Aqueous Hydroxylamine Research Articles

A Novel Bioanalytical Method for the Determination of Opioids in Blood and Pericardial Fluid.

Opioids are the drugs most commonly detected in overdose deaths and the second most consumed worldwide. An analytical methodology has been optimized and fully validated for the determination of codeine, morphine, 6-acetylmorphine, 6-acetylcodeine, oxycodone, oxymorphone and fentanyl in whole blood and pericardial fluid. The internal standards used were codeine-d3, morphine-d3, 6-acetylmorphine-d3 and fentanyl-d5. Before solid-phase extraction, volumes of 250μL of blood and pericardial fluid were subjected to a protein precipitation (with 750μL of ice-cold acetonitrile) and a microwave-induced oximation was performed using a solution of 1% aqueous hydroxylamine hydrochloride in phosphate-buffered saline (1:2, v/v). Finally, the dried extracts were further derivatized with a solution of n-methyl-n-(trimethylsilyl) trifluoroacetamide+5% trimethylchlorosilane under microwave irradiation. The chromatographic analysis was carried out using gas chromatography-mass spectrometry operating in electron impact and selected ion monitoring mode. For all analytes, the method was linear between 5 and 1,000ng/mL with determination coefficients (r2) >0.99. Depending on the analyte and matrix, the limit of detection varies between 3 and 4ng/mL. Intra- and intermediate precision (<20%) and bias (±20%) were acceptable for all analytes in both matrices. The stability of the substances in the studied matrices was guaranteed, at least, 24h in the autosampler, 4h at room temperature and 30days after three freeze/thaw cycles. This methodology was applied to real samples from the Laboratory of Chemistry and Forensic Toxicology, Centre Branch, of the National Institute of Legal Medicine and Forensic Sciences, Portugal.

Efficient autocatalytic oximation of bio-based 2,5-diformylfuran with aqueous hydroxylamine under mild conditions

An efficient and clean method for preparation of 2, 5-Diformylfuran dioxime (DFFD) was presented through an acid-autocatalytic oximation of bio-based 2,5-diformylfuran (DFF) with aqueous hydroxylamine under mild conditions.

One-pot synthesis of aldoximes from alkenes via Rh-catalysed hydroformylation in an aqueous solvent system

Aldoxime synthesis directly starting from alkenes was successfully achieved through the combination of hydroformylation and subsequent condensation of the aldehyde intermediate with aqueous hydroxylamine in a one-pot process.

A Convenient and Safer Synthesis of Diaminoglyoxime

A new procedure for the synthesis and isolation of diaminoglyoxime (DAG) is described. A previous procedure involved treating glyoxal with 2 equiv each of hydroxylammonium chloride and sodium hydroxide to form glyoxime, followed by further treatment of this intermediate with two additional equivalents of hydroxylammonium chloride and sodium hydroxide at 95 °C to form DAG. Two recrystallizations were needed to obtain the desired product in pure form. Another previous procedure employed glyoxal in the presence of 4 equiv each of hydroxylammonium chloride and sodium hydroxide at 95 °C to form DAG. Though this latter procedure gives product after a few hours, yields do not exceed 40%, and the reaction is prone to thermal runaway. Furthermore, the use of decolorizing carbon and recrystallization of the crude solid are necessary to obtain a pure product. The new disclosed procedure involves treating a preheated aqueous hydroxylamine solution (50 wt %, 10 equiv) with aqueous glyoxal (40 wt %), followed by heatin...

Initial Decomposition Pathways of Aqueous Hydroxylamine Solutions.

This work examined the reaction pathways involved in the initial decomposition of aqueous hydroxylamine solutions via the overall reaction, 2NH2OH → NH3 + HNO + H2O, using quantum chemistry calculations incorporating solvent effects. Several possible decomposition mechanisms were identified and investigated: three neutral-neutral bimolecular, two water-catalyzed, one neutral trimolecular, two ion-neutral bimolecular, and one cation-catalyzed. Optimized structures for the reactants, products, and transition states were obtained at the ωB97XD/6-311++G(d,p)/SCRF = (solvent = water) level of theory, and the total electron energies of such structures were calculated at the CBS-QB3 level of theory. The cation-catalyzed reaction 2NH2OH + NH3OH+ → NH4+ + HNO + H2O + NH2OH (maximum energy barrier (ΔE0‡) = 53.6 kJ/mol) and the anion-neutral bimolecular reaction NH2OH + NH2O- → NH3 + 1NO- + H2O (ΔE0‡ = 79.0 kJ/mol) were both found to be plausible candidates for the dominant step in the initial decomposition. The results of this study indicate that both acidic and basic conditions can affect the thermal stability of hydroxylamine in water.

Theoretical and experimental studies of 3β-acetoxy-5α-cholestan-6-one oxime

Steroidal oxime (3β-acetoxy-5α-cholestan- 6-one oxime) has been synthesized using microwave-induced reaction in 3.5 min using saturated steroidal ketone and aqueous hydroxylamine hydrochloride in ethanol. The structure of the compound was elucidated by UV, IR, 1H NMR and X-ray single crystal structure. The computational quantum chemical studies like, IR, UV analysis were performed by density functional theory (DFT) at Becke-3-Lee-Yang-Parr(B3LYP) exchange-correlation functional in combination with 6-31++G(d,p) basis sets. The harmonic vibrational frequencies, the optimized geometric parameters have been interpreted and compared with experimental values. Theoretical wavelength at 214.88 cm−1 correspond to the experimental value 214.0 cm−1. The nature of this transition is n → π*. The theoretical results are in good agreement with experiment results.

Synthesis of Azilsartan and Its Selected Potential Impurities

Synthesis of angiotensin II AT1 receptor antagonist azilsartan is described. The results include reinvestigation of the described process as well as its novel modification. This new process includes transformation of the CN group into amidoxime moiety by aqueous hydroxylamine, its treatment with alkyl chloroformates and a base-initiated cyclization of the formed (alkoxycarbonyl-oxy)carbamimidoyl intermediates. Several so far undescribed side-products were identified and some of them were synthesized and duly characterized as potential impurities.

Synthesis of 5‐Aminotetrazole‐1 N‐oxide and Its Azo Derivative: A Key Step in the Development of New Energetic Materials

1-Hydroxy-5-aminotetrazole (1), which is a long-desired starting material for the synthesis of hundreds of new energetic materials, was synthesized for the first time by the reaction of aqueous hydroxylamine with cyanogen azide. The use of this unique precursor was demonstrated by the preparation of several energetic compounds with equal or higher performance than that of commonly used explosives, such as hexogen (RDX). The prepared compounds, including energetic salts of 1-hydroxy-5-aminotetrazole (hydroxylammonium (2, two polymorphs) and ammonium (3)), azo-coupled derivatives (potassium (5), hydroxylammonium (6), ammonium (7), and hydrazinium 5,5'-azo-bis(1-N-oxidotetrazolate (8, two polymorphs)), as well as neutral compounds 5,5'-azo-bis(1-oxidotetrazole) (4) and 5,5'-bis(1-oxidotetrazole)hydrazine (9), were intensively characterized by low-temperature X-ray diffraction, IR, Raman, and multinuclear NMR spectroscopy, elemental analysis, and DSC. The calculated energetic performance, by using the EXPLO5 code, based on the calculated (CBS-4M) heats of formation and X-ray densities confirm the high energetic performance of tetrazole-N-oxides as energetic materials. Last but not least, their sensitivity towards impact, friction, and electrostatic discharge were explored. 5,5'-Azo-bis(1-N-oxidotetrazole) deflagrates close to the DDT (deflagration-to-detonation transition) faster than all compounds that have been investigated in our research group to date.

Effect of Hydroxylamine Sulfate on Volumetric Behavior of Glycine, L‐Alanine, and L‐Arginine in Aqueous Solution

The apparent molar volumes of glycine, L‐alanine, and L‐arginine in aqueous hydroxylamine sulfate solutions have been determined at T = 298.15 K and atmospheric pressure. The standard partial molar volumes, , corresponding partial molar volumes of transfer, , and hydration numbers, NH, have been calculated for these α‐amino acids from the experimental data. The values are positive for glycine, L‐alanine, and L‐arginine and are all increased with the increase in the concentration of hydroxylamine ions. These parameters obtained from the volumetric data are interpreted in terms of various mixing effects between amino acids and hydroxylamine sulfate in aqueous solutions.

Improved Process for Azilsartan Medoxomil: A New Angiotensin Receptor Blocker

An improved process for the active pharmaceutical ingredient of a new angiotensin II AT1 receptor antagonist, azilsartan medoxomil, has been developed. The results include reinvestigation of the described process as well as its novel modifications. This new process includes transformation of the CN group into amidoxime moiety by aqueous hydroxylamine, its cyclization into the corresponding oxadiazole by treatment with dialkyl carbonates, and the following hydrolysis of the ester and transformation into the medoxomil ester. Several thus far undocumented side products were identified, and some of them were synthesized and duly characterized as potential impurities. Formation and control of possible critical impurities are described.

ChemInform Abstract: Regioselective Synthesis of 3‐Arylamino‐ and 5‐Arylaminoisoxazoles from Enaminones.

A highly regioselective synthesis of 3-arylamino- and 5-arylaminoisoxazoles from enaminones based on reaction condition selection is reported. 3-Arylaminoisoxazoles were produced by treating enaminones with aqueous hydroxylamine in DMF at 100 °C, whereas 5-arylaminoisoxazoles were synthesized by subjecting enaminones to aqueous hydroxylamine in the presence of KOH and TBAB in water under reflux. A mechanism for the regioselective synthesis of 3-arylamino- and 5-arylaminoisoxazoles is proposed.

Regioselective Synthesis of 3-Arylamino- and 5-Arylaminoisoxazoles from Enaminones

A highly regioselective synthesis of 3-arylamino- and 5-arylaminoisoxazoles from enaminones based on reaction condition selection is reported. 3-Arylaminoisoxazoles were produced by treating enaminones with aqueous hydroxylamine in DMF at 100 °C, whereas 5-arylaminoisoxazoles were synthesized by subjecting enaminones to aqueous hydroxylamine in the presence of KOH and TBAB in water under reflux. A mechanism for the regioselective synthesis of 3-arylamino- and 5-arylaminoisoxazoles is proposed.

ChemInform Abstract: Hydroxylamine as a Source for Nitric Oxide in Metal‐Free 2,2,6,6‐Tetramethylpiperidine N‐Oxyl Radical (TEMPO) Catalyzed Aerobic Oxidation of Alcohols.

The communication reports on the metal- I free 2,2,6,6-tetramethylpiperidine N-oxyl radical (TEMPO) catalyzed aerobic oxidation of various alcohols to aldehydes and ketones. A novel catalyst system that uses 1―4 mol% of TEMPO in combination with 4―6 mol% of aqueous hydroxylamine is introduced. No other additives are necessary and corrosive by-products are not formed during oxidation. Nitric oxide which is important for the catalytic cycle is generated in situ by reaction of the hydroxylamine with TEMPO. A catalytic cycle for the overall oxidation process is suggested.

Hydroxylamine as a Source for Nitric Oxide in Metal‐Free 2,2,6,6‐ Tetramethylpiperidine N‐Oxyl Radical (TEMPO) Catalyzed Aerobic Oxidation of Alcohols

AbstractThe communication reports on the metal‐free 2,2,6,6‐tetramethylpiperidine N‐oxyl radical (TEMPO) catalyzed aerobic oxidation of various alcohols to aldehydes and ketones. A novel catalyst system that uses 1–4 mol% of TEMPO in combination with 4–6 mol% of aqueous hydroxylamine is introduced. No other additives are necessary and corrosive by‐products are not formed during oxidation. Nitric oxide which is important for the catalytic cycle is generated in situ by reaction of the hydroxylamine with TEMPO. A catalytic cycle for the overall oxidation process is suggested.

Preparation of amidoximated bacterial cellulose and its adsorption mechanism for Cu2+ and Pb2+

AbstractAmidoximated bacterial cellulose (Am‐BC) was prepared through successive polymer analogous reactions of bacterial cellulose with acrylonitrile in an alkaline medium followed by reaction with aqueous hydroxylamine. It was used as an adsorbent to remove Cu2+ and Pb2+ from aqueous solutions. The adsorption behaviors of Cu2+ and Pb2+ onto Am‐BC were observed to be pH‐dependent. The maximum adsorption capacity of 84 and 67 mg g–1 was observed, respectively, for Cu2+ and Pb2+ at pH 5. Scanning electronic microscopy (SEM) indicated that the microporous network structure of Am‐BC was maintained even after the modifacation. The adsorption mechanisms for Cu2+ and Pb2+ onto Am‐BC were investigated by fourier transform infrared spectroscopy (FTIR), ζ potential measurement and X‐ray photoelectron spectroscopy (XPS). The results revealed that the mechanism for the adsorption of Cu2+ onto Am‐BC could be mainly described as between metal ions and nitrogen atom in the amidoxime groups or oxygen atom in the hydroxyl groups. However, in the adsorption process for Pb2+, precipitation played the important role along with electrostatic interactions, although chelation action also existed in the process accounted for the adsorption process. The regeneration of Am‐BC was studied by treatment with a strong complexing agent, ethylenediaminetetracetic acid (EDTA). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Unexpected formation of ammonium thiocyanate from the reaction of aqueous hydroxylamine with carbon disulfide

Abstract Reaction of aqueous hydroxylamine with carbon disulfide in acetonitrile or in tetrahydrofuron unprecedentedly results in the formation of ammonium thiocyanate and sulfur.

Synthesis of Hydroxamic Acids by Activation of Carboxylic Acids with N,N′-Carbonyldiimidazole: Exploring the Efficiency of the Method

Activation of carboxylic acids with N,N′-carbonyldiimidazole followed by the reaction with anhydrous or aqueous hydroxylamine hydrochloride was demonstrated to be an operationally simple method for the synthesis of hydroxamic acids in good yield and high purity after aqueous workup. The potential by-product, N,O-diacylhydroxylamine, is cleanly transformed to hydroxamic acid in these reaction conditions.

Physicochemical Properties of Aqueous Hydroxylamine Sulfate and Aqueous (Hydroxylamine Sulfate + Ammonium Sulfate) Solutions at Different Temperatures

The densities of an aqueous solution of pure hydroxylamine sulfate at T = (283.15, 288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and a solution of hydroxylamine sulfate containing ammonium sulfate at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K have been determined over a wide range of concentrations. The viscosities of binary and ternary mixtures of these compounds at T = (298.15, 303.15, and 308.15) K are also presented. The Masson-type equation and extended Jones−Dole equation in terms of ionic strength are used to correlate the density and viscosity, respectively, of aqueous solutions of hydroxylamine sulfate. The ideal mixing rule of Young has been successfully applied to predict the ternary densities and viscosities of aqueous hydroxylamine sulfate + ammonium sulfate based on relevant binary solution properties.

Ketonitrones via Cope-Type Hydroamination of Allenes

The synthesis of ketonitrones from N-alkylhydroxylamines and monosubstituted allenes is accomplished via a Cope-type hydroamination reaction in moderate to good yields. Allenes also undergo a similar reaction with aqueous hydroxylamine to give oximes in excellent yield. DFT calculations support a proposed concerted, five-membered hydroamination process, and calculated transition state energies are in excellent agreement with experimental observations.

Covalent Modification of the Wool Fiber Surface: The Attachment and Durability of Model Surface Treatments

Exposure of reactive chemical functional groups through controlled surface lipid removal provides a means for covalent attachment of novel molecular entities to the wool fiber surface. Cleavage of the dominant lipid in the epicuticle, 18-methyleicosanoic acid (18-MEA), from the underlying proteinaceous layer was employed, prior to further surface modification, by means of aqueous hydroxylamine treatment. Treatments utilizing covalent bonding to the surface through thiol, carboxyl, amine, or other reactive chemical groups offer improved durability to textile processing, such as dyeing and laundering. This surface modification investigation compared and assessed the attachment and durability of various wool fiber surface modification technologies and provided proof of principle for the manipulation of surface properties via covalent attachment of treatment compounds, providing enhanced fiber performance. Following removal of the surface lipid layer, wool fibers were modified using fluorescent and hydrophobic compounds and micro and nanoparticles. The extent of modification was assessed using scanning electron, light, and fluorescence microscopy, wettability testing and X-ray photoelectron spectroscopy (XPS). Surface treatments were evaluated with regard to effectiveness and durability to dyeing and laundering. Surface modification via attachment to thiol and other nucleophilic functionalities was observed to be greatly improved after hydroxylamine treatment, demonstrating the advantage of a customized exposed and accessible surface before secondary treatment. Increased durability and effective microparticle attachment was best accomplished employing zero or short-range crosslinking mechanisms, with zero-length attachment enhanced with the use of the crosslinking promoters, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Fluorescent and hydrophobic surface modifications exhibited high durability to laundering and demonstrated the viability of customizing surface hydrophobicity.