Differential thermal analysis and temperature profile analysis of pyrotechnic delay systems: Slow burning mixtures of boron and potassium dichromate

The slow burning pyrotechnic reaction between boron and potassium dichromate has been studied by differential thermal analysis and temperature profile analysis. The latter technique in which the combustion process is studied directly, shows the presence of two reaction stages and validates the results from differential thermal analysis obtained under non-ignition conditions. In the first stage potassium dichromate is reduced by boron to form potassium chromate. Differential thermal analysis shows that the reaction takes place below the melting temperature of potassium dichromate and becomes much more rapid above this temperature. The second stage which occurs in the region of 1000 K involves the reaction of potassium chromate with more boron. The first stage acts as a trigger for the second and it is this latter stage which propagates the combustion.     

Spectrophotometric determination of boron in cobalt and nickel coatings by means of carminic acid

A method is proposed for the determination of boron in cobalt and nickel coatings deposited from borane-type baths. The deposit is dissolved in hydrochloric acid in the presence of platinum chloride as catalyst, potassium chloride and mannitol are added, and the solution is evaporated to dryness. Boron is then distilled as methyl borate into sodium hydroxide solution, the distillate is evaporated to dryness, and the boron is determined spectrophotometrically with carminic acid. The mannoitol prevents volatilization of boron during the evaporation. Evaporating the hydrochloric acid solution to dryness eliminates excess of acid and water, both of which cause incomplete recovery of boron in the distillation. The potassium, cobalt, and nickel chlorides left after the evaporation dissolve in the hot methanol during the distillation and do not interfere.     

当雄错盐湖卤水提钾盐田日晒工艺扩大试验研究

西藏现代钾锂硼特种盐湖的钾盐开发将对我国钾盐需求形成有利补充。本文首次采用蒸发结晶、分步分离的方法,进行了当雄错盐湖碳酸盐型卤水提钾多级盐田日晒工艺扩大试验研究。通过对卤水蒸发析盐全过程做化学分析和物料衡算,确定了钾、硼等重要无机元素的成盐类型和析盐阶段,以及锂、铷等稀有元素的富集规律,最终获得了较高品位钾混盐和高浓母卤,并取得了大量第一手数据资料,为今后实现当雄错盐湖卤水钾盐资源的产业化开发提供了切实可靠的中试基础和设计参考。     

The preparation of sodium and potassium borohydrides by the reduction of boron halides by sodium and potassium hydrides in the presence of aluminum triethyl

Summary It was found that sodium and potassium hydrides readily react with boron halides in hydrocarbon solvents in the presence of aluminum triethyl to form the borohydrides of sodium and potassium, respectively.     

Fitting the boron peak and resolving interferences in the 450–490 keV region of PGAA spectra

Prompt gamma activation analysis (PGAA) is one of the most powerful analytical methods for the determination of boron because of its very large neutron capture cross section. The peak of boron in the PGAA spectra is highly broadened due to the Doppler-effect. An improved method is presented to fit the boron peak, and to resolve interference with the gamma-rays of sodium and other matrix components. The method has been checked on test samples and on geological samples as well.     

Detection limits in epithermal neutron activation analysis of geological material

The improvement of detection limits for trace elements in geological samples by epithermal neutron activation analysis is examined. The relative merits of cadmium, boron and composite cadmium+boron filters are compared for trace elements Ni, As, Pd, Cd, Sb, W, Ir, Pt and Au, and interfering elements Na, K, Sc, Cr, Fe, Co and Cu. A boron filter gives optimum sensitivity for the trace elements based on interference from⁴⁶Sc, but the detection limits are only improved 2–5 times. Ma imum possible improvement, which is shown by Ni, gives sensitivities 5 times better under cadmium and 15 times under boron.     

Evaluation of boron for the epithermal neutron activation analysis of short-lived radionuclides in geological and biological matrices

The value of boron, in addition to cadmium, as a thermal neutron filter for the epithermal neutron activation of short-lived radionuclides is shown to depend on sample matrix. Activation ratios of fifty nuclides are measured and the improvement in sensitivity is calculated for geological and biological matrices. The addition of boron, in the case of geological samples where the major interference is Al, improved detection for only F, Y, Sn, Ba, Er, W and Pt. In biological samples where Na is a problem the detection limits for F, Br, Rb, Y, Mo, Pd, Sn, Sb, I, Ba, Nd, Sm, Gd, Er, Hf, W, Re, Pt, Au, Th and U are all theoretically improved.     

Synthesis and Characterization of a Boronated Metallophthalocyanine for Boron Neutron Capture Therapy

Synthesis of the first fully characterized, water-soluble boronated phthalocyanine is reported. Reaction of 4-nitrophthalonitrile with dimethyl malonate in the presence of base yielded dimethyl (3,4-dicyanophenyl)malonate which was converted into dimethyl (3,4-dicyanophenyl)propargylmalonate by sequential treatment with potassium hydroxide and propargyl bromide. Formation of the o-carborane cage was accomplished by reaction of the alkyne with decaborane in acetonitrile at reflux. High-temperature solid state condensation of the resulting o-carboranylphthalonitrile with cobalt(II) chloride followed by ester deprotection and cation exchange provided the water-soluble closo-carbonylphthalocyanine product. The product contains 40 boron atoms (27% boron by weight) and may be useful as a tumor-seeking boron delivery agent for boron neutron capture therapy of cancer.     

Suzuki-Miyaura cross-coupling reactions of benzyl halides with potassium aryltrifluoroborates

[reaction: see text] The palladium-catalyzed cross-coupling of potassium aryltrifluoroborates with benzylic halides occurs in good yield with high functional group tolerance. The increased stability of potassium aryltrifluoroborates compared to other boron coupling partners makes this an effective route to functionalized methylene-linked biaryl systems.     

锆硼陶瓷材料中总硼分析方法研究

对锆硼陶瓷材料中总硼的分析方法进行了研究，采用硫酸和硫酸铵及重铬酸钾氧化两步溶解法分解样品，氮气载带硼酸三甲酯蒸馏分离硼与锆（氦气流速150mL/min水溶加热，NaOH溶液吸收），材料中成分为Zr粉＋B4C粉，Zr含量≥99％（ut），经阳离子交换法除去吸收液中Na后采用ICP-AES法测定硼。方法的相对标准偏差（n=6）小于2．0％；标准加入回收率为99％。     

Synthesis of Fluorine-Containing Aryl(halo)boranes from Potassium Aryl(fluoro)borates

Russian Journal of General Chemistry - Fluorine-containing aryldihalogenoboranes have been obtained by the reaction of boron and aluminum chlorides and bromides with potassium aryltrifluoroborates...     

盐湖资源开发利用进展

本世纪头十年里,国际上再度掀起盐湖资源开发热潮。这很大程度上是由于锂的开发热带动的,同时也是和钾肥的广泛施用、价格一路走高有关。南美安第斯高原地区盐湖蕴藏世界70%以上的锂资源,且卤水锂、钾、硼浓度高。该地区极度干旱,少雨多风,非常适合采用卤水盐田蒸发的节能浓缩工艺技术。老的盐湖开发企业则在钾肥需求的带动下,稳步发展。在我国,新疆罗布泊和青海柴达木盆地盐湖则钾锂镁硼产品多元化,经营多元化取得长足进步。本文对近十年来,国内外盐湖开发的新动向做了概括介绍,特别着重于南美"锂三角"地区这一新的生长点。     

Determination of total,leachable and mobile boron in sedimentary rocks by ICP-AES

An ion exchange batch technique is described, which allows to determine the amount of mobile boron in geological material. Boron selective ion exchange resin IRA-743 (0.5 g, effective size 0.45 mm) was slurried together with 5 g sample (grain size smaller than 0.04 mm) at 70 °C in aqueous solution. After separating resin and suspension by sieving, elution was done in columns with 3N HCl. Boron was determined in the eluates by ICP-AES. Possible corrections for the iron interferences on the boron emission lines are discussed. The mobile boron content in the investigated shallow marine sedimentary rocks ranged between 5 and 10% of the total. It must be assumed that most of the boron in the shales is fixed in the lattice of the minerals.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Sensitive determination of traces of boron in waters,fertilizers na geological and biological materials by isotope-dilution mass spectrometry

A method is described for determining traces of boron in water, fertilizers, geological and biological (reference) materials by isotope-dilution mass spectrometry after separation on an Amberlite IRA-743 borate-selective ion-exchange column. Boron (–250 ng g^?1) in water can be determined with an accuracy of 5–20% (computed on a 2s basis). After correction for weighing errors and for moisture, content, which varied from 0 to 8% for the samples tested, 1–35 μg g^?1 boron in “dry” fertilizer, biological or geological sample can be assayed with an accuracy of 5–30% (2s). In an IAEA interlaboratory program on a simulated fresh water, the method yielded a value of 24.3 +? 2 μg l^?1, compared to the make-up value of 25 μg l^?1.     

Determination of boron,beryllium and lithium in coal ash and geological materials by spark optical emission spectrometry

A method is described for the accurate and precise determination of boron, beryllium and lithium in coal ash and geological materials by a point-to-plane high-voltage spark optical emission spectrometric technique. A 200-mg sample is crushed and blended with graphite, copper oxide internal standard and cellulose powders, and briquetted. Synthetic calibration standards are prepared from spectrographically pure materials blended into graphite. Corrections are made for spectral interference by iron and silicon on boron. Accurate results are presented for certified reference materials. The precision of the method, about 5%, is superior to that obtained by d.c. arc optical emission.     

The thermodynamics of aqueous borate solutions I. Mixtures of boric acid with sodium or potassium borate and chloride

Potentials for the cell without liquid junction where M is sodium or potassium are reported over a range of ionic strength to I=3 mol-kg^–1 at 5 to 55°C. Total boron concentration in the solutions was restricted to low levels to minimize formation of polynuclear boron species. Cell potentials are treated with the Pitzer ion interaction treatment for mixed electrolytes, with linear ionic strength dependence assumed for the activity coefficient of undissociated boric acid. Trace activity coefficients of sodium and potassium borates in chloride media are calculated at various temperatures.     

Synthesis and Investigation of Energetic Boron Compounds for Pyrotechnics

The energetic boron esters tris(1‐ethyl‐5‐aminotetrazolyl) borate, tris(2‐ethyl‐5‐aminotetrazolyl) borate, tris(1‐ethyltetrazolyl) borate, tris(2‐ethyltetrazolyl) borate, and tris(2‐(3‐nitro‐1, 2,4‐triazolyl)ethyl) borate were synthesized and analyzed by NMR and IR spectroscopy, elemental analysis, and mass spectrometry. Two tetracoordinate borates potassium tetrakis(3‐nitro‐1, 2,4‐triazolyl)borate and potassium bis(4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolyl)borate were synthesized and fully characterized as well. Moreover, the energetic and thermal properties of the energetic boron esters and tetracoordinate borates were determined. The ¹¹B NMR chemical shifts of potassium tetrakis(3‐nitro‐1, 2,4‐triazolyl)borate and potassium bis(4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolyl)borate were calculated and compared to the experimental values. Tris(1‐ethyl‐5‐aminotetrazolyl) borate was tested as colorant in pyrotechnic formulations with respect to the combustion behavior and color properties as well as the energetic and thermal properties.     

Analysis of Borosilicate Catalysts by Inductively Coupled Plasma Atomic Emission Spectroscopy

Abstract

A method was developed for the analysis of borosilicate catalysts. Samples were prepared by fusion technique with potassium hydroxide and analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The method was applied to a borosilicate NIST SRM 93 which was analyzed for major and minor elements (aluminum, sodium, silicon and boron). Despite the presence of relatively high concentration of the potassium, no matrix interferences were observed. This method provides precision and accuracy better than ±4% and ±6%, respectively.     

Determination of boron in silicon-bearing alloys, steel, and other alloys by pyrohydrolysis and inductively-coupled argon-plasma spectroscopy

Boron is quantitatively separated from silicon-bearing and other inorganic materials by pyrohydrolysis. Microgram amounts of boron are separated by passing oxygen-saturated steam over a sample mixed with vanadium oxide and copper oxide. The distillate is collected in dilute potassium hydroxide solution and determined by inductively-coupled argon-plasma spectroscopy.     

History of the discovery of potassium and sodium (on the 200th anniversary of the discovery of potassium and sodium)

This article presents the history of the discovery potassium and sodium, barium, calcium, boron, and cadmium by Humphrey Davy. It illustrates the continuity of research into electrophysiology, physics, and electrochemistry that led Davy to his discovery. The biographical sketch of Davy is given.