Absence Of Boric Acid Research Articles

Derivatives of 14H-naphtho[2,3-a]phenothiazine-8,13-dione—III. Syntheses via boric acid complexes of α-hydroxy-anthraquinones

The reaction of α-hydroxy (and amino) derivatives of anthraquinone with 2-aminobenzenethiol in the presence of boric acid is evaluated. The formation of the resulting 14H-naphtho[2,3-a]phenothiazine-8,13-diones proceeds with greater facility than with previously reported reactions in the absence of boric acid, giving products in generally good yield and high purity. The use of ethanolic media, such as 2-methoxyethanol, is more convenient than alternative methods involving, for example phenol or Zn HCl in the reaction system.

Formation of beta-fructosyl compounds of pyridoxine in growing culture of Aspergillus niger.

Two pyridoxine compounds were found to be formed in a culture filtrate of Aspergillus niger and A. sydowi, when grown in a medium containing sucrose and pyridoxine. Each of the two compounds I and II was obtained as a white powdered preparation by preparative paper chromatography, gel filtration on Toyopearl HW-40S and Sephadex G-10 columns, DEAE-cellulose column chromatography, and lyophilization. Compounds I and II were identified as 5'-O-(beta-D-fructofuranosyl)-pyridoxine and 5'-O-[beta-D-fructofuranosyl-(2-->1)-beta-D-fructofuranosyl]-pyridoxine, on the basis of the various experimental results, viz., elementary analyses, UV, 1H-, and 13C-NMR spectra, products by hydrolysis with acid and yeast beta-D-fructofuranosidase, migration on paper electrophoresis, and Gibbs reaction in the presence and absence of boric acid. Levansucrase from Microbacterium laevaniformans and yeast beta-D-fructofuranosidase did not catalyze the beta-D-fructofuranosyl transfer from sucrose to pyridoxine to give rise to beta-D-fructofuranosyl-pyridoxine.

ワット浴からのニッケルめっきに及ぼすホウ酸の影響

Investigations were conducted on variations in the pll of solutions in the vicinity of a copper substrate by means of micro-electrode plated with Sb, on the resistance between a copper substrate and a tip of Luggin capillary by means of current interrupter electrolysis, and on the partial current density for nickel deposition by means of atomic absorption analysis of the deposits. The results indicated that with increasing current density the action of boric acid in nickel deposition changed from that of pH buffer in solution to that of inhibitor of the hydrogen evolution reaction.Variation in solution pH near the copper substrate in plating baths containing boric acid was always smaller than that in baths without boric acid, although the current efficiency of the former was lower than that of the latter at current densities below 1.0A/dm2. This effect is attributed to the pH buffering action of a complex formed between boric acid and nickel ion.At higher current densities (3.0 to 12.0A/dm2), on the other hand, the partial current density for hydrogen evolution was depressed more than that for nickel deposition in the presence of boric acid, and the current efficiency for nickel deposition was eventually enhanced to ca. 100% with increasing current density. This effect is attributed to the adsorptive interactions of boric acid at the electrode surface. In the absence of boric acid, however, solution pH near the copper substrate increased to ca. 6.5 in a fluctuating manner, resulting in the deposition of a green-black thin film consisting of a mixture of Ni(OH)2 and Ni metal, the surface of which had many cracks, and the morphology of rock covered with moss.

Formation of β-galactosyl compounds of pyridoxine in growing culture of Sporobolomyces singularis

Several pyridoxine compounds were found to be formed in a high yield in a growing culture of Sporobolomyces singularis containing lactose and pyridoxine. Three compounds, I, II and III, were isolated from cultured broth by Dowex 50W-X8 colum chromatography, paper chromatography, lyophilization, and then obtained as needle crystals (m.p. (decomp.): I, 204–206°C; II, 192–194°C; III, 222–223°C. [α] D 16: I, −27.7° ( c = 3.82, H 2O); II, −1.6° ( c = 2.52, H 2O); III, + 8.3° ( c = 3.98, H 2O)). Compounds I, II, and III were identified as 5′-O-(β- d-galactopyranosyl)-pyridoxine , 4′-O-(β- d-galactopyranosyl)-pyridoxine , and 4′-O-(β- d-galactopyranosyl -(1 → 4)-β- d-galactopyranosyl)-pyridoxine , respectively, on the basis of the various experimental results, viz., ultraviolet, infra-red, 1H-NMR, and 13C-NMR spectra, products by hydrolysis with acid and with α- and β-galactosidases, migration on paper electrophoresis, and Gibbs reaction in the presence and absence of boric acid. Also, the yeast produced a remarkable amount of β-glucosyl compounds of pyridoxine in cultured broth, when grown on cellobiose and pyridoxine.

Studies on the chemistry of the determination of boron with curcumin

The stability of the reagent curcumin (H 3A) in sulphuric acid-acetic acid medium both in the presence and absence of boric acid has been studied. Kinetic measurements show that protonated curcumin decomposes according to a second-order rate law. The decomposition is inhibited by the addition of boric acid which forms a complex with curcumin. This complex has a much slower decay rate. The complex was analyzed and found to be a 1:2 boric acid-curcumin compound. The chemical behaviour as well as the physical data are in good agreement with results from the investigation of rosocyanin synthesized as described by Spicer and Strickland. The necessity of water removal and the use of curcumin in excess in the analytical procedures is explained. The acid dissociation constant of curcumin in water-ethanol solution has been determined and K a= ([H +][H 2A -])/[H 3A]=10 -7.9. For roso-cyanin, B(H 2A) 2 +, the acid dissociation constant for the equilibrium B(H 2A) 2 +→2 H + + B(H 2A)(HA) was found to be lO -5·7 in the same medium. From two-phase experiments with chloroform, rosocyanin in the form of an ion-pair with chloride was found to dissolve in the organic phase just as well as the neutral form. The consequences ofthe results for analytical purposes are discussed.

Liquid phase oxidation of alkylbenzenes in the presence of esterifying agents

1. 1. Oxidation of n-alkylbenzenes in the presence of boric acid is very low and is accompanied by intensive resin formation in the oxidate. In the absence of boric acid, oxidation is normal with a high degree of conversion. An increased length of the side chain of alkylbenzene facilitates oxidation. 2. 2. With acetic anhydride as esterifying agent, oxidation of n-octylbenzene to alcohols is approximately 60% compared with 7·0% obtained during oxidation of n-octylbenzene in the presence of boric acid. 3. 3. The alcohols obtained by oxidizing n-octylbenzene in the presence of boric acid and with acetic anhydride are the same. They are largely secondary alcohols present in the same molar proportions which demonstrates the identical reactivity of secondary carbon atoms to oxygen.

Inhibition by boric acid of the oxidation of zirconium in high pressure steam

A substantial reduction in the corrosion of iodide zirconium exposed to high pressure steam has been obtained by adding boric acid to the steam. In steam only at 500° C and 1000 psi (68 at), iodide zirconium is almost completely oxidised in 24 hours, weight gains of about 5400 mg/dm 2 being obtained. Inhibition by boric acid reduces the weight gain to about 30 mg/dm 2 in 24 hours, increasing to only 120 mg/dm 2 at 70 days' exposure. No marked reduction in corrosion rate occurred with a more corrosion-resistant alloy of zirconium (0.5 wt % Cu, 0.5 wt % W), although a small reduction was obtained with Zircaloy 2. Somewhat less effective inhibition was obtained by alloying zirconium with up to 1.0 wt % of boron. Boric acid was shown to suppress the heavy localised corrosion experienced by iodide zirconium in uninhibited steam. Capacity measurements of films formed in inhibited steam showed them to be less cracked than those formed in the absence of boric acid. Hydrogen uptake, as a function of weight gain was, however, unaffected. A few experiments suggested that the corrosion of aluminium and beryllium may also be inhibited by boric acid.