Phenoxypropionic acids

Phenoxyalkanoics. The phenoxyalkanoic herbicide grouping is composed of two subgroups, the phenoxyacetic acids and the phenoxypropionic acids. The phenoxyacetic acid herbicides include some of the first commercially successhil herbicides, eg, 2,4-D. They continue to be widely used for foUar control of broadleaf weeds. The more heavily functionalized phenoxypropionic acid herbicides are relatively new herbicides compared to the phenoxyacetic acids and are used primarily for selective control of grassy weeds in broadleaf crops (2,296,297). 

With regard to the resolution of enantiomers, some applications can be found with modified silica gel supports. Thus, a Pirkle-type CSP was used for the separation of 200 mg of a racemic benzodiazepinone [75]. Also tris-(3,5-dimethylphenyl)carba-mate of cellulose coated on silica [91, 92] was applied successfully to the resolution of the enantiomers of 2-phenoxypropionic acid and to oxprenolol, alprenolol, propranolol among other basic drugs. However, the low efficiency of this technique and the relative high price of the CSPs limits its use to the resolution of milligram range of sample. 

Phenoxy herbicides, 10 520 Phenoxypropionic acid herbicides, 13 314 Phenoxy resins, 10 6, 364-365 Phentermine, 3 91... 

Ibuprofen, naproxen, etodolac 2-phenoxypropionic acid, dichlorprop, 2-... 

Guillaume, Y.C. et al.. Chiral discrimination of phenoxypropionic acid herbicides on teicoplanin phase effect of mobile phase modifier, Chromatographia, 55, 143, 2002. 

MTD and MTD approaches will be discussed and compared using QSAR of insecticidal benzoylphenyl-ureas, DDT-type analogs and benzylchrysanthemates, herbicidal benzonitriles and nitrophenols, and plant-growth regulating phenoxypropionic acids. 

Another example of the use of the MTD and MTD approaches can be found in a series of optically active o-phenoxypropionic acids with auxin-like activity, partly published in ( ). The R-stereo isomers are much more active than the S-analoges. Both series were analyzed by Lien et al. (10) and a correlation with ir, a and the Van der Waals volume was found. The Pfeiffer rule is explained in terms of different structural requirements for the substituents as measured by and van der Waals volume. Analysing the series using STERIMOL delivered equations containing too many parameters. In Table III the equations are given as a result of... 

Table III Auxin-activity of phenoxypropionic acids (pC5p)...

Figure 6. Standards used in Equation 13 (left) and in Equation 17 (right) to obtain MTD values in a series of stereo isomers of phenoxypropionic acids.

HPOPS=(i )-2-(4-hydroxyphenoxy)propionic acid POPS=(R)-2-phenoxypropionic acid (Dingier et al, 1996)... 

Phenoxypropionic acid [940-31-8] 266 /758mm. Crystd from water. 

Fluazifop-butyl (26) (78BEP865137) is a promising heterocyclic representative of a new group of phenoxypropionic acids that are not auxin mimics. 

Other herbicidal phenoxyacetic and phenoxypropionic acids have some properties similar to those of (2,4-dichlorophenoxy)acetic acid, but often have quite different species selectivity. Some of the differences can be explained on the basis of molecular stability, persistence, or mobility in the toxic form, as well as on the basis of differences in solubility and in absorption through leaves or roots. 

Analytical Properties Separation of the drugs ibuprofen, ketoprofen, naproxen, 2-phenoxypropionic acid, bendroflumethiazide, ethotoin, hexobarbital, disopyramide, and RAC 109 retention and selectivity of the solutes can be regulated by addition of the tertiary amine /V,/V-dimethyloctylamine (DMOA) to the mobile phase DMOA decreases retention time and the enantioselectivity of the weaker acids but has opposite effects on the stronger acids Reference 3... 

Phenoxypropionic acid (249.0 g, 1.50 mol) is dissolved in four equivalents of thionyl chloride (438.0 ml, 6.0 mol) and heated to reflux until the HCI evolution has ceased. The solution is then cooled to room temperature and concentrated under reduced pressure to give 281.0 g (100% yield) of phenoxypropionyl chloride as a brown oil which solidifies on cooling. 

Phenoxypropionic acid (6.64 g, 0.04 mol) is mixed with excess ethanol (10 ml) and concentrated sulfuric acid (0.5 ml) is added. The reaction mixture is refluxed for 3 hours, cooled to room temperature and concentrated. The residue is washed with 1 N NaOH and brine, dried (Na2S04), and concentrated to yield 7.32 g (94.3% yield) of the ester which can be used directly for the subsequent reaction without further purification. 

The phenoxypropionic acid herbicides (Chapter 31) rely on an SN2 reaction to convert the S-2-chloropropionic acid (1) to the ff-2-aryloxy derivative 2.3 These compounds are also available from lactic acid by substitution reactions -lactic acid (3) requires two inversions, whereas S-lactate (4) only requires one (Schemes 22.2 and 22.3).4... 

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