Phosphorus pentaoxide

The hydroperoxide is violently explosive and shock-sensitive, especially on warming great care is necessary in handling. It explodes violently in contact with phosphorus pentaoxide, and a 50% aqueous solution decomposed explosively on warming with spongy platinum. The barium salt is dangerously explosive when dry. 

Sayah et al. <2000JOC2824> attempted direct cyclization of acid 115a with phosphorus pentaoxide and isolated the expected compound 116 in poor yield (20%). They could improve the yield (57%) of this ring closure via the mixed anhydride 115b which was isolated prior to its cyclization in the presence of BF3 OEt2 (Scheme 18). 

Formic acid, Palladium-carbon catalyst, 0418 Formic acid, Phosphorus pentaoxide, 0418 Furan-2-amidoxime, 1872... 

The isoquinoline framework is derived from the corresponding acyl derivatives of P-hydroxy-P-phenylethylamines. Upon exposure to a dehydrating agent such as phosphorus pentaoxide, or phosphorus oxychloride, under reflux conditions and in an inert solvent such as decalin, isoquinoline frameworks are formed. 

NH4)H2P04 decomposes under strong oxidizing conditions producing nitrogen, water, and phosphorus pentaoxide. 

Formula P2O5 MW 141.95 exists as P4O10 units as molecular entities Synonyms phosphorus pentaoxide phosphorus(V) oxide phosphoric anhydride... 

A warm solution of 5.57 g. (30 mmoles) of p-nitrobenzoyl chloride in 50 ml. of dry pyridine is cooled to 0° under stirring, and to the stirred suspension is added, in small portions over a period of 15 min., 0.08 g. (6 mmoles) of finely divided 2-deoxy-D-n o-hexose. Stirring is maintained at 0a for 1.5 hr., and the mixture is set aside in a refrigerator for 4 days. The excess p-nitrobenzoyl chloride is neutralized by the careful addition of 60 ml. of saturated, aqueous sodium hydrogen carbonate, and the mixture is added to 11. of ice-water. The precipitate is removed by filtration, washed with water, and dried in the open at room temperature and then in a desiccator over phosphorus pentaoxide. Most of the water of crystallization is removed by heating the material at 110°/0.1 mm. for 16 hr. The dry product is crystallized from nitromethane (decolorized) giving 3.46 g. (76%) of 2-deoxy-l, 3,4,6-tetra-0-p-nitrobenzoyl-D-n o-hexose, m.p. 201-202°, of satisfactory quality for the following conversion. Its specific rotation is +106° in chloroform. 

Polycondensation of D-glucose also followed when a mixture of D-glucose (20 g.) and water (2 ml.) was heated at 95° with phosphorus trichloride (13), phosphorus pentachloride (14), or phosphorus pentaoxide (15), 82 The addition of water was essential, since these three compounds apparently failed to catalyze polycondensation under anhydrous conditions. Under optimum conditions, polymers of Pn 11-13 were obtained in 10-15% yield after 20-30 min. reaction times, when (13) and (14) were used for catalysis. With (15), polymers of Pn 8-11 were obtained in 10-30% yield, but such polycondensations required 1-2 hr., instead of a few minutes (as for 13 and 14). In no case did polymerization appear to be as efficient as when sulfuric acid was used. 

It was found, by study1 of reaction conditions, that polycondensation of (3) to form polymeric products is most satisfactory when a solution of (3) (1 g.) and phosphorus pentaoxide (1 g.) in methyl sulfoxide (1 ml.) and... 

See Formic acid Phosphorus pentaoxide Hydrogen fluoride... 

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