Pesticides fluoro compounds

A limited number of pure substances are available from NIST, primarily clini-cally-relevant compounds such as cholesterol, urea, uric acid, creatinine, glucose, cortisol, tripalmitin, and bilirubin (NIST SRM website). These compounds are certified for purity (greater than 99 %) and are used as primary calibrants in definitive methods for these clinical analytes (see below). Several additional pure substances are available for specific applications such as microchemistry, i.e. elemental composition (acetanilide, anisic acid, cystine nicotinic acid, o-bromobenzoic acid, p-fluoro-benzoic acid, m-chlorobenzoic acid), polarimetric standards (sucrose and dextrose), acidimetric standard (benzoic acid and boric acid). Only three pure substance NIST RMs are available for environmental contaminants, namely the chlorinated pesticides, lindane, 4,4 -DDT, and 4,4 -DDE. 

Bowman and Beroza [472] hydrolysed carbamates by heating with 10% NaOH solution and condensed the phenol produced with chlorothiophosphate in the presence of pyridine (Scheme 5.37). The resulting derivative is highly specific for the compound under analysis and, with the use of a flame photometric detector, it permits its sensitive analysis (at the level of hundredths of 1 ppm in foodstuffs). A column packed with 10% of DC-200 was used for the analysis at 190°C. Holden et al. [473] also obtained a high sensitivity in the analysis of N-methyl- and dimethylcarbamates if they condensed amines released by alkaline hydrolysis with l-fluoro-2,4-dinitrobenzene and applied an ECD for detection (2% of XE-60, 190°C). Different substituted anilines were similarly analysed as products from the decomposition of different pesticides [474] in the form of different perfluorinated acyl derivatives. 

The preparation of a range of 3-difluoromethyl-l-methylpyrazole-4-carboxamides and 5-fluoro-l,3-dimethyl-4-carboxamides and carboxanilides are described in some patents. These compounds display important activities as fungicides (Fig. 8a) and bactericides (Fig. 8b) [99], Finally, the 3-trifluoromethylthyopyrazole motif is present in some pesticide hydrazide derivatives [100], and oxazolidines bearing a 3-trifluoromethyl-l-methyl-5-(2,2,2-trifluoro)ethoxypyrazole substituent show activity as herbicides [101]. 

---