Hydrogen phosphate, preparation

X)8 695 m potassium dihydmgen phosphate. 0.030 43 m disodium hydrogen phosphate. Prepare like Buffer 5 dissolve 1.179 g KH2PO4 and 4.30 g Na2HPOA in water to give 1L erf solution at 25°C. 

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). 

Coesite. Coesite, the second most dense (3.01 g/cm ) phase of silica, was first prepared ia the laboratory by heating a mixture of sodium metasibcate and diammonium hydrogen phosphate or another mineraliser at 500—800°C and 1.5—3.5 GPa (14,800—34,540 atm). Coesite has also been prepared by oxidation of silicon with silver carbonate under pressure (67). The stmcture is monoclinic = 717 pm, Cg = 1.238 pm, and 7 = 120°. 

Deoxy-D-jcylo hexose 6-(dihydrogen phosphate) (21) has also been synthesized (2) the reaction sequence makes use of 3-deoxy l 2,5 6-di-O-isopropylidene D-galactofuranose (16), a compound that can be easily prepared from D-glucose (2, 60). The mono-isopropylidene derivative (17) formed by partial hydrolysis of the di-ketal is converted into the 6-tosylate (18) by reaction with one molar equivalent of p-toluenesulfonyl chloride. From this the epoxide (19) is formed by reaction with sodium methoxide. Treatment of the anhydro sugar with an aqueous solution of disodium hydrogen phosphate (26) leads to the 6-phosphate (20)... 

The same pyrophosphate5 can be prepared in high yield from dibenzyl hydrogen phosphate by reaction for a short time with tetraphenyl pyrophosphate at room temperature in an-... 

Dibasic calcium hydrogen phosphate may be prepared by several methods. It is precipitated by mixing solutions of calcium chloride and disodium hydrogen phospate ... 

Sodium diphosphate is prepared by the following procedure. Disodium hydrogen phosphate dihydrate, Na2HP04 2H20, (7.12 g, 40 mmole) is placed in a 60-mL platinum crucible and heated in air at 400° for 12 hours (Product Merck for analysis K 6580). According to Porthault,2 this method leads to a tetrasodium diphosphate, Na4P207, the purity of which is better than 99.5%. No impurities can be found by chromatographic or potentiometric analysis. 

Phosphates have been formed by slow hydrolysis of trialkyl phosphates, hydrogen phosphate ions, or metaphosphoric acid, which liberate phosphate ions (see p. 46 in Ref. 31). This may be of interest as a precursor for the preparation of phosphide semiconductors. 

Monolayers prepared from arachidic acid, bovine-brain phosphatidylserine (16), and n-hexadecyl-4- vinylbenzamido)undecyl hydrogen phosphate (4) Size-quantized CdS, ZnS, PbS, and CuS semi-conductor particulate films generated in situ under monolayers... 

Peroxyphosphtnic Acids. Two are known—peroxymonophosphoric acid, H00P(0)(0H)2, prepared by treatment of P4Oic with hydrogen peroxide. and peroxydiphosphoric acid, (H0)2(0)P00P(0j (OH)2. prepared from metaphosphoric acid and peroxide or by electrolysis of an alkali hydrogen phosphate solution (cf. preparation of peroxydisulfunc acid). They and their salts are strong oxidants. 

Salts therefore, are prepared (1) from solutions of acids and bases by neutralization and separation by evaporation and crystallization (2) from solutions of two salts by precipitation where the solubility of the salt formed is slight (e.g., silver nitrate solution plus sodium chloride solution yields silver chloride precipitate [almost all as sulid], and sodium nitrate present in solution as sodium cations and nitrate anions [recoverable as sodium nitrate, solid by separation of silver chlondc and subsequent evaporation of the solution]) (3) from fusion of a basic oxide (or its suitable compound—sodium carbonate above) and an acidic oxide (or its suitable compound—ammonium phosphate), since ammonium and hydroxyl are volatilized as ammonia and water. Thus, sodium ammonium hydrogen phosphate... 

Screening of ENRO, CIPRO, DAN, NOR, FLU, OXO, and NALA in pork muscle was based on HPTLC after the SPE procedure (195). Tissue samples were extracted with MeCN-NaOH, the supernatant dried, and the residues dissolved in dipotassium hydrogen phosphate buffer (pH 7.4) hexane was added. The aqueous phase was cleaned up using the SPE technique. After washing the cartridge, analytes were eluted with MeOH-ammonia solution (75 25). After the preparation step, extracts were spotted and eluted on silica gel plates. The plate is first inspected under UV illumination at 312 nm and then sprayed with terbium chloride. The method was validated at the levels of 15 yug/kg for ENRO, CPRO, DAN, and NOR and 5 yug/kg for FLU, 0X0, and NALA. 

Method. Hie metal chelates are prepared by extracting the metal ion from aqueous solution with 20-, 20- and 10-ml volumes of chloroform after addition of an appropriate amount of a solution of DDTC [0.22S g of the sodium salt in 75 ml of water and 25 ml of an ammonia-ammonium nitrate (1 1) buffer, 3 M in total ammonia]. The exact volumes which are used depend on whether the metal is uni-, bi- or tri-valent. The combined chloroform extracts are diluted to at least 50 ml for chromatography. The metal chelates are separated on plates of silica gel G or N which have been activated at 110 °C for 1 h. The Rp values of a number of DDTC metal chelates in a variety of solvent systems are listed in Table 4.31. The dried plates are sprayed with a solution consisting of 1 10 4A/ Pd(II), 7.0 10 5Af calcein and 0.02Mphosphate buffer [dihydrogen phosphate-hydrogen phosphate (1 1)]. This solution must be allowed to stand for 12 h in order to ensure that equilibrium is attained. For quantitative work with low concentrations, the solution of DDTC should be washed with chloroform before use. This removes fluorescent impurities which may cause interference in the chromatography. 

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