Alkali Metal Salt as Catalyst for Direct Synthesis of Carbamate from Carbon Dioxide

Mixtures of potato starch with oils (rapeseed and sunflower) were extruded. To improve the complexation of edible oils, a catalyst was added in amounts of 3 g, 6 g, and 9 g per 100 g of sample. The aim was to obtain potato starch extrudates with a high degree of complexation and edible oils during physical modification (extrusion) with the innovative use of K2CO3 as a catalyst. Selected functional properties (water solubility index and fat absorption index) and technological properties of the obtained extrudates (radial expansion index); color in the L*, a*, and b* systems, and the specific surface area was determined from the water vapor adsorption isotherm (SBET). The fat content was determined as external, internal, or bound, and complexed by amylose to assess the degree and manner of fat complexation during extrusion. Iodine-binding capacity and the complexing index were determined to confirm the formation of amylose-lipid complexes. The incorporation of edible oils resulted in a decrease in the radial expansion index and water solubility index compared to control samples. The extrudates were dark orange. Extrudates obtained at the temperature profile L: 80/80/80/60/60/50 °C, depending on the cooking oil, complexed from 48-79% of the introduced rapeseed oil and from 36-40% of the sunflower oil. The extrusion temperature profile (H: 100/100/100/75/75/60 °C) reduced the amount of bound lipid fractions. Using potassium carbonate in the extrusion of starch-lipid systems gives hope for further increasing the share of lipids in extruded mixtures.

In the present study, it was aimed to develop novel-activated carbon/zeolite and carbon nanotube/zeolite composites for CO2 and CH4 adsorption. The study consists of two parts; in the first part of the study, activated carbon has been obtained from elaeagnus stones and zeolite/activated carbon composites have been prepared from the activated carbon and commercial zeolite with the use of K2CO3 at different temperatures. In order to make comparisons, zeolite/multiwalled carbon nanotube composites have been prepared by using commercial-multiwalled carbon nanotube by the same method. All the composites have been characterised by N2 adsorption – desorption, Barrett-Joyner-Halenda (BJH) desorption pore size distributions and SEM-EDX techniques. In the second part of the study, CO2 and CH4 adsorption processes have been performed for obtained composites at room temperature and 760 mmHg pressure. The relationship between CO2 and CH4 adsorption capacities, Brunauer-Emmett-Teller (BET) surface areas and pore volumes of zeolite/activated carbon and zeolite/multiwalled carbon nanotube (MWCNT) composites have been investigated. Freundlich, Langmuir, BET, Temkin, Dubinin–Radushkevich (DR) and Harkins – Jura (HJ) isotherms have been plotted and the isotherm parameters have been calculated. It was observed that the CO2 and CH4 adsorption capacities of the zeolite/activated carbon composites are higher than the adsorption capacities of both zeolite and activated carbon. It was also observed that the zeolite/MWCNT composite ZN700 showed higher CO2 and CH4 adsorption capacity than both zeolite and nanotube. Results showed that the zeolite/activated carbon and zeolite/multiwalled carbon nanotube composites which were obtained with the use of K2CO3 are promising adsorbents for CO2 and CH4 adsorption for industrial use.

Several zinc salts were employed as catalysts for the synthesis of carbamates directly from aromatic amines, CO2 , and silicate esters. Zn(OAc)2 offered the best performance among the salts tested. The addition of an N-donor ligand such as 1,10-phenanthroline increased the yield. The best catalytic performance of Zn(OAc)2 can be explained by carboxylate-assisted proton activation. The interaction between the substrate and the catalyst can be observed by chemical shifts in 1 H and 15 N NMR spectra. Isocyanate was a key intermediate, which was generated from amine and CO2 . Silicate ester was finally converted to siloxane, which was determined by 29 Si NMR. The commercially available catalyst system could be reused. The yield of isolated carbamate could reach up to 96 % with various substrates, and the catalytic reaction was amine-selective in the presence of other functional groups.

1-Alkynes are the important precursors for the CuAAC click chemistry. The hybrid of 1,2,3-triazole ring to the chromene ring and sugar moiety could bring some remarkable biological properties. Propargyl derivatives are usually used in the click chemistry. This article reported the synthesis of 2-amino-4-aryl-7-propargyloxy-4-aryl-4H-chromene-3-carbonitriles using propargyl bromide as alkylation agent and the use of potassium carbonate and sodium hydride as bases in the conversion of 2-amino-4-aryl-7- hydroxy-4-aryl-4H-chromene-3-carbonitriles into corresponding propargyl ethers in Williamson's ether synthesis. The use of CTAB for the synthesis of benzylidene malononitriles and anhydrous potassium carbonate as a catalyst in absolute ethanol in the synthesis of 2-amino-7-hydroxy-4H-chromene-3- carbonitriles is an efficient and simple synthetic method. Propargyl ether compounds of these 4H-chromene-3- carbonitriles were obtained from the alkylation reaction by propargyl bromide. Two procedures were applied: K2CO3 as a base in acetone solvent (Procedure A) and NaH as a base in DMF solvent (Procedure B). The single-crystal X-ray structure of propargyl ether 5e has been studied. The use of K2CO3 and NaH as bases in the Williamson's ether synthesis from 2-amino-7-hydroxy-4Hchromene- 3-carbonitriles showed that Procedure B was the better route and gave ethers in the higher yields. 2- Amino-4-aryl-7-propargyloxy-4-aryl-4H-chromene-3-carbonitriles were obtained from corresponding 7- hydroxy-4H-chromene-3-carbonitriles. Yields of ethers 5a-i were 70-89% and 80-96%, respectively depending on the used procedures. The described methods are simple, clean and environmentally friendly alternatives for the preparation of 2-amino-4-aryl-7-hydroxy-4H-chromene-3-carbonitriles. The conditions for the transformation of these compounds into propargyl ethers include dried DMF as a solvent, NaH as a base and reaction time of 2 h at the room temperature. A series of 2-amino-4-aryl-7-hydroxy-4-aryl-4H-chromene-3-carbonitriles were obtained based on investigated reaction condition.

Beaches are good indicators for local microplastic distribution and pollution. Multiple methods have been developed for extracting microplastics from sediment through density separation. However, the chemicals applied are often expensive and harmful to the user or the environment. We briefly review the problems associated with the use of these chemicals and present a new floatation medium, potassium carbonate (K2CO3), that has many advantages over other available media. It is non-toxic and cheap, and with a density of 1.54 g/cm3 the K2CO3 solution yielded a mean recovery rate of around 90% for PVC, one of the densest polymers, that cannot be easily extracted with alternative floatation media. We propose that the use of K2CO3 is particularly promising for long term and large-scale monitoring studies, because it allows involving citizen scientists in such studies, leading to an increased public awareness of the plastic problem in the seas.

Inhibitory effects of water mist containing alkali metal salts on hydrogen–natural gas diffusion flames

Enhancement of CO2 removal from flue gas in an oscillatory baffled column using potassium carbonate solution

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Effect of precipitating agent on the properties of cobalt catalysts promoted with cerium and barium for NH3 synthesis obtained by co-precipitation

Potassium carbonate as a supplement to improve milk fat concentration and yield in early-lactating dairy goats fed a high-starch, low-fiber diet

A novel potassium carbonate mediated synthesis of 2‐amino‐1,3‐thia/oxa zoles, 2‐amino‐1,3,4‐thia/oxa diazines and 2‐hydrazino‐1,3,4‐thiadiazines has been described here. The use of K2CO3 allows for an aqueous workup thereby eliminating the organic solvent from both the reaction step and post reaction stage, without compromising the yield and reaction time.

Direct CO2 capture from air is of prime importance to mitigate the negative effects of global warming. Potassium carbonate (K2CO3) is a promising sorbent for the capture of CO2 from air. K2CO3 chemisorbs CO2 from air in the presence of water (the so-called carbonation reaction), even in very low concentrations (410 ppm). To make efficient use of K2CO3, it is dispersed on a support. Carbon-based supports are promising because of their high hydrothermal stability. Carbons have different structural and chemical properties; however, these can be tuned during preparation. Little is known about the relation between carbon properties and their performance, after K2CO3 deposition. We investigated the role of support surface composition on the performance of carbon-supported K2CO3. By using carbons with different numbers of surface oxygen groups, that is, different polarities, we show that K2CO3 supported on an apolar carbon results in a higher capacity CO2 capture. We propose that a polar support attracts polar H2O molecules on the K2CO3 sorbent, resulting in a low carbonation. In contrast, an apolar support lowers the local H2O concentration on the sorbent and favorably attracts apolar CO2 molecules, hence promoting carbonation.

Both long chain alkyl thiols and alkyl amines behave as size focusing agents for gold nanoparticles, a process that is under thermodynamic control. However, amines do not oxidize surface gold atoms while thiols do oxidize surface gold to gold(I) with evolution of hydrogen gas. Therefore, alkyl amines participate in digestive ripening by a different mechanism. The efficiency of alkyl amines for this process is described and compared, and ultimate gold particle size differences are discussed. Reported herein is a detailed investigation of alkyl chain lengths for alkyl amines, aromatic amines (aniline), and unusually reactive amines (2-phenylethyl amine). Also, two methods of preparation of the crude gold nanoparticles were employed: gold ion reduction/inverse micelle vs. metal vaporization (Solvated Metal Atom Dispersion—SMAD).

A continuous, scalable, and solvent-free method for the synthesis of various naphthalic imides and perylene diimides (PDIs) using twin-screw extrusion (TSE) is reported. Using TSE, naphthalic imides were obtained quantitatively without the need for excess amine reactant or product purification. With good functional-group tolerance, alkyl and benzyl amine derived PDIs (incl. commercial dyes) were obtained in 50-99 % yield. Use of K2 CO3 , enabled synthesis of more difficult aniline-derived PDIs. Furthermore, an automated continuous TSE process for Pigments Black 31 and 32 is demonstrated, with a throughput rate of about 1500 g day-1 , corresponding to a space time yield of about 30×103 kg m-3 day-1 , which is 1-2 orders of magnitude greater than for solvent-based batch methods. These methods provide substantial waste reductions and improved efficiency compared to conventional solvent-based methods.

Enzyme changes in neonatal skeletal muscle: effect of thyroid deficiency