Features of the synthesis of highly dispersed alumophosphates AlPO4·nH2O

Aluminum orthophosphate of the composition AlPO4·2H2O with a monoclinic structure identical to the structure of the natural mineral metavariscite was obtained by condensation method during hydrothermal treatment of alumophosphate solutions with a concentration (g/l) of Al2O3 90 – 115, P2O5 340 – 440 in the temperature range 95–99 °C. For the first time, the role of aging of the alumophosphate system in shortening of the induction period, simultaneous nucleation of primary particles in the entire volume of the solution and the formation of a pasty product with a predominant particle size of 1–10 μm, in contrast to 30–50 μm, characteristic of a fine-crystalline product obtained without aging of the solution, is established. It is shown that pasty AlPO4·2H2O, in comparison with fine-crystalline, is hardly soluble in HCl even under prolonged heating. The influence of P2O5 content in the alumophosphate solution, the conditions of its aging and the duration of hydrothermal treatment on the particle size distribution for synthesized aluminum orthophosphates have been established. Anhydrous alumophosphate obtained by dehydration of pasty AlPO4·2H2O in the temperature range of 150–200 °C with subsequent heat treatment at 900 °C is readily soluble in acids, and the predominant particle size is 5–13 μm.

Identification of the Crystalline Product of Liquid-Phase Oxidation of α-Pinene with Atmospheric Oxygen in the Presence of Cobalt (II) Stearate

One of the possible directions of liquid-phase oxidation of α-pinene by atmospheric oxygen leads to the formation of a mixture of terpene oxygen-containing compounds (epoxides, alcohols, ketones, etc.). The problem of this direction is the formation of a large amount of 2,3-epoxypinane which over time turns into trans-sobrerol, campholene aldehyde, trans-pinocarveol, trans-carveol, and trans-3-pinen-2-ol as a result of hydrolysis. One of the abovementioned substances with a solid crystalline structure is trans-sobrerol. Sobrerol is widely used in perfumery for synthesis of synthetically fragrant substances and pharmaceutical industry, in particular, it is a part of medicines with mucolytic action, as well as in the treatment of headaches and diseases such as rhinorrhea and chronic bronchitis. The aim of this work is to identify a crystalline product produced by liquid-phase oxidation of α-pinene with atmospheric oxygen in the presence of cobalt (II) stearate. The process of liquid-phase oxidation was carried out in the following conditions: temperature – 70 °С, air consumption – 16.67 cm3/s, duration – 5 h, amount of catalyst – 0.2–0.5 wt.%. Then the mixture was exposed to steam distillation in order to separate monomers (they contain terpene oxygen-containing compounds and hydrocarbons) from polymers. As a result of settling and storage of the mixture, crystals were found and isolated from the mother liquor solution. Their identification was carried out using IR and 13C NMR spectroscopy as well as scanning electron microscopy. It was found that the spatial organization of the isolated crystals and the standard sample (Sigma Aldrich) is represented by multilayer rectangular plates. Analysis of the IR spectra of the crystals showed that the absorption band at a wave number of 3318 cm–1 corresponds to intramolecular and intermolecular hydrogen bonds in hydroxyl groups, at wave numbers of 2887, 2935, 2975 cm–1 it corresponds to methyl groups. The results obtained are comparable with the results of the IR-spectrum of the standard sample. Given the results of previous studies of 1H NMR spectrum [15] and 13C NMR spectrum, it was determined that the resulting crystalline product of liquid-phase oxidation of α-pinene is trans-sobrerol.

Four Different Crystalline Products from One Reaction: Unexpected Diversity of Products of the CuCl2 Reaction with N-(2-Pyridyl)thiourea

The reaction of N-(2-pyridyl)thiourea with CuCl2 in methanol yields four different crystalline products: yellow dimeric complex, [Cu2Cl2(μ-Cl)2(L)2] (1), red polymeric complex, [Cu3Cl8L2]n (2), orange crystalline product with ionic structure, L2[CuCl4] (3), and colourless ionic compound LCl (4), where L = 2-amino-[1,2,4]thiadiazolo[2,3-a]pyridin-4-ium cation as a result of oxidative cyclization of N-(2-pyridyl)thiourea. The crystal structures of all these crystalline products have been determined by single-crystal X-ray diffraction analysis. Compound 1 involves a copper(I) ion while in 2 and 3 the copper centre is in the divalent state. 1H NMR spectra for compounds 1–3 are identical and confirm deprotonated thioamide groups of N-(2-pyridyl)thiourea and the formation of a thiadiazolopyridinium cation in solution. The hydrogen bonding and π–π stacking interactions were investigated in the solid state. In addition, all crystalline products 1–4 exhibit also S···Cl bonding interactions which consolidate the complexes into networks. The X-ray diffraction analyses indicate the absence of other crystalline phases in the crude reaction mixture.

Rapid, Ambient Temperature Synthesis of Imine Covalent Organic Frameworks Catalyzed by Transition Metal Nitrates

<div> <p>Covalent Organic Frameworks (COFs) are crystalline, porous organic materials with promise for applications including catalysis, energy storage, electronics, gas storage, water treatment, and drug delivery. Conventional solvothermal synthesis approaches to COFs require elevated temperatures, inert reaction environments, and long reaction times. Here, we report that transition metal nitrates can catalyze the rapid synthesis of imine COFs. We tested a series of transition metal nitrates as catalysts for the synthesis of a model COF and found that all transition metal nitrates produced crystalline COF products for reactions conducted at ambient temperatures. The reactions were insensitive to the presence of oxygen. Fe(NO₃)₃·9H₂O was found to produce the most crystalline product, and by optimizing the catalyst loading we found that crystalline COF could be produced within 10 minutes. We further tested Fe(NO₃)₃·9H₂O as a catalyst for 6 different COF targets varying in linker lengths, substituents, and stabilities, and found that Fe(NO₃)₃·9H₂O effectively catalyzed the synthesis of all imine COFs tested. This work demonstrates a simple, low-cost approach for the synthesis of imine COFs and will significantly lower the barrier for the development of imine COFs for various applications. </p> </div>

Rapid, Ambient Temperature Synthesis of Imine Covalent Organic Frameworks Catalyzed by Transition Metal Nitrates

<div> <p>Covalent Organic Frameworks (COFs) are crystalline, porous organic materials with promise for applications including catalysis, energy storage, electronics, gas storage, water treatment, and drug delivery. Conventional solvothermal synthesis approaches to COFs require elevated temperatures, inert reaction environments, and long reaction times. Here, we report that transition metal nitrates can catalyze the rapid synthesis of imine COFs. We tested a series of transition metal nitrates as catalysts for the synthesis of a model COF and found that all transition metal nitrates produced crystalline COF products for reactions conducted at ambient temperatures. The reactions were insensitive to the presence of oxygen. Fe(NO₃)₃·9H₂O was found to produce the most crystalline product, and by optimizing the catalyst loading we found that crystalline COF could be produced within 10 minutes. We further tested Fe(NO₃)₃·9H₂O as a catalyst for 6 different COF targets varying in linker lengths, substituents, and stabilities, and found that Fe(NO₃)₃·9H₂O effectively catalyzed the synthesis of all imine COFs tested. This work demonstrates a simple, low-cost approach for the synthesis of imine COFs and will significantly lower the barrier for the development of imine COFs for various applications. </p> </div>

Critical features and some properties polymer compositions containing high-dispersal hexanitrohexaazaizowurcitan

The use of hexanitrohexaazaizowurcitan can in mixed energy compositions based on various polymer binders faces a number of problems caused by the specific properties of this component: resistance under normal conditions most polymorphic modifications of the crystalline product, the difficulty of obtaining a crystalline product of the required dispersal and polymorphic modification, re-crystalization and remodification of the product in polymer mixtures compositions, increased ability to form crystals with most traditional components of energy compositions. Relatively low and selective, in comparison, for example, with compositions based on octogen, the increase in energy efficiency when using hexanitrohexaazaizowurcitan in energy compositions with polymer binders of different nature, puts forward the task of simultaneously addressing the issues of reducing energy losses when burning energy compositions in energy installations of various purposes. The solution of these issues is associated with the use of high-dispersal and nanoscale fillers in the compositions of mixed energy materials. For the use of hexanitrohexaazaizowurcitan in compositions, along with the problem of choosing a polymer binder, solving the issues of obtaining a crystal product required modification and different variance, including nanoscale, experimental research is needed: critical characteristics of filling polymer compositions (maximum degree of filling; filling corresponding to percolation transitions), their effect on basic properties energy compositions – characteristics of combustion, physical-mechanical and explosive characteristics, physical and chemical stability of properties, etc.; to assess the prospects of using alternative compositions based on the co-crystalyzates of hexanitrohexaazaizowurcitan with other components of mixed compositions. Taking into account the above and in the development of earlier works, the article provides some results of the definition of critical volume – maximum and critical for the formation of percolatin cluster – degrees of filling polymer compositions with inert hexanitrohexaazaizowurcitan powders of varying variances, including high-dispersal and nanoscale. In addition, data on the relationship of critical characteristics with the characteristics of combustion, physical-mechanical, rheological characteristics of compositions are presented. Data on the effect of high-dispersal and nanoscale powders of hexanitrohexaazaizowurcitan on shock-wave sensitivity of samples of mixed energy materials are presented. The results of tests of alternative homogeneous energy compositions based on the co-crystalyzates of hexanitrohexaazaizowurcitan with a brief analysis of the prospects of their use are also presented.

Potassium chloridotris(hypersiloxy)aluminate dimer

The tris(trimethylsilylsiloxide) ligand, also known as hypersiloxide, is an extremely bulky group. In an attempt to make the monomeric Al(OSi(SiMe3)3)3, AlCl3 was combined with 3 equiv. of potassium hypersiloxide. The crystalline product isolated (40% yield), namely di-μ3-chlorido-bis[μ2-tris(trimethylsilyl)silanolato]tetrakis[tris(trimethylsilyl)silanolato]dialuminiumdipotassium, [Al2K2Cl2(C19H27OSi4)6], is a KCl adduct of aluminium tris(hypersilyloxide) that is dimerized through a planar K2Cl2 ring, with K—Cl distances of 3.1131 (8) and 3.319 (3) Å, and ring angles of 77.41 (2) and 102.60 (2)°. This ring is on an inversion center, and there is no supramolecular coordination.

Structural, Spectroscopic and Hirshfeld Surface Analysis of Anilinium Malonate

The comprehensive elucidation of the crystal structure, vibrational and Hirshfeld surface analysis of new crystalline product anilinium malonate C6H5NH3 +. C3H3O4 – are presented in this communication. Single crystals of anilinium malonate have been grown by the method of slow evaporation at room temperature. Single crystal XRD study has been carried out to study the structural properties of the grown crystal and it reveals that the crystal crystallizes in the monoclinic system with centrosymmetric space group P2(1)/n. Room temperature powder infrared and Raman spectra of the aniline malonic acid molecular complex (1:1) were carried out. All the characteristic frequencies present in the crystal gives the notable vibrational effect. Hirshfeld surface analysis has been carried out to know the intercontact between the atoms in the structure of the grown crystal.

Chiral Separation of the Phenylglycinol Enantiomers by Stripping Crystallization

Stripping crystallization (SC) is introduced in this work for chiral purification of R-phenylglycinol from the enantiomer mixture with an initial concentration ranging from 0.90 to 0.97. As opposed to the solid–liquid transformation in melt crystallization, the three-phase transformation occurs in SC at low pressures during the cooling process. SC combines melt crystallization and vaporization to produce a crystalline product and mixture vapor from a mixture melt due to the three-phase transformation. Thermodynamic calculations were applied to determine the operating pressure for the three-phase transformation during the cooling process in the SC experiments. To consider the possible deviations between the calculated and the actual three-phase transformation conditions, the product purity and the recovery ratio of R-phenylglycinol were investigated within a range of operating pressures during the cooling process.

Synthesis and Characterization of Co/Ni/CoNi-ZSM-5 Catalyst for Hydrogen Production

Nickel is commonly used as a catalyst in hydrogen production. However, the use of nickel catalysts in the steam reforming process has the disadvantage of coke formation and high cost. Therefore, in this research, Ni/ZSM-5 catalyst synthesis was used to reduce production cost and an addition of cobalt (Co) metal to avoid coke formation. The method consists of a synthesis of ZSM-5 catalyst using hydrothermal process. Furthermore, the crystalline product was impregnated with the metal cobalt, nickel and combination of cobalt-nickel as much as 2% by weight metal/weight of the catalyst. Then the XRD and EDX characterization of Co/ZSM-5, Ni/ZSM-5, and CoNi/ZSM-5 was done followed by catalytic testing in the production of hydrogen from glycerol using steam reforming process. From XRD characterization results showed that Co/ZSM-5 catalyst has a crystallinity of 78.69%, Ni/ZSM-5 catalyst has 70.04% crystallinity and CoNi/ZSM-5 catalyst has 76.99% crystallinity. Catalytic testing on hydrogen production showed that CoNi/ZSM-5 catalyst produced the highest hydrogen concentration of 1,756.33 ppm while Ni/ZSM-5 catalyst produces 1,240 ppm and Co/ZSM-5 catalyst produces 491 ppm.