Phenolic ester pesticides

Table VII. Absorption Maxima for Phenolic Ester Pesticides and their Parent Chromophores...

OV1701 BP10 14% cyanopropyl 86% methyl polysiloxanes Medium polarity Alcohols, phenols, esters, ketones, pesticides... 

With the exception of picloram and phenols (Fig. 10, Table 3), acidic pesticides are considered nonvolatile from aqueous and soil systems [153]. Some ester formulations of these compounds also behave as herbicides. They do not ionize in solution and are less water-soluble than the acid or salt forms. They are eventually hydrolyzed to acid anions in aqueous and soil systems, but in the ester form are non-ionic and relatively volatile. 

Those degradation products which have been identified in our investigations are 1-naphthol from carbaryl, 2,4-D acid and 2,4-dichlorophenol from 2,4-D ester, 2-chloro-2, 6 -diethylacetanilide from alachlor, o,o,oe-trifluro-2-nitro-6-amino-N,N-dipropyl-p-tolu-idine and o,o,o-trifluro-2,6-diamino-N,N-dipropyl-p-toluidine from trifluralin, and a variety of phenols and acids from the degradation of the aromatic solvents used in the formulation of the liquid pesticides as emulsifiable concentrates (41,42). 

Twenty-five acidic pesticides, most of which resulted from the rapid hydrolysis of the ester formulations, were isolated from the two pits. Thirty-nine substituted aromatic acids and phenols were also isolated from the pits. The source of these components was most likely the degradation of aromatic pesticides and the... 

SFE/derivatization of several chlorinated acid pesticides (those listed in EPA method 515.1) have been performed using conditions similar to those used for the bacterial phospholipids. The derivatized products from the SFE procedure for several representative organics are shown in Figure 6. As would be expected using the TMPA/methanol reagent, the carboxylic acids form the methyl esters (2,4-D and dicamba) while the phenols form the methyl ethers (pentachlorophenol). Esters of the carboxylic acids (e.g., the di-isopropyl amine ester of 2,4-D) also form the methyl esters. For ethers, two derivatized products resulted since the ether linkage could be cleaved on either side of the oxygen and methylated as shown by acifluorfen. 

Reduction of aromatic nitro groups occurs in three steps, via nitroso and hydroxylamine intermediates, to the amine. The amine can go on to form polymeric residues by a mechanism analogous to that for oxidative coupling of phenols, as in Equation 2. Abiotic nitro reduction is well documented for pesticides that contain aromatic nitro groups, such as the phosphorothioate esters methyl and ethyl parathion (22, 30-33). 

Highly selective to halogenated and oxygenated compounds Electron capture detector EDB, DBCP (EPA 8011) Acrylamide (EPA 8032) Phenols (EPA 8041) Phthalates (EPA 8061) Organochlorine pesticides (EPA 8081) PCBs (EPA 8082) Nitroaromatics and cyclic ketones (EPA 8091) Haloethers (EPA 8111) Chlorinated herbicides (EPA 8151) CLP SOW for organic analysis Interferences from Elemental sulfur (S8) Waxes, lipids, other high molecular weight compounds Phthalate esters, which are common laboratory contaminants Oil in PCB analysis... 

Organic compounds (PAHs, phenol and derivatives, PCBs, diben-zofurans and dibenzodioxins, pesticides, humic compounds, phthalic acid esters, amines, drugs) Natural waters, waste, serum, biological fluids, plant and animal samples, sediments LC, HPLC... 

Highly hydrophobic sorbents including porous carbon and copolymers of styrene and divinylbenzene (SDB) were widely investigated for environmental applications. The particle-loaded membranes containing modified SDB particles with surface sulfonic acid groups were successfully used for recovering different alcohols, phenols, aldehydes, ketones, or esters from aqueous samples [221]. Carbon-based PLM were also used for isolation of highly polar pesticides from water [222]. 

ACD is a skin reaction resulting from contact dermal contact with allergens. ACD progresses in two phases. Sensitization is acquired in the initial phase. In the second phase, subsequent exposure elicits an inflammatory reaction. F°1 Large numbers of chemical compounds are known to cause ACD. These include acrylates, aldehydes, amines, anhydrides, etha-nolamines, formaldehyde, resins, metals, pesticides, phenols, phthalate esters, preservatives, isocyanates, solvents, and others. Table 27.4 contains a partial list of these. A more complete list can be found on the webJ21l... 

Hammett (and related sigma) relationships have been applied to aquatic reactions of several classes of aromatic contaminants. For example, alkaline hydrolysis of triaryl phosphate esters fits a Hammett relationship (Table 3) is t he sum of the substituent constants for the aromatic groups and k0 is the hydrolysis rate constant for triphenyl phosphate (0.27 M 1 s-1 t1/2 = 30 days at pH 8). Triaryl esters thus hydrolyze much more rapidly than trialkyl or dialkyl-monoaryl esters under alkaline conditions. Rates of photooxidation of deprotonated substituted phenols by singlet oxygen have been found to be correlated with Hammett a constants (Scully and Hoigne, 1987). The electronic cllects of substituents on pKa values of substituted 2-nitrophenols also fit a I lammett relationship this, of course, is not a kinetic LFER. Two compounds (4-phenyl-2-NP and 3-methyl-2-NP) did not fit the relationship and were not included in the regression. Steric effects may account for the discrepancy for the latter compound. Nitrophenols are used as intermediates in synthesis of dyes and pesticides and also used directly as herbicides and insecticides. 

In general, the N-substituted derivatives of carbamic acid are unstable compounds, especially under alkaline conditions, their decomposition results in the formation of an alcohol or phenol, ammonia, amines and carbon dioxide. These salts and esters of N-substituted carbamic acid are more stable, this enhanced stability is the basis for their use as biologically active pesticides. 

Mexacarbate. 4-(Dimethylaminoy-3,5-dimethyl phenol mcthylcarbamate (ester) melhylcarbamic acid 6(ii-methylamino)-3,S-xylyl ester 4-dimethylamino-3,5-xylyl methylcarbamate Zectran. C.,HttN,0, raol wt 222.29. C 64.84%, H 8.]6%, N 12.60%, 6 14.40%. Outline of prepn starting with 3,5-xylenol Marquardt in Analyl Methods for Pesticides 2 (Academic Press, New York, 1964) pp 581 596. Metabolic studies Roberts et al, J. Agr. Food Chem. 17, 107 (1969). Toxicity studies to insects El-Aziz et al, J. 

Diethyl 0-[4-(melhylsulfinyl)phenyl] phosphoro-thioate, AI3-24945 BAY 25141 Bayer 25141 BRN 2219515 Caswell No. 343 Chemagro 25141 Daconit Dasanit Diethyl p-methylsulfinylphenyl thiophosphate p,0-Diethyl O-p-(methylsuifinyl)phenyl thiophosphate EINECS 204-114-3 ENT 24,945 EPA Pesticide Chemical Code 032701 Fensulfothion HSDB 1580 OMS 37 0,0-Diaethyl-0-4-methylsulfinyl-phenyl-monothiophos-phat 0,0-Diathyl-0-4-methylsulfinyl-phenyl-monothio-phosphat 0,0-Diethyl 0-p-(methylsulfinyl)phenyl thiophosphate 0,0-Diethyl 0-4-methylsulphinylphehyl phosphorothioate 0,0-Diethyl 0-(p-(methylsulfinyl)-phenyl) phosphorothioate 0,0-Diethyl 0-(4-(methylsulfinyl)phenyl) phosphorothioate Phenol, p-(methylsulfinyl)-, 0-ester with 0,0-diethyl phosphoro-thioate Phosphorothioic acid, 0,0-diethyl 0-(4-(methylsulfinyl)phenyl) ester S 767 Terracur P VUAgT 96 ... 

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