Round-bottomed Flask Research Articles

Synthesis, Characterization and Biological Studies of Gemifloxacin Mesylate with Nickel(II) and Copper(II)

Gemifloxacin mesylate, a fourth-generation fluoroquinolone-type antibiotic, is widely used for community treatment of acquired pneumonia and severe bacterial infections. The Cu(II) and Ni(II) complexes of gemifloxacin mesylate were synthesized by refluxing an aqueous solution of the ligand with the required amount of metal(II) salts in a round bottom flask with 2:1 (L:M) ratio in an oil bath at 90 ºC with a continuous stirring for 4 h. The mixture was kept overnight to obtain a coloured solid complex. The synthesized metal(II) complexes were characterized by physico-chemical parameters and spectral analyses, including UV-Vis, FT-IR and 1H NMR. The structures of the complexes were further confirmed by elemental (CHNS) and TG-DTA analyses. The spectral findings revealed that metal-ligand interaction has successfully occurred where the ligand acted as a bidentate chelate in the synthesized metal(II) complexes. The IR studies showed that upon complexation the characteristic carboxylic stretching frequency at 1714 cm-1 disappeared and the pyridone stretching frequency shifted to a lower frequency region. The 1H NMR data of the complexes confirm the effective interaction between the metal and the ligand via 3-carboxyl group and 4-oxo groups. The thermal and elemental analyses data were also in agreement with the proposed interaction. The ligand as well as its metal(II) complexes showed significant activity against all the studied 11 bacterial strains and one of the fungal strains, Candida sp.

Comparison of milk-clotting activity measurement using the Berridge's operator-based approach and a proposed digital method

The milk clotting activity (MCA) analysis of coagulants used in the production of cheese is an important parameter used in the modern dairy industry. The MCA is calculated using the estimated milk-clotting time (MCT). The standard method used for estimation of MCT is presented in the ISO 23058/IDF 199 Standard using the Berridge's operator-based approach. In this paper a new method is presented to estimate the MCT using digital image acquisition and signal processing. The estimate is obtained by processing a sequence of images of the wall of a round bottom flask containing milk and the coagulant. Digital signal processing and filter techniques were used to remove interferences and artifacts and improve the clotting time estimation. A set of 28 samples of milk plus coagulant were processed. The method's accuracy is about 1/30 s and the average relative error, when compared to an experienced human operator, was με = 2.82%, according to the experimental results, with an associated standard deviation of σε = 3.07% and a median of mε = 1.92%. The method may be used to replace the human operator during the MCT estimation procedure.

A highly sensitive and colorimetric fluorescent probe for visualizing hydroxylamine in immune cells

BackgroundHydroxylamine (HA) is vital industrial raw material and pharmaceutical intermediate. In addition, HA is an important cellular metabolite, which is intermediate in the formation of nitric oxide and nitroxide. However, excessive amounts of HA are toxic to both animals and plants. Conventional methods for the detection of HA are cumbersome and complicated. The detection of HA with fluorescent probes is convenient and sensitive. There are few probes available for the detection of hydroxylamine. Therefore, a fluorescent probe for the sensitive and selective detection of HA was developed in this work. ResultsA coumarin derivative SWJT-22 was synthesized as a colorimetric fluorescent probe to detect hydroxylamine (HA), with high sensitivity and selectivity. The detection limit of the probe to HA was 0.15 μM, which was lower than most probes of HA. Upon the addition of HA to aqueous solution containing SWJT-22, the color of the solution changed from orange to yellow, and the fluorescence color also changed from orange to green. The reaction mechanism of SWJT-22 to HA was confirmed by 1H NMR titrations, mass spectrometry and round bottom flask experiments. Moreover, SWJT-22 had been fabricated into portable test strips for the detection of HA. SWJT-22 had been successfully used in cellular imaging and could detect both endogenous and exogenous HA in HeLa cells and RAW 264.7 cells. SignificanceDue to the physiological role of hydroxylamine in organisms, it is crucial to detect hydroxylamine selectively and sensitively. This work provided a convenient tool for the detection of hydroxylamine, not only to detect endogenous and exogenous HA in cells, but also made into portable test strips. The HA fluorescent probe SWJT-22 is expected to promote the study of HA in physiological processes.

An Eco-friendly Strategy for the Synthesis of Spiro-benzimidazoquinazolinone and Spiro-benzothiazoloquinazolinone Derivatives using β-cyclodextrin as a Supramolecular Catalyst.

Cyclodextrins selectively bind with reactants and facilitate chemical reactions through supramolecular catalysis, similar to the mechanisms employed by enzymes. In this paper, β-cyclodextrin was used as a supramolecular catalyst in water as a green, reusable, and ecofriendly solvent system to synthesize spiro-benzimidazoquinazolinones and spiro-benzothiazoloquinazolinones. A supramolecular catalyst β-cyclodextrin (β-CD) is used to synthesize spiro- benzimidazoquinazolinones and spiro-benzothiazoloquinazolinones via multicomponent reaction involving the condensation of dimedone, isatin, and 2-aminobenzimidazole/2-aminobenzothiazole. In a 50 mL round bottom flask were added the respective mixture of substituted isatin (1 mmol), dimedone (1mmol), and 2-aminobenzimidazole/2-aminobenzothiazole (1 mmol) in water (5 ml) containing β-CD (113 mg, 10 mol. %) was stirred at 60oC for 30 min. The desired product was obtained with excellent yield. After completion of the reaction (monitored by TLC), the reaction mixture was quenched with water and extracted with ethyl acetate (4X5 ml). The combined organic layers were washed with brine solution, dried over anhydrous Na2SO4 and evaporated under reduced pressure. The crude product was purified by silica gel chromatography. β-cyclodextrin catalyst showed very good efficiency in the synthesis of the desired compounds and can be easily recovered and reused at least five times with minimal deactivation in catalytic activity. The catalyst demonstrated remarkable effectiveness in producing the target compounds and conducting the reaction with different initial substances, resulting in excellent yields of the products, thereby confirming the broad applicability and versatility of this method.

Solar-Assisted Green Synthesis, Molecular Docking, Antibacterial, and Cytotoxicity Studies of Symmetrical N, N’-Alkylidene Bisamides Bearing Lower E-Factors

N, N'-alkylidene bisamides show promise in biological and pharmaceutical uses. Advanced chemistry now explores cleaner and more environmentally friendly methods. One such method involves using concentrated solar radiation (CSR) to facilitate the green synthesis of N, N'-alkylidene bisamides. This approach simplifies the process by combining aldehydes and amides in a one-pot reaction. Its solvent-free nature sets it apart, aligning with environmentally friendly practices. Any regular catalyst aids the response, making it efficient. The simplicity continues with an easy filtration step to isolate the products. Notably, there's no need for column chromatography, making the purification process straightforward. In general, a mixture of aldehyde, aryl/alkylamide was taken in a round bottom flask. The reaction mass in RBF was then kept under the concentrated solar radiation (CSR) setup with continuous stirring on a magnetic stirrer. After few hours of stirring the precipitate was observed. After completion of the reaction, the precipitated product was washed with water and recrystallized from hot ethanol to afford pure product symmetrical N, N'-alkylidene bisamide. Dimethyl sulfoxide (DMSO) was used as a solvent to prepare a stock of derivatives. Luria Bertani broth (LB) used for the present study viz; Staphylococ-cus aureus MCC 2408, Escherichia coli MCC 2412, Pseudomonas aeruginosa MCC 2080 and Klebsiella pneumoniae MCC 2451 used to evaluate the antibacterial property of the derivatives. Indeed, this method offers an eco-friendly solution and showcases the potential of using renewable energy sources in chemical synthesis. It is a significant step towards sustainable practices in chemistry, particularly in producing complex organic compounds for biological and pharmaceutical purposes.

Flow Chemistry for Synthesis of 2-(C-Glycosyl)acetates from Pyranoses via Tandem Wittig and Michael Reactions.

C-Glycosyl compounds (C-glycosides) are a class of saccharide derivatives with improved stability over their O-linked counterparts. This paper reports the synthesis of several trans-2-(C-glycosyl)acetates via a tandem Wittig-Michael reaction from pyranoses (cyclic hemiacetals) using continuous flow processing, which gave improvements compared to reactions conducted in round-bottom flasks. Products were isolated in yields of >60% from reactions of benzyl-protected xylopyranoses, glucopyranoses, and galactopyranoses at higher temperatures and pressures, which were superior to yields from batch procedures. A two-step procedure involving the Wittig reaction followed by Michael reaction (intramolecular oxa-Michael) of the unsaturated ester obtained in the presence of DBU was developed. Reactions of protected mannopyranose gave low yields in corresponding reactions in flow due to competing C-2 epimerization.

Synthesis of New Glycosylamine Derivatives based on Carbohydrates

Background: Glycosylamine play an important role in living organisms. Most plants store their chemical resources in the form of inactive glycosides, which are broken down and con-verted into sugar in the body of herbivores by hydrolyzing enzymes. Glycosylamine are obtained from the secondary metabolism of plants and consist of two parts. One part of it contains sugar like glucose and is inactive in most substances, and has a good effect on the solubility of the glycosyla-mine derivatives and its absorption and even its transfer from one organ to another. The therapeutic effect is related to the second part, which is called aglycan (or aglucan). Glycosylamine derivatives form a large group of valuable medicinal substances, which at the same time include some of the most dangerous and toxic substances in nature. These substances are present in many groups of flowering plants. Glycosides are made in different ways in different metabolic pathways. These materials have a complex and special chemical structure and leave special effects on the human body. Glycosylamine derivatives are called O-glycosid, N-glycosid, S-glycosid in terms of atoms coupling to anomeric carbon. Carbohydrate esterification reaction to prepare new glycosylamine derivatives is one of the most important carbohydrate reactions. The anomeric position of carbohy-drates with strong leaving groups is very important for the preparation of glycosides. Preparation of glycosylamine derivatives based on acetylated carbohydrates is the main purpose of this article. Dif-ferent carbohydrates were acetylated under mild conditions and high yields. The anomeric position was deacetylated by a magnesium oxide heterogeneous catalyst in methanol solvent. In order to pre-pare new glycosides acetylated/ deacytylated carbohydrate reacted with N-Methyl-(naphtha-2-ylmethoxy)amine. The final product was identified by various spectroscopic methods. Methods: Anhydrous sodium acetate (4 g) and α-D-glucose (28 mg, 5 g) were mixed. The mixture was transferred to a 200 ml Round-bottom flask . Acetic acid (260 mg, 25 ml) was added to the reaction mixture. The reaction mixture was heated in a boiling water bath for 2 h until complete dissolution of the glucose. Then 100 ml of ice was added. After 1 hour, White crystals formed and were washed with cold water. And then 1 mol of glucose pentaacetate per 50 ml of methanol was dissolved by a magnetic stirrer. After thatMgO (0.2gr) was added to the reaction mixture. The re-action mixture was refluxed at room temperature within 4-5 hours. After 5 hours, the solvent was removed and separated by chromatography. It is then washed with hexane and crystallized by ether-hexane. And the final step reacted with N-Methyl- (naphtha-2-ylmethoxy) amine in order to prepare new glycosylamine derivatives. Results: Magnesium oxide in methanol solvent is one of the best effective catalysts in the deacetyla-tion of the anomer position of acetylated carbohydrates. It is done under ambient temperature and in very easy conditions and makes carbohydrates susceptible to extensive chemical reactions. One of these reactions is the formation of glycosides. Various carbohydrates are acetylated by acetic anhy-dride in the presence of sodium acetate, and the anomeric position is deacetylated by a heterogeneous catalyst. In order to prepare N-glycoside, the glycosides are reacted with N-alkoxy N-methylglycosyl amine. The final products are identified by various spectroscopic methods. Conclusion: Glucose, mannose, for example, were acetylated by acetic anhydride in the presence of sodium acetate. And the anomeric position of pentaacetate glucose was selectively deacetylated with magnesium oxide in a methanol solvent. Then, the reaction for the preparation of glycosylamine de-rivatives was carried out under very mild and easy conditions. The aminoglycosides synthesized in this article are used as raw materials for the synthesis of a wide range of antibacterials.

Utilizing magnetic xanthan gum nanocatalyst for the synthesis of acridindion derivatives via functionalized macrocycle Thiacalix[4]arene

An effective method for synthesizing acridinedione derivatives using a xanthan gum (XG), Thiacalix[4]arene (TC4A), and iron oxide nanoparticles (IONP) have been employed to construct a stable composition, which is named Thiacalix[4]arene-Xanthan Gum@ Iron Oxide Nanoparticles (TC4A-XG@IONP). The process used to fabricate this nanocatalyst includes the in-situ magnetization of XG, its amine modification by APTES to get NH2-XG@IONP hydrogel, the synthesis of TC4A, its functionalization with epichlorohydrine, and eventually its covalent attachment onto the NH2-XG@IONP hydrogel. The structure of the TC4A-XG@IONP was characterized by different analytical methods including Fourier-transform infrared spectroscopy, X-Ray diffraction analysis (XRD), Energy Dispersive X-Ray, Thermal Gravimetry analysis, Brunauer–Emmett–Teller, Field Emission Scanning Electron Microscope and Vibration Sample Magnetomete. With magnetic saturation of 9.10 emu g−1 and ~ 73% char yields, the TC4As-XG@IONP catalytic system demonstrated superparamagnetic property and high thermal stability. The magnetic properties of the TC4A-XG@IONP nanocatalyst system imparted by IONP enable it to be conveniently isolated from the reaction mixture by using an external magnet. In the XRD pattern of the TC4As-XG@IONP nanocatalyst, characteristic peaks were observed. This nanocatalyst is used as an eco-friendly, heterogeneous, and green magnetic catalyst in the synthesis of acridinedione derivatives through the one-pot pseudo-four component reaction of dimedone, various aromatic aldehydes, and ammonium acetate or aniline/substituted aniline. A combination of 10 mg of catalyst (TC4A-XG@IONP), 2 mmol of dimedone, and 1 mmol of aldehyde at 80 °C in a ethanol at 25 mL round bottom flask, the greatest output of acridinedione was 92% in 20 min.This can be attributed to using TC4A-XG@IONP catalyst with several merits as follows: high porosity (pore volume 0.038 cm3 g−1 and Pore size 9.309 nm), large surface area (17.306 m2 g−1), three dimensional structures, and many catalytic sites to active the reactants. Additionally, the presented catalyst could be reused at least four times (92–71%) with little activity loss, suggesting its excellent stability in this multicomponent reaction. Nanocatalysts based on natural biopolymers in combination with magnetic nanoparticles and macrocycles may open up new horizons for researchers in the field.

Sunlight-powered total green synthesis of silver nanoresonators from aqueous extract of soybean (Glycine max) chunks: A highly specific colorimetric probe for H2S

We report herein a total green synthesis of silver nano resonators having 43.77 nM concentration with their most frequent average size of ∼ 17 nm. The reaction mixture comprising of aqueous extract of soybean (Glycine max) chunks (15 mL) and AgNO3 (1 mL, 0.1 M) in a 100 mL round bottom flask was irradiated with sunlight for 3 hrs to bring out this synthesis. The as prepared AgNPs were fully characterized through various spectroscopic (FTIR & UV–Vis) and microscopic (SEM, TEM, SAED, EDX, AFM and DLS) studies. The same AgNPs were further exploited for highly selective detection and determination of a janus faced analyte like H2S from its aqueous solution at submicromolar level (LOD 7.39×10-7 M). The H2S is known for its role as one of the gaso-neurotransmitters in humans beside playing dubious role towards our environment. Two spiked real samples of water from pond and sewage were subjected for determination of their H2S content against these AgNPs, showed recoveries of 99 % and 106 % respectively.

Magnetically separable new Fe3O4@AgZr2(PO4)3 nanocomposite catalyst for the synthesis of novel isoxazole/isoxazoline-linked 1,2,3-triazoles in water under ultrasound cavitation

In this work, we report a novel magnetically separable Fe3O4@AgZr2(PO4)3 as heterogeneous nano-composite catalyst for the one-pot four-step cascade sulfonylation/Huisgen 1,3-dipolar cycloaddition/azidation/click reactions in water under ultrasound cavitation. This strategy appears to be suitable for obtaining new analogues of isoxazole/isoxazoline-linked 1,4-disubstituted 1,2,3-triazoles in sustainable way starting from propargyl or allyl alcohol/sulfonyl chloride/oximes/sodium azide/and terminal alkynes. The effects of ultrasonic probe position as well as vessel shape on the chemical reaction were investigated. Three different types of 25 mL glass vessels were used in this study: round-bottomed flasks, erlenmeyer flasks and pear-shaped flasks. The heterogeneous nanocomposite was synthesized by supporting magnetic Fe3O4 nanoparticles on AgZr2(PO4)3 material (Fe3O4@AgZr2(PO4)3). The crystalline nature and purity of the catalyst were characterized using various techniques, including FT-IR, EDX, and XRD. Dispersity and morphology were characterized by SEM analysis. The findings indicate that Fe3O4 particles ranging in size from 50 to 75 nm were evenly distributed on the surface of AgZr2(PO4)3. The use of an aqueous reaction medium, the simple and inexpensive recovery of the catalyst by the application of an external magnet and the high and constant catalytic efficiency over at least five consecutive cycles make this protocol more interesting from an operational point of view. All synthesized products 6a–j and 7a–f were prepared in excellent yields (86–95 %) in short reaction time (2.25h). Their structures were confirmed by FT-IR, 1H NMR, 13C NMR, ESI-MS and HPLC analyses.

Synthesis and Antibacterial Activity of Spiro[4H-pyran-3,3'-oxindoles] Catalyzed by Tröger's Base Derivative.

Two classes of spiro[4H-pyran-3,3'-oxindole] derivatives were prepared via the one pot reaction of chain diketones (1-phenyl-1,3-butanedione or dibenzoyl methane), substituted isatins and malononitrile successfully catalyzed by a Tröger's base derivative 1b (5,12-dimethyl-3,10-diphenyl-bis-1H-pyrazol[b,f][4,5]-1,5-diazadicyclo[3.3.1]-2,6-octadiene). The antibacterial activity of products against three wild-type bacteria (B. subtilis, S. aureus, and E. coli) and two resistant strains (Methicillin-resistant S. aureus (18H8) and E. coli carrying the BlaNDM-1 gene (18H5)) was evaluated using the minimum inhibitory concentration (MIC).. 1-Phenyl-1,3-butanedione 2 or dibenzoylmethane 2' (0.42 mmol), substituted isatin 3 (0.4 mmol), malononitrile 4 (0.8 mmol), Tröger's base derivative 1b (0.08 mmol), and 10 mL of acetonitrile were added to a 50 mL round bottom flask and refluxed. After the completion (TLC monitoring), water (10 mL) was added to the reaction mixture; pH = 7 was adjusted with saturated NaHCO3 (aq.), and the mixture was extracted with CH2Cl2 (50 mL × 3). Organic layers were combined and dried with anhydrous Na2SO4; the solvent was removed under vacuum, and the residue was purified by column chromatography (VDCM: VMeOH = 80: 1) to afford product 5. The antibacterial activity was tested by the MTT method. Seventeen spiro[4H-pyran-3,3'-oxindole] derivatives were synthesized through the reaction of chain diketones (1-phenyl-1,3-butanedione or dibenzoyl methane), substituted isatins, and malononitrile in one-pot in medium to high yields. Four compounds showed antibacterial activity, and two of them showed the same activity as the positive control Ceftazidime on S. aureus (MIC = 12.5 μg/mL). Two classes of spiro[4H-pyran-3,3'-oxindole] derivatives were prepared, and their antibacterial activity was evaluated. Tröger's base derivative 1b (5,12-dimethyl-3,10-diphenyl-bis-1H-pyrazol[b,f][4,5]- 1,5-diazadicyclo[3,3,1]-2,6-octadiene) was used as an efficient organocatalyst for the reaction of low reactive chain diketones (1-phenyl-1,3-butanedione or dibenzoyl methane), substituted isatins, and malononitrile in one-pot successfully and effectively by providing multiple active sites and alkaline environment. By the theoretical calculation, we explained the possible reaction sequence and mechanism. Due to the superiority and high efficiency of the TB framework as an organocatalyst, the reaction showed many advantages, including mild reaction conditions, low catalyst loading, and a wide substrate range. It expanded the application of Tröger's base to the multicomponent reaction in organocatalysis. Some products were screened due to their high antibacterial activity in vitro, showing their potential in new antibacterial drug development.

Rapid Lewis Acid Screening and Reaction Optimization Using 3D-Printed Catalyst-Impregnated Stirrer Devices in the Synthesis of Heterocycles.

We describe the development of Lewis acid (LA) catalyst-impregnated 3D-printed stirrer devices and demonstrate their ability to facilitate the rapid screening of reaction conditions to synthesize heterocycles. The stereolithography 3D-printed stirrer devices were designed to fit round-bottomed flasks and Radleys carousel tubes using our recently reported solvent-resistant resin, and using CFD modeling studies and experimental data, we demonstrated that the device design leads to rapid mixing and rapid throughput over the device surface. Using a range of LA 3D-printed stirrers, the reaction between a diamine and an aldehyde was optimized for the catalyst and solvent, and we demonstrated that use of the 3D-printed catalyst-embedded devices led to higher yields and reduced reaction times. A library of benzimidazole and benzothiazole compounds were synthesized, and the use of devices led to efficient formation of the product as well as low levels of the catalyst in the resultant crude mixture. The use of these devices makes the process of setting up multiple reactions simpler by avoiding weighing out of catalysts, and the devices, once used, can be simply removed from the reaction, making the process of compound library synthesis more facile.

Bottom-Up Then Top-Down Synthesis of Gold Nanostructures Using Mesoporous Silica-Coated Gold Nanorods.

Gold nanostructures were synthesized by etching away gold from heat-treated mesoporous silica-coated gold nanorods (AuNR@mSiO2), providing an example of top-down modification of nanostructures made using bottom-up methodology. Twelve different types of nanostructures were made using this bottom-up-then-top-down synthesis (BUTTONS), of which the etching of the same starting nanomaterial of AuNR@mSiO2 was found to be controlled by how AuNR@mSiO2 were heat treated, the etchant concentration, and etching time. When the heat treatment occurred in smooth moving solutions in round-bottomed flasks, red-shifted longitudinal surface plasmon resonance (LSPR) was observed, on the order of 10-30 min, indicating increased aspect ratios of the gold nanostructures inside the mesoporous silica shells. When the heat treatment occurred in turbulent solutions in scintillation vials, a blue shift of the LSPR was obtained within a few minutes or less, resulting from reduced aspect ratios of the rods in the shells. The influence of the shape of the glassware, which may impact the flow patterns of the solution, on the heat treatment was investigated. One possible explanation is that the flow patterns affect the location of opened pores in the mesoporous shells, with the smooth flow of solution mainly removing CTAB surfactants from the pores along the cylindrical body of mSiO2, therefore increasing the aspect ratios after etching, and the turbulent solutions removing more surfactants from the pores of the two ends or tips of the silica shells, hence decreasing the aspect ratios after etching. These new stable gold nanostructures in silica shells, bare and without surfactant protection, may possess unique chemical properties and capabilities. Catalysis using heat-treated nanomaterials was studied as an example of potential applications of these nanostructures.

Numerical investigation of turbulent mixed convection in a round bottom flask using a hybrid nanofluid

In this study, we conducted a numerical investigation of the turbulent mixed convection of a hybrid nanofluid (HNF) in a flask equipped with an agitator, which is commonly used in organic chemistry synthesis. The bottom wall and the middle section of the flask were maintained at a constant high temperature Th, while the upper, left, and right walls up to the middle of the flask were kept at a low temperature Tc. The HNF consisted of Graphene (Gr) and Carbon nanotubes (CNTs) nanoparticles (NP) dispersed in pure water. The governing equations were solved numerically using the finite size approach and formulated using the Boussinesq approximation. The effects of the NP volume fraction φ (ranging from 0% to 6%), the Rayleigh number Ra (ranging from 104 to 106), and the Nusselt number ( Nu) were investigated in this simulation. The results indicated that the heat transfer is noticeably influenced by the Ra number and the increase in the φ ratio. Additionally, the agitator rotation speed had a slight effect on the heat transfer.

Catalytic Pyrolysis of Plastic Waste to Liquid Fuel Using Local Clay Catalyst

Plastics are nonbiodegradable, and safe disposal of this waste poses an environmental challenge all over the world. Catalytic pyrolysis is superior to thermal pyrolysis as it uses lower temperatures and hence less energy. The main objective of this study was to produce liquid fuel from plastic waste using indigenous clay as a catalyst through catalytic pyrolysis. The clay from Kisumu County was characterized through an X-ray fluorescence spectrometer (XRFS) and an X-ray diffractometer (XRD). The reaction setup consisted of a round-bottom flask reactor through which plastic feed and catalyst were heated in a temperature-controlled furnace. Vapor product was condensed using a Liebig type water condenser to give pyrolysis liquid product. Solid char was recovered from the flask at the end of the reaction. Optimization studies using central composite design (CCD) and response surface methodology (RSM) were performed in design expert software to predict optimal conditions of the operating variables for maximum yield of the liquid fuel. Results show that clay has a composition of silica and alumina at 64.5 wt% and 16.3 wt%, respectively, indicating high acidity of the clay, being a requirement for a good pyrolysis catalyst. For high-density polyethylene and polypropylene, the highest liquid yield of 87.23 wt% and 60.36 wt%, respectively, was at 300°C and a catalyst concentration of 10 wt%. Indigenous clay was established to be a suitable catalyst for catalytic pyrolysis of plastic waste, with the potential to replace imported catalysts since high yields of liquid fuel were obtained at lower reaction temperatures of 300-450°C, as compared to the 600°C required for thermal pyrolysis. In conclusion, waste plastics can be used to generate alternative fuel for industrial use. The liquid fuel can be used in diesel engines as a transport fuel, in turbines for electricity generation, and as a heating source in boilers and furnaces. Further studies on the modification of the surface and structure of clay are suggested to enhance its catalytic performance in the pyrolysis process for a better fuel yield.

Applications of Flow Chemistry in Total Synthesis of Natural Products

Abstract: A vital driving force for chemists to discover novel synthetic protocols is the improvement of more effective synthetic technologies and sustainable methodologies. This is associated with the development of innovative research that stimulates the creative reevaluating of known conceptions. Currently, these robust methodologies, as well as green synthetic procedures, have been designed for the total synthesis of secondary metabolites. Flow chemistry and flow photochemistry have emerged as powerful tools to promote valuable transformations in the total synthesis of natural products as key step(s). Flow chemistry development offers many merits over a traditional batch format, namely a round-bottom flask. The advantages of this green tool comprise waste minimization, simple scale-up, reduction of reaction time, safety betterment as, well as energy and cost efficiency. Flow chemistry comprises a fascinating prospect for the synthesis of promising organic molecules and bioactive complex natural products as it represents a suitable modern synthetic technology for the improvement of sustainable chemistry. Continuous flow chemistry is an assembly of chemical processes carried out in continuous flowing streams. Compared to conventional organic synthesis, it is a process that strengthens technology and is superior in enhancing and scaling up synthesis, accurately controlling reaction rate, and providing the desired products with maximum yields. In the past and likely in the future natural products and their analogue will continue to deliver the stimulation for drug discovery and development programs. Total synthesis of natural products is very useful to synthesize natural products in the laboratory as many secondary metabolites are available in low quantities from their sources of origin. So, this review wishes to cover the brilliant applications of flow chemistry in the total synthesis of natural products in the field of novel technological advances.

Low-profile frequency-reconfigurable antenna for 5G applications

The demand for higher data rates has increased in recent years. The reconfigurable antenna that operates in the millimeter-wave spectrum (23.5 GHz – 29.64 GHz) was developed. This design is obtained by merging a half-circle radius of 3.97 mm, and a half-ring inner radius of 4 mm. The shape is similar to the round bottom flask. Two PIN diodes are used in this design to achieve frequency reconfigurability to meet the wideband mobile communication need of the future 5G. The suggested antenna, built on Roger RT5880 substrates and properties of ε = 2.2 and δ = 0.0009, has been used as the antenna substrate. For all the resonant bands, the suggested antenna has a voltage standing waves ratio (VSWR) < 1.11. From 84 % to 92 %, the suggested structure radiation efficiency is calculated. A small antenna element has an excellent end-fire radiation pattern in the desired frequency bands. The antenna shows three reconfigurable bands, 25.17, 26.75, and 27.64 GHz, and gain (2.77-4.4) dBi. The suggested antenna is well suitable for future fifth-generation (5G) networks because of its notable features of small overall size (9.8×13×0.787) mm 3 , wide bandwidth, and frequency reconfigurability.

Synthesis and Antibacterial Activity of 2-[o-imino-(4-thiazolidinone)-phenyl]-3-imino-(4-thiazolidinone)- 6-bromo Quinazolin-4(3H)-one from 2-(o-thiadiaminephenyl)-3-thiadiamine-6-bromo–quinazoline-4(3H)-one

Introduction: Broad range of quinazolinone biological properties including: antibacterial, anticancer, and anti-inflammatory activities motivate us to synthesis some quinazolinone derivatives. These heterocycles are profitable intermediates in organic synthesis. Methods/Experimental: The compound 2-(o-thiadiaminephenyl)-3-thiadiamine-6-bromo–quinazoline-4(3H)-one (1), was produce when 2-(o-aminophenyl)-3-amino-6-bromo–Quinazolin-4(3H)-one (0.055M) was dissolved in minimum amount of dil. HCl in a round bottom flask. Ammonium thiocyanate (0.11M, 9.68gm) was then added and the mixture refluxed for 7 hrs. A mixture of 2-(o-thiadiaminephenyl)-3-thiadiamine-6-bromo–Quinazolin-4(3H)-one (0.037M, 16.095gm) and fused sodium acetate (0.074M, 6.068gm) was taken in absolute alcohol (300ml) and refluxed for 10 hours to give 6-bromo-2-[o-imino-(4-thiazolidinone)-phenyl]-3-imino-(4-thiazolidinone)-Quinazolin-4(3H)-one(2). These Compounds were evaluated for their antibacterial activity (against some gram positive and gram negative microorganism) and antifungal activity (against Candida albicans). Study Design: This study was experimentally design and the antibacterial activity was evaluated against some microorganism, <i>Staphylococcus aureus, Bacillus specie</i>s, <i>Aspergillus Species</i>, <i>Pseudomonas aeruginosa</i>, <i>Escherichia coli,</i> Klebsiella<i> pneumonia</i>, and <i>candida albicans</i> Result: The compounds exhibited significant antibacterial activity with a zone of inhibition in the range of 10 – 20mm in comparison to control. Conclusions: From our findings, the compounds synthesized have higher antibacterial activities against <i>Staphylococcus aureus,</i> <i>Aspergillus Species</i>, as compared to Ciprofloxicin (CPX) and Ketonaxol (PEF) standard antibacterial drugs.

Synthesis and Characterization of Stimuli-Responsive Poly (Maleic Acid-Co-Malic Acid-Co-Propane-1,2-Diol-Co-Adipic Acid)

Poly (Maleic acid-co-Malic acid-co-Propane-1,2-diol-co-Adipic acid) was synthesized using the Dean-Stark apparatus. Stoichometric proportions of maleic acid, malic acid, adipic acid and propane-1, 2-diol were taken in a round bottom flask along with a trace amount of anhydrous ferric chloride which worked as catalyst and o-xylene &nbsp;used as reaction medium. The total system was heated at temp. 135-1400C for about 5 hours. Molecular weight, FTIR-spectra, thermo gravimetric and elemental analysis, solubility tests in common organic solvents, melting point and degradation tests were used for the characterization of the synthesized co-polyester. At room temperature (300C) the hydrolytic degradation study of the co-polyester in solutions of various pH values (pH=1.15-4.40) showed that, there has no degradation of the co-polyester, but it gradually degraded in solutions of pH values 6.50-8.99. This showed its stimuli-responsive characteristics. The co-polyester almost 70% degraded in normal soil within 30 days indicating its biodegradable nature. If satisfactory toxicity result of the synthesized co-polyester is observed, it might be usable as an enteric coating material.

Enhanced Semi‐Preparative Biotransformation of Cumene Dioxygenase: From Analytical Scale to Product Isolation

AbstractScale‐up of oxygenase catalyzed reactions is often challenging due to the limited oxygen mass transfer in aqueous solutions. To overcome such limitation, we studied different scale‐up conditions using recombinant resting cells of E. coli JM109(DE3), harboring the cumene dioxygenase of Pseudomonas fluorescens IP01, for the dihydroxylation of naphthalene to (1R,2S)‐cis‐1,2‐dihydro‐1,2‐naphthalenediol. Thereby, vigorous stirring of the biotransformation in a 2 L round bottom flask in combination with an oxygen‐enriched headspace exhibited outstanding product formation after 1 h. Furthermore, the enhanced setup was used for the cumene dioxygenase catalyzed biosynthesis of 240 mg of valuable (+)‐trans‐carveol from (R)‐(+)‐limonene, demonstrating the application of our workflow for volatile compounds.