Hypophosphite, determination

In the alternative method of reduction, which is particularly valuable for the determination of small amounts of tellurium, the procedure is as follows. Treat the solution containing, say, up to about 0.01 g Te in 90 mL with 10 mL of 1 3-sulphuric acid, then add 10 g sodium hypophosphite (phosphinate), and heat on a steam bath for 3 hours. Collect and weigh the precipitated tellurium as above. 

Electron Diffraction. - Three gas-phase molecular structures have been determined by electron diffraction. They are the hypophosphite (80)224 trif1uorophosphine sulphide,225 and dichlorotrifluorophosphorane.224... 

As a last example on the fabrication of silver clusters, it is worth mentioning that they can also be prepared in microemulsions, where the small droplets of water act as nanoreactors. The surfactant used was AOT and the reducing agent was a very mild one, i.e. sodium hypophosphite. In this manner, fluorescent silver clusters with less than ten atoms are formed and showed planar shape when deposited onto gold substrates, as determined by scanning tunneling microscopy [67, 68]. 

Calcium hypophosphite instead of the sodium salt may be used in the presence of hydrochloric acid,9 and the reaction may be applied for the gravimetric estimation of the element, the arsenic in the residues being redissolved and determined as magnesiumpyroarsenate,10 or by titration.11... 

Copper.—In an aliquot part of the hydrochloric acid solution obtained in determination No. 2 (above) the ferric salts are reduced by means of sodium hypophosphite and the copper then precipitated with hydrogen sulphide, the precipitate being dissolved in nitric acid and the copper then determined electrolytically. 

For synthesizing tris-chelates (or bis-tridentate chelates) the ideal source material is RuC13 3 H20 simply because of its availability. Hypophosphite reduction in the presence of the ligand provides a fairly general, rapid synthetic technique. While there will always be questions of purity for compounds prepared by this route, it is a valuable method for the initial synthesis of a compound to determine general properties before exploring other synthetic routes. 

The decay involves attack by HO at phosphorus followed by hydride shift to cobalt or a direct hydride shift to cobalt from coordinated ammonia. The hydrido-cobalt intermediate so generated is believed to rapidly reduce another molecule of the hypophosphito complex in a post-rate-determining step to produce one equivalent of hypophosphite. 

Hypophosphite and phosphite may also be determined by oxidation with iodine. In alkaline bicarbonate solutions phosphites are oxidised quickly to phosphates, while hypophosphites are hardly affected, i.e. they do not use any measurable amount of decinormal iodine after standing for two hours at ordinary temperatures. In acid solution hypophosphorous acid is slowly oxidised to phosphorous acid, but no further, according to the equation... 

Nickel nickel/copper (electroless) Determination of hypophosphite, phosphite, citric acid, succinic acid, Ni2+/Co2+ ratio... 

Iron(II) and total iron can be determined with phenanthroline or bipyridyl after reduction of Fe(III) to Fe(II). Hydroxylamine reduces Fe(III) within a few minutes in a weakly acidic medium (pH 3 ) ascorbic acid is a better reductant in a fairly acidic solution (pH 0-1). Other reducing agents used are sulphite, dithionite, and hypophosphite [28 ]. 

Hypophosphite can be determined, in the presence of phosphate, from the colour it gives with ammonium molybdate in H2SO4 medium [145]. Hypophosphite may also be determined by its bleaching of the colour of the Fe(III)-SCN complex [146 ]. 

Density functional calculations of dimethylamine borane, formaldehyde, and hypophosphite oxidation on Ag surfaces indicate initial addition of OH to form a five-coordinated intermediate species resulting in the destabilization of the hydrogen bond (see [20] and references cited therein). The isotopic molecules containing either R-H or R-D bonds are involved in elementary reaction in which the R-H or R-D bond is broken in the rate-determining step (19.4) a decrease in reaction rate... 

Minor variations in hypophosphite oxidation rate on the electrode potential (Figures 19.2A(b) and 19.3A(a)) could be interpreted as the evidence of a non-electrochemical rate-determining step in the anodic oxidation of hypophosphite, for example, catalytic dehydrogenation [19], possibly, via hypophosphite radical intermediate formation, as was evidenced from the electron spin-trap resonance spectroscopy measurements [73], although this was not confirmed by in situ IR spectroscopy, apparently, due to a short lifetime of the radical intermediate [74]. 

It should be noted that such a stoichiometry of the phosphorus formation reaction during electroless Ni-P deposition was confirmed by using analytical methods to determine the amounts of Ni and P deposited, the overall amount of hypophosphite used, and the isotopic composition of the evolved gas, which allows to quantify the contribution of reaction (19.12) under these conditions [78,79]. Therefore, anodic partial current is equal to the sum of cathodic currents during electroless Ni-P plating under open-circuit conditions ... 

Fig. 28. Determination of interfering nitrates in a nickel-plating bath. Leading (L) and terminating (T) anions chloride and glutamate, resp. Other components of the bath, namely hypophosphite (hypo P-ite), phosphite, (P-ite), phosphate (P-ate), and lactate (Lac) are also separated...

In the future, analytical isotachophoresis will find wide application in analytical control in industry. Particularly in the field of anions, this technique may bring about progress, due to its rapid application and easy interpretation of the record as demonstrated by Figs. 28 and 29. Figure 28 illustrates the determination of interfering nitrates in the presence of an active component (hypophosphite) in... 

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