Potassium Methoxide Research Articles

Fatty acid methyl esters production with glycerol metal alkoxide catalyst

Metal hydroxides and alkoxides are popular base catalysts for production of fatty acid methyl esters (FAME). Hydroxides dissolved in alcohols produce water. Some of that water reacts with triacylglycerols (TAGs) to produce free fatty acids instead of desired FAME, thus decreasing the yield of the transesterification reaction. Metal alkoxides are expensive, their production is hazardous and energy intensive, therefore, less expensive safer and more efficient catalysts for transesterification are desirable. Glycerol derived non‐toxic alkoxide base catalysts were synthesized by heating KOH solution (50 wt%) and glycerol at three different mole ratios (KOH: glycerol, denoted KGly, at 1:1, 2:1, and 3:1) under four different vacuum pressures. Transesterification reactions were conducted. The reaction rate and yield of FAME synthesis from TAG achieved by catalyst prepared at 3:1 mole ratio of KOH: glycerol achieved superior or similar FAME yield to conventional potassium methoxide catalyst under same reaction conditions. At 120 s after adding catalyst, the reactions achieved satisfactory yield (74.3–78.9%) which was similar to that of KOCH3 catalyst (77.9%). The reactivity of catalyst at initial stage of the reaction was in the following order: KGly (1:1) < KGly (2:1) < KOCH3 < KGly (3:1).Glycerol derived non‐toxic alkoxide base catalysts were synthesized by heating KOH solution (50 wt%) and glycerol at three different mole ratios (KOH: glycerol, 1:1, 2:1, and 3:1) under four different vacuum pressures. The catalysts were used for transesterification reaction and the catalyst prepared at 3:1 mole ratio achieved superior or similar FAME yield to conventional potassium methoxide catalyst.

CO2electro-valorization to dimethyl carbonate from methanol using potassium methoxide and the ionic liquid [bmim][Br] in a filter-press electrochemical cell

BACKGROUND The electrochemical valorization of CO2 into added-value products appears a promising strategy for reducing CO2 emissions and mitigating climate change. Dimethyl carbonate (DMC) is an environmentally friendly valuable chemical, with multiple applications, and has been suggested as a potential gasoline additive. However, DMC has traditionally been produced from hazardous phosgene and CO routes, which encourages the interest in developing new processes. The aim of this work is to study the valorization process for the direct electrosynthesis of DMC from CO2 and methanol using CH3OK and the ionic liquid 1-butyl-3-methylimidazolium bromide, avoiding the addition of carcinogenic compounds. RESULTS The evolution of the concentration of DMC was studied in a filter-press electrochemical cell with anodic and cathodic compartments separated by a Nafion 117 membrane, operating for 48 h. A final DMC concentration of 15.07 mmol L−1 was observed. Analysis of the by-products obtained in the process revealed the formation of tetramethyl orthocarbonate and dimethoxymethane, which were detected and quantified in the liquid phase. A simplified reaction scheme was also proposed based on the results obtained. CONCLUSION Unlike all previous work that used an undivided cell, the new experimental results of this study using a divided cell can serve as a reference for further research to overcome current limitations. © 2014 Society of Chemical Industry

Methanolysis of MoCl5 in the presence of different alkaline agents; molecular structures of the polynuclear molybdenum(V) methoxides and electron charge density distribution from X-ray diffraction study of the new K–Mo cluster

The influence of the solution total alkalinity and the base cation and anion types on the structure and properties of molybdenum oxo-methoxides formed in reaction of MoCl5 in methanol as following: MoCl5+CH3OH+M+A−, where M+=K+ or Na+, and A−=OCH3− or OH− was studied. The investigation has shown that hetero-bimetallic oxo-methoxides containing Na or K ions – [NaMo2O2(OCH3)7(CH3OH)] (1), [KMo2O2(OCH3)7(CH3OH)2] (2) – are formed in alkaline media with sodium or potassium methoxides taken as a base. Single crystal X-ray structure determination (XRD) of the complexes 1 and 2 revealed that their crystal structures can be considered as consisting of anionic [Mo2O2(OCH3)7]− and cationic [Na(CH3OH)]+ or [K(CH3OH)2]+ fragments assembled into different supramolecular aggregates. When Na, K or Mg methoxides are used as a base, while the medium remains to be acidic, regardless the cation type the same compounds are formed, namely, [Mo2Cl2(OCH3)8] (3) or [Mo2Cl4(OCH3)6] (4) (in the absence of alkali). When KOH or NaOH are used instead of respective methoxides it has been shown that at weakly acidic (close to neutral) media the octanuclear molybdenum cluster [Mo8O8(μ3-O)4(μ2-O)4(μ3-OCH3)2(μ2-OCH3)4Cl2(CH3OH)4]·6CH3OH (5·6CH3OH) is formed as a main product. The DFT calculations of the mechanism of complex 5 formation were carried out. The process of octanuclear Mo(V) cluster formation from initially formed binuclear ones was shown to be a thermodynamically favorable. The detailed analysis within QTAIM theory of an electron density distribution function ρ(r) in the crystal of 2 obtained directly from its X-ray diffraction data has been performed. This analysis has provided the direct and convincing experimental evidence of the Mo–Mo bond presence in a dimolybdenum clusters and, in addition, allowed to estimate the energy of some important interatomic interactions in 2 and related clusters.

Dimethyl carbonate mediated production of biodiesel at different reaction temperatures

Methanol was replaced by dimethyl carbonate for biodiesel production. In the process, fatty acid methyl ester (FAME) was produced through transesterification of soybean oil with dimethyl carbonate (DMC) using potassium methoxide as a catalyst. This method produced a more attractive by-product, glycerol carbonate (GC). Factors affecting the reaction such as vegetable oil to DMC molar ratio, catalyst concentration, reaction time and reaction temperature were optimized. Triglyceride conversion of 95.8% was obtained at the optimized condition. This process provided an insight into the reactivity of DMC at different temperature. Co-production of FAME and glycerol carbonate (GC) proceeded through carboxymethylation reaction because methoxyl group and carbonyl group are generated which subsequently attacked the carbonyl moiety in glyceride molecules to form the required products.

PEMANFAATAN ABU KULIT BUAH KELAPA SEBAGAI KATALIS PADA REAKSI TRANSESTERIFIKASI MINYAK SAWIT MENJADI METIL ESTER

Transesterification is the reaction to produce methyl esters in which this reaction’s catalyst involves coconut shell burnt ash at temperature of 550, 600, 650 °C for 8 hours and uses 1%, 2%, 3% (w/w) of ash. Ash used was dissolved in 75 ml of methanol to obtain potassium methoxide compound and was analyzed by AAS (Atomic Absorption Spectrophotometer) to determine potassium content. Palm oil involved in the processing stage of degumming with the addition of 0,6% (w/w) H3PO4 85% to remove gum then followed by an esterification reaction using 3,0% (w/w) H2SO498% as the catalyst to reduce FFA<1%. The temperature of transesterification reaction was at 65 °C for 2 hours, ratio of methanol: CPO 6:1 (n/n) and 500 rpm agitation. Quantitatively, the optimum yield of 81% methyl esters is gained with shell burnt ash at temperature of 600 ° C, 1% (w/w) of ash with the specification of methyl esters as density, kinematic viscosity and flash point are relatively conformed to SNI04-7182-2006 biodiesel and 92.99% purity methyl ester with 4.62% total glycerin,2.39% free glycerin based on GC (Gas Chromatography).

Biodiesel production from biobutanol. Improvement of cold flow properties

Experimental design methods have been successfully applied to develop and optimize the process of synthesis of butyl esters from rapeseed oil (RSO), the most common oil feedstock for biodiesel production in Europe and used frying oil (UFO), as a cheaper raw material, using biobutanol, and potassium methoxide (KOCH3) as catalyst. The optimum conditions were found to be a catalyst concentration of 1.1% and 0.9%, an operation temperature of 78°C and 80°C for rapeseed oil butyl esters (RSOBE) and used frying oil butyl esters (UFOBE), respectively, obtaining ester yields of 96.86% and 96.54% with 6:1 biobutanol/oil molar ratio. Results show that biodiesel produced using biobutanol as alcohol in the transesterification process improved cold flow properties in terms of cloud point (CP), pour point (PP) and cold filter plugging point (CFPP) without significantly affecting the other fuel properties.In order to determine the effects of long storage on oxidation stability, the biodiesel samples were stored for a period of 12months, the analysis of fuel properties: peroxide value (PV), acid value (AV), iodine value (IV) and viscosity (ν) have been applied in oxidation studies. According to the results obtained, the RSOBE and UFOBE samples showed a good oxidative stability during the storage period. The resulting butyl esters can be used as a diesel fuel substitute, since it matches the European Biodiesel Standard EN 14214.

Catalyst consumption during one and two steps transesterification of crude soybean oils

In this work, the transesterification reaction of refined and crude oils was studied. The reaction was carried out using methanol, with the aim of studying the effect of different catalysts, such as sodium and potassium hydroxides and methoxides, all of them in the same molar concentration. The saponification is an important side-reaction in this system, and was carefully analyzed in order to compare the yields and the rate of soaps formation with each catalyst. Significant differences among them have been found. The catalyst and soaps distribution between the biodiesel and the glycerine phases was also determined. It was found that a very important fraction of the hydroxides, both sodium and potassium, are consumed by the saponification reaction, thus decreasing the final acyl-glycerides conversion. Carrying out the reaction in two steps, it was found that not improvement was obtained regarding the catalyst consumption and soap formation, what indicates that the water fed to the system and the water formed by free fatty acid neutralization, determine these values independently of the reaction strategy followed in the process.The importance of this study is that in medium and small scale plants, the biodiesel production is often carried out with crude oils, and consequently, the selection of the catalyst that minimizes soap formation and its solubility in the biodiesel phase, is an important issue.

Ultrasound assisted interesterification of waste cooking oil and methyl acetate for biodiesel and triacetin production

Intensification of the interesterification reaction of waste cooking oil with methyl acetate using potassium methoxide as a catalyst has been carried out using ultrasonic horn (frequency of irradiation of 22kHz and rated power of 750W). Experiments have been performed at different operating parameters viz. reaction temperature (30, 40 and 50°C), oil to methyl acetate molar ratio (over the range of 1:4 to 1:14), catalyst concentration (0.5, 1.0 and 1.5% by weight of oil) and amplitude of ultrasound (40, 50, 60 and 70%) with an objective of understanding the effect of important operating parameters on the extent of conversion of waste cooking oil to the ester. It has been observed that maximum yield (90%) of biodiesel from waste cooking oil using sonochemical reactors was observed at a molar ratio of 1:12, catalyst concentration of 1.0% and temperature of 40°C. It is also observed that higher conversion was obtained in the presence of ultrasound as compared to the conventional method. Kinetic studies have been carried out to determine the rate constant by fitting the obtained experimental data to a second-order rate equation. It has been observed that rate constant increases with an increase in temperature and the activation energy is found to be 56.97kJ/mol.

Preparation and characterisation of Citrulus colocynthis oil biodiesel: Optimisation of alkali‐catalysed transesterification

AbstractA non‐edible oil of Citrulus colocynthis was investigated as a prospective feedstock for biodiesel production by transesterification reaction with methanol. The content of fatty acid methyl ester in the produced oil obtained by four alkaline‐catalysed transesterifications, i.e. sodium hydroxide, sodium methoxide, potassium methoxide and potassium hydroxide was evaluated. Important fuel properties of the produced biodiesel such as ester content, density, kinematic viscosity and acid value were measured and compared. The ester ingredients in the biodiesel product were myristic, palmitic, stearic, oleic and linolenic. The best quality of Citrulus colocynthis oil at the highest yield of 97.8% was produced at a constant mixing rate of 600 rpm, methanol/oil molar ratio of 6:1, 60°C reaction temperature for 60 min, using 1.0 wt% of NaOH.

A Development of Rapid, Practical and Selective Process for Preparation of Z-Oximes

Oximes are important functional groups in organic chemistry due to their synthetic utility as protecting groups for carbonyl groups and their ability to form other functionalities, 1�4 and their biological activity. 5 Oximes are commonly prepared by condensing aldehydes and ketones with hydroxylamines. These reactions do not always go to completion and reaction times can be long, and therefore there has been interest in more convenient and efficient methods. To avoid the typical disadvantage, conversion of aldehydes and ketones to the corresponding oximes was accomplished by using various catalysts such as organic acid/bases, 1,2,6 AcONa, alumina, 7 TiO2/SO4 2� , 2 silica gel, 8 Oxone®, 9 NaOH, 10 basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, 11 polyoxometalates, 12 Na2SO4, 13 and CuSO4/K2CO3 14 under the solvent, the solvent-free or the microwave conditions. These are one and more drowbacks such as long reaction time, use of catalysts, inconvenients due to solid-sate reaction, low yields and limitaion of some carbonyl compounds. On the other hand, H. Sharghi, et al., 14 reported the catalysis of the stereoselectivity of CuSO4 and K2CO3 in the oximation of aldehydes and ketones under solvent-free conditions. Although this method show high selectivity, it is inconvenient for the large scale experiments and the industrial process due to the solvent-free condition. Therefore, we attempted to develop a more convenient and efficient solution method. According to the literatures, 15 treatment of potassium carbonate with methanol generates slightly the potassium methoxide, which may be useful for forming the free NH2OH from its salts. We describe the oximation of aldehyde and ketone using NH2OH·HCl/K2CO3 in methanol solvent.

E/Z Oxime Isomerism in PhC(NOH)CN

The reaction of nitric oxide with benzyl cyanide in the presence of potassium methoxide at low temperature gave the dipotassium salt of a bis-diazeniumdiolate 2 in excellent yield. Two new stereospecific syntheses of E or Z 2-(hydroxyimino)-2-phenylacetonitrile from 2 have been found. The thermodynamics of the E/Z isomerization has been investigated spectroscopically in solution, in the solid state by differential scanning calorimetry (DSC), and theoretically in the gas phase. Evidence of catalysis by NO of E/Z oxime isomerization has been observed.

Fire and explosion hazards related to the industrial use of potassium and sodium methoxides

Sodium and potassium methoxides are used as an intermediary for a variety of products in several industrial applications. For example, current production of so called “1G-biodiesel” relies on processing a catalytic reaction called “transesterification”. This reaction transforms lipid resources from biomass materials into fatty acid methyl and ethyl esters. 1-G biodiesel processes imply the use of methanol, caustic potash (KOH), and caustic soda (NaOH) for which the hazards are well characterized. The more recent introduction of the direct catalysts CH3OK and CH3ONa may potentially introduce new process hazards. From an examination of existing MSDSs concerning these products, it appears that no consensus currently exists on their intrinsic hazardous properties. Recently, l’Institut National de l’Environnement Industriel et des Risques (France) and the Canadian Explosives Research Laboratory (Canada) have embarked upon a joint effort to better characterize the thermal hazards associated with these catalysts. This work employs the more conventional tests for water reactivity as an ignition source, fire and dust explosion hazards, using isothermal nano-calorimetry, isothermal basket tests, the Fire Propagation Apparatus and a standard 20L sphere, respectively. It was found that these chemicals can become self-reactive close to room temperature under specific conditions and can generate explosible dusts.

Determination of Optimum Catalyst Concentration for Biodiesel Yield from Coconut (Cocos nucifera) Oil

The determination of optimum catalyst concentration for biodiesel yield from Coconut (Cocos nucifera) oil was studied. The oil was transesterified using potassium methoxide as catalyst to obtain the crude biodiesel. The reaction was carried out at different catalyst concentrations of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1% and 1.2% w/v KOH, while the speed of stirring, reaction time (60 min), alcohol to oil ratio (6:1) and reaction temperature (60C) were kept constant. The crude biodiesel were purified by washing with water severally to obtain the relatively pure biodiesel. They were dried using solar dryer for a period of four (4) days to obtain moisture-free pure biodiesel. They were subsequently analyzed for various parameters; Kinematic viscosity, acid value, free fatty acid (FFA), specific gravity, iodine value, ash value and flash point. The different variants gave results of the parameters analyzed comparable to International standards of biodiesel. The results of the study showed that, the optimum yield was obtained at 0.7% w/v catalyst concentration giving a biodiesel yield of 87.2%. At the Research Article International Research Journal of Pure & Applied Chemistry, 3(4): 357-365, 2013 358 catalyst concentrations of 1.1% and 1.2%, no biodiesel yield were obtained, instead there was formation of emulsion. General results obtained show that the optimum yields of biodiesel obtainable from Coconut oil when transesterified using KOH/methanol at the catalyst concentration of 0.7% w/v KOH is about 87%. Overall results indicate that Coconut oil can serve as a veritable feedstock for biodiesel production.

Production of biodiesel from Jatropha oil (Curcas Oil)

This work deals with the production of Biodiesel from Jatropha oil also known as Curcas oil. Material used for the production was sourced for locally. Basic test for the suitability of the Jatropha oil was carried out in the lab. The test carried out to determine if the produced Biodiesel met standards set was carried out at the NNPC Kaduna Refinery. The production consisted of very few materials which makes the fuel easily produced without much complication. Jatropha oil was heated to 60oC, a solution of Potassium methoxide also at 600C was added and stirred continuously for one hour. It was left to settle for 24 hours. Glycerine is then removed from the sample by decantation. The sample is then washed and dried. Test carried out on the biodiesel found it well within limits set for biodiesel’s properties by ISO 14214 specification on Biodiesel.Keywords: Biodiesel, Jatropha Oil, Refinery, Potassium Methoxide, Glycerine, By-product, Filtering.

Methanol-enhanced chemical interesterification of sunflower oil with methyl acetate

The aim of this work was to investigate the commercial mixture of methanolic potassium methoxide as catalyst in chemical interesterification of sunflower oil with methyl acetate. The presence of methanol significantly enhanced the reaction process because it increased the reaction rate, improved the safety of the process and facilitated the manipulation of the catalyst. The reactions were performed at 50°C using a methyl acetate-to-oil molar ratio (MAOMR) of 12–48 and a catalyst-to-oil molar ratio (COMR) of 0.1–0.2. The optimum conditions were achieved with the MAOMR of 48 and the COMR of 0.1 and the final product composition was: fatty acid methyl esters (77.0wt.%), triacetin (12.1wt.%), diacetinmonoglyceride (4.0wt.%) and diacetin, monoacetin and glycerol fraction (6.8wt.%). Finally, technical feasibility of the intermediate diacetinmonoglyceride elimination through the addition of higher amounts of methanol was also evaluated.

Thermal hazards related to the use of potassium and sodium methoxides in the biodiesel industry

The introduction of sodium and potassium methoxides in processes leading to biodiesel production has triggered several questions about their stability under actual biofuel manufacturing conditions. In most biodiesel production facilities, basic homogenous catalysis is obtained through the introduction of caustic potash (KOH) or caustic soda (NaOH) in the reactor. In this process, the hydroxides are converted into their corresponding methoxide forms (CH3OK/Na), which then become the actual catalysts in the reactor. Supplying the actual catalyst directly, instead of the low cost hydroxides, may offer several advantages, but may also introduce new hazards that deserve further characterisation work. From a review of the available literature, it was found that very little was known about the thermal decomposition properties of these methoxides. Therefore, as a starting point, l’Institut National de l’Environnement Industriel et des Risques (France) and the Canadian Explosives Research Laboratory (Canada) have recently undertaken a joint effort to better characterise their thermal behaviour. This was achieved by means of a variety of calorimetric techniques including differential scanning calorimetry, accelerating rate calorimetry and ‘large scale’ thermogravimetry–differential thermal analysis. It was found that these chemicals can become self-reactive close to room temperature under specific physical conditions.

Determination of the kinetics and mechanism of methyl formate synthesis in the presence of a homogeneous catalyst

The kinetics and mechanism of methyl formate synthesis, the key intermediate of the formic acid process was determined. Methyl formate was prepared from carbon monoxide and methanol in the presence of potassium methoxide as a homogeneous catalyst. Experimental work was carried out in a laboratory-scale semi-batch autoclave to obtain the intrinsic reaction kinetics. The experimental results were described with a plausible reaction mechanism comprising the reaction of potassium methoxide with carbon monoxide, followed by the proton transfer from methanol to the reaction intermediate to restore the catalyst. It was observed that simple first order kinetics fits the experimental data of the catalyst decomposition. A model for the gas–liquid mass transfer, coupled to the synthesis reaction was developed and the reaction of potassium methoxide was assumed to be the rate-determining step. The equilibrium, mass transfer and rate parameters included in the completely new kinetic model were determined with non-linear regression analysis. A comparison of the modelling results with the experimental data illustrated a good agreement between the model and the actual data. The kinetic and mass transfer models can be used for the scale-up of the methyl formate synthesis.

Product Separation after Chemical Interesterification of Vegetable Oils with Methyl Acetate. Part I: Vapor–Liquid Equilibrium

Chemical interesterification of triglycerides with methyl acetate yields biodiesel and triacetin. This reaction is highly reversible, which implies the presence of intermediate compounds such as diacetinmonoglycerides. In addition, the use of methanolic potassium methoxide as the catalyst causes the appearance of diacetin, monoacetin, and glycerol. Vacuum distillation becomes an interesting alternative for the separation of biodiesel and triacetin. Vapor–liquid equilibrium (VLE) determination requires information related to the vapor pressures of the different compounds and the nonideality of the liquid phase (activity coefficients). The lack of literature information for some compounds was supplemented with experimental data and predictive models for vapor pressure and activity coefficients (UNIFAC and UNIFAC Dortmund). The suitability of using vacuum distillation was evaluated using the Fenske equation and experimental results from a structured packed distillation column. According to the results, removal of diacetinmonoglycerides can be easily accomplished, unlike the elimination of diacetin, monoacetin, and glycerol, which form azeotropes with triacetin.

Oligoethylene Glycols as Highly Efficient Mutifunctional Promoters for Nucleophilic‐Substitution Reactions

Herein, we report the promising use of n-oligoethylene glycols (oligoEGs) as mutifunctional promoters for nucleophilic-substitution reactions employing alkali metal salts. Among the various oligoEGs tested, pentaethylene glycol (pentaEG) had the most efficient catalytic activity. In particular, when compared with other nucleophiles examined, a fluorine nucleophile generated from CsF was significantly activated by the pentaEG promoter. We also performed various facile nucleophilic-displacement reactions, such as the halogenation, acetoxylation, thioacetoxylation, nitrilation, and azidation of various substrates with potassium halides, acetate, thioacetate, cyanide, and sodium azide, respectively, in the presence of the pentaEG promoter. All of these reactions provided their desired products in excellent yields. Furthermore, the combination of pentaEG and a tert-alcohol medium showed tremendous efficiency in the nucleophilic-displacement reactions (fluorination and methoxylation) of base-sensitive substrates with basic nucleophiles (cesium fluoride and potassium methoxide, respectively). The catalytic role of oligoEGs was examined by quantum-chemical methods. The oxygen atoms in oligoEGs were found to act as Lewis bases on the metal cations to produce the "flexible" nucleophile, whereas the two terminal hydroxy (OH) groups acted as "anchors" to orientate the nucleophile and the substrate into an ideal configuration for the reaction.

Clean and facile synthesis of triuret from urea and dimethyl carbonate (DMC) under mild conditions

Triuret has been successfully synthesized by the reaction of urea with dimethyl carbonate (DMC) under mild conditions in the presence of potassium methoxide as a catalyst. It has been fully characterized by FT-IR, 1H-NMR, 13C-NMR, and MS. Effects of the catalyst, the molar ratio of starting materials, and the reaction time on the obtained product were examined in detail. It was found that when n (urea): n (DMC)=1.2: 1, 6 h, and 0.8% catalyst, the yield of triuret can reach 98.1%. Especially, this novel procedure is reported for the first time and has many significant advantages such as easy and clean synthesis, simple work up, and high yields.