Pentoxide, phosphorus reaction

Phosphorus Pentoxide. Violent reaction may be moderated using acetonitrile as diluent.21... 

Alcohols react with a large excess of dimethoxymethane, (bp 41-42 C) via an acetal exchange process at room temperature in the presence of acidic catalysts such as phosphorus pentoxide. The reaction was adapted to the construction of a K3-dioxane ring system in a synthesis of Mycalamide B [Scheme 4.257], After installing a MOM ether at a hindered secondary alcohol 257.1, the ketone was converted to its TBS enol ether 2S13. Oxidation with //i-chloroperoxybenzoic acid returned a stable oxirane 257.4 that reacted with dimethoxymethane and phosphorus pentoxide to afford the desired 1.3-dioxane ring in 257.6 in 77% overall yield from 2573. Presumably, O-alkyla-... 

The rubidium and ammonium dibromoiodides were prepared by placing an open beaker of liquid bromine and a weighing bottle containing a finely ground 5-g sample of the appropriate iodide in a desiccator over phosphorus pentoxide. The reactions which occur are represented by the equations... 

Phosphorus(III) oxide reacts slowly with oxygen at ordinary temperatures to give the pentoxide, P40,g. The reaction is rapid if the oxide is heated in air. It is oxidised vigorously by chlorine and bromine which form the oxidehalides, POX3. 

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... 

Peroxomonophosphoric acid can be prepared by the hydrolysis of peroxodiphosphates ia aqueous acid and by the reaction of hydrogen peroxide with phosphorus pentoxide (45). It is not produced or used commercially and the salts that have been prepared are unstable and impure. 

Toluenesulfonic anhydride has been prepared from the acid by the use of thionyl chloride and phosphorus pentoxide. It has also been obtained by heating oxime -toluenesulfonates, by reaction of -toluenesulfonic acid with di- -tolylcarbodiimide, and by the interaction of methoxyacetylene and -toluenesul-fonic acid. ... 

Phosphoric acid made by the wet process, in which phosphate rock is treated with sulfuric acid, is highly inert toward lead in any concentration for temperatures up to 150°C, However, in the dry process, where hydrogen phosphate (H3PO4) is made directly from phosphorus or phosphorus pentoxide (P2OS), a chemical reaction with lead occurs. 

Tetrahydroharman, m.p. 179-80°, has been prepared by a number of workers by a modification of this reaction, viz., by the interaction of tryptamine (3-)5-aminoethylindole) with acetaldehyde or paraldehyde and Hahn et al. have obtained a series of derivatives of tetrahydronorharman by the use of other aldehydes and a-ketonic acids under biological conditions of pH and temperature, while Asahina and Osada, by the action of aromatic acid chlorides on the same amine, have prepared a series of amides from which the corresponding substituted dihydronorharmans have been made by effecting ring closure with phosphorus pentoxide in xylene solution. 

Trifluoromethanesulfonic (triflic) anhydride is commercially available or can be prepared easily by the reaction of triflic acid with phosphorus pentoxide [66] This moderately hygroscopic colorless liquid is a useful reagent for the preparation of various organic derivatives of triflic acid A large variety of organic ionic triflates can be prepared from triflic anhydride A recent example is the preparation of unusual oxo-bridged dicatiomc salts of different types [SS, 89, 90, 91, 92, 93] (equations 38-44) Stabilized dication ether salts of the Huckel aromatic system and some other systems (equations 38 and 39) can be prepared in one step by the... 

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

The reaction mixture was poured into 25 ml of water and the mixture made strongly basic with ION sodium hydroxide solution. The mixture was extracted 3 times with 50 ml portions of benzene, the combined extracts washed with water and concentrated to a volume of approximately 50 ml. The solution was saturated with dry hydrogen chloride and the white crystalline product collected and dried. The yield of product, MP 251.6° to 252.6°C (dec.) was 2.5 g. Recrystallization from a mixture of absolute alcohol and absolute ether gave a product, MP 252.6° to 253.6°C. A sample was analyzed after drying for 7 hours at 110°C over phosphorus pentoxide in vacuo. 

After diluting the reaction liquid with acetone it is filtered, and the residue obtained after the evaporation of the filtrate in vacuo, and complete drying over pentoxide of phosphorus is then dissolved in absolute alcohol, and to this is added about the same volume of dry ether. 

A solution of 100 g (1.7 mols) of isopropylamine in 60 cc of water was stirred into a solution of 4-hydroxyphenoxypropylene oxide. After the exothermic reaction has subsided, the reaction mixture was heated for two hours at 60Thereafter, the aqueous ethanol was distilled off, and the solid residue was dissolved in aqueous hydrochloric acid comprising more than the theoretical stoichiometric molar equivalent of hydrochloric acid. The aqueous acid solution was extracted with ether and was then made alkaline with sodium hydroxide, whereby a solid crystalline precipitate was formed which was filtered off and dried over phosphorus pentoxide. The product was 1,1 -(4 -hvdroxvphenoxv)-2-hvdroxv-3-isopropylamino-pro-pane. Its hydrochloride had a melting point of 166°Cto 169°C. 

A solution of 52.8 g. (0.20 mole) of o-xylylene dibromide (Note 6) in 300 ml. of purified dimethylformamide is added dropwise with stirring at such a rate as to maintain a temperature of 60-70° (Note 7). Subsequently the reaction mixture is stirred at room temperature for 3 hours and then poured into 600 ml. of ice water in a 2-1. Erlenmeyer flask. After standing at room temperature overnight the product is collected by suction filtration, pressed on the funnel, and washed twice with 100-ml. portions of water. The crude product is air-dried on filter paper for 2-3 hours and is then dissolved in 1.21. of boiling 95% ethanol. The solution is filtered through a heated funnel, and the filtrate is refrigerated overnight. The crystals are collected on a Buchner funnel and washed on the funnel with 100 ml. of cold 95% ethanol. The product is dried over phosphorus pentoxide in a vacuum desiccator. The yield of white crystals of 2-(% tolylsulf onyl)-dihydroisoindole is 41-46 g. (75-84%), m.p. 174-175° (dec.). 

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