Potassium borates formate

Although B(0H)3 and B(OH)4 are monomeric in dilute solutions, at concentrations above about O.lmolL, condensed borate species that are often referred to as polyborates form. Titration of a boric acid solution with one molar equivalent of a strong base leads to formation of the tetrahydroxyborate anion, B(OH)4, as the principal species in solution. Mixtures of boric acid and its conjugate base, the tetrahydroxyborate anion, form what appears to be a classical buffer system where the pH is determined primarily by the acid salt ratio with [H+] = K[B(OH)3]/[B(OH)4 ]. This relationship is approximately correct for sodium and potassium borates with a sodium boron ratio of 1 2. Here the B(0H)3 B(0H)4 ratio equals one, and the solution pH remains near 9 over a wide range. However, for borate solutions with pH values significantly above or below 9,... 

A potentiometric study of complexes formed by boric acid or potassium borate with mannitol in water or aqueous KCl solution has been carried out.2 The formation constant -Kcn of the mono-mannitoboric complex was determined (pAcn = 0.20 in HgO as solvent). 

For this purpose the effect of the concentration of potassium chloride added to a borate buffer solution (total concentration of boric acid and potassium borate 0,10 mole/liter, pH 8,4) on polaro-gp ams for the Co (II) - cysteine system, with constant cobalt chloride (1,74 mmole/liter) and cysteine (0,08 mmole/liter) concentrations, was investigated. The borate buffer solution was used in place of the traditional ammoniacal buffer solution in order to avoid a number of complications and, primarily, decrease in the buffer capacity of the ammoniacal solution near the electrode when potassium chloride is added, since ammonium ions (being proton donors) also participate in the formation of the outer layer of the electric double layer. The pH value of the solution was selected so that the solution would contain approximately equal amounts of anions and cysteine zwitterions (pl am 8.33). 

Poloxamers are used primarily in aqueous solution and may be quantified in the aqueous phase by the use of compleximetric methods. However, a major limitation is that these techniques are essentially only capable of quantifying alkylene oxide groups and are by no means selective for poloxamers. The basis of these methods is the formation of a complex between a metal ion and the oxygen atoms that form the ether linkages. Reaction of this complex with an anion leads to the formation of a salt that, after precipitation or extraction, may be used for quantitation. A method reported to be rapid, simple, and consistently reproducible [18] involves a two-phase titration, which eliminates interferences from anionic surfactants. The poloxamer is complexed with potassium ions in an alkaline aqueous solution and extracted into dichloromethane as an ion pair with the titrant, tet-rakis (4-fluorophenyl) borate. The end point is defined by a color change resulting from the complexation of the indicator, Victoria Blue B, with excess titrant. The Wickbold [19] method, widely used to determine nonionic surfactants, has been applied to poloxamer type surfactants 120]. Essentially the method involves the formation in the presence of barium ions of a complex be-... 

Discussion. Potassium may be precipitated with excess of sodium tetraphenyl-borate solution as potassium tetraphenylborate. The excess of reagent is determined by titration with mercury(II) nitrate solution. The indicator consists of a mixture of iron(III) nitrate and dilute sodium thiocyanate solution. The end-point is revealed by the decolorisation of the iron(III)-thiocyanate complex due to the formation of the colourless mercury(II) thiocyanate. The reaction between mercury( II) nitrate and sodium tetraphenylborate under the experimental conditions used is not quite stoichiometric hence it is necessary to determine the volume in mL of Hg(N03)2 solution equivalent to 1 mL of a NaB(C6H5)4 solution. Halides must be absent. 

In most commercial processes, borax is obtained from lake brines, tincal and colemanite. The primary salt constituents of brine are sodium chloride, sodium sulfate, sodium carbonate and potassium chloride. The percent composition of borax as Na2B40 in brine is generally in the range 1.5 to 1.6%. Borax is separated from these salts by various physical and chemical processes. The brine solution (mixed with mother liquor) is subject to evaporation and crystahzation for the continuous removal of NaCl, Na2C03 and Na2S04, respectively. The hot liquor consists of concentrated solution of potassium salts and borate components of the brine. The insoluble solid particles are filtered out and the liquor is cooled rapidly in continuous vacuum crystallizers under controlled conditions of temperatures and concentrations to crystallize KCl. Cystallization of borax along with KCl from the concentrated liquor must not occur at this stage. KCl is separated from the hquor by filtration. Bicarbonate then is added to the liquor to prevent any formation of sodium... 

In equation 7.1. a 4-chloropyridine was coupled with diethyl(3-pyridyl)borane.3 The reaction was run in aqueous THF in the presence of potassium carbonate. The role of the base is to facilitate the transmetalation step through the formation of a borate ion, as organoboranes are usually not nucleophilic enough to transfer their organic moiety onto the palladium. An alternate function of the base is to increase the electrophilicity of the palladium through exchange of the halide to carbonate. 

The reaction of potassium dienoxy borates with A-fluorobis(phenylsulfonyl)amine (la) gives y-fluoro enones in good yield. The potassium dienoxy borates are prepared by treating potassium enolates derived from unsaturated ketones with 2-phenyl-1,3,2-benzodioxaborole. This methodology offers a convenient alternative to the traditional fluorination of dienol acetates, ethers, or enamines.145 An example is given by the formation of 13.145... 

Metavanadates of the alkalis are white or colourless, and give colourless aqueous solutions which rapidly become yellow, and, on addition of acids, red or orange. These coloured solutions contain polyvanadates, the formation of which is comparable to that of the polychromates and other salts formed by condensation of weakly acid oxides of metals, e.g. molybdates and borates. Thus, under definite conditions of temperature and concentration, potassium metavanadate is converted into the acid salt 2K20.3Va05, in accordance with the equation ... 

Figure 4. Reactions of borate with mannitol with the log formation constants of the complexes at 25°C and 0.15M in potassium nitrate...

The omission of the bicarbonate buffer gave latexes of lower pH with weak-acid groups. The formation of weak-acid groups in these latexes is not merely an effect of pH during the polymerization potassium dihydrogenphosphate, sodium borate, and sodium... 

Valyashko and Gode (414) have summarized the conditions necessary for formation of borates of sodium, potassium, ammonium, calcium, and magnesium. The effect of varying the cation is to alter the type of borate that is stable in contact with the aqueous solution. The stability ranges for solid phases in the sodium and calcium systems are shown in Table V. 

A tris(imidazolyl)borate (138) complex of thallium(I) has been synthesized.The solid-state structure of hydrotris(imidazolyl)boratothallium(I) consists of one-dimensional, twisted, ladderlike strands, and three-coordinate thallium centers. Due to the position of the nitrogen donors, the tris(imidazolyl)borate ligand is not capable of forming metal chelates as are observed in tris(pyrazolyl)borates. Poly(benzotriazolyl)borate ligands have some features of both tris(pyrazo-lyl)borate and tris(imidazolyl)borate systems. Thallium(I) complexes of bis-, tris-, and tetrakis (benzotriazolyl)borates are reported. These adducts have been synthesized by treating the corresponding potassium derivative with an equimolar quantity of thallium(I) formate. ... 

Although the ratio of biaryls formed in these halogenative oxidations is somewhat sensitive to the reaction medium, it is noteworthy that the amount of biaryl formation is quite dependent both on the nature of the solvent and the metal ion (L, Na" ", or K+). Although potassium phenyl(tri-/7-tolyl)borate (58) dissolved in chloroform reacted with iodine to yield a 1.4 1.0 ratio of biaryl to p-iodotoluene, the same reaction in dimethylformamide gave almost exclusively p-iodotoluene. Likewise, the sodium analog of 58 gave a biaryl p-iodotoluene ratio of 1 32 (48). 

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