Boric Acid complexes with

Curves which are of the same form as curve B have been obtained for the diazo-coupling (52) and iodination (, 7,13) of 8-hydroxyquinoline-5-sulfonic acid and its metal complexes and for the oxidation of glucose and its boric acid complex with ferricyanide (50). 

The complexes with boric acid and borates have been of more interest. The ability of D-mannitol to render boric acid more acidic is well known and forms the basis of an anal3rtical method allowing boric acid to be titrated as a monobasic acid. The boric acid complexes have been... 

The reactions of boric acid solutions with diols have been used for almost a century to examine structural differences among carbohydrates. The complexity of these reactions seems to arise not only from simple structural differences but also from differences in carbohydrate configuration and conformation. The precise nature of these reactions is not clear. Recent studies of the chemistry of polyol-boric acid solutions have clarified some aspects of these reactions that have important bearing on the structure of carbohydrates in solution. Nevertheless, some of the most fundamental questions about the nature of the reaction are still unanswered. 

An example of some recent data which was interpreted to support this assumption is the work of Knoeck and Taylor (12). Using PMR spectra of mannitol-boric acid solutions, they observed that a decrease in pH resulted in a decrease in the mannitol-boric acid complex concentration. These results are supported by nB nuclear magnetic resonance (NMR) spectroscopy (16) which showed that the complex between mannitol and boric acid increased with increasing pH. However, Knoeck and Taylor (12) reasoned that since an increase in pH resulted in an increase in the borate anion concentration, as well as an increase in the complex concentration, the diol reacts only with the borate ion to produce the complex. 

Expressions VII and VIII are identical in form they differ only in the meaning of the constants they contain. In both cases an increase in the borate ion concentration would result in an increase in the diol-boric acid complex. Therefore, an examination of the effect of pH on the equilibrium concentrations of various components of the system cannot be used to determine which of the two boroxy species actually reacts with the diol. 

Fig. 29.—The mode of iodine binding in the amylopectin-boric acid complex. (Reprinted with permission from J. Hollo and J. Szejtli, Fette. Seifert. Anschtrichmittel, 59 (1957) 94-98.)...

Didesoxydihydrostreptose formed an acidic complex with boric acid. In accordance mth the extensive work of Boeseken and his students, this is indicative of a configurationally cis a-glycol grouping and the configuration of didesoxydihydrostreptose would be one of the two formulas shown (XLVII or XLVIII). Streptose itself would then have either the configurational system of L-ribose or L-lyxose and would... 

Boron (B, at. mass 10.81) is a metalloid with properties somewhat similar to those of silicon. In chemical analysis, only boron(III) compounds are of importance. Boron forms complexes with fluoride and polyalcohols (e.g., mannitol and glycerol). In an anhydrous medium, boric acid reacts with methanol to form the volatile trimethyl borate. 

Complex tungstic acids arc numerous mid interesting. I hosplnirir, arsenic, antimonic, vanadic, and boric, acids condense with varying aiunuuis of tungstic acid. The ratio of the, otlner oxide, to W(), varies from 1 7 in 1 24 or more-... 

Figure 8-17 shows the flow through a heat-resistant alloy-metal converter joined to a waste-heat boiler, and the recovery system. The absorber is loaded with a water solution of polyalcohol-boric acid complex made from 8.3 parts pentaerythritol and 2.5 parts boric acid. In the cold, this solution dissolves HCN and ties up NH3 as the ammonium salt of the complex, thereby preventing polymerization of HCN in the presence of free NHj. The HCN is removed first in the stripper under moderately reduced pressure (10 in. Hg) at about 88°C, after which the NHj is stripped out by breaking up the ammonium salt at about 132°C under 25 psig. 

The boric acid complexes of a-pyridoin have recently been investigated using semiempirical calculations. For AM 1-optimized structures, spectroscopic parameters were calculated by CNDO/S and INDO/S methods and a good agreement with observed values was found <93JPC8602>. 

Initially, BN was synthesized by the pyrolysis of boric acid and urea in the presence of ammonia [27]. In this reaction, boric acid presumably reacts with urea to form a urea-boric acid complex gel, which on pyrolysis in an ammonia atmosphere results in the formation of BN [28]. Precursors for BN recently received the greatest attention, with emphasis on borazine-derived polymers. It has been recognized that borazine (1) can form polymeric chains of B and N, which can form BN ceramics on thermal pyrolysis [29]. The polymerization gives a graphitelike hexagonal layered structure (2) ... 

One method to reduce the volatility of sulfur dioxide is to complex it with imidazole and then add the complex to the adhesive. Chelates of boric acid derivatives with polyhydroxy compounds have also been prepared as anionic polymerization inhibitors. The chelates can be preformed or prepared in situ by adding the boric acid compound and the polyhydroxy compound to the adhesive. Sulfamides have been used to stabilize cyanoacrylates. The sulfamides (24) in question are prepared by reacting sulfuryl diisocyanate (23) with active hydrogen compounds such as carboxylic acids, as shown in Eq. (7). ... 

Boric acid complexes of sugar compounds have been investigated for well over one hundred years (4). By the end of the nineteenth century it was known that addition of boric acid to aqueous sugar solutions changed the optical rotation of the sugars, increased the acidity of the boric acid, and increased the solution s electrical conductivity (5). Ansdogous complexation studies with boronic acids were apparently not conducted until the middle of the twentieth century. In 1954, Kuivila reported... 

In Reference 108, Wang et al. introduced a di- -amyl L-tartrate-boric acid complex for the enantioseparation of propranolol, sotalol, esmolol, atenolol, bisoprolol, metopro-lol, terbutaline, clenbuterol, cycloclenbuterol, bambuterol, and tulobuterol. Uncoated fused-silica capillaries of 50 p,m i.d. with a total length of 53.0cm and an effective length of 45.0 cm were used. A nonaqueous BGE proved useful for the ion-pair formation and the addition of TEA enhanced the enantiomeric discrimination. When a 100-mM boric acid, 80-niM di-n-amyl L-tartrate, 50-mM TEA in MeOH BGE was used, propranolol, sotalol, esmolol, atenolol, bisoprolol, and metoprolol were baseline separated with resolutions ranging from 2.3 (sotalol) to 3.0 (propranolol). Terbutaline, clenbuterol, cycloclenbuterol, bambuterol, and tulobuterol could be baseline separated with resolutions ranging from 3.2 (bambuterol) to 4.2 (clenbuterol) using a 120-mM boric acid, 100-mM di-n-amyl L-tartrate, 50-mM TEA in MeOH BGE. 

Tetraalkyl titanates react with organic borates, B(OR )2, to give complexes of the general formula Ti(OR)4 B(OR )2, which are useful as catalysts and cross-linking agents (562). Mixtures of chelated organic titanates such as TYZOR TE and TYZOR LA with alkaU metal borates, such as borax, or boric acid can be used to produce shear-stable fracturing fluids (563). 

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