Phenoxyacetic acids Table

There are several correlations for estimating the film mass transfer coefficient, kf, in a batch system. In this work, we estimated kf from the initial concentration decay curve when the diffusion resistance does not prevail [3]. The value of kf obtained firom the initial concentration decay curve is given in Table 2. In this study, the pore diffusion coefficient. Dp, and surface diffusion coefficient, are estimated by pore diffusion model (PDM) and surface diffusion model (SDM) [4], The estimated values of kf. Dp, and A for the phenoxyacetic acids are listed in Table 2. 

Table 2. Kinetic parameters of the phenoxyacetic acids in a batch reactor (298 K, pH 3.5).

It is seen from Table 16.4, for example, that TCA a phenoxyacetic acid type of herbicide has a solubility exceeding 500000pg L 1 while chlorotoluron, a phenyl urea herbicide has a water solubility of 70mg L-1. Thus, due to rainfall over a period of time the concentration of TCA in soil will reduce considerably more rapidly than that of chlorotoluron. 

Table 27. The stimulation of the growth of cultures of plant tissues under the action of 4-chloro-phenoxyacetic acid and its silatranylmethyl ester...

Gas chromatography has been used extensively for the determination of phenoxyacetic acid-type herbicides in soil extracts (Table 4.9). 

Other applications of gas chromatography to the determination of phenoxyacetic acid herbicides in non saline waters are discussed in Table 15.9. 

Other organic compounds that have been determined in waste waters include petroleum hydrocarbons, carboxylic acids, aliphatic and aromatic chlorocompounds and phenoxyacetic acid herbicides. See Table 15.14. 

Table III. Vapor Pressures of Esters of Phenoxyacetic Acid Herbicides by the Knudsen Effusion Method...

The important thing concerning volatility at various temperatures is the relative amount of material in the atmosphere at the different temperatures. If one knows the latent heat of vaporization, the tendency of the material to vaporize can be calculated from Equation 3. If we now consider preparations of derivatives whereby vapor loss can be reduced, it is immediately apparent that the latent heat of vaporization must be increased. This can be done with the phenoxyacetic acid compounds in preparing the so-called low volatile esters as represented by the butoxy-ethanol ester as illustrated in Table II. Determinations of the ratio of the latent heat of vaporization of the butoxyethanol ester to that of the isopropyl ester indicated a value of about 2. 

As Table I illustrates, the chemical classes represented by the pesticides studied include thiophosphates [0,0-diethyl-o-p-nitrophenyl phos-phorothioate], carbamates [1-naphthyI-N-methylcarbamate], dinitrophe-nols [2,4-dinitro-o-sec-butylphenol and 2,4-dinitro-o-cyclohexylphenol], and chlorophenoxy acids [2,4-dichlorophenoxyacetic acid, 2,4,5-trichloro-phenoxyacetic acid, and 2-(2,4,5-trichlorophenoxy)propionic acid]. In addition, a number of molecularly related nitrophenols have been studied to establish the effects of molecular geometry and substituent groups on adsorption of pesticide-type materials. 

The five parent compounds in Table III are arranged in order of increasing pKa of their ionizable protonic groups. For phenoxyacetic acid (pKa = 3.17) and phenylacetic acid (pKa = 4.31), the primary ionization is that of the carboxylic acid side chain. The acidity of the TFMS parent compound (pKa = 4.45) is attributable to the loss of the relatively labile proton from the parent side chain (< -NH-SOo-CF3 < -N -S02-CF3 -f- H+). For aniline, the process with pKa = 4.63 is associated with protonic ionization of the anilinium cation. The pKa = 9.89 process in phenol refers to the formation of phenolate anion. 

Although the pKa s of phenoxyacetic acid, phenylacetic acid, TFMS, and aniline are all quite similar, differing by less than 1.5 pK units for the most extreme comparison (phenoxyacetic acid vs. aniline), this similarity ends when the partitioning behavior of these same parent compounds is compared. Whereas the logarithm of the octanol/water partition coefficient (F) varies only from log F = 0.90 for aniline to log F = 1.41 for phenylacetic acid, TFMS (log F = 3.05) is 1.6 orders of magnitude more lipophilic than phenylacetic acid, the most hydrophobic of the other parent compounds exhibiting a similar pKa. If the w values for the side chains of the parent compounds listed in Table III are calculated using Equation 5 as shown on p. 196 ... 

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.

The use of hindered handles or functionalized solid supports would minimize piperazine-2,5-dione formation. Thus, the tertiary alcohol handle 4-(l, l -dimethyl-l -hydroxy-propyl)phenoxyacetic acid (DHPP, 1, Table and the 2-chlorotrityl chloride resin [Trt(2-Q)-C1 resin, are both very convenient for this purpose.t 1 An alternative proce-... 

Taking n values from the phenoxyacetic acid in Table 7 in Appendix 3. Taking n values from the phenol in Table 7 in Appendix 3. 

Ethacrynic acid (Table 10-11) is a powerful loop diuretic whose molecular mechanism of action is not fully clear. However, it has marked pharmacodynamic similarities to the mercurial diuretics such as merbaphen (see above) and mersalyl, both of which are also phenoxyacetic acid derivatives, as well as in vitro and in vivo comparability in its reaction with SH groups It competes with them for the same receptors. It is not surprising that an analogy, if not identity, of mechanism of action at the cellular level has been proposed. Equation 10.5, which illustrates a Michael-type addition, might represent a possible enzyme inactivation. 

H3BO3 and H4S1O4 (or Si(OH)4). These acids remain uncharged inmost agricultural soils and do not form anionic or cationic bonds. Important weak acids that dissociate to form anionic bonds with soil include the phenoxyacetic acids (2,4-D and 2,4,5-T) and carbonic acid (H2CO3). Their p/fa values are also given in Table 9.2. 

The substituent X has a tr value defined from the partitioning of substituted phenoxyacetic acids between n-octanol and water. Thus tt for the parent (x = H) is defined as zero. Both w and log P (Table 17) may be used as parameters, the former in a restricted series of substituted phenyl groups and the latter in more general correlations. 

EKC methodologies for aromatic sulfonates in industrial effluents, mono- and dinaphthale-nesulfonates as well as hydroxy- and amino-derivatives in river water, and phenoxyacetic acids in spiked water and soils are compiled in Table 31.8. Figure 31.9 illustrates the electromigration separation of aromatic sulfonates. 

The results of simple extraction experiments by the three new ligands synthesized are reported in Table I. For comparison the data obtained with the parent macrocycle (1) and the acyclic p.t-buty1-phenoxyacetic acid, both of which are unable to extract in organic media most of the cation tested, are also shown. 

New layers have been studied and introduced for the separation of 30 organic acids. For example, phenoxyacetic acid herbicide was separated from cinnamic, citric, gallic, maleic, oxalic acid, etc., on a calcium sulfate layer containing /r-dimethyl-aminobenzaldehyde and developed with distilled water (87) (Table 7). 

According to the Ref. [9], substituted phenoxyacetic acids were prepared by the condensation of corresponding substituted phenols with chloroacetic acid in the presence of alkali, such as sodium hydroxide (method M4-A). The synthetic route is shown in Scheme 2.7. Substituted phenoxyacetic acids M4-1-M4-16 prepared by this method M4-A are summarized in Table 2.3. 

In the reaction of chloroacetic acid with fluoro-substituted phenols or trifluo-romethyl-substituted phenols in the presence of sodium hydroxide, products had low yields because of a strong electron-withdrawing nature of the substituent. However, by using the method of Brayer et al. [10], fluoro-substituted phenoxy-acetic acids and trifluoromethyl-substituted phenoxyacetic acids M4-17-M4-27 (Table 2.4) could be prepared in satisfactory yields by the reaction of fluoro-substituted phenols or trifluoromethyl-substituted phenols with ethyl bromoacetate in the presence of K2CO3 in DMSO followed by alkaline hydrolysis (Scheme 2.8, method M4-B). Thus, a series of substituted phenoxyacetic acids M4-1-M4-27 was prepared by method M4-A or M4-B. 

The method for preparations of substituted phenoxyacetic acids M4 and substituted phenoxyacetyl chlorides MS has been discussed in Sect. 2.1.3. MS were prepared from corresponding substituted phenoxyacetic acids M4. M4-1-M4-3, M4-6-M4-8, and M4-9-M4-14 which were used to prepare IGr-U are shown in Table 2.7. M4 could be prepared according to the general synthesis procedure of M4 in Sect. 9.1.5. 

Lovenberg, Buchanan, and Rabinowitz (65) tested the response of ferredoxin to mercury compounds. Two mercurial reagents used, p-mer-curibenzoate (PCMB) and o-((3-hydroxymercuri-2-methoxypropyl)car-bamyl)phenoxyacetate (sodium mersalyl) reacted rapidly with ferredoxin and caused a bleaching of the visible spectrum and a concomitant loss of biological activity. C. pasteurianum ferredoxin was titrated with PCMB as described by Boyer (24) and the results showed that 20 moles of PCMB reacted with 1 mole of ferredoxin. In another determination, 2 moles of PCMB reacted with 1 mole of sodium sulfide. Since ferredoxin contained 7 moles of inorganic sulfide and 8 moles of half-cystine residues, 22 (7 x 2 = 14 14 + 8 = 22) moles of PCMB would be expected to react with 1 mole of ferredoxin. These data, summarized in Table 8, are consistent with the existence of two types of sulfur in ferredoxin. This conclusion was supported by the presence of half-cystine residues in ferredoxin after inorganic sulfide had been removed by acid hydrolysis, as well as results of sulfur analyses, which showed an amount of sulfur greater than could be attributed to half-cystine residues. 

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