Phosphoric Oxide

Phosphorus pentoxide. This is an extremely efficient reagent and is rapid in its reaction. Phosphoric oxide is difficult to handle, channels badly, is expensive, and tends to form a syrupy coating on its surface after a little use. A preliminary drying with anhydrous magnesium... 

By the interaction of aleohols or glyeols with potassium iodide and 95 per eent. orthophosphoric aeid (the last named is prepared from the eommercial 85 per eent. aeid and phosphoric oxide), for example ... 

In a 500 ml. three-necked flask, equipped with a thermometer, a sealed Hershberg stirrer and a reflux condenser, place 32-5 g. of phosphoric oxide and add 115-5 g. (67-5 ml.) of 85 per cent, orthophosphoric acid (1). When the stirred mixture has cooled to room temperature, introduce 166 g. of potassium iodide and 22-5 g. of redistilled 1 4-butanediol (b.p. 228-230° or 133-135°/18 mm.). Heat the mixture with stirring at 100-120° for 4 hours. Cool the stirred mixture to room temperature and add 75 ml. of water and 125 ml. of ether. Separate the ethereal layer, decolourise it by shaking with 25 ml. of 10 per cent, sodium thiosulphate solution, wash with 100 ml. of cold, saturated sodium chloride solution, and dry with anhydrous magnesium sulphate. Remove the ether by flash distillation (Section 11,13 compare Fig. II, 13, 4) on a steam bath and distil the residue from a Claisen flask with fractionating side arm under diminished pressure. Collect the 1 4-diiodobutane at 110°/6 mm. the yield is 65 g. 

Wet the papers thoroughly with water before throwing them away, as the residual phosphoric oxide may cause them to smoulder. 

The acetonitrile may be dried over anhydrous calcium sulphate or by distilling from phosphoric oxide. 

Place 45 g. of benzamide (Section IV, 188) and 80 g. of phosphorus pentoxide in a 250 ml. Claisen flask (for exact experimeutal details on the handling and weighing out of phosphoric oxide, see under Acetamide, Section 111,111). Mix well. Arrange for distillation (Fig.//, 29, 1 or Fig. II, 20, 1) under reduced pressure use a water pump with an air leak in the system so that a pressure of about 100 mm. is attained. Heat the flask with a free flame until no more liquid distils the nitrile will pass over at 126-130°/100 mm. Wash the distillate with a little sodium carbonate solution, then with water, and dry over anhydrous calcium chloride or magnesium sulphate. Distil under normal pressure (Fig. II, 13, 2 or II, 13, 6) from a 50 ml. flask the benzonitrile passes over as a colourless liquid at 188-189° (compare Section IV,66). The yield is 28 g. 

Ethyl nicotinate upon treatment with concentrated ammonia solution yields nicotinamide, which gives p-cyanopjTidine upon heating with phosphoric oxide ... 

P-Cyanopyridine. Mix 25 g. of powdered nicotinamide with 30g. of phosphoric oxide in a 150 ml. distilling flask by shaking. Immerse the flask in an oil bath and arrange for distillation under a pressure of about 30 mm. Raise the temperature of the oil bath rapidly to 300°, then remove the oil bath and continue the heating with a free flame as long as a distillate is obtained. The nitrile crystallises on cooling to a snow-white solid. Redistil the solid at atmospheric pressure practically all of it passes over at 201° and crystallises completely on cooling. The yield of p-cyanopyridine, m.p. 49°, is 20 g. 

It may be pointed out that dehydration of p hydroxy esters with fused potassium hydrogen sulphate, acetic anhydride, phosphoric oxide or with tliionyl chloride in benzeue solution leads to ap unsiiturated esters containing some PY-unsaturated ester the proportion of the latter depends not only upon the structure of the ester but also upon the dehydrating agent used. Elehydration occasionally occurs during the reaction itself or upon attempted distillation. 

Properties and Structure. Phosphoms(V) oxide, the extremely hygroscopic acid anhydride of the phosphoric acids, exists in several forms but is often referred to by its empirical formula, P2O3. Three crystalline polymorphs, two distinct Hquids, and several amorphous or glassy soHds are recogni2ed. Some properties of the various forms of phosphoric oxide are Hsted in Table 10. 

P-Coniceine is the chief product of the action of phosphoric oxide on conhydrine and was shown by Loffler and collaborators to be 2-propenylpiperidine, CjHgNH. CH CH. CHg. 

Pellotine and Anhalonidine. The A -acetyl derivative of mezcaline (I NHj— NHAc), on treatment with phosphoric oxide, yields 6 7 8-trimethoxy-l-methyl-3 4-dihydrowoquinoline (picrate, m.p. 181-2°), which, on successive catalytic hydrogenation and treatment with methyl sulphate, yields 6 7 8-trimethoxy-l 2-dimethyl-l 2 3 4-tetrahydro-isoquinoline identical with 0-methylpellotine (picrate, m.p. 167-8°), whence it appears that pellotine must be a dimethyl ether of 6 7 8-trihydroxy-1 2-dimethyl-l 2 3 4-tetrahydrowoquinoline. Pellotine and anhalonidine on complete methylation yield the same product, and as anahalonidine is a secondary base and differs from pellotine by containing —CHj less, it must be a dimethyl ether of 6 7 8-trihydroxy-l-methyl-1 2 3 4-tetrahydrowoquinoline, and pellotine should be A -methyl-anahalonidine. 

The position of the free hydroxyl group in these two alkaloids is either C or C , since Spath has shown that the OiV-diacetyl derivative of -5-hydroxy-3 4-dimethoxyphenylethylamine, when heated in toluene solution with phosphoric oxide, yields a product which must be either 6-acetoxy-7 8-dimethoxy-, or 8-acetoxy-6 7-dimethoxy-l-methyl-3 4-dihydrowoquinoline. On reduction with tin and hydrochloric acid t is converted into anhalonidine, which must therefore be 6-hydroxy-7 8-dimethoxy- (or 8-hydroxy-6 7-dimethoxy-)-l-methyl-l 2 3 4-tetrahydrofsoquinoline. Similarly the methiodide of the acetoxy-com-pound on reduction yields, by loss of acetic acid and addition of two hydrogen atoms, pellotine, proving the latter to be A -methylanhalonidine. The position of the free hydroxyl group was finally shown by Spath to... 

CeH3(OCH3)a. CHOH. CHa. NH. CO. CHg. CeH3(OCH3)2, which when boiled with phosphoric oxide in xylene solution lost 2 mols. of water and formed papaverine (IV). ... 

A complete synthesis of laudanosine was effected by Pictet and Finkelstein by the condensation of omoveratrylamine (I) with homo-veratroyl chloride (II), giving omoveratroyl omoveratrylamine, which with phosphoric oxide undergoes cyclisation to 3 4-dihydropapaverine (III), which was converted into the methochloride and reduced to laudanosine (IV). 

The synthesis of meconin has been referred to already (p. 201). Cotarnine has been synthesised by Salway from myristicin (I) as a starting-point. This was transformed into jS-3-methoxy-4 5-methylenedioxy-phenylpropionic acid (II), the amide of which was converted by Hofmann s reaction into )S-3-methoxy-4 5-methylenedioxyphenylethylamine, and the phenylacetyl derivative (HI) of this condensed, by heating it in xylene solution with phosphoric oxide, giving rise to the two possible dihydroiso-quinoline derivatives. The first of these substances, 8-methoxy-6 7-methylenedipxy-1-benzyl-3 4-dihydroiioquinoline (IV), on conversion into the methochloride and reduction with tin and hydrochloric acid, gave... 

A new process for the partial oxidation of n-butane to maleic anhydride was developed by DuPont. The important feature of this process is the use of a circulating fluidized bed-reactor. Solids flux in the rizer-reactor is high and the superficial gas velocities are also high, which encounters short residence times usually in seconds. The developed catalyst for this process is based on vanadium phosphorous oxides... 

Phosphorus Pentoxide (Phosphoric anhydride, Phosphoric oxide, Diphosphorus pentoxide). 

Jameson, R. F. Salmon, J. E. (1954). Aluminium phosphates Phase-diagram and ion-exchange studies of the system aluminium oxide-phosphoric oxide-water at 25 °C. Journal of the Chemical Society, 4013-17. 

The preparation of 4-methylcoumarin is an example of the Pechmann reaction, which consists in the interaction of a phenol with a p-ketonic ester In the presence of a condensing agent (sulphuric acid, aluminium chloride, phosphorus oxychloride or phosphoric oxide) ... 

G-series nerve agents Volatile decomposition products may include HF, HCl, HCN, sulfur oxides (SO ), phosphorous oxides (PO ), as well as potentially toxic oiganophosphates. In addition, toxic phosphate residue may remain. 

By distilling the amide with phosphoric oxide at ordinary pressure, fluoromethyl cyanide was obtained as a colourless, mobile liquid. This compound had been obtained by Swarts,6 who claimed that it was necessary to distil the amide with... 

Chemical/Physical. Releases very toxic fumes of chlorides and phosphorous oxides when heated to decomposition (Sax and Lewis, 1987). 

The manganese phosphorous oxide catalyst has been prepared with... 

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