Phosphoric acid preparation

To the residue is added 10 c.c. of dilute phosphoric acid, prepared by miiiug alx)Ul 3 5 c.c. cf hH per cent, acid w ith 100 c.c. of carbjn dioiide-free distilled water. 

Kiba et al. [93] has described a method for determining this element in marine sediments. The sample is heated with a mixture of potassium dichromate and condensed phosphoric acid (prepared by dehydrating phosphoric acid at 300 °C). The ruthenium is distilled off as RuC>4, collected in 6 M hydrochloric acid-ethanol and determined spectrophotometrically (with thiourea) or radiometrically. Osmium is separated by prior distillation with a mixture of condensed phosphoric acid and Ce(S04)2. In the separation of ruthenium-osmium mixtures recovery of each element ranged from 96.8 to 105.0%. 

Nakagome and co-workers effected the successful cyclization of N-ethyl-N-arylaminomethylenemalonates (749) in poly phosphoric acid, prepared from orthophosphoric acid and phosphorus pentoxide in polyphosphate ester (PPE), prepared from phosphorus pentoxide and anhydrous diethyl ether in chloroform in phosphoryl chloride on the action of boron trifluoride etherate on the action of acetic anhydride and concentrated sulfuric acid or on the action of phosphorus pentoxide in benzene [71GEP2033971, 71JHC357 76JAP(K) 18440]. Depending on the work-up process, l-ethyl-4-oxoquinoline-3-carboxylates (750, R1 = Et), l-ethyl-4-oxoquinoline-3-carboxylic acids (750, R2 = H) and 3-ethoxycarbonyl-4-chloroquinolinium iodides (751) were obtained. Only the cyclization of... 

Vanadium leaches soil from a large number of diverse sources, including waste effluents from the iron and steel industries and chemical industries. Phosphate industries are also a major source of vanadium pollution because vanadium becomes soluble along with phosphoric acids when rock phosphates are leached with sulfuric acid. Vanadium is present in all subsequent phosphoric acid preparations, including ammonium phosphate fertilisers, and is released into the environment along with them. Other sources of vanadium pollution are fossil fuels, such as crude petroleum, coal and lignite. Burning these fuels releases vanadium into the air, which then settles in the soils. 

Subsequent work with salts of 12-tungsto-phosphoric acid prepared from a number of monovalent cations has revealed that those of potassium and cesium are also microporous while those of the sodium, methylammoniurn and tetranethylammonium cations show no evidence of microporosity (refs. 20, 22). Similar results have been obtained for the monovalent salts of 12-molybdophosphoric, 12-tungstosi1icic, and... 

Asensio JA, Borr6s S, G6mez-Romero P (2004) Proton-conducting membranes based on poly (2,5-benzimidazole) (ABPBI) and phosphoric acid prepared by direct acid casting. J Membr Sci 241 89-93... 

The aldehyde is visualized either by spraying the plate with a solution of dinitrophenylhydrazine in phosphoric acid prepared according to Johnson, or by the chlorine-tolidine reagent described above. A solution of the product in hexane kept at —20° deposited 58 mg of product (m.p. 78°-80°) with the NMR spectrum anticipated for an A"-acyl phenylalaninal. 

Lecithins are fatty acid esters of glycero-phosphoric acid derivatives. Commercially glycerophosphoric acid is used to prepare the medicinal glycerophosphate salts, c.g. the calcium salt. 

Phosphonic acid, H3PO3, often called just phosphorous acid , is prepared by the hydrolysis of phosphorus trichloride a stream of air containing phosphorus trichloride vapour is passed into ice-cold water, and crystals of the solid acid separate ... 

It is however more complicated, esters of phosphorous acid being also formed (c/. p. 308). Iodides are usually prepared by a modification of this method, the ethanol being mixed with red phosphorus, and iodine added. The phosphorus iodide is thus formed in situ, and at once reacts with ethanol to give the corres ponding iodide. 

A satisfactory bath suitable for temperatures up to about 250° may be prepared by mixing four parts by weight of 85 per cent, ortho-phosphoric acid and one part by weight of meta-phosphoric acid the mixed components should first be heated slowly to 260° and held at this temperature imtil evolution of steam and vapours has ceased. This bath is liquid at room temperatures. For temperatures up to 340°, a mixture of two parts of 85 per cent, ortho-phosphoric acid and one part of meta-phosphoric acid may be used this is solid (or very viscous) at about 20°. 

Phosphoric acid method. The advantages of phosphoric acid as a dehydrating agent in this preparation are the absence of carbonisation and the freedom of the product from sulphur dioxide. 

The O-S exchange method in presence of a-halogenated carbonyl compound is a very good one for thiazole compounds. The thioamide is prepared in situ by the action of amide upon phosphorus pentasulphide with solvent. The a-halogenated aldehyde reacts directly. But the O-Se exchange cannot be performed with a-halogenated carbonyl compounds because of the apparition of phosphoric acid. (Scheme 3), The C-Se bond is very sensitive to add pH. 

Ma.nufa.cture. Mesityl oxide is produced by the Hquid-phase dehydration of diacetone alcohol ia the presence of acidic catalysts at 100—120°C and atmospheric pressure. As a precursor to MIBK, mesityl oxide is prepared ia this manner ia a distillation column ia which acetone is removed overhead and water-saturated mesityl oxide is produced from a side-draw. Suitable catalysts are phosphoric acid (177,178) and sulfuric acid (179,180). The kinetics of the reaction over phosphoric acid have been reported (181). 

The catalyst used in the production of maleic anhydride from butane is vanadium—phosphoms—oxide (VPO). Several routes may be used to prepare the catalyst (123), but the route favored by industry involves the reaction of vanadium(V) oxide [1314-62-1] and phosphoric acid [7664-38-2] to form vanadyl hydrogen phosphate, VOHPO O.5H2O. This material is then heated to eliminate water from the stmcture and irreversibly form vanadyl pyrophosphate, (V(123,124). Vanadyl pyrophosphate is befleved to be the catalyticaHy active phase required for the conversion of butane to maleic anhydride (125,126). 

Isopropylnaphthalenes can be prepared readily by the catalytic alkylation of naphthalene with propjiene. 2-lsopropylnaphthalene [2027-17-0] is an important intermediate used in the manufacture of 2-naphthol (see Naphthalenederivatives). The alkylation of naphthalene with propjiene, preferably in an inert solvent at 40—100°C with an aluminum chloride, hydrogen fluoride, or boron trifluoride—phosphoric acid catalyst, gives 90—95% wt % 2-isopropylnaphthalene however, a considerable amount of polyalkylate also is produced. Preferably, the propylation of naphthalene is carried out in the vapor phase in a continuous manner, over a phosphoric acid on kieselguhr catalyst under pressure at ca 220—250°C. The alkylate, which is low in di- and polyisopropylnaphthalenes, then is isomerized by recycling over the same catalyst at 240°C or by using aluminum chloride catalyst at 80°C. After distillation, a product containing >90 wt % 2-isopropylnaphthalene is obtained (47). 

Nickel Phosphate. Tri nickel orthophosphate [14396-43-17, Ni2(P0 2 7H20, exists as apple-green plates which decompose upon heating. It is prepared by the reaction of nickel carbonate and hot dilute phosphoric acid. Nickel phosphate is an additive to control the crystal size of ziac phosphate ia coaversioa coatiags which are appHed to steel prior to its being paiated (see Metal surface treatments). 

Condensed Phosphoric Acid. The largest use of polyphosphoric (superphosphoric) acid is as an intermediate in the production of high quahty Hquid fertilizers. The TVA pioneered the development of electric-furnace superphosphoric acid for this appHcation. However, wet-process superphosphoric acid prepared by evaporation of water from wet-process phosphoric acid has almost completely replaced furnace-grade acid in fertilizer manufacture. 

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