Parent series, model

Table V gives substituent tr values measured in the absence of surfactant for the five parent series previously compared in Table III. Examination of the table indicates that the experimentally measured TFMS series tt values do not coincide with those of any of the other parent series but lie roughly midway between the corresponding tt values of the phenoxyacetic acid and phenol series. In those cases where comparisons are possible, ir values for the 4-CH3, 4-F, 4-OCH3, 3-COCH3, and 3-OH substituents in the TFMS series lie closer to the tt values of the corresponding substituents in the phenoxyacetic acid series than they do to those in the phenol series. In contrast, w values for TFMS 4-C1, 3-CF3, 3-C1, and 3-F substituents lie closer to corresponding phenol series tt values. On the basis of the direct comparison between parent series afforded by Table V, it is evident that none of the partitioning data previously presented by Fujita et al. (II) for the various model parent series adequately describe the partitioning behavior of the substituted trifluoromethanesulfonanilide herbicides.

Model Parent Compound Series. Experimental partition coefficient data for a variety of substituted benzenes and seven other related parent compound series (phenoxyacetic acid, phenylacetic acid, benzoic acid, benzyl alcohol, phenol, aniline, nitrobenzene) were reported in 1964 by Fujita et al. (II). The ir values (see Equation 3) derived for individual substituents in each of the above-mentioned parent compound series have since been frequently used (with varying degrees of success) by many investigators to approximate tt values for the corresponding substituents in other related parent compounds for which no experimental partitioning data are available. For example, Hansch and Deutsch (26), in a correlation study of structure—activity relationships in cholinesterase inhibitors, used tr values derived for aromatic ring substituents (X) in the phenoxyacetic acid series... 

Before experimentally measuring the partition coefficients of our 15 trifluoromethanesulfonanilide (TFMS) series members, we too had given serious consideration to approximating the TFMS substituent tt values with appropriately chosen ir values from one of the above-mentioned parent series studied by Fujita et al. (II). The appropriate choice of an approximating parent compound was difficult to make, however, as can be judged from the ionization and partitioning data tabulated in Table III for several reasonable model series chosen from Ref. II. 

Therefore, it is difficult to define a reasonable basis for selecting any of the parent series previously examined by Fujita et al. (11) as a model for the TFMS series of the present study. Indeed, some initial Hansch analyses of our TFMS pre-emergence herbicidal activity data using Fujita s phenoxyacetic acid substituent n values produced very poor correlations. We thus deemed it prudent (if not essential) to determine experimentally w values for all substituents in the TFMS series. 

Complexes of the composition RCo (dioximeH)2L (R = alkyl, L = neutral ligand) and their parent complexes with BR2 bridges RCo(dioxime-BR2)2L 127 (Fig. 33) are known as organocobaloximes [173-178] and have received attention being models for vitamin B12 (cobalamines) [183]. A series of related complexes of the composition Fe (dioxime-BR2)LL 128 (Fig. 33) without the metal-carbon bond is also known [179, 180]. 

Pharmacokinetic Model—A set of equations that can be used to describe the time course of a parent chemical or metabolite in an animal system. There are two types of pharmacokinetic models data-based and physiologically-based. A data-based model divides the animal system into a series of compartments which, in general, do not represent real, identifiable anatomic regions of the body whereby the physiologically-based model compartments represent real anatomic regions of the body. 

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