Migration phosphorus

With the aid of Fig. 7 it is illustrated that if during the action of phosphodiesterase this cyclic bond is broken, the diester is converted into a monoester with two dissociable hydroxyls. Consequently, in the pH range of 7 to 9, the diesterase-treated protein should move faster than pepsin and be in contrast to the more slowly migrating phosphorus-free protein. That this is the case is demonstrated w ith the aid of the superimposed tracings of the electrophoretic patterns shown in Fig. 8. Here the full line represents pepsin, the dashed line being the pattern after treatment Avith the diesterase. 

An alkyl group can also migrate from oxygen to nitrogen or phosphorus [I, 72] (Michaelis-Arbuzov rearrangement) With this methodology, tetrafluoro-pyndine phosphonates and phosphmates can be obtained [75, 74], Chlorine fluoride... 

Benzonitrile with [(i -Cp )P W(CO)5 2] gives 82, the result of migration of the phosphorus atom, insertion of the nitrile moiety into the P-C bond and further C-H bond activation (01AGE3413). 

In early experiments, the pentamethyl ether (18) was treated with phosphorus pentachloride in the hope of obtaining a chloropentol reducible to ( — )-proto-quercitol. (Allowing for the benzoyl migration, the expected product would have been (— )-uibo-quercitol (11).) Surprisingly, the quercitol actually obtained after demethylation and dehalogena-tion was neither of these but still another previously known isomer, meso-scyllo-quercitol (24) (27). 

This result is attributed to participation by the neighboring methoxy group at position 1 (formula 18) in the phosphorus pentachloride displacement reaction. A cyclic methoxonium ion (22) is postulated as the intermediate. The overall result is methoxyl migration from 1 to 6, with inversion of configuration at both positions (27). 

The migrating group retains its configuration. Some reaction conditions can lead to syn-anti isomerization at a rate exceeding rearrangement, and when this occurs, a mixture of products is formed. The reagents that have been found least likely to cause competing isomerization are phosphorus pentachloride and p-toluenesulfonyl chloride.283... 

An n.m.r. study of the permutational isomerisations within a series of amidium fluorophosphates (133) has revealed an irregular mechanism with dissociation of the P-N and also the P-0 bonds of the bidentate ligands and the formation of five-coordinate intermediates (134)61. Reversible intramolecular migrations of pentaco-ordinate phosphorus in the N-C-N triad of amidines (e.g. 135, 136,... 

Migration of phosphorus from oxygen to aromatic carbon is induced by lithium diisopropylamide and provides a convenient... 

Noteworthy NMR studies involving nuclei other than phosphorus have been carried out for some P-chloro-NHPs where the possible occurrence of spontaneous P-Cl bond dissociation was probed by II NMR titrations and 35C1 NMR [20], and for P-cyclopentadienyl derivatives where measurement of solid-state 13C CP-MAS NMR spectra allowed one to substantiate the preservation of the circumambulatory ring migration of cyclopentadienyl groups in the solid state [47], Several neutral and cationic derivatives have also been studied by 15N NMR [20, 53],... 

The migration of borane from the phosphorus atom in 1,3,2,5-dioxa-boraphosphorinane to the phosphorus atom in 1,5,3,7-diazadiphospha-cyclooctane is evidence of a lower phosphorus nucleophilicity in the P(III)—C—O—B(III) system than in the P—C—N fragment, which may result from the phosphorus-boron interaction in 1,3,2,5-dioxaboraphosph-orinane (90IZV1120). 

However, other reaction directions via the formation of the phosphorane structure with migration of the methyl anion from one phosphorus atom... 

In the mildest of these reactions the hydroxylamine is refluxed in ether over phosphorus pentachloride and the same order of migration aptitudes is observed as in the pinacol rearrangement. The range in... 

Figure 6.16 Oxygen-to-carbon migration of phosphorus in an aromatic system.

Apatite exploration takes place in various regions of the World, and the most known are Kola Peninsula (Russia) and northwest Africa (Morocco). In both places, the apatite ores contain not only phosphorus as a main element but also many heavy metals, which are toxic for humans and animals. The given elements are F, As, Y, some rare earth species, Sr, Pb, Cd, Sn. The underground waters in these regions are enriched by F, Fi, Nb, some rare earth species with alkaline reaction that facilitates the migration of many ore elements. Some phosphorus containing ores are radioactive owing to the mixtures of uranium and thorium. 

The excessive amounts of nitrogen and phosphorus as well as heavy metals migrate with water fluxes and enter into surface waters. This is accompanied by eutrophication of surface water bodies. 

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