Oxidative Hydrolysis Research Articles

Synthesis, Characterization and Crystal Structure of 2-Pyridinecarboxamide

2-Pyridinecarboxamide was synthesized from 2-picoline through two-steps reaction. Initially, 2-picoline was converted into 2-cyanopyridine by ammoxidation in a stainless-steel fixed-bed reactor at 370 ºC with V2O5 loaded on TiO2 as catalyst. The 2-cyanopyridine was transformed into 2-pyridinecarboxamide through oxidation hydrolysis in basic solution using MnO2 as oxidant at 70 ºC. The final product was characterized by FT-IR, NMR and UV-visible analysis, and 2-pyridinecarboxamide in the final product was determined using HPLC. The crystal structure of 2-pyridinecarboxamide was investigated using X-ray diffraction and SHELX 2018/3 (sh) software and the result indicated that 2-pyridinecarboxamide crystallized in the monoclinic system, space group P21/n with a = 5.207(2), b = 7.097(3), c = 16.243(6) Å, V = 595.7 (4) Å3; Z = 4.

Highly Crystalline Ni-Co Layered Double Hydroxide Fabricated via Topochemical Transformation with a High Adsorption Capacity for Nitrate Ions.

Layered double hydroxide (LDH) has emerged as promising candidates for removing harmful oxoanions (i.e., SO42-, HPO42-, andNO3- ions) from wastewater because of their intrinsic ability to accommodate anionic species in the interlayer space. Highly crystalline [Ni0.67Co0.33(OH)2]Cl0.29·0.53H2O (Ni-Co LDH) particleswith an exceptionally high anion-exchange capacity of 58.8 mg g-1 and a distribution coefficient (Kd) of 2396 mL g-1 for NO3- ions were successfully prepared by the flux method and a topochemical strategy. Layered Na0.97Ni0.67Co0.33O2 (NNCO) was prepared using a high-temperature flux and used as a starting material for topotactic transformation consisting of oxidative hydrolysis with KOH and NaClO and subsequent reduction with H2O2 and NaCl. During the transformation from NNCO to Ni-Co LDH, a drastic change in the valences of the Ni and Co belonging to the host layer and in the cationic and anionic species occurs in interlayer space; the valences of the Ni and Co in NNCOwereincreased from Ni2+,3+ and Co2+,3+ to Ni3+ and Co2+,3+,4+ by an oxidative hydrolysis reaction with simultaneous intercalation of K+ionsand deintercalation of Na+ions,and subsequentlydecreased from Ni3+ and Co2+,3+,4+ to Ni2+ and Co2+,3+ by a reduction reaction with simultaneous intercalation of anionic species such as CO32- and Cl-ionsand deintercalation of Na+ and K+ions. Through synchrotron powder X-ray diffraction analysis and Rietveld refinement, the resultant Ni-Co LDH was clearly shown to exhibit high crystallinity with less compositional deviation even after topochemical transformation in comparison with the one prepared by traditional coprecipitation and solid-state methods. Furthermore, the adsorption isotherm for NO3- ions elucidated that homogeneous adsorption sites are consistently constructed in the crystal structure, which could be found from the fitting to a Langmuir curve, with the R2 value being 0.98. This work opens up a new route for the fabrication of excellent not only ion-exchangeable but also ion-conductive inorganic materials for direct utilization in environmental and energy-storage processes.

A water-soluble colorimetric and fluorescent probe for rapidly sensing of ClO− in organisms

A simple colorimetric and fluorescent probe bearing coumarin and p-toluenesulfonyl hydrazide moieties was developed, which was capable of displaying excellent selectivity for hypochlorite. The distinct absorption spectral shift (49 nm) was induced by ClO−-triggered oxidative hydrolysis of CN double bonds in aqueous solution, which was accompanied by the optical variation from yellow to colorless. Besides, this probe solution underwent a dramatic intensification (162-fold) of the fluorescence signaling at 444 nm via the addition of ClO− (3 equiv.) within a short time. More importantly, the results achieved by fluorescence spectra revealed an excellent linear relation of probe 1 for ClO− with excellent sensitivity (9.1 nM). Further, the good recoveries and cellular experiments verified the prospective functions of this probe in real water environment and SW 480 cells.

STABILITY-INDICATING METHOD DEVELOPMENT AND VALIDATION OF ITRACONAZOLE AND TERBINAFINE HCL IN BULK AND PHARMACEUTICAL TABLET DOSAGE FORM

Objective: The objective of the present work was to develop and validate the stability-indicating method for the simultaneous estimation of itraconazole and terbinafine HCl in bulk and pharmaceutical tablet dosage form by reversed-phase high-performance liquid chromatography (HPLC). This combination of drugs is not reported for simultaneous HPLC analysis as of now.
 Methods: The analysis of the developed method was carried on Shimadzu LC Prominence-i 2030 model with Lab Solution software and the separation was done on Shim-pack C18 GIST (250 mm×50 mm, 5 μm) column with a flow rate of 1.2 ml/min and run time of 12 min. The injection volume was 10 μl and mobile phase consisted of acetonitrile and 0.1% triethylamine in the ratio of 90:10 and 225 nm was used as a detection wavelength.
 Results: The retention time was found to be 3.464 min and 8.705 min for itraconazole and terbinafine HCl, respectively. The calibration curve was found to be linear and r2 values were 0.9989 and 0.9995 for itraconazole and terbinafine HCl, respectively.
 Conclusion: The stability-indicating method was developed by subjecting itraconazole and terbinafine HCl marketed formulation to various stress conditions such as acidic, basic, oxidative, thermal, and water hydrolysis degradation conditions and the degraded product peaks were well resolved from sample peaks.

Preparation of nano-alkalinecellulose carboxylates (NACCs) as the methylene blue sorbent and as the catalyst for the large-scale nifedipine synthesis

In this work, various new nano-alkalinecellulose carboxylates (NACCs) were prepared by oxidative hydrolysis of microalkalinecellulose (MACp) given from prewashed cotton. After the optimization of the reaction time, temperature, oxidant system, and oxidant loading, the new flake-shape anionic NACC24 with base capacity 10.8 mmol HO−/g was obtained from MACp at 50 °C. The characterized NACC24 and MACp were comparatively used as bio-sorbent for removal of methylene blue (MB) from wastewater and as the catalyst in the large-scale synthesis of nifedipine. With the Langmuir model and monolayer pseudo-second-order kinetic mechanism, the negatively charged polymer NACC24 represented high sorption capacity for the MB removal at 780 ± 10 mg/g. A high regeneration stability and 90.5% original efficiency was verified for the NACC24 after five consequence adsorption-desorption cycles, where acidic methanol and aqueous NaOH were used for the efficient desorption of electrostatically interacted MB to NACC24 and respective reactivation of the NACC24 for further runs. Besides, NACC24 showed a high catalytic activity in the base-catalyzed rapid synthesis of anti-hypertension nifedipine even after the five times reusing of catalyst.

Acid Hydrolysis of Chitosan to Oligomers Using Hydrochloric Acid

AbstractThe natural polymer chitosan is widely used for medical and drug delivery applications. Low molecular weight chitosan (LMWC) has superior properties compared to high molecular weight chitosan (HMWC), which open new applications of LMWC, especially in the cosmetics, food, and pharmaceutical industries. LMWC is often produced from HMWC by acid, enzymatic, or oxidative hydrolysis. Industrially, hydrolysis with dilute HCl is preferred, since it is simple, practical, and gives a high yield. In this study 2M HCl was used to prepare LMWC. A high average depolymerization yield of 87% was obtained. The LMWCs were characterized by FTIR spectroscopy, and the molecular weight and degree of deacetylation were determined. The prepared LMWCs are fully deacetylated, and their production by this method is reproducible.

Metal-Free Synthesis of 1,3-Disiloxanediols and Aryl Siloxanols

The first example of metal-free oxidative hydrolysis of hydrido-siloxanes is reported. Both base-catalyzed and organocatalytic hydrolysis methods are demonstrated to transform 1,3-dihydrido-disiloxanes into 1,3-disiloxanediols. The first example of a chemoselective silane hydrolysis is demonstrated.

Synthesis of Titanium Dioxide Nanopowder via Oxidative Hydrolysis of Titanium Nitride

A new technique has been proposed for TiO2 synthesis via oxidative hydrolysis of TiN powder. We have examined the effect of factors determining the rate of TiN dissolution (temperature, concentration, and nature of the oxidant) on the phase composition and particle size of resulting TiO2 powders and assessed the photocatalytic activity of the synthesized powders in comparison with commercially available photocatalysts.

Isolation and Characterization of the Pymetrozine-Degrading Strain Pseudomonas sp. BYT-1.

In this study, we isolated and characterized the bacterial strain Pseudomonas sp. BYT-1, which is capable of degrading pymetrozine and using it as the sole carbon source for growth. Strain BYT-1 could degrade 2.30 mM pymetrozine within 20 h under the optimal conditions of 30 °C and pH 7.0. Investigation of the degradation pathway showed that pymetrozine was oxidatively hydrolyzed to 4-amino-6-methyl-4,5-dihydro-2 H-[1,2,4]triazin-3-one (AMDT) and nicotinic acid (NA). The former accumulates as the end product in the culture, whereas the latter was hydroxylated to 6-hydroxynicotinic acid (6HNA) and subjected to further degradation. The transformation of pymetrozine to AMDT and NA by the cell-free extracts of strain BYT-1 also supported that the oxidative hydrolysis of the C═N double bond in pymetrozine was the initial degradation step. This is the first report on a pure bacterial culture with the ability to degrade pymetrozine. These findings enhance our understanding of the microbial degradation mechanism of pymetrozine.

Antileishmanial Evaluation of the Leaf Latex of Aloe macrocarpa, Aloin A/B, and Its Semisynthetic Derivatives against Two Leishmania Species.

The currently available antileishmanial drugs are either toxic or too expensive for routine use in developing countries where the disease is most common. Local people in the Somalia region of Ethiopia use the leaves of Aloe macrocarpa Todaro for the treatment of malaria, jaundice, and skin diseases. In our ongoing search for new, efficient, and safe antileishmanial drugs, we investigated the leaf latex of Aloe macrocarpa and its acid-hydrolyzed product aloin A/B (1), as well as the semisynthesized derivatives of aloin A/B, namely, aloe-emodin (2) and rhein (3) against promastigotes and axenically cultured amastigotes of Leishmania aethiopica and L. donovani clinical isolates. Activity study was carried out based on the fluorescence characteristic of resazurin added to drug-treated cultures. Oxidative hydrolysis of aloin A/B by ferric chloride and concentrated hydrochloric acid afforded aloe-emodin (2), which was further oxidized using sodium nitrite and concentrated sulfuric acid to furnish rhein (3). Cytotoxicity study of test substances was performed against human monocytic cell line THP-1 using Alamar Blue and cell viability was measured fluorometrically. The test compounds showed lower activity (IC50 = 6.7 to 12.1 μM for promastigotes and IC50 = 3.6 to 10.2 μM for axenic amastigotes) than the reference drug amphotericin B (IC50 = 1.3 to 2.7 μM). However, amphotericin B (LC50 = 11.1 μM) was much more toxic than the test compounds (LC50 = 369.2 – 611.6 μM) towards human monocytic cell line (THP-1) despite its efficiency. As demonstrated in the current study, high selectivity indices (SIs) of the test compounds represent a remarkable advantage over the reference drug and highlight their potential use as templates for further development of safe leishmanicidal drugs.

Photothermal hydrogen production from oxidative hydrolysis of electrochemically synthesized nano-sized zinc

Proof of concept is established for low cost, scalable and safe access of hydrogen via photo-assisted oxidative hydrolysis of nano-sized zinc (Zn NPs). The Zn NPs with diameter of 40–50 nm are electrochemically grown on copper plate in conventional three electrode system at applied bias of 0.7 V. These NPs have long-range absorptivity from Visible-NIR region and directly employed for photothermal hydrogen production. The highest H2 production rates of 0.2 mmolh−1 and 0.43 mmolh−1 are observed under illumination of tungsten light and concentrated sunlight respectively. In addition, Zn nanoparticles have shown great potential for CO2 photoreduction. Under CO2 microenvironment and tungsten light illumination, maximum H2 production rate of 0.3 mmolh−1 is achieved along with formation of 0.116 mgL−1 formic acid. The significant enhancement may attribute to zinc nanoscale dimension which eventuates the hydroxylation rate and also increases the localized temperature by oscillating its surface electrons in resonance with incident radiation.

Synthesis of PEI-Functionalized Magnetic Nanoparticles for Capturing Bacteria

Polyethyleneimine (PEI) functionalized Fe3O4 MNPs were synthesized by a modified hypothermal oxidative hydrolysis method. The magnetic nanoparticles showed positively charged surface, strong magnetic responsivity and uniform particle size distribution at 56.1±0.6 nm. Aggregation of these magnetic nanoparticles were observed on the surface of different type of bacteria. Magnetic capturing of bacteria were facilitated by these magnetic nanoparticles. The capturing efficiency could reach 90% after two rounds of interactions of 5 minutes. The mechanism and process of interactions between bacteria and polyethyleneimine functionalized Fe3O4 magnetic nanoparticles were explored and discussed. The present study not only provides insight into interactions between Fe3O4@PEI MNPs and bacterial cells, but also opens a new avenue for designing and applying Fe3O4@PEI MNPs as biosensors in microbiology, medicine, and environmental science.

A simple hypochlorous acid signaling probe based on resorufin carbonodithioate and its biological application.

A novel hypochlorous-acid-selective signaling probe based on the carbonodithioate derivative of resorufin (RT-1) was developed. Probe RT-1 showed prominent colorimetric and turn-on type fluorescence signaling behavior exclusively toward hypochlorous acid, induced by oxidative hydrolysis, to regenerate resorufin dye. Hypochlorous acid signaling was not affected by the presence of common metal ions and anions as background, except for the redox active bromide and iodide anions. The detection limit of RT-1 for hypochlorous acid was found to be 2.18 × 10-9 M (0.11 ppb), and the signaling was completed within 3 min. It was also confirmed that hypochlorous acid signaling by the carbonodithioate-based probe RT-1 was superior to that of the closely related carbonothioate derivative RT-2. This was rationalized by density functional theory calculations, which demonstrated that the C[double bond, length as m-dash]S sulfur atom of the former is more negatively charged than that of the latter. Finally, as a biological application of the probe, visualization of hypochlorous acid in RAW 264.7 murine macrophages and HeLa cells was successfully conducted to detect the cellular response to hypochlorous acid.

A novel effective approach of nanocrystalline cellulose production: oxidation–hydrolysis strategy

In this work, we have applied, for the first time, solution plasma processing of cellulose-containing material to produce cellulose nanocrystals (CNC). The CNC samples produced in three different modes of solution plasma treatment were characterized using methods of dynamic light scattering, infrared spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The proposed method of CNC production comprising the oxidation–hydrolysis strategy has proved to be effective and allowed us to reduce significantly the time of acid hydrolysis and to increase considerably the total CNC yield.

Effects of hydrolysis and oxidative hydrolysis pretreatments on upgrading of the water-soluble fraction of bio-oil via decarboxylation

Conversion of the carboxylic acids in bio-oil into ketones via decarboxylation is a highly efficient approach for bio-oil upgrading. However, the char formation during decarboxylation is due to the existence of a considerable amount of pyrolytic sugars in bio-oil, which severely weakens the upgraded bio-oil yield and the energy efficiency. In this paper, two pretreatment approaches, hydrolysis and oxidative hydrolysis, were employed to solve this problem. The pyrolytic sugars in bio-oil were firstly enriched into the water-soluble fraction through water extraction, followed by hydrolysis or oxidative hydrolysis pretreatment before decarboxylation. With the aid of hydrolysis pretreatment, the upgraded bio-oil yield was increased from 27.55 to 30.74%, and the energy efficiency was increased from 77.59 to 88.67% after decarboxylation, whereas the char yield was decreased from 5.67 to 3.81% in comparison with the results without hydrolysis. In the case of oxidative hydrolysis pretreatment, the upgraded bio-oil yield and the energy efficiency were further enhanced to be 32.68% and 92.70% respectively, while the char yield was drastically decreased to only 1.15%. To clarify the effect of the pretreatment, two pentoses and four hexoses were used to investigate the reaction pathways for their conversion in the water-soluble fraction during hydrolysis or oxidative hydrolysis pretreatment. The experimental results showed that hydrolysis of the water-soluble fraction could effectively convert pyrolytic sugars to carboxylic acids. In contrast, oxidative hydrolysis could convert not only the pyrolytic sugars, but also most of the aldehydes and ketones in the water-soluble fraction into carboxylic acids. The reaction pathways for conversion of pentose and hexose into organic acids via oxidative hydrolysis were also investigated.

Electrophilic Aromatic Formylation with Difluoro(phenylsulfanyl) methane

Difluoro(phenylsulfanyl)methane (PhSCF2H) was found to undergo a reaction with aromatic compounds mediated by SnCl4, through a thionium intermediate characterized by NMR and TD-DFT analyses, leading to the formation of a mixture of S,S′-diphenyl dithioacetal and aromatic aldehyde which, after oxidative hydrolysis, provides the aromatic aldehyde in good to excellent yields. The salient feature of the present work is the reaction of activated aromatic compounds containing a deactivating ester functional group, leading to the formylated products in good yields.

Development of a validated liquid chromatographic method for quantification of sorafenib tosylate in the presence of stress-induced degradation products and in biological matrix employing analytical quality by design approach.

The current research work envisages an analytical quality by design-enabled development of a simple, rapid, sensitive, specific, robust and cost-effective stability-indicating reversed-phase high-performance liquid chromatographic method for determining stress-induced forced-degradation products of sorafenib tosylate (SFN). An Ishikawa fishbone diagram was constructed to embark upon analytical target profile and critical analytical attributes, i.e. peak area, theoretical plates, retention time and peak tailing. Factor screening using Taguchi orthogonal arrays and quality risk assessment studies carried out using failure mode effect analysis aided the selection of critical method parameters, i.e. mobile phase ratio and flow rate potentially affecting the chosen critical analytical attributes. Systematic optimization using response surface methodology of the chosen critical method parameters was carried out employing a two-factor-three-level-13-run, face-centered cubic design. A method operable design region was earmarked providing optimum method performance using numerical and graphical optimization. The optimum method employed a mobile phase composition consisting of acetonitrile and water (containing orthophosphoric acid, pH 4.1) at 65:35 v/v at a flow rate of 0.8 mL/min with UV detection at 265 nm using a C18 column. Response surface methodology validation studies confirmed good efficiency and sensitivity of the developed method for analysis of SFN in mobile phase as well as in human plasma matrix. The forced degradation studies were conducted under different recommended stress conditions as per ICH Q1A (R2). Mass spectroscopy studies showed that SFN degrades in strongly acidic, alkaline and oxidative hydrolytic conditions at elevated temperature, while the drug was per se found to be photostable. Oxidative hydrolysis using 30% H2 O2 showed maximum degradation with products at retention times of 3.35, 3.65, 4.20 and 5.67 min. The absence of any significant change in the retention time of SFN and degradation products, formed under different stress conditions, ratified selectivity and specificity of the systematically developed method.

A cyanobiphenyl based fluorescent probe for rapid and specific detection of hypochlorite and its bio-imaging applications

A fluorescence probe (HBM) based on conjugation of 3′-formyl-4′-hydroxy-4-biphenylcarbonitrile to 2,4-dinitrophenylhydrazune for the detection of hypochlorite has been developed. The probe exhibited a highly sensitive and selective response toward hypochlorite (ClO−) with a low detection limit of 49 nM. The sensing mechanism was considered that the hypochlorite triggered oxidative hydrolysis of probe HBM and the cyanobiphenyl fluorophore was released, which also have been evidenced by the MS analysis. Most notably, the response time of the probe HBM to the OCl− is only a few seconds. The probe was also successfully applied to fluorescence imaging of OCl− in the living cells.

Transcriptomic analysis reveals unique molecular factors for lipid hydrolysis, secondary cell-walls and oxidative protection associated with thermotolerance in perennial grass

BackgroundHeat stress is the primary abiotic stress limiting growth of cool-season grass species. The objective of this study was to determine molecular factors and metabolic pathways associated with superior heat tolerance in thermal bentgrass (Agrostis scabra) by comparative analysis of transcriptomic profiles with its co-generic heat-sensitive species creeping bentgrass (A. stolonifera).ResultsTranscriptomic profiling by RNA-seq in both heat-sensitive A. stolonifera (cv. ‘Penncross’) and heat-tolerant A. scabra exposed to heat stress found 1393 (675 up- and 718 down-regulated) and 1508 (777 up- and 731 down-regulated) differentially-expressed genes, respectively. The superior heat tolerance in A. scabra was associated with more up-regulation of genes in oxidative protection, proline biosynthesis, lipid hydrolysis, hemicellulose and lignin biosynthesis, compared to heat-sensitive A. stolonifera. Several transcriptional factors (TFs), such as high mobility group B protein 7 (HMGB7), dehydration-responsive element-binding factor 1a (DREB1a), multiprotein-bridging factor 1c (MBF1c), CCCH-domain containing protein 47 (CCCH47), were also found to be up-regulated in A. scabra under heat stress.ConclusionsThe unique TFs and genes identified in thermal A. scabra could be potential candidate genes for genetic modification of cultivated grass species for improving heat tolerance, and the associated pathways could contribute to the transcriptional regulation for superior heat tolerance in bentgrass species.

N-Heterocyclic Carbene Boranes as Reactive Oxygen Species-Responsive Materials: Application to the Two-Photon Imaging of Hypochlorous Acid in Living Cells and Tissues.

N-Heterocyclic carbene (NHC) boranes undergo oxidative hydrolysis to give imidazolium salts with excellent kinetic selectivity for HOCl over other reactive oxygen species (ROS), including peroxides and peroxynitrite. Selectivity for HOCl results from the electrophilic oxidation mechanism of NHC boranes, which stands in contrast to the nucleophilic oxidation mechanism of arylboronic acids with ROS. The change in polarity that accompanies the conversion of NHC boranes to imidazolium salts can control the formation of emissive excimers, forming the basis for the design of the first fluorescence probe for ROS based on the oxidation of B-H bonds. Two-photon microscope (TPM) ratiometric imaging of HOCl in living cells and tissues is demonstrated.