Presence Of Potassium Hydroxide Research Articles

Orthorhombic polymorph of 4-[(1H-benzimidazol-1-yl)methyl]benzoic acid

We reported recently the first polymorph of the title compound [Kuai & Cheng (2011a ▶). Acta Cryst., E67, o2787]. A second polymorph of the title compound, C15H12N2O2, was unexpectedly obtained by the hydro­thermal reaction of the title compound with manganese chloride in the presence of potassium hydroxide at 413 K. The benzimidazole ring system is almost planar, with a maximum deviation from the mean plane of 0.015 (2) Å. The benzimidazole and benzene rings are inclined at a dihedral angle of 79.00 (1)°. In the crystal, adjacent mol­ecules are connected through O—H⋯N hydrogen bonds into a one-dimensional chain along the [001] direction.

Structure and magnetic properties of hexanuclear 3d–4f clusters with {MnIII2LnIII4} (Ln=Sm, Eu, Gd, Tb, Dy, Ho) core

Reactions between hexanuclear manganese pivalate with lanthanide salts (chlorides or nitrates), in the presence of potassium hydroxide, 2-pyridylmethanol and sodium azide leads to formation of a new family of hexaheteronuclear manganese-lanthanide clusters.

Oximes as products in the reactions of 5‐substituted 2‐nitrothiophenes with arylacetonitriles

AbstractIt has been shown that reactions 5‐substituted 2‐nitrothiophenes with arylacetonitriles in the presence of potassium hydroxide in methanol lead to the formation of the new [2‐(hydroxyimino)‐5‐R‐3(2H)‐thienylidene](aryl)acetonitriles. Under proposed reaction conditions, the formation of thieno[2,3‐c]isoxazole was not the case. J. Heterocyclic Chem., (2011).

Divergent synthesis of fully substituted isoxazoles and spiro-fused pyrazolin-5-ones from cyclopropyl oximes

Efficient and divergent synthesis of fully substituted isoxazoles and spiro-fused pyrazolin-5-ones is developed from cyclopropyl oximes based on selection of reaction conditions. Under Appel conditions (PPh 3/CBr 4), substituted isoxazoles were synthesized from cyclopropyl oximes via a ring-opening and intramolecular cyclization process, whereas by treatment of cyclopropyl oximes with p-toluenesulfonyl chloride in the presence of potassium hydroxide, spiro-fused pyrazolin-5-ones were obtained via tandem ketoxime tosylation and intramolecular cyclization.

Synthesis of Bis-heterocyclic phenyl containing -4 – oxo – 1,3 – thiazolidine, 2,3 – dihydrothiazole, 1, 2,4 – triazolo [3, 4b ] – 1,3,4 – thiadiazine and pyrazol derivatives

This research describes the synthesis of some new different substituted bicyclic phenyl derivatives. To obtain the target compounds, the reaction steps shown in scheme (I) and (II) were of a feasible strategy. The synthon terphthalic acid hydrazide [2] which was prepared from methyl terphthalate [1] with hydrazine hydrate, was used for the preparation of six types of new heterocyclic derivatives. Acid hydrazide [2] reacts with carbon disulfide in the presence of potassium hydroxide and p–hydroxy benza ldehyde to give the corresponding potassium carbodithioate salt [3] and shiff’s base [5] derivatives respectively. Treatment of the latter salt with p - bromophenacyl bromide afforded thiazolidine -2- thione[4], cyclization of shiff ’s base [5] usi ng mercapto acetic acid resulted in the formation of -4- oxo-1,3 - thiazolidne [6]. 1,2,4 – triazolo [3, 4b] - 1,3,4 – thiadiazine [9] was synthesized from basic cyclization of the intermediate product [8] which was obtained from the reaction between 2 – mercapto – 1,3,4 – oxadiazole [7] and p-bromo phenacyl bromide. Furthermore, the hydrazino – 1,3,4 – oxadiazole [10], which was obtained from the reaction between of compound [7] with hydrazine hydrate, was then reacted with CS2 / pyridine and acetyl aceton to give the corresponding 1,3,4 – triazolo [5,1b] oxadiazole [11] and pyrazole [12] derivatives respectively, scheme (II). All synthesized compounds structures were characterized by measurements some of its physical proprieties and some specific reactions and spectral methods FTIR, 1 H NMR for compound [6] and [8].

Visible Light Responsive Perovskite BiFeO3 Pills and Rods with Dominant {111}c Facets

Constraint of the growth directions or exposed facets of nano-/microstructures has been long regarded as a popular research topic due to the various anisotropic properties of crystals. We report here, for the first time, not only uniform and phase-pure but also tunable perovskite BiFeO3 crystallites with different predominantly exposed facets have been successfully synthesized via a facile one-pot hydrothermal approach at 200 °C under the presence of potassium hydroxide and polyethylene glycol. Pills and rods with dominant {111}c facets and cubes with {100}c exposed facets have been obtained by adjusting the alkaline conditions of the precursor solution. Furthermore, due to the distinct dominant facets of BiFeO3 crystallites, {111}c dominant pills and rods grant a significant enhanced visible light response, suggesting that the designed structures can give rise to better performance in future photovoltaic and photocatalytic applications of BiFeO3.

Synthesis and characterization of novel optically active polyesters with high thermal stability

A new optically active diacid (DA) was prepared by nucleophilic substitution reaction of R-(−)-mandelic acid with terephthaloyl chloride in the presence of potassium hydroxide. This DA named terephthalic acid bis(carboxyphenylmethyl) ester was used as a monomer for the preparation of related optically active polyesters. Polycondensation of DA with different aromatic diols, including hydroquinone, 1,5-dihydroxy naphthalene, 1,4-dihydroxy anthraquinone, 1,8-dihydroxy anthraquinone, 2,4-dihydroxy benzophenone, and bisphenol A, in the presence of 4-toluenesulfonyl chloride using high temperature solution method led to preparation of different polyesters. The prepared monomer and all the polymers were characterized by conventional methods. Thermal and physical properties of the polyesters, including thermal stability, thermal behavior, solution viscosity, and solubility behavior, in addition to optical activity were studied. The optically active polyesters showed high thermal stability, whereas the presence of bulky groups improved their solubility. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Synthesis of novel 2-quinolone derivatives

In this work, N-amino quinoline-2-one (2) has been synthesized by the reflux of coumarin (1) with hydrazine hydrate (99%) in ethanol for 12 h. The azomethines (3-6) were prepared from the corresponding aryl aldehydes and ketones. Tetrazine derivative (7) was prepared from the reaction of compound (2) with CS2 and hydrazine hydrate in the presence of potassium hydroxide. However, the reaction of compound (2) with thiol compounds afforded the derivatives (8-14).Finally, condensation of compound (11) with 4-hydroxy benzaldehyde brought about the derivative (15). The structures of the synthesized compounds were deduced by using some spectroscopic methods, FT-IR, UV-Visible and NMR. Key words: 2-quinolone, Schiff bases, hydrazine hydrate.

ChemInform Abstract: Synthesis of 4‐(2‐Hydroxy‐1‐methyl‐5‐oxo‐1H‐imidazol‐4 (5H)‐ylidene)‐5‐oxo‐1‐aryl‐4,5‐dihydro‐1H‐pyrrole‐3‐carboxylates, a New Triazafulvalene System.

Abstract (2E,3Z)-2-(1-Methyl-2,5-dioxoimidazolidin-4-ylidene)-3-[(arylamino- or heteroarylamino)methylene]succinate 5 obtained by [2+2] cycloaddition of (5Z)-5-[(dimethylamino)methylene]-3-methylimidazolidine-2,4-dione (1) and dimethyl acetylenedicarboxylate (2) followed by substitution of the dimethylamino group with aromatic or heteroaromatic amines, afforded by heating in ethanol in the presence of potassium hydroxide, potassium salts 6. Acidification of 6 with hydrochloric acid afforded mixtures of (E)- and (Z)-isomers of methyl 4-(2-hydroxy-1-methyl-5-oxo-1H-imidazol-4(5H)-ylidene)-5-oxo-1-phenyl-4,5-dihydro-1H-pyrrole-3-carboxylates. On the other hand, alkylation of compounds 6 with methyl iodide or benzyl bromide produced the corresponding methyl (E)-4-(2-methoxy- or 2-benzyloxy-1-methyl-5-oxo-1H-imidazol-4(5H)-ylidene)-5-oxo-1-phenyl-4,5-dihydro-1H-pyrrole-3-carboxylates 9, derivatives of a new triazafulvalene system.

Synthesis of 4-(2-hydroxy-1-methyl-5-oxo-1 H-imidazol-4(5 H)-ylidene)-5-oxo-1-aryl-4,5-dihydro-1 H-pyrrole-3-carboxylates, a new triazafulvalene system

(2 E,3Z)-2-(1-Methyl-2,5-dioxoimidazolidin-4-ylidene)-3-[(arylamino- or heteroarylamino)methylene]succinate 5 obtained by [2+2] cycloaddition of (5 Z)-5-[(dimethylamino)methylene]-3-methylimidazolidine-2,4-dione ( 1) and dimethyl acetylenedicarboxylate ( 2) followed by substitution of the dimethylamino group with aromatic or heteroaromatic amines, afforded by heating in ethanol in the presence of potassium hydroxide, potassium salts 6. Acidification of 6 with hydrochloric acid afforded mixtures of ( E)- and ( Z)-isomers of methyl 4-(2-hydroxy-1-methyl-5-oxo-1 H-imidazol-4(5 H)-ylidene)-5-oxo-1-phenyl-4,5-dihydro-1 H-pyrrole-3-carboxylates. On the other hand, alkylation of compounds 6 with methyl iodide or benzyl bromide produced the corresponding methyl ( E)-4-(2-methoxy- or 2-benzyloxy-1-methyl-5-oxo-1 H-imidazol-4(5 H)-ylidene)-5-oxo-1-phenyl-4,5-dihydro-1 H-pyrrole-3-carboxylates 9, derivatives of a new triazafulvalene system.

Direct determination of bromine in plastics by electrothermal vaporization/inductively coupled plasma mass spectrometry using a tungsten boat furnace vaporizer and an exchangeable sample cuvette system

A tungsten boat furnace vaporization inductively coupled plasma mass spectrometry (TBF/ICP-MS) method has been applied to the direct determination of bromine in plastic samples. In the pretreatment, the plastic sample is spread over a small sample cuvette made of tungsten by treating it with a strongly basic organic solution, e.g., octanol or diisobutyl ketone in the presence of potassium hydroxide. The cuvette is placed on a tungsten boat furnace, with which the electrothermal vaporizer is equipped. At the vaporization step, a widely spread thin layer of the sample facilitates its efficient evaporation and introduction into an ICP mass spectrometer. The most remarkable feature is that all the bromine species in plastic samples are decomposed to form a thermally stable inorganic salt during the pretreatment procedure. Therefore, the bromine content in plastic samples can be measured by a calibration curve method constructed with an aqueous standard solution of potassium bromate(V). The detection limit (3sigma) was estimated to be 0.77 pg of bromine, which corresponds to a concentration of 0.31 ng g(-1) of bromine in plastic samples when a sample amount taken of 2.5 mg is studied. The relative standard deviation was calculated to be 2.2%. Analytical results of some plastic samples, which contained both inorganic bromide salts and also organic bromine species, are given.

Reaction of secondary phosphine oxides with acylacetylenes

Secondary phosphine oxides reacted with 1-alkanoyl-2-phenylacetylenes in chemoselective fashion under mild conditions (20°C, THF) in the absence of a catalyst (diphenylphosphine oxide) or in the presence of potassium hydroxide [bis(2-phenylethyl)phosphine oxide] to give 1-alkyl-1-diphenyl(or 2-phenylethyl)-phosphoryl-3-phenylprop-2-yn-1-ols in up to 96% yield. The reaction of diphenylphosphine oxide with 1-alkanoyl-2-phenylacetylenes in the system KOH-THF (20°C) afforded not only adducts at the carbonyl group but also products of double α,β-addition at the triple bond, 2,3-bis(diphenylphosphoryl)-3-phenylpropan-1-ones.

Cyanothioacetanilide Intermediates in Heterocyclic Synthesis, Part 1: Synthesis and Biological Evaluation of Some Novel Thiazole, Thiophene, Pyrazole, and Pyrazolo[1,5-a]Pyrimidine Derivatives

Some novel thiophenes (4a,b, 5, and 9a,b) were obtained from the cycloalkylation of the thiocarbamoyl group in the cyanothioacetanilide derivative (1) with α-halocarbonyl compounds. Also, the reaction of cyanothioacetanilide derivative with phenyl isothiocyanate in the presence of potassium hydroxide followed by in situ heterocyclization of the resulting adduct with α-halocarbonyl compounds furnished the corresponding thiazole (12, 14, and 15), pyrazole (19), and pyraozlo[1,5-a]pyrimidine (22, 25, and 26) derivatives. Compounds (4b, 5, 9a, 12, 13, 18, 22, 25, and 26) were tested to evaluate their antimicrobial activity. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

High Functionality Polyether Polyols Based on Polyglycerol

Polyglycerol (PGL) is a polyhydroxyl compound obtained by selfcondensation of glycerol in the presence of alkaline catalysts. It is a very attractive polyol as a starter for the synthesis of polyether polyols for rigid polyurethane foams. It is liquid, easy to handle and has a very high average functionality of 4—20 (or more) hydroxyl groups/mol. By propoxylation of PGL or PGL—sucrose mixtures, we obtained new polyether polyols with very high functionalities, which are very difficult or impossible to obtain by other methods. A new technology for PGL-based polyether polyols preparation was investigated. In the first step the self-polycondensation of glycerol to PGL in the presence of potassium hydroxide or potassium methoxide as a catalyst was carried out. In the second step, the crude alkaline PGL was alkoxylated with PO without removing the catalyst, followed by purification of the resulting polyether polyols. Rigid polyurethane foams prepared from the synthesized PGL-based polyether polyols and crude MDI displayed good physical and mechanical properties, excellent dimensional stability, and low friability.

Synthesis of biodiesel from waste cooking oil using sonochemical reactors

Investigation into newer routes of biodiesel synthesis is a key research area especially due to the fluctuations in the conventional fuel prices and the environmental advantages of biodiesel. The present work illustrates the use of sonochemical reactors for the synthesis of biodiesel from waste cooking oil. Transesterification of used frying oil with methanol, in the presence of potassium hydroxide as a catalyst has been investigated using low frequency ultrasonic reactor (20 kHz). Effect of different operating parameters such as alcohol–oil molar ratio, catalyst concentration, temperature, power, pulse and horn position on the extent of conversion of oil have been investigated. The optimum conditions for the transesterification process have been obtained as molar ratio of alcohol to oil as 6:1, catalyst concentration of 1 wt.%, temperature as 45 °C and ultrasound power as 200 W with an irradiation time of 40 min. The efficacy of using ultrasound has been compared with the conventional stirring approach based on the use of a six blade turbine with diameter of 1.5 cm operating at 1000 rpm. Also the purification aspects of the final product have been investigated.

KINETIKA REAKSI HIDROLISIS GULA DARI TETES TEBU MENJADI ASAM OKSALAT

The kinetics of the hydrolysis of sucrose from molasses have been studied in basic aqueous solutions in the presence of potassium hydroxide. This chemical reaction is to produces oxalic acid as main product. The experiments were conducted in the flask which was completed with stirrer, heater, condenser, and thermometer, at temperatures from 80 to 100oC and at reaction times from 30 to 60 minutes. The product of hydrolysis of molasses was analyzed by using standard solution of potassium permanganate to determine the amount of oxalic acid. The results of these investigations show that the kinetics reaction of the hydrolysis of molasses was found to be first order reaction with respect to sucrose. The reaction rate constant was found to be k = 0,2055 exp(−3367,7663/RT) (in minutes−1) or the activation energy and pre-exponential factor was 3367,7663 cal/gmol and 0,2055 minutes−1, respectively.

The transesterification of rapeseed and waste sunflower oils: Mass-transfer and kinetics in a laboratory batch reactor and in an industrial-scale reactor/separator setup

We have investigated the transesterification of rapeseed (RO) and waste sunflower (SO) oils with methanol in the presence of potassium hydroxide as a catalyst. The transesterification of tri-acylglycerols was first conducted in a batch reactor. The effect of the temperature on the reaction rates was studied at a constant molar ratio of the alcohol to tri-acylglycerols (6:1) and for a constant concentration of the catalyst (1.0 wt%). Size-exclusion chromatography and 1H NMR spectroscopy were used to quantitatively monitor the transesterification reaction. The mass-transfer coefficients of the tri-acylglycerols during the initial transesterification stage were found to be 0.2–1.2 × 10 −5 m min −1, depending on the type of oil and the temperature. Calculated activation energies implied that at higher temperatures the formation of mono-acylglycerols and glycerole was favored for the SO (93 kJ/mol for the forward and 48 kJ/mol for the backward reaction) and the RO (47 kJ/mol for the forward and 36 kJ/mol for the backward reaction), respectively. For the continuous industrial reactor/separator setup, the optimum methanol recycle ratio was established as 0.0550.

Synthesis and Characterization of Some New Heterocycles Incorporating the 1-Phenyl-5-(2-thienyl)pyrazole Moiety

1-Phenyl-3-(2-thienyl)-1H-pyrazole-5-carbohydrazide 4 was prepared from 2-acetylthio- phene by reaction with diethyl oxalate and phenylhydrazine followed by hydrazine hydrate. The reaction of the hydrazide 4 with phthalic anhydride, aromatic aldehydes, and alkene derivatives gave imide 5, hydrazones 6a–d, and bis-pyrazoles 7 and 8, respectively, while its reaction with phenyl isothiocyanate led to thiosemicarbazide 9. The reaction of the latter with ethyl bromoacetate and phenacylbromide afforded 4-thiazolidinone 10 and 1,3-thiazole 11 derivatives, respectively. Reaction of 4 with carbon disulfide in the presence of potassium hydroxide gave potassium hydrazinecarbodithioate derivative 12, which was used as a starting material in the preparation of 2-thioxothiazol-3(2H)-yl)-5-(2-thienyl)-1H-pyrazole-3-carboxamide 14; 1,3,4-thiadiazol-2(3H)-ylidene)-1-phenyl-5-(2-thienyl)-1H-pyrazole-3-carbohydrazides 16a–c; 4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)pyrazole derivative 13; Schiff bases 17a,b; and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine derivatives 18 and 19a–e.

Biodiesel Production from Freshwater Algae

A novel approach in the production of renewable energy carrier—namely, biodiesel—was performed using algal biomass as a raw material. The effect of drying algal biomass and its role on lipid content during extraction process was also investigated. Transesterification of algal oil was conducted, using ethanol in the presence of potassium hydroxide as a catalyst. A gas chromatography−mass spectroscopy (GC-MS) chromatogram was used to analyze the organic compounds present in the crude biodiesel sample after the transesterification process. The lipid content in the algal biomass was determined to be 45% ± 4%. Biodiesel derived from algae had a fuel value with the following characteristics: density, 0.801 kg/L; ash content, 0.21%; flash point, 98 °C; pour point, −14 °C; cetane number, 52; minimum gross calorific value, 40 MJ/kg; and water content, 0.02 vol %. Copper strip corrosion showed a value less than that of Class 1, which was close to light orange, when compared to the polished strip (i.e., slight tarnish).

Flow Synthesis of Cyanine Dyes for Absorbing Orange Light from the Neon Gas Discharge

Color compensation technology made it possible to enhance the image quality of plasma panel display (PDP) devices. We examined the chemicals used in color compensation filters for PDP units in this study. Neon excitation during the plasma discharge causes orange light with an emission wavelength of 585 nm to be emitted from PDP devices. 1 This emitted orange light is mainly responsible for the degradation of color purity in PDP devices. 2 We synthesized three types of closed chain trimethine cyanines to attenuate unwanted spectral emissions having a wavelength 585 nm. Their common uses in PDP are near infrared absorbance filter. In this study, cyanines have been applied to neon orange light absorbing filter. By varying the number of carbons in the methine bridge of cyanine compound or by modifying the cyanine ring structure, 3,4 it is possible to synthesize cyanine structure absorbing particular wavelength and solvent solubility. A simple closed chain trimethine cyanine chromophore was synthesized by the condensation of 3-ethyl-2,4-dimethyl- pyrrole (kryptopyrrole) and TMOP with perchloric acid as shown in Scheme 1. Cyanine 1 was continuously synthesized using microchannel mixer and an extension tube. Kryptopyrrole was fed into one side of the microchannel mixer and the other reactants were fed into the other side. The reactants were mixed at the microchannel mixer and the reaction was carried out in the extension tube by heating at 60 o C. The microchannel mixer was operated at room temperature to avoid clogging it with precipitated solid particles. The volume of the extension tube was 10 mL, causing the retention time to vary from 0.37 s to 1.6 s depending on the total flow rate used in the experi- ment. We observed that a retention time of 0.37 s was sufficient to convert all reactants into product. A higher mass flow rate resulted in a shorter reactant retention time, thereby reducing the formation of byproducts. Cyanine 1 was produced with a yield of 95% and was 99.5% pure and dissolved in 2-butanone had a sharp absorption band at 580 nm with a half bandwidth of 36 nm. In comparison, azo or anthraquinone compounds typically had bandwidths of over 100 nm. 5 The width of the absorption band is dependent upon how closely the molecular structure in the first excited state resembles that in the ground state. The long conjugated chain structure of 1 was accompanied by a corresponding decrease in bandwidth. 6 The molar absorptivity of 1 was measured as 136,130 M -1 cm -1 . We synthesized a closed chain trimethine cyanine structure using 1-butyl-3-acetyl-2,4-dimethylpyrrole and 1,1,3,3-tetra- methoxypropane in the presence of perchloric acid as shown in Scheme 2. For the first step, several basic reagents were tested to generate a pyrrolyl anion for the alkylation of the nucleus in 3-acetyl-2,4-dimethylpyrrole with 1-bromobutane. Alkylation in the presence of potassium hydroxide in dimethyl sulfoxide gave 1-butyl-3-actyl-2,4-dimethylpyrrole with a 75 % yield. Other strong basic reagents such as potassium hydroxide in a solution of sodium amide or aqueous potassium hydroxide (50%) with tetrabutylammonium bromide in dichloromethane were also tested and delivered yields of 50% and 48%, respec- tively. Alkylation with sodium hydride in dimethyl sulfoxide increased the yield to 95%. The strong base, sodium hydride, reacts with dimethyl sulfoxide to produce dimsyl ions, which can effectively remove protons from the nucleus in 3-acetyl-2,4- dimethylpyrrole, thereby resulting in a more efficient alkylation with 1-bromobutane. The experimental result showed that 2 was obtained with a 70% yield and 98% purity. Some product loss took place during the washing and solid recovery steps. Cyanine 2 dissolved in 2-butanone had a maximum absorption at 580 nm with a half bandwidth of 39 nm. The molar absorp- tivity of 2 in 2-butanone was 32,303 M -1 cm -1 .