Phosphorous acid , successive

Finally, Czobik et al. [4] reported that in the analyte—interferent systems Pb—CdCl2, Sn—CdCl2, Sn—CuCl2, Zn—PbCl2, Zn—CuCl2, and Zn—CdCl2, sulphuric acid and phosphoric acid successfully removed the interferences. Nitric acid was found to be less effective although it removed the interference in the Pb—NaCl system. 

If the three esterifiable OH groups of phosphoric acid have to be esterified successively with different alcohols, they have to be protected. 

Potassium Phosphates. The K2O—P20 —H2O system parallels the sodium system in many respects. In addition to the three simple phosphate salts obtained by successive replacement of the protons of phosphoric acid by potassium ions, the system contains a number of crystalline hydrates and double salts (Table 7). Monopotassium phosphate (MKP), known only as the anhydrous salt, is the least soluble of the potassium orthophosphates. Monopotassium phosphate has been studied extensively owing to its piezoelectric and ferroelectric properties (see Ferroelectrics). At ordinary temperatures, KH2PO4 is so far above its Curie point as to give piezoelectric effects in which the emf is proportional to the distorting force. There is virtually no hysteresis. 

The use of dehydrating agents such as sulfuric or phosphoric acid on (555 X = OH) was also successful, and these closures may proceed via mixed anhydrides 67AHC(8)277, 75MIP41600). Carbonyldiimidazole effected the conversion of hydroxamic acid (557) into a 3-hydroxy-1,2-benzisoxazole derivative (79JHC1277). The mixed anhydride (558) where... 

In primer formulations for adhesive bonding of metals, the coupling agents that are most frequently used are those based on epoxy and amine functionalities. Aqueous solutions of aminosilanes have been successfully used for obtaining stable adhesive bonds between epoxy and steel [10] and epoxy and titanium [11,12], while epoxy functional silanes are preferable for applications involving aluminum substrates [13,14], A simple solution of % epoxy functional silane in water is currently used for field repairs of military aircraft [15] where phosphoric acid anodization would be extremely difficult to carry out, and performance is deemed quite acceptable. 

Evaporators have performed successfully in a number of industrial applications. Typical materials that are processed in evaporators include Caustic Soda, Caustic Potash, Sodium Carbonate, Sodium Dichromate, Sodium Nitrate, Ammonium Nitrate, Phosphoric Acid Superacid, Potash, Urea, Glue, Glycerine,... 

Of the many methods which have been published so far for the substitution of existing crowns, probably the most straightforward are Friedel-Crafts alkylation or acylation reactions. Cygan, Biernat and Chadzynski have reported the successful di-t-butylation of dibenzo-24-crown-8 using t-butanol as alkylating agent s . The crown was heated at 100° for 4 h in the presence of excess t-butanol and 85% phosphoric acid. The product was obtained as a crystalline (mp 52—74°) solid in 93% yield. The alkylated crowns are presumably a mixture of isomers substituted once in each ring as illustrated in Eq. (3.14). 

The results for dinuclear and polynuclear oxoacids are also consistent with this interpretation. Thus for phosphoric acid, H4P2O7, the successive p/fa values are 1.5, 2.4, 6.6 and 9.2 the 10-fold decrease between p/f and p/f2 (instead of a decrease of 10 ) is related to the fact that ionization occurs from two different PO4 units. The third stage ionization, however, is less than the first stage and the differ-... 

Phosphoric acid forms several series of salts in which the acidic H atoms are successively replaced by various cations there is considerable commercial application for many of these compounds. 

Solvolysis of phosphoric acids in the system HF/P2O5/H2O gave successively H2PO3F, HPO2F2 and H30+PFfi , as shown by F and P nmr spectroscopy. Raman studies show that KNO3 solvolyses according to the reaction... 

Preparation of 6-azacytidine-5 -phosphate by direct phosphorylation with cyanoethylphosphate was not successful. The substance could be prepared, however, on ammonia treatment of 4-thio-6-azauridine-5 -phosphate which was obtained by phosphorylation of 2, 3 -isopropyl-iden-4 thio-6-azauridine with pyrophosphoryl chloride. From mor-pholidate of 6-azacytidine-5 -phosphate, 6-azacytidine-5 -diphosphate was prepared by the action of phosphoric acid. ... 

Tlie condensation of nitromalonic aldehyde (26) with 2,6-diaminopyridine (27) in the presence of phosphoric acid, affording 2-amino-6-nitro-l,8-naphthyridine (28,37%) (77TL2087), is another example of a successful application of a nitro aliphatic compound in the synthesis of nitronaphthy-ridines. 

Electrophilic addition of HX to alkenes is successful not only with HBr but with HC1 and HI as well. Note that HI is usually generated in the reaction mixture by treating potassium iodide with phosphoric acid. 

Phosphoric acid esters of alcohols or ethoxylated alcohols are recommended as surfactants which are mild to the skin. Thus they are successfully used in cosmetics such as shampoos and lotions. In analogy to alkyl sulfates and alkyl ether... 

A wide variety of bases, nucleosides and nucleotides have been separated using porous layer bead ion exchangers. A representative chromatogram of the separation of ribonucleoside mono-phosphoric acids from the work of Smukler ( ) is shown in Figure 4. Recently, ion exchangers chemically bonded to small particle diameter (> 10 ym) silica have been successfully applied to the separation of nucleic acid constitutents (37). The rapid separations using such supports undoubtedly mean that they will find increasing use in the future. 

Several successful cyclizations of quite complex structures were achieved using polyphosphoric acid trimethylsilyl ester, a viscous material that contains reactive anhydrides of phosphoric acid.58 Presumably the reactive acylating agent is a mixed phosphoric anhydride of the carboxylic acid. 

Benzyl esters of phosphoric acid have been employed also with success in organic synthesis. Usually palladium catalysts are used to remove the benzyl protecting group (Scheme 4.50). 

More successful applications of periodate oxidation to substituted sugars were made employing the sugar phosphates and phosphoric acids,63 66 the chloraloses, 62 70 the benzyl ethers of sugars,71 72 a dimethyleneoxy sugar,73... 

A mixture of 10 g. of D-galactose, 10 ml. of ethyl acetoaeetate, 10 ml. of ethanol, and 5 g. of zinc chloride is heated on a steam bath during 75 minutes. The mixture is cooled, 45 ml. of water is added, and the solution is extracted with two 30-ml. portions of benzene. The aqueous layer is then extracted with nine 15-ml. portions of ethyl acetate. The united extracts are washed successively with an aqueous solution of sodium bisulfite and with an aqueous solution of sodium bicarbonate, dried with anhydrous sodium sulfate, filtered, and the filtrate evaporated to dryness, affording 4.5 g. of a sirup. This is saponified with 12.5 ml. of 10% sodium hydroxide solution, and then acidified (to Congo Red) with phosphoric acid. The aqueous solution is extracted with successive 30-ml. portions of ethyl acetate, and these are dried with anhydrous sodium sulfate, and individually evaporated to dryness. Extracts after the fourth yield a solid product m. p., 130°. Recrystallized from petroleum ether plus acetic acid, the compound has m. p. 132-134° yield, variable, ca. 2%.54... 

A mixture of 2.65 g. of freshly distilled 2,3-O-isopropylidene-D-glycerose, 1.5 ml. of ethyl acetoacetate, 0.7 g. of zinc chloride, 20 ml. of N sulfuric acid, and 20 ml. of 96% ethyl alcohol is kept at room temperature for twenty-four hours. After addition of 3 g. of crystalline sodium acetate and keeping for a further 48 hours at room temperature, the mixture is heated for 15 minutes at 90°. It is then repeatedly extracted with ether, and the united extracts are successively washed with water, an aqueous solution of sodium bisulfite, and a small quantity of aqueous sodium hydroxide solution. The ether layer is dried with anhydrous sodium sulfate and the solvent is evaporated, yielding an oil which is saponified with aqueous sodium hydroxide solution (4 ml. of 10%) by heating on a steam bath for one hour. The aqueous solution is extracted with ether, acidified (to Congo Red) with phosphoric acid, and then repeatedly extracted with ether the united extracts are dried with anhydrous sodium sulfate and the solvent is evaporated, giving a residue which crystallizes from water yield, 0.2 g. of the product (X) m. p., 153-155°. 

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