Phosphorus oxides synthesis

A versatile route for the synthesis of a phosphorus oxide template is presented (Scheme 12). Ring-closing enyne metathesis using Ig on these types of substrates 37a and 37b led to the formation of mono- and bicyclic phosphorus heterocycles 38a and 38b. 

The oxidation of butane (or butylene or mixtures thereof) to maleic anhydride is a successful example of the replacement of a feedstock (in this case benzene) by a more economical one (Table 1, entry 5). Process conditions are similar to the conventional process starting from aromatics or butylene. Catalysts are based on vanadium and phosphorus oxides [11]. The reaction can be performed in multitubular fixed bed or in fluidized bed reactors. To achieve high selectivity the conversion is limited to <20 % in the fixed bed reactor and the concentration of C4 is limited to values below the explosion limit of approx. 2 mol% in the feed of fixed bed reactors. The fluidized-bed reactor can be operated above the explosion limits but the selectivity is lower than for a fixed bed process. The synthesis of maleic anhydride is also an example of the intensive process development that has occurred in recent decades. In the 1990s DuPont developed and introduced a so called cataloreactant concept on a technical scale. In this process hydrocarbons are oxidized by a catalyst in a high oxidation state and the catalyst is reduced in this first reaction step. In a second reaction step the catalyst is reoxidized separately. DuPont s circulating reactor-regenerator principle thus limits total oxidation of feed and products by the absence of gas phase oxygen in the reaction step of hydrocarbon oxidation [12]. 

Especially the phosphorus oxides are classics of inorganic chemistry and have gained considerable relevance for basic research and industrial chemistry as well. Single representatives of the title compounds have been mentioned already in the early times of quantitative chemistry, e.g., P4O10 and P406 in 1816 (2). At the turn of the last century, some fundamental work on their synthesis and constitution had been... 

An alternative common method of nitrile oxide synthesis, frequently referred to as the Mukaiyama method (60JA5339), involves dehydration of primary nitroalkanes using, for example, phenyl isocyanate in the presence of a catalytic amount of triethylamine (Scheme 5). Phosphorus oxychloride (730S59 90S817), chloroformate esters (86BCJ2827), aryl... 

Vanadium-Phosphorus-Oxides from Fundamentals of n-Butane Oxidation to Synthesis of New Phases... 

Chiral phosphoramides, particularly C2-symmetric examples, are widely used in asymmetric synthesis (see section 3.2). One example is the asymmetric catalysis of Aldol reactions, where the phosphoramide catalyst is used in combination with a Lewis base. A solid state and solution study of the structure of chiral phosphoramide-tin complexes used in such reactions has now been reported. A number of chiral, non-racemic cyclic phosphoramide receptors (387) have been synthesised and their interactions with homochiral amines studied using electrospray ionisation MS. Although (387) bind the amines strongly, no evidence of chiral selectivity was found. Evidence from a combination of its X-ray structure, NMR, and ab initio calculations suggests that the cyclen phosphorus oxide (388) has an N-P transannular interaction in the solid state. A series of isomers of l,3,2-oxazaphosphorino[4,3-a]isoquinolines(389), containing a novel ring-system, have been prepared and their stereochemistry and conformation studied by H, C, and P NMR spectroscopy and X-ray crystallography... 

Among numerous compounds formed in vanadium-phosphorus-oxide system, vanadyl pyrophosphate is known to be an efficient catalyst for C4-C5 paraffins partial oxidation [1]. Typical process of its synthesis can be represented by a following scheme ... 

The similar structural and catalytic properties of the SiOj-supported and unsupported samples prepared from the same precursor suggest that the same active surface is formed on both types of samples. The higher conversions obtained with the supported samples could be attributed to higher dispersions of the VPO compounds. The slightly lower maleic anhydride selectivity observed for catalyst A than B or the bulk catalyst could be due to some phosphorus atoms interacting with the silica surface rather than with vanadium atoms, such that the P/V ratio is less than two in the VPO compounds. Addition of phosphorus to catalyst B replenished this lost phosphorus. Previous studies of supported vanadium-phosphorus oxides have shown that some phosphorus atoms can be associated with the silica [2,8]. The catalytic properties of the supported samples as well as the LRS are similar to the SiOj-supported PA =2 VPO samples prepared previously [2,3]. These earlier samples were prepared by adding H3PO4 to PA =1 samples synthesized by various synthesis routes. Thus, for the supported samples, the method of preparation is much less important than the composition. 

The diphosphoric tetrafluoride for this synthesis is best prepared18 by reaction of phosphorodifluoridic acid with an excess of phosphorus ) oxide. Extremely pure P203F4 is not required. It contains about 5 % of the starting material. The same procedure, but using 18.6 g. (0.1 mole) of diphosphoric tetrafluoride instead of the acid in the method given above, may be utilized to prepare POF2Cl. The purification step described above is not necessary in this synthesis.12 The yield is 23 g. (95 %). 

The red metastable product obtained from potassium hydroxide and phosphorus does not appear to be an intermediate in this tertiary phosphine oxide synthesis. A solution of the red compound prepared separately in etlianol was not decolorized by acrylamide, and only minor amounts of the tertiary phosphine oxide were obtained. This result... 

Recently, the susceptibility of this ligand class to oxidation was the topic of a comprehensive study [69]. Despite their fairly electron-rich nature, these phosphines were found to be only moderately prone to oxidation, a property explained mainly by the unfavorable conformations in a transition-state model due to the interactions between an arene and the lone pair on the phosphorus. The synthesis of this ligand class was successfully scaled up to multi-hundred kilogram level, illustrating the importance of these ligands in chemical industry [70]. 

Phosphorus oxide chloride Vilsmeier aldehyde synthesis s. 31, 105... 

Vanadium-Phosphorus Oxide Catalyst for /t-Butane Selective Oxidation From Catalyst Synthesis to the Industrial Process... 

Centi G., Manenti I., Riva A. and Trifiro F. (1984). The ehemistry of catalysts based on vanadium-phosphorus oxides Note HI Catalytic hehaviour of different phases in 1-butene oxidation to maleic anhydride, AppL Catal., 9, pp. 177-190 Centi G., Trifiro F., Ebner J.R. and Franchetti V.M. (1988). Mechanistie aspects of maleic anhydride synthesis from C4 hydrocarbons over phosphorus vanadium oxide, Chem. Rev., 88, pp. 55-80. 

Guliants, V. and Carreon, M. (2005). Vanadium-Phosphorus-Oxides From Fundamentals of n-Butane Oxidation to Synthesis of New Phases, in J.J. Spivey (ed.). Catalysis (vol. 18), The Royal Society of Chemistry, London, pp. 1 5. 

Phosphorus oxide chloride Synthesis of 0x0 compounds from carboxyiic acid amides... 

Olefin synthesis starts usually from carbonyl compounds and carbanions with relatively electropositive, redox-active substituents mostly containing phosphorus, sulfur, or silicon. The carbanions add to the carbonyl group and the oxy anion attacks the oxidizable atom Y in-tramolecularly. The oxide Y—O" is then eliminated and a new C—C bond is formed. Such reactions take place because the formation of a Y—0 bond is thermodynamically favored and because Y is able to expand its coordination sphere and to raise its oxidation number. 

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