Cyanation Research Articles

Long-term storage for reanalysis purposes: A stability study of extracts from post-explosion/burning residues of fuel-oxidizer explosive mixtures

Post-explosion residue analysis is vital in forensic chemistry, providing valuable insights into incidents involving explosives. One significant challenge in this field is preserving samples for long-term storage for reanalysis. Presently, many laboratories conducting post-explosion analyses worldwide do not retain samples for reanalysis purposes, since the extraction process for sample preparation often necessitates the complete consumption of the scarce material. Even in cases where a portion of the material remains, such as a swab, it is difficult to ensure its representativeness and select a specific portion for preservation. One possible solution to overcome this challenge is to consider preserving the extracts used in the analyses for potential reanalysis. However, the stability characteristics of these extracts are currently unknown. The results presented in this article provide valuable insights into the feasibility of long-term storage for samples containing target analytes in extracts from post-explosion/burning residues of frequently encountered fuel-oxidizer explosive mixtures, such as flash powder, explosive emulsion, and black powder. These results shed light on the potential viability of preserving such extracts for future reanalysis, offering promising prospects for enhancing forensic investigations in this field. Based on the current findings, it has been demonstrated that the aqueous extracts can be effectively preserved as long-term storage samples for a minimum of 24 months, encompassing all the studied explosives. Only cyanate ion showed significant degradation among the 27 compounds studied. Additionally, the organic extract, specifically in the case of emulsion explosive, can be maintained for at least 12 months.

Synthesis of a benzothiazole-based structure as a selective colorimetric-fluorogenic cyanate chemosensor

Abstract In this study, a new heterocyclic compound incorporating a benzothiazole moiety was specifically designed for the detection of cyanate anions, employing a hydrogen bonding mechanism. Through strategic integration of triazine and phenylenediamine cyclic groups into the compound’s structure, intramolecular hydrogen bonding interactions between the donor and acceptor sites were enhanced, leading to exceptional sensitivity towards cyanate anions. Utilizing the amino-type excited-state intramolecular proton transfer phenomenon, this new compound exhibited dual signals and achieved a significant Stokes’ shift via proton transfer, coupled with aggregation-induced emission properties. This unique combination resulted in visible color changes and an impressive fluorescence response, offering a promising solution for the sensitive detection of cyanate ions in critical environmental matrices. Cyanate detection at low concentrations by this as-synthesized compound (L1), accompanied by a distinct color change and a gradual fluorescence increase upon incremental cyanate addition demonstrated L1’s selectivity, as confirmed in the presence of various competing anions F−, Cl−, Br−, I−, ClO 3 − {\text{ClO}}_{3}^{-} , ClO 4 − {\text{ClO}}_{4}^{-} , NO 3 − {\text{NO}}_{3}^{-} , BrO 3 − {\text{BrO}}_{3}^{-} , CN− and CNO−. Spectrofluorometric investigations demonstrated that L1 shows significant potential as a selective cyanate anion detection candidate.

Study on The Ability of H2O2 and The Effective Concentration of CuSO4 in Degrading Cyanide

PT. Aneka Tambang conducts gold processing using NaCN reagents, then from the gold processing process produces waste containing cyanide which can cause damage to the environment. One method used to reduce cyanide concentrations is the Degussa method. The Degussa method is a method to degrade free cyanide in waste by using H2O2 and Cu2+ ions as a catalyst source so that it becomes a harmless cyanide compound (cyanate ion). The purpose of the study was to determine the ability of hydrogen peroxide and determine the effective concentration of copper sulfate in degrading cyanide in the Degussa process and determine the level of stability of hydrogen peroxide oxidizers in the open air. Sample testing was carried out by varying the H2O2 retrieval time, variations in H2O2 dilution factor and copper sulfate concentration variations, then the sample was stirred with a jartes stirrer for 15 minutes. Cyanide is determined by spectrophotometer, the absorbance obtained is fed into the linear regression equation so that the final free cyanide concentration is obtained. From the experiment, it can be concluded that the concentration of cyanide degradation is effectively obtained when hydrogen peroxide and copper sulfate that have been mixed in the mixing tank are right out of use.

Progress toward a better understanding of the urea oxidation by electromediation of Ni(III)/Ni(II) system in alkaline media

Current treatments of wastewater containing urea are energy intensive and release significant quantities of gaseous nitrous oxide. The anodic oxidation of urea by electromediation of Ni(III)/Ni(II) system in alkaline media is a promising alternative: the nitrogenous pollution is decreased while producing hydrogen at the cathode. Firstly, this study aims to deeply investigate the phenomena occurring at the interface, between electrode and electrolyte, in particular by proposing an original methodology enabling to separately study both steps,i.e. the Ni(II) electro-oxidation and the subsequent indirect heterogeneous urea oxidation. Indeed, the variation the potential scan rate, enables (i) to study the effect of the operating parameters (concentration, temperature, angular velocity of a rotating disk electrode) on the rate of each mechanism step, and to (ii) determine key parameters of the overall process (activation energy, diffusion coefficient, anodic charge transfer coefficient and heterogeneous electron transfer rate constant). In a second time, results of urea electrolysis exhibiting high (∼ 80%) urea conversions, carried out at laboratory scale (1.4 g of urea) are discussed. The effect of some operating parameters (alkalinity, temperature, presence of an anionic separator or not) is examined, thanks to a set of analytical methods developed to establish complete mass balances of the products on the liquid phase. Cyanate, ammonium, carbonate and nitrite ions are identified to represent more than 80 % of the destroyed urea. Their respective quantities appear to be dependent of the operating conditions. This study constitutes an essential preliminary step before designing urea electrochemical process operating at larger scale.

Chemical shift tensors as probes of chalcogen bonds: solid-state NMR study of telluradiazole-XCN− (X = O, S, Se) salt cocrystals

We report experimental 125Te magic-angle spinning solid-state nuclear magnetic resonance (MAS NMR) measurements of the tellurium chemical shift (CS) tensors in three [K(18-crown-6)]+ 3,4-dicyano-1,2,5-telluradiazole-XCN− (X = O, S, Se) salt cocrystals featuring chalcogen bonds. These data are compared to those for pure 3,4-dicyano-1,2,5-telluradiazole (1). A reduction in the span of the 125Te CS tensor is consistently noted in the salt cocrystals compared to pure 1. Isotopically 15N-labelled [K(18-crown-6)]+[1-OC15N]−, which features a chalcogen bond between Te and the cyanate nitrogen atom, is synthesized using KOC15N, and the nitrogen CS tensors are measured for both samples via 15N slow MAS NMR spectroscopy. Possible dynamic disorder of the cyanate ions in KOCN is ruled out. Two crystallographically distinct nitrogen sites are resolved for the salt cocrystal. Upon formation of [K(18-crown-6)]+[1-OC15N]−, the 15N isotropic CS and CS tensor span both decrease relative to the values for pure KOC15N, and the axial symmetry of this tensor is lost. These findings are supplemented with a series of density functional theory calculations of magnetic shielding tensors using cluster models or periodic boundary conditions. Inclusion of spin–orbit relativistic effects in the calculation of tellurium shielding tensors is particularly important in achieving agreement with experiment.

Formation of the Simplest Amide in Molecular Clouds: Formamide (NH2CHO) and Its Derivatives in H2O-rich and CO-rich Interstellar Ice Analogs upon VUV Irradiation

The astronomical detection of formamide (NH2CHO) toward various star-forming regions and in cometary material implies that the simplest amide might have an early origin in dark molecular clouds at low temperatures. Laboratory studies have proven the efficient NH2CHO formation in interstellar CO:NH3 ice analogs upon energetic processing. However, it is still under debate, whether the proposed radical–radical recombination reactions forming complex organic molecules remain valid in an abundant H2O environment. The aim of this work was to investigate the formation of NH2CHO in H2O- and CO-rich ices under conditions prevailing in molecular clouds. Therefore, different ice mixtures composed of H2O:CO:NH3 (10:5:1), CO:NH3 (4:1), and CO:NH3 (0.6:1) were exposed to vacuum ultraviolet photons in an ultra-high vacuum chamber at 10 K. Fourier-transform infrared spectroscopy was utilized to monitor in situ the initial and newly formed species as a function of photon fluence. The infrared spectral identifications are complementarily secured by a temperature-programmed desorption experiment combined with a quadrupole mass spectrometer. The energetic processing of CO:NH3 ice mixtures mainly leads to the formation of NH2CHO, along with its chemical derivatives such as isocyanic acid (HNCO) and cyanate ion (OCN−). The formation kinetics of NH2CHO shows an explicit dependency on ice ratios and compositions; the highest yield is found in H2O-rich ice. The astronomical relevance of the resulting reaction network is discussed.

One-Dimensional Nanoscale Si/Co Based on Layered Double Hydroxides towards Electrochemical Supercapacitor Electrodes.

It is well known that layered double hydroxides (LDHs) are two-dimensional (2D) layered compounds. However, we modified these 2D layered compounds to become one-dimensional (1D) nanostructures destined for high-performance supercapacitors applications. In this direction, silicon was inserted inside the nanolayers of Co-LDHs producing nanofibers of Si/Co LDHs through the intercalation of cyanate anions as pillars for building nanolayered structures. Additionally, nanoparticles were observed by controlling the preparation conditions and the silicon percentage. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal analyses have been used to characterize the nanolayered structures of Si/Co LDHs. The electrochemical characterization was performed by cyclic voltammetry and galvanic charge–discharge technique in 2M KOH electrolyte solution using three-electrode cell system. The calculated specific capacitance results indicated that the change of morphology from nanoparticles or plates to nanofibers had a positive effect for improving the performance of specific capacitance of Si/Co LDHs. The specific capacitance enhanced to be 621.5 F g−1 in the case of the nanofiber of Si/Co LDHs. Similarly, the excellent cyclic stability (84.5%) was observed for the nanofiber. These results were explained through the attribute of the nanofibrous morphology and synergistic effects between the electric double layer capacitive character of the silicon and the pseudo capacitance nature of the cobalt. The high capacitance of ternary Si/Co/cyanate LDHs nanocomposites was suggested to be used as active electrode materials for high-performance supercapacitors applications.

Reproducibility of cavity-enhanced chemical reaction rates in the vibrational strong coupling regime.

One of the most exciting and debated aspects of polariton chemistry is the possibility that chemical reactions can be catalyzed by vibrational strong coupling (VSC) with confined optical modes in the absence of external illumination. Here, we report an attempt to reproduce the enhanced rate of cyanate ion hydrolysis reported by Hiura et al. [chemRxiv:7234721 (2019)] when the collective OH stretching vibrations of water (which is both the solvent and a reactant) are strongly coupled to a Fabry-Pérot cavity mode. Using a piezo-tunable microcavity, we reproduce the reported vacuum Rabi splitting but fail to observe any change in the reaction rate as the cavity thickness is tuned in and out of the strong coupling regime during a given experiment. These findings suggest that there are subtleties involved in successfully realizing VSC-catalyzed reaction kinetics and therefore motivate a broader effort within the community to validate the claims of polariton chemistry in the dark.

What is an organic substance?

No exact definition of an “organic” substance has been agreed upon by the chemical community and textbook definitions vary substantially. The question of what exactly constitutes an “organic” substance is explored in this paper. Various carbon-containing substances that have been by some considered to be “inorganic” are examined in an attempt to ascertain whether carbon in these compounds display different chemical behavior than what is expected of carbon in an “organic” substance. Types of substances considered are carbon allotropes, carbides, carbonates and bicarbonates, cyanide and cyanate ions, carbido clusters, carbon oxides, and compounds without hydrogen.

Numerical Investigation on the Urea Deposit Formation Process in a Selective Catalytic Reduction System of a Diesel Engine Based on a Fluid-Solid Coupling Method.

Currently, selective catalytic reduction (SCR) systems have become an essential part in diesel engines, and urea crystallization is one of the most serious issues in SCR systems. In this paper, the urea deposit formation processes in the SCR system were investigated by numerical simulations based on a fluid–solid coupling method. The results show that the masses of the wall film and solid urea are larger at conditions with lower temperatures and higher injection rates. At higher temperatures, cyanate ions and ammonium ions are the most predominant compositions in the wall film, while at lower temperatures, solid urea is the main composition. It could also be deduced that the location of urea crystallization is more affected by the design of mixer at higher temperatures, whereas at lower temperatures, the location and installation angle of urea-water solution injector play a more important role.

Stereospecific cyanation of the olefinic C–H bond enabled by 1,4-rhodium migration

Rhodium-catalyzed stereospecific cyanation of the olefinic C–H bond for the synthesis of β,β-disubstituted acrylonitriles has been developed.

Synthesis, application and AIE properties of novel fluorescent tetraoxocalix[2]arene[2]triazine: The detection of a hazardous anion, cyanate

A highly effective, new heterocalixarene fluorescent receptor comprised of 2-(2-aminophenyl)benzothiazole and tetraoxacalix[2]arene[2]triazine was designed and synthesized by one-step reaction. The sensor candidate exhibiting aggregation induced emission (AIE) was tested for its photophysical behaviour towards detection of various anions. The results showed that our receptor undergo AIE in >40% H2O-DMSO along with large pseudo Stokes shift (Δλ = 219 nm) and exhibit selective and sensitive detection towards hazardous cyanide’s oxidation product, cyanate (CNO-) ion over other tested anions. The blue-shifted fluorescence emission (λem = 492 nm) enhancement with large Stokes shift (Δλ = 144 nm) was observed with the increase in cyanate concentration. The synthesized turn-on sensor towards cyanate detection could be applied in real sample analyses as an improvement to the method currently carried out by international standards and hereby a different approach has been made for the detection of cyanide through its oxidation form, cyanate.

Development of Ti/Ni Nanolayered Structures to Be a New Candidate for Energy Storage Applications

Development of electrochemical supercapacitor electrode is the best way to improve the performance and conductivity of the alone materials and support energy storage devices. In this work, cyanate anions have used as building blocks to build series of nanolayered materials based on Ti/Ni layered double hydroxides (LDHs). The structural and morphological characteristics of the prepared Ti/Ni LDHs were examined using different techniques. The electrochemical supercapacitive behavior of the prepared LDHs was observed in the three-assembly electrochemical cell. These results showed that the optimized ratio of the nickel and titanium plays an important role to enhance the electrochemical performance of the LDHs. The optimized Ti/Ni LDHs, which has the highest content of titanium, showed the highest specific capacitance (675 F/g) value. In this trend, this LDH also retain a high percentage of the cyclic retention after long cyclic charging-discharging process. The enhanced performance could be due to the double layer structure, enough interplanar distance between the layer, and large number of exposed active site within the double layer structure of the LDHs. Finally, although there are no reports for the electrochemical supercapacitive performance of Ti/Ni LDHs in the literature, it is interesting to produce a new candidate for energy storage applications.

Characterisation of the Cyanate Inhibited State of Cytochrome c Oxidase

Heme-copper oxygen reductases are terminal respiratory enzymes, catalyzing the reduction of dioxygen to water and the translocation of protons across the membrane. Oxygen consumption is inhibited by various substances. Here we tested the relatively unknown inhibition of cytochrome c oxidase (CcO) with isocyanate. In contrast to other more common inhibitors like cyanide, inhibition with cyanate was accompanied with the rise of a metal to ligand charge transfer (MLCT) band around 638 nm. Increasing the cyanate concentration furthermore caused selective reduction of heme a. The presence of the CT band allowed for the first time to directly monitor the nature of the ligand via surface-enhanced resonance Raman (SERR) spectroscopy. Analysis of isotope sensitive SERR spectra in comparison with Density Functional Theory (DFT) calculations identified not only the cyanate monomer as an inhibiting ligand but suggested also presence of an uretdion ligand formed upon dimerization of two cyanate ions. It is therefore proposed that under high cyanate concentrations the catalytic site of CcO promotes cyanate dimerization. The two excess electrons that are supplied from the uretdion ligand lead to the observed physiologically inverse electron transfer from heme a3 to heme a.

Mineralization of cyanide originating from gold leaching effluent using electro-oxidation: multi-objective optimization and kinetic study

This study examines the electro-oxidation (EO) of cyanide originating from an industrial plant´s gold leaching effluent. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes consisting of graphite (anode) and aluminum (cathode) was employed, operating in galvanostatic mode. Response Surface Methodology (RSM), based on a Box–Behnken experimental Design (BBD), was used to optimize the EO operational conditions. Three independent process variables were considered: initial cyanide concentration ([CN−]0 = 1000–2000 mg L−1), current density (J =7–107 mA cm−2), and stirring velocity (η = 250–750 rpm). The cyanide conversion $$\left( {X_{{{\text{CN}}^{ - } }} } \right)$$, Chemical Oxygen Demand (COD) removal percentage (%RCOD), and specific Energy Consumption per unit mass of removed cyanide (EC) were analyzed as response variables. Multi-objective optimization let to establish the most effective EO conditions ([CN−]0 = 1000 mg L−1, J = 100 mA cm−2 and η = 750 rpm). The experimental data ($$X_{{{\text{CN}}^{ - } }}$$, %RCOD, and EC) were fitted to second-order polynomial models with adjusted correlation coefficients ($$R_{\text{adj}}^{2}$$) of ca. 98, 99 and 87%, respectively. The kinetic analysis, performed at optimal EO operational conditions, allowed determination of time required to meet Colombian permissible discharge limits. The predictive capacity of kinetic expressions was verified against experimental data obtained for gold leaching effluent. Total cyanide removal and 96% of COD reduction were obtained, requiring EC of 71.33 kWh kg−1 and 180 min. The BOD5 (biological oxygen demand)/COD ratio increased from 4.52 × 10−4 to 0.5573, confirming effluent biodegradability after EO treatment. The variation of cyanide (CN−), cyanate (CNO−) and ammonium (NH4+) ions concentrations vs. time at alkaline conditions. EO operational conditions: [CN−]0 = 1000 mg/L, J = 100 mA/cm2 , η = 750 rpm, [NaCl] = 0.15 M and pH 11.1.

Structure, polymorphism and luminescence of cyanate iodides MI(OCN) (M = Ba, Eu, and Sr).

A series of new compounds MI(OCN) were prepared from the mixtures of MI2 and K(OCN) (M = Sr, Eu or Ba) by solid-state reactions that were controlled by differential scanning calorimetry (DSC) and differential thermal analysis (DTA) techniques. The presence of two phases is highlighted for BaI(OCN) which crystallizes in the Pnma (α-BaI(OCN)) and Cmcm (β-BaI(OCN)) space groups. The SrI(OCN), EuI(OCN) and β-BaI(OCN) compounds crystallize in the same orthorhombic Cmcm space group and the structure consists of a layered arrangement of [M2I2]2+ blocks separated by single layers of cyanate ions that are found to be related to the Sillén-type structure. The polymorphism of BaI(OCN) was also observed by analyzing the infrared (IR) spectra. This analysis showed for β-BaI(OCN) splitting bands, which were ascribed to the presence of more than one resonant cyanate form that can be induced by the dynamical disorder of OCN units. In contrast, the α-BaI(OCN) vibration modes suppose the existence of one cyanate form that adopts a defined orientation. The SrI(OCN) and BaI(OCN) compounds were doped with Eu2+. The luminescence spectra recorded under excitation at 340 and 350 nm revealed a blue emission of Eu2+ at 431 nm for the β-BaI(OCN) and SrI(OCN) phases and at 427 nm for the α-BaI(OCN) phase that was ascribed to the 4f65d1→8S7/2 (4f7) transition.

Cyanate and Cyanurate Adsorption at Silver Electrodes in Neutral Solutions: In Situ ATR-SEIRAS and DFT Studies

The adsorption and reactivity of cyanate at silver electrodes is studied spectroelectrochemically in sodium perchlorate solutions and compared to those of cyanuric acid (1,3,5-triazine-2,4,6-trione, C3H3N3O3). The surface enhanced infrared reflection absorption spectra obtained under attenuated total reflection conditions (ATR-SEIRAS) for low cyanate concentrations show that some amount of adsorbed CO is formed at the silver electrode surface at low electrode potentials. Adsorbed cyanate species are formed at higher potentials and predominate at the electrode surface. However, for cyanate concentrations above 1 mM, the ATR-SEIRA spectra show potential-dependent absorption features between 1800 and 1300 cm-1, which are similar to those obtained after dosing cyanuric acid to the sodium perchlorate solution. This observation suggests that adsorbed cyanuric acid related species are formed from cyanate anions at the silver surface sites as the result of an electroless trimerization reaction. The infrared spectra collected in the cyanuric acid containing solutions also show a higher amount of adsorbed CO at low potential when compared to that observed in cyanate-containing solutions, thus indicating certain instability of cyanuric acid at the silver surfaces. Density functional theory (DFT) calculations have allowed the study of the effect of crystallographic orientation and bonding geometry on the adsorption energy and vibrational frequencies of adsorbates. Also, the effect of adsorbate coverage on the vibrational frequencies has been investigated. In the case of cyanate, DFT calculations show that the most favorable adspecies is N-bonded cyanate adsorbed in 4-fold hollow (100) sites. The experimental spectra in cyanuric acid solutions agree with the formation of adlayers of specifically adsorbed triketo-monocyanurate species that adsorb, in a tridentate configuration, perpendicular to the electrode surface. The polyoriented nature of the silver surface used in the spectroelectrochemical experiments, together with the eventual existence of cyanate in domains with different local coverages, can explain the broadness of the band for the asymmetric OCN stretching. For adsorbed triketo-monocyanurate, high local coverages are at the origin of the band observed experimentally at ca. 1790 cm-1 that can be associated with the in-phase collective CO stretching.

Acetonitrile as CN-Source in Nickel(0)-Catalyzed Cyanation

Acetonitrile as CN-Source in Nickel(0)-Catalyzed Cyanation

Degradation of cyanide, aniline and phenol in pre-treated coke oven wastewater by peroxide assisted electro-oxidation process.

The present study explored the feasibility of using graphite electrodes for the electrochemical oxidation of cyanide, thiocyanate, phenol and aniline with hydrogen peroxide. The dosing effects of hydrogen peroxide and current density were examined in the pre-treated coke oven wastewater. It was found that 0.025 M hydrogen peroxide and 13.63 mA/cm2 of current density were more favorable for the removal of 100%, 90%, 71% and 40% cyanide, thiocyanate, phenol and aniline respectively. The increased removal of phenol in the coke oven wastewater was attributed to the pre-treatment of wastewater. Initially, 28% phenol was converted to phenolate ion by air stripping process, which increased the removal rate of phenol by the electro-oxidation process as the removal of phenolate is quite easy compared to phenol. The advanced oxidation process degrades the more toxic cyanide into less toxic intermediate cyanate ions (CNO─), which further cut down into nontoxic end products such as N2, HCO3 and CO2. The experimental results show that the primary mechanisms in the oxidation of cyanide and phenol are mediated electro-oxidation by hydroxyl radicals and hypochlorite ions. The operating cost under the optimized conditions for the removal of 100% cyanide and 71% phenol was estimated to be 616.95 INR/m3.

Nucleophilic Ring Opening of Donor-Acceptor Cyclopropanes with the Cyanate Ion: Access to Spiro[pyrrolidone-3,3'-oxindoles

The nucleophilic ring opening of donor-acceptor cyclopropanes with the cyanate ion is reported for the first time. Cyclopropanes, spiro-activated with oxindole fragments as acceptors, are shown to undergo transformations into biologically relevant spiro[pyrrolidone-3,3'-oxindoles] while being treated with potassium cyanate under microwave assistance.