Potassium Permanganate In Presence Research Articles

Stability of the Glycated Amino Acid 6-(2-Formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine (Pyrraline) During Oxidation.

Food proteins may be modified during processing and storage through reactions with reducing sugars (Maillard reaction, glycation) or by reactive oxygen species (protein oxidation). Little is known about particular reactions at the interface of glycation and oxidation. In the present study, the glycated amino acid pyrraline (6-(2-formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine) and the proteinogenic amino acids tyrosine and tryptophan were subjected to different types of oxidation. The stability of the amino acids was assessed by HPLC with UV detection, whereas oxidation products were assigned by HPLC with triple quadrupole or time-of-flight mass spectrometric detection. Conditions that lead to oxidation of aromatic proteinogenic amino acids can also lead to oxidation of pyrraline. Pyrraline was particularly unstable in the presence of permanganate, hypochlorite, and under hydroxyl radical-generating conditions (iron, ethylenediaminetetraacetic acid, ascorbic acid). Evidence obtained by high-resolution mass spectrometry revealed the oxidation of pyrraline to 6-(2,5-diformyl-1-pyrrolyl)-l-norleucine, 6-(2-carboxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine, 6-(2-formyl-5-carboxy-1-pyrrolyl)-l-norleucine, and 6-(2,5-dicarboxy-1-pyrrolyl)-l-norleucine in the presence of potassium permanganate. The latter product was isolated by semipreparative HPLC and characterized by NMR. Under hydroxyl radical-generating conditions, pyrraline is hydroxylated at the ring under formation of 6-(2-formyl-4-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine or 6-(2-formyl-3-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine. This study shows that the so-called "advanced glycation end products" are no end products of the Maillard reaction, but may undergo further chemical degradation reactions.

8-Hydroxyquinoline incorporated ZIF-8 nanocomposites for efficient decomposition and detection of manganese ions in aquatic environments

The presence of potassium permanganate in aquatic environment poses a significant issue that requires resolution. In response, zeolitic imidazolate framework nanoparticles with large pore sizes, extensive surface areas, and high chemical stability in water were synthesized. Subsequently, 8-hydroxyquinoline was incorporated into ZIF-8 (named 8-HQ@ZIF-8) to enhance its capability to decompose potassium permanganate in aquatic environment. The synthesized material underwent thorough characterization using powder X-ray diffraction, Fourier-transform infrared spectroscopy, nitrogen isothermal adsorption-desorption at 77 K, thermogravimetric analysis, and scanning electron microscopy. Electrical conductivity tests revealed that the 8-HQ@ZIF-8 material can decompose potassium permanganate within 5 min and be recycled over five runs. Furthermore, the nanocomposite of 8-HQ and ZIF-8 exhibited greater stability than the original ZIF-8 under strong oxidizing conditions. This suggests that functionalizing with organic ligands can enhance the durability and performance of the material. In addition to its degradability, the 8-HQ@ZIF-8 material, which carries manganese oxide, also displays variable fluorescence properties, making it a potential sensor for detecting residual potassium permanganate in drinking water treatment systems. Therefore, the 8-HQ@ZIF-8 material shows considerable promise for both the treatment and detection of pollutants in aquatic environments.

A Simple Fluorescence Sensor Based on Merocyanine 540-MnO2 System to Detect Hypochlorite

Merocyanine 540 (MC540)- Manganese oxide (MnO2) system-based fluorescence sensor is reported as an anion sensor in aqueous solution. MnO2 was synthesized in the presence of Potassium permanganate (KMnO4) and Cetyltrimethylammonium bromide (CTAB) using 3-(N-morpholino) propane sulfonic acid (MOPS) buffer. The formation of MnO2 was first confirmed by a color change and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Ultraviolet–Visible (UV–Vis). absorption spectroscopy techniques. Next, the interaction of MC540 with MnO2 in aqueous solution was investigated at various conditions by UV–Vis. absorption and fluorescence spectroscopy. The sensing ability of the MC540-MnO2 was tested to detect hypochlorite (ClO-) ion as a “Turn-off” fluorescent sensor. The MC540-MnO2 revealed to be high selectivity and sensitivity to detect hypochlorite (ClO-) ion without being affected by the other thirteen anions. The detection limits for ClO- were evaluated in two different concentration ranges and calculated to be 0.14 μM at 0.33-4.46 μM and 0.38 μM at 5.06-14.30 μM, respectively.

A Spectroscopic Approach on Permanganate Oxidation of 1-[(4-Chlorophenyl)methyl]piperidin-4-amine in Presence of Ruthenium(III) Catalyst with DFT Analysis on Reaction Mechanism Pathway

The kinetic oxidation of 1-[(4-chlorophenyl)methyl]piperidin-4-amine (CMP) using alkaline potassium permanganate in presence of Ru(III) as catalyst was conducted spectrophotometrically at 303 K. The Pseudo first-order reaction was maintained with regard to oxidant and substrate during the reaction at an ionic strength of 0.01 mol dm-3. The first-order kinetics has been depicted with respect to catalyst Ru(III) chloride and less than unit order with substrate and medium. For the slow step, different activation parameters including ΔH# (kJ mol-1), Ea (kJ mol-1), ΔG# (kJ mol-1) and ΔS# (J K-1 mol-1) were calculated. The effect of temperature, variation of substrate concentration, oxidant, ionic strength were studied. The stoichiometry ratio of the reaction to the substrate and oxidizing agent was found to be 1:4. The products of reaction were isolated and identified as chlorobenzene and L-alanine, N-(2-aminomethylethyl)-carboxylic acid by LC-MS spectra, a suitable mechanism has been proposed and the rate laws are derived. The frontier molecular orbital (FMO) and frontier electron density (FED) of piperidiamine and the oxidative products were studied using density functional theory (DFT). The results of the theoretical calculations supported the suggested reaction pathways.

Electrocapacitive and electrocatalytic performances of hydrochar prepared by one-step hydrothermal carbonization without further activation

Abstract Hydrochar was produced from extracted avocado seed using one-step hydrothermal carbonization (HTC) at a temperature of 200 °C for 12 h. The effects of various feedstock solutions on the specific surface area, morphology, pore characteristics, crystallinity, and chemical bonding were investigated to confirm the changes in the electrochemical performances of the produced hydrochar. The presence of potassium permanganate (KMnO4) and ammonia (NH4OH) solution in the HTC process successfully produced a porous graphite-like structure of hydrochar with the highest surface area and specific capacitance. Moreover, it also exhibits excellent electrocatalytic performance toward the Oxygen Reduction Reaction (ORR), with a current density of 2.15 mA cm−2 via the 2-electron pathway. These results imply that the HTC process can produce hydrochar with high electrocapacitive and electrocatalytic performances even without further activation at high temperatures.

Ozonolytic synthesis of 2-hydroxybenzyl alcohol for the production of gastrodin

2-Hydroxybenzyl alcohol is an important active pharmaceutical ingredient for the production of many drugs, in particular gastrodin, which has a wide range of beneficial effects on epilepsy, Alzheimer’s disease, Parkinson’s disease, affective disorders, cerebral ischemia, cognitive disorders. It is known that 2- and 4-hydroxybenzyl alcohols and mixtures of both compounds are obtained by the interaction of phenol with formaldehyde in the presence of basic catalysts. Due to its high reactivity with formaldehyde, the isolation of pure compounds from the reaction mixtures obtained during the interaction of phenol with formaldehyde is a big problem. Isolation of 2-hydroxybenzyl alcohol in pure form from reaction mixtures is possible only using processes that cannot be carried out on an industrial scale and is accompanied by low yields of the target product. It is possible to get rid of these problems by means of the process of direct oxidation of the 2-hydroxytoluene with ozone in the liquid phase since methods of selective ozonation of methylbenzene to the oxygen derivatives are already known. Therefore, the development of a new low-temperature synthesis of 2-hydroxybenzyl alcohol using ozone is an urgent task. The aim of the work is to study the reaction of the oxidation of 2-hydroxytoluene by ozone in a solution of a stop reagent and catalytic impurities of compounds of transition metals and mineral acids for the development of a new method of synthesis of 2-hydroxybenzyl alcohol. Materials and methods. For the experiments, acetic anhydride of p. a. qualification was used; glacial acetic acid of puriss. qualification, which before use was purified by distillation under vacuum in the presence of potassium permanganate, 2-hydroxytoluene of puriss. Qualification, manganese (II) acetate of pur. Qualification, sulfuric and phosphoric acids of puriss. qualification. To determine the concentration of ozone in the gas phase, a spectrophotometric method was used, based on the measurement of the optical density of the gas flow in the UV region. For this purpose, a spectrophotometer SF-46 LOMO was used, in the measuring chamber of which a flow cuvette with quartz windows was installed. The material of the cuvette was Teflon. Continuous monitoring of the current concentration of ozone, with the recording of the analysis results in the form of a kinetic curve, was carried out when ozone-containing gas passed through the curette at a certain wavelength of a monochromatic light source. Results. The reaction of oxidation of 2-hydroxytoluene by ozone in a solution of the stop reagent – acetic anhydride was studied. It was shown that in the presence of sulfuric acid, it was possible to carry out direct ozonation of 2-hydroxytoluene to 2-hydroxybenzyl alcohol, which was formed in the kind of 2-acetoxybenzyl acetate with a yield of 13.0 %. The main products of the reaction under these conditions are aliphatic compounds, which are formed after the destruction of the aromatic ring. The selectivity of oxidation by alcohol was significantly increased when a catalyst – manganese (II) acetate – was added to the system. In its presence, a catalytic system As2O – H2SO4 – Mn(III) was created, which prevents ozonolysis and directed oxidation mainly to the methyl group of the substrate with the formation of 2-acetoxybenzyl acetate with a yield of 63.2 %. Conclusions. An environmentally friendly, low-temperature method for the synthesis of 2-hydroxybenzyl alcohol was developed by conducting the oxidation of 2-hydroxytoluene with ozone in a solution of the stop reagent – acetic anhydride in the presence of sulfuric acid and manganese (II) acetate.

Recovery of Lithium from Spent Coin-Type Lithium Manganese Dioxide CR Cells by Acidic Leaching in the Presence of Potassium Permanganate as Oxidant

Recovery of Lithium from Spent Coin-Type Lithium Manganese Dioxide CR Cells by Acidic Leaching in the Presence of Potassium Permanganate as Oxidant

A new method for the synthesis of 4-aminobenzoic acid – an intermediate for the production of procaine

Procaine is one of the oldest local anesthetics used in medicine. When absorbed and entering the systemic circulation reduces the excitability of peripheral cholinoreactive systems. Has a blocking effect on the autonomic ganglia, reduces smooth muscle spasms, and reduces the excitability of the myocardium and motor areas of the cerebral cortex. It is synthesized by oxidizing 4-nitrotoluene to 4-nitrobenzoic acid, which is subsequently reacted with thionyl chloride, the resulting acid chloride is then esterified with 2-diethylaminoethanol to give nitrocaine. Finally, the nitro group is reduced by hydrogenation over a Raney nickel catalyst. The oxidation stage is characterized by the formation of toxic, difficult to dispose of wastewater, valuable mineral oxidants, or high temperatures and excess pressure, in the case of using oxygen as an oxidant. Therefore, the search for new environmentally friendly and low-temperature methods of obtaining 4-nitrobenzoic acid is an urgent task. The aim of the work is to study the products, conditions, and study kinetics of the reaction of ozone with 4-nitrotoluene in acetic acid solution to develop a new method for the synthesis of 4-nitrobenzoic acid. Materials and methods. The glacial acetic acid qualification “P. F. A.” before use was purified by distillation under vacuum in the presence of potassium permanganate. Salts of metals of qualification “P. F. A.” and potassium bromide qualification “Ch. P.” were used without prior purification. A gas-phase gradient-free catalytic duck reactor was used for kinetic studies. The mixing of gas and liquid phases in the reactor was achieved by shaking the reactor at a speed that allowed it to work in the kinetic region. The kinetics of the reaction was studied by changing the concentration of ozone in the gas phase at the outlet of the reactor by spectrophotometric method on a spectrophotometer “SF-46 LOMO”. Results. The products, conditions, and kinetics of ozone reaction with 4-nitrotoluene were studied. It was shown that at temperatures of 20–90 °C is mainly ozonolysis of the aromatic ring, and the total yield of oxidation products by methyl group does not exceed 24.2 %, among which identified in the early stages of 4-nitrobenzyl alcohol and 4-nitrobenzaldehyde, and at deeper – 4-nitrobenzoic acid. The introduction of cobalt (II) acetate into the catalyst system almost completely was prevented ozonolysis and the main reaction product is 4-nitrobenzoic acid with a yield of 86.5 %. The addition of potassium bromide to the solution reduced the concentration of the catalyst by seven times and increased the reaction rate and yield of 4-nitrobenzoic acid to 95.6 %. Conclusions. A new environmentally friendly, low-temperature method for the synthesis of 4-nitrobenzoic acid by conducting the process of ozonation of 4-nitrotoluene in a solution of glacial acetic acid in the presence of a mixed cobalt bromide catalyst was developed.

Synthesis of novel keto-bromothymol blue in different media using oxidation–reduction reactions: combined experimental and DFT-TDDFT computational studies

A crystalline ((3-bromo-5-isopropyl-2-methyl-4-oxocyclohxa-2,5-dien-1-yl)methyl 4ʹ-hydroxy-5ʹ-isopropyl-2ʹ-methyl-[1,1ʹbiphenyl]-2-sulfonate) [BTB]Keto was synthesized in different media at 25 °C based on an oxidation method in the presence of potassium permanganate. The redox reactions occur in alkaline and acidic media. In alkaline medium, two distinct stages were observed: The first stage was relatively fast and the second stage was relatively slow. The first step coexists with the formation of intermediate complexes involving transient species relatively quickly of the blue hypomanganate (V) and green manganate (VI). The slowly decomposed intermediate formed to produce soluble colloidal manganese (IV) and the BTB keto-derivatives as second slow-stage oxidation products. But in acidic medium, oxidation reaction occurs in one stage because the first stage was found to be very fast and cannot be followed and the second stage was found to be slow so the reaction occurs in one stage (slow stage) to give rise to the final oxidation product [BTB]Keto. Thin films were produced through physical vapor deposition. Both the resulting dye particles and prepared thin films were deeply discussed using various techniques including Fourier transform infrared (FTIR), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), and optical properties. DMol3 and Cambridge Serial Total Energy Package (CASTEP) program performed the optimization of the samples using density functional theory (DFT). An XRD and FT-IR study established the structural properties of the resultant dye. The XRD tests of thin films (monoclinic 2) display crystal structure. An optical measurement found that with growing photon energy the optical constants (refractive index n, absorption index k, dielectric constants, and optical conductivity) decreased. The optical properties of the dye thin films found in model FTIR, XRD, and CATSTEP are in strong alignment with the experimental research. The dye thin films show a compelling outcome to be a successful choice for applications in optoelectronics and solar cells. Experimental XRD data of both [BTB]TF and [BTB]keto thin films

Corrosion Behavior of Aluminum alloy AD31 in the Presence of Potassium Permanganate in an Acidic Media

The chronoamperometry method was used to study corrosion of the aluminum alloy AD31 in the presence of potassium permanganate in chloride-containing acidic media. A rotating disk electrode was used to establish the kinetic features, and the mechanisms of cathodic oxygen reduction on AD31 in permanganate-containing acidic solutions were proposed.

Complete Mineralization of Fluorinated Ionic Liquids in Subcritical Water in the Presence of Potassium Permanganate

Reactions of [Me₃PrN][(CF₃SO₂)₂N] and [C₃mpip][(CF₃SO₂)₂N] (C₃mpip = 1-methyl-1-propylpiperidium) in subcritical water were investigated to develop a technique for recycling fluorine element. By adding KMnO₄ to the system, quasi-complete mineralization of the ionic liquids was achieved at 300 °C. When [Me₃PrN][(CF₃SO₂)₂N] was reacted for 18 h with 158 mM KMnO₄, F–, SO₄²–, and NO₃– yields were 98, 98, and 91%, respectively, and the amount of total organic carbon (TOC) was below the detection limit. [C₃mpip][(CF₃SO₂)₂N] was also almost completely mineralized via the same treatment, affording F–, SO₄²–, and NO₃– yields of 94, 97, and 96%, respectively, with no detectable TOC. The rest of the nitrogen atoms were well accounted for by the formation of NO₂–. Compared with a previous reported method using FeO, our approach reduces the reaction temperature for complete mineralization by 76 °C and suppresses the formation of environmentally undesirable CHF₃.

Effect of Oxidizing Agents on the Expansion Characteristics of Natural Graphite

In an attempt to study the expansion characteristics of natural graphite in presence of two different oxidizing agents in concentrated acid medium, potassium permanganate and potassium dichromate have been chosen. Under identical reaction conditions, for the same concentrations of oxidizing agents, the expansion of natural graphite in presence of potassium permanganate - con. sulphuric acid mixture has been found to be higher when the heat treatment temperature is varied from 400 °C to 1030 °C. The expanded volume of natural graphite is observed to be four times greater in presence of potassium permanganate/con.sulfuric acid mixture when compared to potassium dichromate in presence of con. sulfuric acid. Also, at 400 °C, potassium permanganate in con. sulfuric acid treated natural graphite resulted in appreciable expansion which has not been observed in the case of potassium dichromate added graphite in presence of con. sulfuric acid. The XRD analysis clearly proved that the crystallite size of natural graphite after intercalation of sulfuric acid decreases and upon further heat treatment, the decrease in crystallite size is appreciable. The full width at half maximum (FWHM) of the most prominent (002) peak of graphite increases with heat treatment temperature even at 500 °C. The optical microscope images very clearly prove the formation of more fluffy structure after intercalation of acid followed by heat treatment at 700 °C. The formation of graphite nanosheets has been proved through FESEM images when the synthesized expanded graphite is sonicated in acetone for few minutes. The present study clearly reveals the possibility of optimizing reagents concentrations and reaction time so that maximum expansion can be obtained.

Highly sensitive determination of copper (II) ions using fluorescence and chemiluminescence emissions of modified CdS quantum dots after it’s preconcentration by dispersive liquid–liquid microextraction

Two highly sensitive and selective methods based on fluorescence (FL) and chemiluminescence (CL) emissions of 8-mercaptoquinoline-capped CdS quantum dots (MCQ-CdS QDs) were described for the determination of copper (II) after it’s preconcentration. High fluorescent CdS QDs, synthesized in an aqueous medium, generated a relatively intense CL emission in the presence of potassium permanganate as an oxidant. Furthermore, low quantities of copper (II) ions showed a remarkable quenching effect on both of the CL and FL emissions of MCQ-CdS QDs. Based on this effect, two selective and simple methods were established for Cu2+, and the detection limits of 0.28 and 0.026 ng mL−1 were obtained for the FL and CL methods, respectively. Also, due to the high propensity of MCQ to Cu2+, good selectivity was obtained and no sensible interfering effects from other metal ions were observed. To more sensitize the developed method, an efficient preconcentration process was designed based on the high-yield ultrasound-assisted temperature-controlled ionic liquid dispersive liquid–liquid microextraction (UA-TIL-DLLME) method. Under the optimum conditions, the extracted Cu2+ showed a suppressing effect on the FL and CL emissions of CdS QDs proportional to its initial concentration over the ranges of 0.008–1.4 and 0.001–1.4 ng mL−1, respectively. The limits of detection of 3.7 and 0.37 pg mL−1, respectively, were also achieved. The established methods showed great features and were satisfactorily applied to the monitoring of ultratrace Cu2+ in some different environmental samples.

Synthesis, characterization and optical properties of β-substituted pyrrolo- and indolo[1,2-a]quinoxalinoporphyrins

A convenient synthesis of β-substituted copper(II) pyrrolo- and indolo[1,2-a]quinoxalinoporphyrins have been achieved through a Pictet–Spengler reaction of various copper (II) β-formyl-5,10,15,20-tetraarylporphyrins and 1-(2-aminophenyl)pyrrole or 2-(3-methyl-indol-1-yl)-phenylamine in the presence of 10 mol% p-dodecylbenzenesulfonic acid as Brønsted acid catalyst in 1,4-dioxane at 25–40 °C followed by in-situ oxidation in the presence of potassium permanganate at ambient temperature. Furthermore, the corresponding free-base porphyrin analogues were obtained in good yields after the treatment of copper(II) porphyrins with concentrated sulfuric acid at 0 °C. On metal insertion by using nickel acetate or zinc acetate, these free-base porphyrins afforded the nickel and zinc complexes of pyrrolo[1,2-a]quinoxalinoporphyrins in good yields. The newly synthesized porphyrins were characterized on the basis of spectral data. The preliminary photophysical studies of these pyrrolo- and indolo[1,2-a]quinoxalinoporphyrins demonstrate a significant red shift in their electronic absorption and emission spectra due to the extended π-conjugation in comparison to the corresponding meso-tetraphenylporphyrins.

Facile and sensitive paper-based chemiluminescence DNA biosensor using carbon dots dotted nanoporous gold signal amplification label

A facile and sensitive chemiluminescence (CL) protocol for the detection of DNA on low-cost paper analytical device using simple, rapid wax-screen-printing method was developed by combining simply covalent modification and signal amplification in this work. The DNA sensor was prepared with N,N′-disuccinimidyl carbonate (DSC) to capture DNA by covalently immobilizing on μPADs, and carbon dots (C-dots) dotted nanoporous gold (C-dots@NPG) was employed for signal amplification label. After the sandwich-type DNA hybridization reaction, C-dots@NPG labeled signal DNA was captured on the DNA biosensor. In the presence of potassium permanganate, the radiative recombination of oxidant injected holes and electrons generated oxidant induced CL reaction of the C-dots@NPG and produced the CL signals. Under optimal conditions, the application of this paper-based DNA sensor was successfully performed with a linear range of 10−18 to 10−14 M and with a detection limit of 8.56 × 10−19 M for target DNA. The newly designed strategy not only provides a simple DSC modified platform to improve the immobilization of capture DNA or antibody, but also offers a high-efficiency C-dots@NPG signal amplification label to enhance the sensitivity, and thus will be a promising potential in public health and environmental monitoring.

Determination of trace amounts of chromium (VI) by flow injection analysis with chemiluminescence detection

A new sensitive chemiluminescence (CL) method combined with continuous flow injection analysis is described for the determination of Cr(VI). Strong CL signals were generated by Cr(VI)-catalysed oxidation of gallic acid in the presence of potassium permanganate and hydrogen peroxide. Effects of reagent concentrations, temperature, pH, flow rates, mixing coil length and mixing flow sequences on the chemiluminescence intensity were studied. Under the optimised experimental conditions, the relationship between the logarithm of concentration (log C) of Cr(VI) and the logarithm of intensity (log I) is linear over the range of 2 × 10−11 – 5 × 10−4 mol L−1, with the detection limit (3σ) of 4 × 10−12 mol L−1. Relative standard deviation of ten measurements of 1 × 10−9 mol L−1 Cr(VI) is 1.7%. This flow injection analysis (FIA) system proved to be able to analyse up to 40 samples h−1. Effects of various interferences possibly present in the water samples were investigated. Most cations and anions, as well as organic compounds, did not interfere with the determination of Cr(VI) in water samples. The experimental results obtained for chromium in reference materials were also in good agreement with the certified values.

Chemiluminescence of a cyclometallated iridium(III) complex and its application in the detection of cysteine

Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow-injection-chemiluminescence (FI-CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10(-9) -5.0 × 10(-6) mol/L with a detection limit of 6.9 × 10(-10) mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal-to-ligand charge-transfer (MLCT) excited states of the iridium complex.

Microwave activated synthesis of 2-aryl-quinazolin-4(3 H)ones

A highly efficient synthesis of 2-aryl-quinazolin-4(3 H)ones was performed by one-pot oxidative heterocyclization of 2-aminobenzamide with aldehydes in the presence of potassium permanganate in dimethylacetamide under microwave irradiation.

Synthesis, Structural Characterisation and Reactions of Some Vinylgold(I) Phosphane Complexes

AbstractA series of vinylgold(I) complexes [Au(CR=CHR)L] (R = H, Me; L = PPh3, PPh2Me, PPhMe2) were prepared from the reaction of the Grignard reagents [MgBr(CR=CHR)] (R = H, Me) with the gold(I) phosphane complexes [AuCl(L)] (L = PPh3, PPh2Me, PPhMe2) at low temperature. The complexes were characterised by various spectroscopic techniques and, in the case of [Au(CMe=CHMe)(PPh3)], by a single‐crystal X‐ray structure determination. The gold–carbon bonds of these vinylgold(I) complexes are easily cleaved by acids and, in the presence of potassium permanganate, by species containing acidic protons. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Root navigation by self inhibition

ABSTRACTCircumventing physical obstacles is critical for a plant's survival and performance. Although the ability of roots to circumvent obstacles has been known for over 100 years, the phenomena and its mechanisms have received relatively little attention. In this study it is demonstrated that roots of Pisum sativum are able to detect and avoid growth towards inanimate obstacles and the hypothesis that this behaviour is based on the sensitivity of roots to their own allelopathic exudates that accumulate in the vicinity of physical obstacles is tested. The development of lateral roots of Pisum sativum towards an obstacle (a piece of nylon string, similar in dimensions to a plant root) was followed. Lateral roots were similar in number, but significantly shorter in the direction of the nylon string. In addition, up to half of the lateral roots that developed towards the nylon string withered, whereas no withering was observed in the absence of the nylon string. These avoidance growth patterns were suppressed in the presence of potassium permanganate or activated carbon, indicating a role of allelopathic exudates in promoting obstacle avoidance. The demonstrated obstacle avoidance by self inhibition could increase plant performance by limiting resource allocation to less promising parts of the root system.