Phosphorus agrochemicals

B. Richter, J. EzzeU, and D. Felix, Single Laboratory Method Validation Report Extraction of Organo-phosphorus Agrochemicals, Chlorinated Herbicides and Polychlorinated Biphenyls Using Accelerated Solvent Extraction (ASE) with Analytical Validation by GC/NPD and GC/ECD, Document 101124, Dionex Sunnyvale, CA (1994). 

Historically organic phosphorus agrochemicals meant insecticides. Today that is not the case. Organic phosphorus agrochemicals (Table 29.10) now include most applications. Just as organic carboxylic acids are vital to various life processes, so too are phosphorus compounds. Thus it is not surprising that phosphorous compounds find their place as versatile agrochemicals. 

The elemental phosphorus that is not converted into phosphoric acid is used mainly to produce phosphorus chlorides (PCI3 and PCI5) and phosphorus oxychloride (POCI3 ). These are important reagents for production of agrochemicals, drugs, and other specialty products. 

The most common final separation techniques used for agrochemicals are GC and LC. A variety of detection methods are used for GC such as electron capture detection (BCD), nitrogen-phosphorus detection (NPD), flame photometric detection (FPD) and mass spectrometry (MS). For LC, typical detection methods are ultraviolet (UV) detection, fluorescence detection or, increasingly, different types of MS. The excellent selectivity and sensitivity of LC/MS/MS instruments results in simplified analytical methodology (e.g., less cleanup, smaller sample weight and smaller aliquots of the extract). As a result, this state-of-the-art technique is becoming the detection method of choice in many residue analytical laboratories. 

The ability to efficiently synthesize enantiomerically enriched materials is of key importance to the pharmaceutical, flavor and fragrance, animal health, agrochemicals, and functional materials industries [1]. An enantiomeric catalytic approach potentially offers a cost-effective and environmentally responsible solution, and the assessment of chiral technologies applied to date shows enantioselective hydrogenation to be one of the most industrially applicable [2]. This is not least due to the ability to systematically modify chiral ligands, within an appropriate catalyst system, to obtain the desired reactivity and selectivity. With respect to this, phosphorus(III)-based ligands have proven to be the most effective. 

Al-Deen, T Saed, Hibbert, D B, Hook, J, and Wells, R (2002), Quantitative nuclear magnetic resonance spectrometry II. Purity of phosphorus-based agrochemicals glyphosate (N-(phosphonomethyl)-glycine) and profenofos (0-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate) measured by 1H and 31P QNMR spectrometry. Analytica Chimica Acta, 474 (1-2), 125-35. 

Oxalvl Chloride. This diacid chloride is produced by the reaction of anhydrous oxalic acid and phosphorus pentachloride. The compound vigorously reacts with water, alcohols, and amines, and is employed for tile synthesis of agrochemicals, pharmaceuticals, and fine chemicals. 

Earthworms are a natural feed source for poultry kept under free-range systems and, live or dried, are highly palatable to poultry. Meal made from earthworms contains about 600g/kg CP, with an amino acid composition comparable to that of fishmeal (Ravindran and Blair, 1983). It can replace fishmeal in chick and layer diets but care must be taken to balance the dietary calcium and phosphorus contents, since these minerals are low in earthworms due to the absence of an exoskeleton. Moreover, earthworms are known to accumulate toxic residues, particularly heavy metals and agrochemicals. 

Concentrating phosphoric acid leads to polyphosphoric acid, a mixture of several polymeric species, a good catalyst and dehydrating agent. Polyphosphate salts are used as water softeners in detergents or as buffers in food. Small quantities of elemental phosphorus are used to make matches, and phosphorus halides to prepare specialty chemicals for the pharmaceutical and agrochemical industries. 

Two other types of element-specific detector for nitrogen currently in use coupled to SFCs are the nitrogen phosphorus detector (NPD) and the thermal energy analyzer (TEA). The NPD uses a hot, catalytically active solid surface immersed in a layer of dissociated H2 and O2 to form electronegative N and P ions which are detected on a nearby electrode [2]. NPD has been shown to have broad application in SFC, especially in the agrochemical industry [3]. The TEA, as described by Fine et al. [4], uses low-temperature pyrolysis, followed by ozone-induced chemiluminescence, for the detection of compounds containing NO2 groups. The TEA has been used for the determination of tobacco-specific nitrosamines and explosives [5]. Both of these detectors require spedlic standards of the analytes of interest for quantitation... 

The other approach to 2-thioxo-l,2-thiaphospholanes 108 and 110 is based on the direct reaction of an unsaturated hydrocarbon, phosphorus pentasulfide and a thiophosphoric acid halide under drastic conditions (autoclave, 150-200 °C, 10-18 h) [142, 143], When cyclic alkenes (e.g. cyclohexene) are used as the starting substrates, bicyclic compounds are formed with one of the rings representing 1,2-thiaphos-pholane (Scheme 64). These reaction products are used as antioxidant additives for motor oils, polymers and agrochemicals. 

Pollution of freshwater lakes by nitrogen and phosphorus is also common in China. LakeTai-hu has nutrient loading with agrochemical discharge estimated at more than... 

Phosphinamide derivatives were prepared mostly for agrochemical uses. Compound 52 (R = p-C C showed 100% control of Pseudospora cubenis at 25 ppm without any harm to cucumber seedlings". Derivatives of tervalent phosphorus are of minor biological importance. As an example of this group, the sodium salt of (4-dimethylamino-u-tolyl)phosphonous acid (53) has found use as a tonic". ... 

The organophosphorus esters represent another class of environmental chemicals that are hydrolyzed by nucleophilic substitution reactions. These chemicals comprise one of the most important classes of agrochemicals with insecticidal activity (Fest and Schmidt, 1983). The organophosphorus esters also have important industrial uses such as oil additives, flame retardants, and plasticizers (Muir, 1988). The wide range of biological activity that this class of chemicals exhibits is due to the variety of substituents that can be attached to the central phosphorus atom. 

The production of phosphorus trichloride from phosphorus and chlorine is an important step in the manufacture of a number of agrochemical products. Raman spectroscopy has been used to monitor the reaction and control the raw material feed rates. This maximises production of phosphoras trichloride, minimizes the formation of phosphorus pentachloride and ensures safe operation when plant shut-down periods are needed. Remote analysis is achieved using optical fibers to provide a safer operation and a more rapid analysis than was previously possible [29, 30]. 

Ehukov, I. L, Biryukova, O. A. Kryschenko, V. S. (2009). The multidiagnostic value for the prediction of winter wheat yield and optimal content of available phosphorus in calcareous chernozem. Agrochemicals, 11, 7-15. 

We revealed eight regularities concerned within-field variability of agrochemical indices. The regularities would be important for technologies of precision agriculture. In the first place it was found that the soil reaction as well as humus and mobile phosphorus and potassium content more or less corresponded to a normal distribution. 

As many agrochemical intermediates, byproducts, and products are corrosive, toxic, flammable, and so forth, they require special materials of construction for a manufacturing plant. Some of the hardest-to-handle intermediates are routinely used in many manufacturing operations, including such materials as chlorine, bromine, hydrogen chloride, sodium, phosgene, phosphorus trichloride, phosphorus oxychloride, carbon disulfide, and many others. 

---