Phosphorus compounds, cyclic

Certain organo cyclic phosphorus compounds have been proved to be particularly efficient for ABS. Some spiro phosphorus compounds are shown in Figure 8.4. 

When the methyl signal of 160-163 appears at relatively low field (6 1.3-1.4), the methyl group apparently lies close to the oxygen atom on the phosphorus, whereas a small S value ( 0.95) indicates that the two groups are remote this may be inferred by analogy with the n.m.r. data for similar, cyclic phosphorus compounds.46,55 85,75... 

T0 prepare models of TA, the corresponding cyclic alkylene phosphoric acids cannot be directly polymerized because the presence of acidic protons of the phosphate group makes the ionic polymerization impossible. Thus, cyclic phosphorus compounds with blocked third functions have to be used. These are phosphates., phosphoramidates and phosphites. After polymerization the obtained polymer is converted by deblocking into the polyalkylene phosphate, e.g. polysalt or polyacid form. 

No studies were located that specifically address white phosphorus metabolism in humans after oral exposure. However, since orthophosphate is a stable end-product of the inorganic oxidation and hydrolysis of white phosphorus, it is appropriate to examine data on serum phosphate levels in humans following oral ingestion of white phosphorus (these data are discussed further in Section 2.2). Although orthophosphate is the stable end-product, linear and cyclic phosphorus compounds do exist that are stable for relatively long periods, and these may be metabolic blockers especially where phosphorus metabolism is on-going. 

It is well known that pentacovalent cyclic phosphorus compounds play an important role as intermediates in reactions involving nucleophilic attack on tetracoordinated phosphorus in biological systems. According to this background it appears to us that it is important to prepare the arsenic derivatives, which are more stable than the corresponding phosphorus compounds and allow the study of their conformation. 

In this case, monomeric donors were, for example, cyclic phosphorus compounds 2-phenyl-1, 3, 2-dioxaphospholane and 2-phenoxy-l, 3, 2-dioxaphos-pholane... 

Cyclic phosphorus compounds Compounds containing P rings... 

Two useful reviews by Fluck and Heckmann on the NMR spectra of cyclic phosphorus compounds should be noted <94RHA65, 95RHA121>. 

Mann and his colleagues have employed the displacement reaction by Grignard reagents on phosphinous halides in the synthesis of cyclic phosphorus compounds 13 (136), 14 (7), and IS (7,83). Yields of the... 

Whilst the majority of the work described in this section involves the synthesis of cyclic phosphorus compounds, most of the chemistry could equally apply to arsenic and antimony and to a lesser extent bismuth. Most of the compounds synthesized have more than one heteroatom in the ring system, and not infrequently there are a number of heteroatoms, several of them often bound to the bridging metalloid atom, M. The methods most sucessfully applied to the synthesis of the parent and monoheterobicyclic compounds have been those involving addition and cycloaddition reactions. 

Interest has also continued in studies of the aromaticity of other unsaturated cyclic phosphorus compounds. A theoretical study of the 1,2-diphosphacyclooctatetraene system (228) has concluded that the ring system is perfectly planar when it has a global charge of —2 or +2, in contrast to the 1,2-diaza analogue which adopts a distorted, non-planar structure in the same oxidation states. However, it is thought unlikely that the phosphorus heterocycle will form planar metallocene complexes with metal ions. Theoretical and experimental studies have also been reported for the lone pair 671-aromatic anions P4 (229) and the arsenic analogue As4 . Both... 

The main topic of the present paper Is the copolymerlzatlon of cyclic phosphorus compounds, 2-phenyl-l,3,2-dloxaphospholane 11 and 2-phenoxy-l,3,2-dioxaphospholane 20 as Mjj. 

The second cyclic phosphorus compound which was successfully adopted as Is 2-phenoxy-l,3,2-dloxaphospholane 20, a cyclic phosphite. The copolymerization of 20 with -keto add 46 Is of big Interest (19). 

Spontaneous alternating copolymerizations of two cyclic phosphorus compounds, 2-phenyl-l,3,2-dloxaphospholane 11 and 2-phenoxy-1,3,2-dloxaphospholane 20, with several electrophilic monomers were discussed. As the electrophilic monomers, /3-proplolactone 13, 3-hydroxypropanesulfonlc acid lactone (propane-sultone) 15, acrylic acid 16, acrylamide 17, acrylate were sucessfully copolymerized with 11. At temperatures lower than those of copolymerization, the combinations of 11—13, 11—16, 11—-17 and 11—acrylate produced trioxyphosphorane derivatives having spiro-ring structures, which were significant in two... 

R. A. Y. Jones and A. R. Katritzky, Infrared and Nuclear Magnetic Response Spectra of Some Cyclic Phosphorus Compounds, J. Chem. Sw. 1960, 4376-4379. 

Table 3 Propagation rate constants and activation parameters in the polymerization of tricoordinated cyclic phosphorus compounds...

Various cyclic phosphorus compounds, mainly 2-ethoxy-2-oxo-l,3,2-dioxaphospholane (11), were copolymerized with lactide (LA), s-caprolactone and six-... 

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