH3— Z), and Pauling electronegativity of the bonded Z atom in various homologous functional group series, CH3—(CH2)m—Z. See References 17b and 18... 

In a homologous series, the compounds have the same general formula or successive members of the series differ by a -CH2- unit (1). The compounds undergo similar chemical reactions or contain the same functional group (1). 

The correct analysis of the homologous ion series has certain limitations. Low abundances of peaks in some series require the attention and experience of a researcher. Usually alkane series are dominated in the mass spectra of the most various compounds. Fragmentation initiated by one functional group may completely suppress or notably camouflage other reactions of polyfunctional substances. In the latter case it is useful to consider IR-spectroscopy data in mass spectral interpretation. 

The slopes, ag, for various n-alkyl substituted homologous series are commonly compared to the universal slope (methylene increment) of —20.6 kJmol-1 calculated for the n-alkanes9. An unanswered question is whether for Targe enough nc the methylene increment should be identical for all functionalized alkanes. In previous studies it is shown that the slopes vary, although not too widely (ca 2 kJ mol-1), and there is no discernible relationship between the functional group and a. With three exceptions, the slopes reported in Table 1 are in line with those calculated for other functional group series. 

The equivalence of the reactivities of the two functional groups in bifunctional reactants has also been demonstrated in many systems. The second column in Table 2-1 shows data for the esterification of a homologous series of dibasic acids ... 

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