Phosphorus phosphoryl radicals

Phosphoryl radicals [10, 18, 38-42] tend to add to double bonds. Owing to the exceptionally high constants of hyperfine coupling of the unpaired electron with the phosphorus nucleus, phosphoryl radicals can be utilized as paramagnetic reporters [10]. Phosphoryl radicals have been prepared by photolysis of diphosphoryl mercury compounds (Scheme 6.5). 

In the phosphoryl fullerenyl radical the unpaired electron is - similar to the alkylfullerenyl radical - delocalized over two six-membered rings adjacent to the C-P bond [10]. The rotation barrier for the radical C5oP(0)(0 Pr)2 was determined to be 4.8 kcal mol Another phosphorus-containing radical fullerenyl adduct, determined via ESR spectroscopy, is PFjjO BujCgQ. It can be obtained by photolytic reaction of Cgo with HPF4 and tert-butylperoxide in tert-butylbenzene [43]. 

Ion-beam irradiation (77 K) of DNA hydrated to T = 18 DjO/ nucleotide resulted in a DNA-phosphorus-centered radical. Samples were irradiated with 60 MeV/u, or 100 Mev/u Ar +. The ESR results showed the presence of an axially symmetric spectrum with large phosphorus couplings (Aj = 77.5 mT and = 61.0 mT, = 2.000,= 2.001), from a radical that constituted ca. 0.1% to 0.2% of the total radical concentration. Earlier literature regarding the origin and ESR spectra of such radicals existed and it was concluded that the radical was a phosphoryl radical (ROPOj, Scheme 6), formed from the electron gain path. In DNA, such a radical could result only from P-O bond cleavage at either the C3 or C5 of the deoxyribose sugar... 

Szabo (1967) found that, when the two alkyl radicals of the phosphonic esters are different, the compounds have a stronger insecticidal action than in the case of identical alkyl radicals. This is in agreement with a similar finding of Melnikov (1963) in relation to parathion derivatives. This fenomenon is evidently due to the fact that asymmetry increases the polarisation of the central phosphorus atom, resulting in an increased phosphorylating ability. 

Poiyoief ins. Polyethylene can be phosphorylated with phosphorus trichloride and oxygen by a free-radical chain reaction (118,149-151). Side reactions include separate oxidation of the phosphorus trichloride and of the polymer. Hydrolysis gives phosphonic acid structures, which can impart flame retardancy and improved adhesion to surfaces. These materials have been explored for dental and bone therapy applications but no commercial use is known. 

Phosphorus is more readily absorbed from the intestinal tract than calcium. Approximately two-thirds of the phosphorus excreted is found in the feces, one-third in the urine. Between 10 and 20 % of phosphorus is found in tissues other than bone, and this phosphorus appears to have metabolic priority. The mechanisms which regulate deposition and release of phosphorus from bone are the same as those for calcium. Phosphorus in soft tissues plays a very vital role in many metabolic processes. The importance of adenosine triphosphate (ATP) in energy transfer systems has been discussed previously (p. 203, Chapter 16). Phosphorylation appears to be essential for the absorption of a number of nutrients, e.g., fatty acids and glucose. The phosphate radical is bound to proteins, fatty acids, carbohydrates, and enzymes. Phosphate is the chief inorganic anion of intracellular fluid, and phosphates of extracellular fluid participate in acid-base regulation. The inorganic phosphate level of blood ranges from 2 to 4 mg. per 100 ml. in adults and 3 to 5 mg. per 100 ml. in children. 

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