Presence Of KOH Research Articles

Synthesis of New Rhodanine, Thiazole, Quinazolin-4-One, Imidazolone and Pyranothiazole Derivatives Incorporating Antipyrine Moiety as Antimicrobial Agents

A new series of heterocycles incorporating antipyrine moiety were synthesized via reactions of 4-aminoantipyrine 1 with carbon disulphide then alkylation and /or chloroacetic acid to produce dithiocarbamate and rhodanine 3, 4 and 9. Multi-component reaction (MCR) of 4-aminoantipyrine with carbon disulfide and DMAD afforded rhodanine 7. The interaction of 9 with diazonium salt, DMF-DMA, nitrous acid and aromatic aldehydes to give thiazolidinone derivatives 10, 11, 13 and 14, respectively. Pyranothiazole 16 was prepared from reaction of 9 with cinamonitrile 15. Thiazolidinone 18 and thiazole 19 derivatives were obtained from reactions of 9 with phenyl isothiocyanate in the presence of KOH then halogenated the pot salt with ethyl bromoacetate and chloroacetone, respectively. Thiourea derivative 20 was prepared from reaction of methyl dithiocarbamate 3 with 4-aminoantipyrine. pyrimidine derivatives 21 and 22 were obtained from cyclocondensation of 3 with dimer of ethyl cyanoacetate and malononitrile. Pyrazolotriazine 24 was prepared from interaction of 3 with hydrazine hydrate. copounds 26 and 28 were obtained via reaction of 3 with glycine and anthranilic acid. Compounds 30, 32 and 34 were prepared via reaction of thiourea 20 with EAA, ECA and DMAD. Reaction of diazonium chloride of 1 with NaN3 afforded azide 36 which rearranged to triazine 39. The structures of the newly synthesized compounds were elucidated via elemental analysis and spectral data. The synthesized products were evaluated for their antimicrobial and anti-fungal activity.

Synthesis and Biological Evaluation of Pyrimidine Derivatives Via Pyrrolyl Chalcones

The appearance to antimicrobial resistance to the antimicrobial agent has become a matter of high concern for health care professionals since last ten years. It will an effort to establish new pyrimidine derivatives as improved antimicrobial agent. In this particular series of novel substituted pyrimidine derivatives (PK1-PK5) were synthesized by simple condensation reaction between different substituted aldehydes and 3 acetyl -2,4-dimethyl pyrrole in presence of a strong ethanolic base to yield the pyrrolyl chalcones. The final synthesized pyrimidine derivative is prepared by the cyclization of pyrrolyl chalcones with urea in presence of KOH as base. The structures of the final synthesized compounds were characterized by IR, mass and 1 H NMR spectra. The synthesized compounds were screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosaby cup plate method. Most of the compounds exhibited promising antibacterial activity.

Half-sandwich iron(ii) complexes with protic acyclic diaminocarbene ligands: synthesis, deprotonation and metalation reactions.

A variety of half-sandwich iron(ii) complexes with diprotic acyclic diaminocarbene ligands (pADCs) have been obtained by reaction of the cationic complexes [Fe(Cp)(CO)2(CNR)]+ and [Fe(Cp)(CO)(CNR)2]+ with methylamine, and their acid-base behaviour was studied, revealing an easy reversible deprotonation reaction of both N-H moieties of the carbene ligands. The deprotonation process is frequently followed by a nucleophilic attack of the nitrogen atom on a vicinal carbonyl or isocyanide ligand, affording the corresponding metallacycles. Metalation of one or two N-H groups of the pADC ligands can be accomplished by reaction of the carbene complexes with either [AuCl(PPh3)] or [Ru(p-cym)Cl2]2 in the presence of KOH or LiHMDS as deprotonating agents. A number of Fe(ii)/Au(i) and Fe(ii)/Ru(ii) heterometallic complexes have been prepared in this way, some of them formally containing unique metalla-N-heterocyclic carbene ligands.

Production of Biodiesel from Waste Cooking Oil Using Transesterification, with the KOH on Carbon Support from Waste Material and Egg Shell, as the Catalyst

Microwave assisted transesterification of waste cooking oil (WCO) is carried out in the presence of KOH on carbonized waste coconut shell support (KOH/CS), and CaO derived from waste egg shell (CaO-ES). The effect of reaction temperature on the yield of fatty acid methyl esters (FAMEs) is studied. Conventional transesterification is also performed for comparison. FAME production is also carried out with new cooking oil (NCO). The results show that a reaction temperature of 80 °C is optimum for FAME production in the presence of either KOH/CS or CaO-ES. The produced biodiesel properties satisfy the criteria according to ASTM D6751 . Acid catalysed esterification of WCO before transesterification leads to higher production of FAMEs due to the reduction of free fatty acids (FFAs). However, conventional transesterification using WCO without esterification yields lower FAMEs. Although the microwave heating decreases the reaction time, it does not necessarily lead to an increase in FAMEs. The production of FAMEs depends on not only the type of transesterification process, but also the type of feedstock. Comparing KOH/CS with CaO-ES, KOH/CS is preferable in terms of the quantity and quality of the produced FAMEs using a two-step process with H 2 SO 4 catalysed esterification, followed by alkali catalysed conventional transesterification.

ChemInform Abstract: General and Efficient Synthesis of Polyfluorinated 2‐Aminotolans and 2‐Arylindoles.

Abstract It was established here that cross-coupling of polyfluorinated 2-iodoanilines with arylacetylenes in MeCN in the presence catalytic amounts of Pd(PPh3)2Cl2, CuI and Et3N produces the corresponding 2-aminotolans although their yields are decreased from 98% to 40% with increasing fluorination of the substrates. It was shown that the 2-aminotolans with six or fewer fluorine atoms in their rings can be heterocyclised by heating in ethanol containing p-TSA to produce the corresponding polyfluorinated indoles. Cyclisation of tolans containing larger numbers of fluorine atoms in their rings proceeds most efficiently in the presence of KOH, resulting in 2-phenylindoles containing the current maximum of eight fluorine atoms.

Thermal transformation of betulin by alkaline activation

Carbonization of betulin (betulinol) as an individual carbon precursor was studied in the temperature range of 400–800°C in the presence of KOH. Differential thermal analysis and IR spectroscopy were used to determine the influence of KOH on major structural changes and the chemical composition of betulin, which occur at 400–500°C. It was shown by scanning electron microscopy and BET analysis that KOH promoted the formation of a developed specific surface (SBET 1350–2100 m2/g) at temperatures of 600–800°C and had the greatest influence on the textural and adsorption properties of the resulting porous carbon adsorbents. It has been found that the formation of microporous carbon materials with a pore size of 1.92 nm and a specific micropore surface area of 1275 m2/g is possible upon the activation of betulin with KOH at 800°C. Betulin may be proposed to control the porosity of the carbon carriers derived from birch wood.

Synthesis of polybutadiene nanoparticles by emulsion polymerization: The effect of electrolyte and initiator type on particle size and reaction kinetics

Emulsion polymerization of the butadiene (Bu) was performed in the presence of disproportionate potassium rosinate (DPR) as anionic emulsifier, potassium hydroxide (KOH), and potassium carbonate (K2CO3) as electrolytes, and three different initiators including potassium persulfate (KPS), 2,2′-azobisisobutyronitrile (AIBN) or 4,4′-azobis(4-cyanovaleric acid) (ACVA, also known as VAZO) at 70 °C. Latexes were prepared with a solid content of about 30 wt%. The particle size and its distribution were measured by dynamic light scattering (DLS) analysis, while the polymerization conversion was determined gravimetrically at different time intervals. Results on the emulsion polymerization of Bu in the presence of KOH and K2CO3 co-electrolytes showed that adding KOH to the reaction media decreases the polymerization rate. Positive effect of co-electrolytes on the control over polybutadiene latex (PBL) particles size and its distribution was also confirmed, where K2CO3 played roles as electrolyte and pH buffer and KOH served double roles as electrolyte and alkaline supplier of the reaction media. Complete solubility of the AIBN in Bu resulted in higher rate of polymerization in the presence of AIBN in comparison to other initiators, i.e., VAZO or KPS. The results showed that initiator type plays a significant role on the formation of PBL nanoparticles and kinetics of the polymerization. The kinetic studies revealed that emulsion polymerization of Bu follows case 1 (i.e., $$\bar{n}$$ ≪0.5, where $$\bar{n}$$ indicates average number of the propagating chains per particle) of the Smith-Ewart kinetics.

Synthesis, Characterization and Biological Investigation of Some New Hydroxy – 1,3,4 – Oxadiazole Derivatives

study the solid compounds of hydroxy 1,3,4 – oxadiazoles have been synthesized by reaction of acid hydrazides with CS2 in the presence of KOH. All the prepared compounds are characterized by using elemental analysis (C, H, N and S) and spectroscopic IR, H1 – NMR and studied the biological activity on four antibacterial (gram +Ve and gram –Ve) and three antifungal organisms. 1,3,4 – Oxadiazole are important compounds because of its versatile biological action such as antimicrobial, antimalarial, anticonvulsant, hypoglycemic, also analgesic, anti – inflammatory and anticancer. In the present

Synthesis, spectral analysis and pharmacological study of N'- substituted-2-(5-((2,4-dimethylphenoxy)methyl)-1,3,4-oxadiazol-2-ylthio)acetohydrazides

A series of molecules bearing multiple functional groups were synthesized to study their antibiotic effect against Gram-positive and Gram-negative bacteria and lipoxygenase activity as well. 2,4-Dimethylcarbolic acid (1) was refluxed with ethyl 2-bromoacetate to synthesize ethyl 2-(2,4-dimethylphenoxy)acetate (2). Compound 2 was converted to the corresponding hydrazide 3, again on refluxing with hydrazine. The compound 5-((2,4-dimethylphenoxy)methyl)-1,3,4-oxadiazol-2-thiol (4) was synthesized by the reaction of 3 and CS2 in the presence of KOH. Compound 4 was further converted to the corresponding ester 5 and then 2-(5-((2,4-dimethylphenoxy)methyl)-1,3,4-oxadiazol-2-ylthio)acetohydrazide (6). The final molecules N'-substituted-2-(5-((2,4-dimethylphenoxy)methyl)-1,3,4-oxadiazol-2-ylthio)acetohydrazide, 8a-m, bearing ether, 1,3,4-oxadiazole, thioether, hydrazone and azomethine functional groups were synthesized by stirring the aryl carboxaldehydes 7a-m with 6 in methanol at room temperature. The depicted structures of all synthesized molecules were corroborated by IR, 1H-NMR and EIMS spectral data analysis. 8m and 8i showed substantial antibacterial activity and lipoxygenase inhibitory activity, respectively.

A Mixed Porphyrin–Schiff Base Dysprosium(III) Single‐Molecule Magnet

The mixed porphyrin–Schiff base potassium dysprosium(III) complex [K(TBPP)Dy(L)(CH3CN)2] [H2TBPP = 5,10,15,20‐tetrakis(4‐tert‐butylphenyl)porphyrin; H2L = N,N′‐bis(3‐methoxysalicylidene)benzene‐1,2‐diamine; 1] was isolated from the reaction between the metal‐free Schiff base ligand H2L and the half‐sandwich porphyrinato dysprosium compound [Dy(TBPP)(acac)] (Hacac = acetylacetone) in the presence of KOH. A sandwich‐type double‐decker structure has been unambiguously revealed by single‐crystal X‐ray diffraction analysis. Static and dynamic magnetic measurements disclosed the slow relaxation behavior of this new double‐decker compound and indicated its single‐molecule magnet (SMM) nature. Comparative studies on the magnetic properties of 1, the homoleptic bis[5,10,15,20‐tetrakis(4‐tert‐butylphenyl)porphyrinato]dysprosium double‐decker [DyH(TBPP)2] (2), and the bis(Schiff base)dysprosium double‐decker {[Dy[Zn(L)Cl]2(DMF)2]·Cl} (3, DMF = N,N‐dimethylformamide) indicate the effect of the ligand field (LF), through the deviation of the dysprosium coordination geometry from the ideal D4d form, on the SMM properties of 1–3 in addition to the effect of the charge distribution over the DyIII ion.

The role of nickel addition and annealing temperature on ion storage performance of nanostructured nickel ferrite thin films

The sol–gel spin-coated nickel ferrite (NF), NiFe2O4, thin films were synthesised and the effect of annealing temperature and compositional ratio on different properties of samples were investigated. Electrochemical performance of the films was measured in the presence of KOH and LiClO4/PC electrolyte. Generally, addition of nickel increases the current density. The NF thin films with molar ratio of 0.5 and annealed at 400 °C have the highest charge density value and the highest capacitance in both electrolytes. Annealing temperature had significant effect on electrochemical properties of NF thin films and the diffusion coefficient enhanced by increasing the annealing temperature. X-ray diffraction patterns of prepared samples showed the rhombohedral structure, hematite phase (α-Fe2O3), of iron oxide sample and the presence of inverse spinel structure confirms the formation of NF. Field emission scanning electron microscopy images revealed that the morphology of films changes from larvae shape to granular structure by nickel incorporation and the grain size increased by raising the annealing temperature. The absorption edge of the hematite shift to higher wavelength by annealing and nickel incorporation and band gap narrowing has been occurred.

A new entry to synthesis of neocryptolepine related skeletons. An unexpected behavior of 3-acety-2-ethoxyindole and isatins

An unexpected and intriguing reaction to the direct construction of indolo[2,3-b]quinoline ring system of neocryptolepine analogues was discovered through simple heating of 3-acetyl-2-ethoxyindole with isatins in 10% aqueous ethanol media with the presence of KOH as the base. The process is very clean and avoids the use of toxic organic solvent, thereby enhancing the greenness of the transformation. Moreover, the newly-synthesized compounds bearing a pendant carboxyl group at the C-11 position of indolo[2,3-b]quinoline skeleton could be potentially applied as useful synthetic building blocks for more complex indolo[2,3-b]quinoline alkaloid derivatives.

Synthesis and antibacterial study of some s-substituted aliphatic analogues of 2-mercapto-5-(1-(4-toluenesulfonyl) piperidin-4-yl)-1,3,4-oxadiazole

Purpose: To synthesize a series of analogues of 1,3,4-oxadiazole and to evaluate their antibacterial activity.Methods: Ethyl piperidin-4-carboxylate (1) was mixed with 4-toluenesulfonyl chloride (2) in benignant conditions to yield ethyl 1-(4-toluenesulfonyl)piperidin-4-carboxylate (3) and then 1-(4- toluenesulfonyl)piperidin-4-carbohydrazide (4). Intermolecular cyclization of 4 into 2-mercapto-5-(1-(4- toluenesulfonyl) piperidin-4-yl)-1,3,4-oxadiazole (5) was obtained on reflux with CS2 in the presence of KOH. Molecule 5 was stirred with alkyl halides, 6a-i, in DMF in the presence of LiH to synthesize the final compounds, 7a-i. The structures of these molecules were elucidated by Fourier transform infra-red (FTIR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) and electron impact mass spectrometry (EI-MS). Antibacterial activity was evaluated against five bacterial strains, namely, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, with ciprofloxacin used as standard antibacterial agent.Results: Out of nine synthesized derivatives, compound 7a was the most active against three bacterial strains, S. typhi, E. coli and P. aeruginosa, with minimum inhibitory concentration (MIC) of 9.11 ± 0.40, 9.89 ± 0.45 and 9.14 ± 0.72 μM, respectively, compared with 7.45 ± 0.58, 7.16 ± 0.58 and 7.14 ± 0.18 μM, respectively, for the reference standard (ciprofloxacin). Similarly, compounds 7a - 7c showed relatively good antibacterial activity against B. subtilis strain while compound 7e - 7g revealed good results against S. typhi bacterial strain.Conclusion: The results indicate that S-substituted derivatives of the parent compound are more effective antibacterial agents than the parent compound, even with minor differences in substituents.Keywords: 1,3,4-Oxadiazole, Antibacterial activity, Ethyl piperidin-4-carboxylate, Sulfonamide

General and efficient synthesis of polyfluorinated 2-aminotolans and 2-arylindoles

Abstract It was established here that cross-coupling of polyfluorinated 2-iodoanilines with arylacetylenes in MeCN in the presence catalytic amounts of Pd(PPh3)2Cl2, CuI and Et3N produces the corresponding 2-aminotolans although their yields are decreased from 98% to 40% with increasing fluorination of the substrates. It was shown that the 2-aminotolans with six or fewer fluorine atoms in their rings can be heterocyclised by heating in ethanol containing p-TSA to produce the corresponding polyfluorinated indoles. Cyclisation of tolans containing larger numbers of fluorine atoms in their rings proceeds most efficiently in the presence of KOH, resulting in 2-phenylindoles containing the current maximum of eight fluorine atoms.

Ball-milled Si powder for the production of H2 from water for fuel cell applications

The development of a safe technique for the supply of hydrogen to small portable fuel cells has emerged as a significant barrier to their deployment in recent years, with solutions centering on the use of hydrogen absorption materials, or the generation of hydrogen through chemical reaction. In the present work we demonstrate that the ball-milling of Si under inert conditions in the presence of KOH and sucrose results in the formation of a fine Si-based powder which reacts spontaneously with water at ambient starting temperature to evolve hydrogen rapidly at high yield. Embedded KOH is capable of accelerating the hydrolysis reaction of silicon by the self-heating effect attributed to dissolution heat of KOH, obviating the need for external heating to initiate the reaction; it also reduces the sensitivity of the reaction to oxide contamination of the Si surface by enabling its dissolution in the form of soluble silicates. Moreover, the silicon–water reaction can be switched on and off by adjusting the ambient temperature. It is shown that ball-milled, KOH-embedded Si powder is able to react with different water sources, such as tap water, river water, and salt water, to produce H2 under aerobic conditions. The method represents a cheap scalable approach for the safe provision of hydrogen fuel to small fuel cells.

ChemInform Abstract: Azide‐Enolate 1,3‐Dipolar Cycloaddition as an Efficient Approach for the Synthesis of 1,5‐Disubstituted 1,2,3‐Triazoles from Alkyl/Aryl Azides and β‐Ketophosphonates.

A simple procedure to prepare 1,5-disubstituted 1,2,3-triazoles efficiently from alkyl/aryl azides and β-ketophosphonates in the presence of KOH by an azide–enolate 1,3-dipolar cycloaddition in good yields was developed.

Characteristics of Block Copolymers of Methyl Oxirane and Oxirane Derivatives of 2-Ethylhexanol as Obtained with KOH and Dimetalcyanide Type Catalyst

Abstract Two series of block copolymers of methyloxirane and oxirane, derivatives of 2-ethylhexanol, were obtained with the use of KOH as a conventional homogeneous alkaline catalyst and a coordinative dimetalcyanide catalyst (DMC), respectively. The DMC type catalyst showed much higher kinetic activities and its reaction exhibited a narrower distribution of homologues, as compared with those obtained in the presence of KOH. The thermogravimetric technique was proposed for the characterization of the fractional content of products. The pluming phenomenon and VOCs content were discussed as a practical aspect of the differences in fractional compositions of the products examined.

N-methylated 25-oxasmaragdyrins: Synthesis, structure and properties

The [Formula: see text]-methylated 25-oxasmaragdyrins were synthesized by reacting 25-oxasmaragdyrins with CH3I in presence of KOH in THF at reflux temperature. Although the reactions were carried out in presence of excess CH3I, we obtained only dimethyl-25-oxasma ragdyrins, where [Formula: see text]-methylations occurred at 24 and 26 “N”s of pyrrole rings of tripyrrane moiety of smaragdyrin core as confirmed by X-ray crystallography. The [Formula: see text]-methylated-25-oxasmaragdyrins were characterized in detail by 1D and 2D NMR spectroscopy, absorption, fluorescence and electrochemical techniques. The effect of distortion induced by methylation, clearly reflected in structural and electronic properties of the macrocycle. All the pyrrole and furan protons experienced upfield shifts in the 1H NMR and maximum upfield shifts were noted for the [Formula: see text]-methylated pyrrole ring protons. The absorption spectra showed broad Soret band and four ill-defined Q-bands with significant reduction in extinction coefficients. The [Formula: see text]-methylated 25-oxasmaragdyrins were comparatively less fluorescent. The redox studies indicated that they are difficult to oxidize and easier to reduce.

Tandem Suzuki–Miyaura/transfer hydrogenation reaction catalyzed by a Pd–Ru complex bearing an anionic dicarbene

A hetero-bimetallic Pd–Ru N-Heterocyclic Dicarbene (NHDC) complex was synthesized from a Ag–Ru complex by transmetalation. The Pd–Ru system displays high catalytic activity in tandem Suzuki–Miyaura cross-coupling/transfer hydrogenation reaction of bromoaryl ketones with boronic acids in toluene and 2-propanol in the presence of KOH.

Is the Formation of Poly-CO2 Stabilized by Lewis Base Moieties in N- and S-Doped Porous Carbon?

The polymerization of CO2 by Lewis basic moieties has been recently proposed to account for the high adsorption ability of N and S-doped porous carbon materials formed from the pyrolysis of sulfur or nitrogen containing polymers in the presence of KOH. Ab initio calculations performed on the ideal CO2 tetramer complex LB-(CO2)4 (LB = NH3, H2O, H2S) showed no propensity for stabilization. A weak association is observed using Lewis acid species bound to oxygen (LA = H+, AlF3, AlH3, B4O6); however, the combination of a Lewis acid and base does allow for the formation of polymerized CO2 (i.e., LB-C(O)O-[C(O)O]n-C(O)O-LA). While the presence of acid moieties in porous carbon is well known, and borate species are experimentally observed in KOH activated porous carbon materials, the low stability of the oligomers calculated herein, is insufficient to explain the reported poly-CO2.