Organophosphorus compounds selectivity

A plefhora of methods developed for the determination of triazine compounds in water, soil, crops, biological fluids, etc., have been reported in the literature, and several excellent reviews are available for the interested reader. " More method papers are published on the determination of triazines in water than for all other sample matrices combined (water > soil > crop). The majority of the water method reports relate to the determination of parent triazine compounds plus compounds from one or more other chemical classes of pesticides (e.g., phenoxy acids, carbamates, pheny-lureas, acetanilides, acetamides, organophosphorus compounds, etc.) for generalized multi-residue screening or monitoring purposes. Addressed in other more selective... 

The plutonium concentration in marine samples is principally due to environmental pollution caused by fallout from nuclear explosions and is generally at very low levels [75]. Environmental samples also contain microtraces of natural a emitters (uranium, thorium, and their decay products) which complicate the plutonium determinations [76]. Methods for the determination of plutonium in marine samples must therefore be very sensitive and selective. The methods reported for the chemical separation of plutonium are based on ion exchange resins [76-80] or liquid-liquid extraction with tertiary amines [81], organophosphorus compounds [82,83], and ketones [84,85]. 

Selected entries from Methods in Enzymology [vol, page(s)] Types of organophosphorus inhibitors, 11,686-688 toxicity hazards, 11,688 purity and analysis, 11,688 solutions of organophosphorus compounds, 11,689 estimation of specific radioactivity of organophosphorus compounds, 11,689-690 method for estimating phosphorus content, 11,691 reactions with enzymes, 11,691 -701 [rate constants, 11,692 phosphorylation of chymotrypsin, 11, 694-696 identification of phosphoryl and phosphonyl peptides,... 

The onset of symptoms depends on the particular organophosphorus compound, but is usually relatively rapid, occurring within a few minutes to a few hours, and the symptoms may last for several days. This depends on the metabolism and distribution of the particular compound and factors such as lipophilicity. Some of the organophosphorus insecticides such as malathion, for example (chap. 5, Fig. 12), are metabolized in mammals mainly by hydrolysis to polar metabolites, which are readily excreted, whereas in the insect, oxidative metabolism occurs, which produces the cholinesterase inhibitor. Metabolic differences between the target and nontarget species are exploited to maximize the selective toxicity. Consequently, malathion has a low toxicity to mammals such as the rat in which the LD50 is about 10 g kg-1. 

An early method for the isolation of an organophosphorus compound from animal or plant tissues was based on extraction by hexane and selective partitioning with acetonit-... 

There are hundreds of organophosphorus and carbamate insecticides in agricultural and household use. Two important examples are malathion, an organophosphorus compound, and carbaryl, a carbamate, both shown in Figure 15.20. Malathion kills a variety of insects, such as aphids, leafhoppers, beetles, and spider mites. Carbaryl, like many other carbamates, is relatively selective in the types of insects it kills. 

The following structures are a few of the organophosphorus compounds and other acetylcholinesterase inhibitors that are selectively toxic to insects. 

Modolo, G., Odoj, R. 1999. Synergistic selective extraction of actinides(IH) over lanthanides from nitric acid using new aromatic diorganyldithiophosphinic acids and neutral organophosphorus compounds. Solvent Extr. Ion Exch. 17 (1) 33-53. 

Alkyl-substituted monoamides are known as extractants for the uranyl cation and they could potentially be considered as alternatives to organophosphorus compounds in nuclear fuel reprocessing. In toluene, the uranyl cation forms complexes with two monoamide molecules. These relatively simple molecules were selected for computer-aided design,14 taking into account a lot of synthetic and experimental work that must be done to prove the modeling predictions. 

In this communication we wish to report results of our studies on the structure, some nucleophilic properties and selected synthetic applications of lithium dia 1kylcuprate adducts to various a,B-unsaturated organophosphorus compounds. 

This review summarizes experimental and theoretical studies which are used to develop theoretical models that explain and predict how clay minerals and metal oxides can affect the adsorption and decomposition of selected organophosphorus compounds. The results can contribute to a better knowledge of the impact of such processes on existing remedial technologies and in the development of new removal and decomposition techniques. 

---