Amine Type Research Articles

Effect of Copper on the Oxidation Mechanisms of Tertiary and Secondary Amines of Methyl-naphthyl- cyclen-Modified Gold Electrodes

Tetraazamacrocycle such as 1,4,7,10-tetraazacyclododecane “cyclen” are known for efficient complexation of metallic ions and were used as an ionic recognition agents in chemical sensors in aqueous medium.The aim of this paper is to examine in more detail the oxidation mechanism of amines in cyclen before copper complexation and after copper complexation. Gold electrodes modified with mono-N-MNCyclen(mono methyl-naphtyl-cyclen) and tetra-N-MNCyclen thin films were obtained by deposition of mono-N-MNCyclen and the tetra-N-MNCyclensynthesized respectively by bisaminal route in three steps (protection, N-mono-alkylation and deprotection) and direct route. The comparative study of the electrochemical oxidation of amines in both cyclens allowed the identification of the tertiary and of the secondary amines. From the potential-pH relation and the variation of the intensities of the oxidation peaks, the redox mechanisms of both types of amines was proposed. The electrochemical redox behaviour of the amines in the copper-mono-N-MNCyclen complex was studied. From the potential-pH relation and the variation of the intensities of the oxidation peaks, the redox mechanisms of amines and the structure of the copper-mono-N-MNCyclen complex were proposed. The intensities of the oxidation peaks of the amines vary linearly with the copper concentration, in the range 10−12 M to 10–6 M, leading to a detection limit of of 1 pM of Cu2+.

Synthesis of Quinoline‐4‐carboxamides and Quinoline‐4‐carboxylates via a Modified Pfitzinger Reaction of N‐Vinylisatins

AbstractA synthetic approach for the accelerated assembly of quinoline‐4‐carboxamide and quinoline‐4‐carboxylate nuclei is presented. The methodology is based on the rearrangement of N‐vinylisatins promoted by different types of amines (or ethanol) in a Pfitzinger‐type mechanism that, in turn, builds the quinoline ring system. The reaction took place only by heating the starting materials in ethanol, without any additive.

Chiral Primary Amine/Ketone Cooperative Catalysis for Asymmetric α-Hydroxylation with Hydrogen Peroxide.

Carbonyls and amines are yin and yang in organocatalysis as they mutually activate and transform each other. These intrinsically reacting partners tend to condense with each other, thus depleting their individual activity when used together as cocatalysts. Though widely established in many prominent catalytic strategies, aminocatalysis and carbonyl catalysis do not coexist well, and, as such, a cooperative amine/carbonyl dual catalysis remains essentially unknown. Here we report a cooperative primary amine and ketone dual catalytic approach for the asymmetric α-hydroxylation of β-ketocarbonyls with H2O2. Besides participating in the typical enamine catalytic cycle, the chiral primary amine catalyst was found to work cooperatively with a ketone catalyst to activate H2O2 via an oxaziridine intermediate derived from an in-situ-generated ketimine. Ultimately, this enamine-oxaziridine coupling facilitated the highly controlled α-hydroxylation of several β-ketocarbonyls in excellent yield and enantioselectivity. Notably, late-stage hydroxylation for peptidyl amide or chiral esters can also be achieved with high stereoselectivity. In addition to its operational simplicity and mild conditions, this cooperative amine/ketone catalytic approach also provides a new strategy for the catalytic activation of H2O2 and expands the domain of typical amine and carbonyl catalysis to include this challenging transformation.

Effect of Water Addition on CO2 Solubility of Glycol-Based Deep Eutectic Solvents

Secure, affordable, and reliable energy supplies are essential for economic growth, but a tremendous increase in CO2 emission is the cause of serious concern. Conventionally, aqueous amines are used for CO2 capture in a variety of different capture. However, these solvents suffer from a problem such as degradation of amine absorbents, evaporative loss, and high regeneration energy requirement. Deep Eutectic Solvents (DESs) similar to that of Ionic Liquids are omnipotent to capture CO2. They constitute hydrogen bond donor (HBD) and Hydrogen Bond Acceptor (HBA) resulting in a low melting point mixture; due to the formation of their intermolecular hydrogen bonds. DESs have a wide range of applications in different engineering fields due to the combinations and ratios of HBA and HBD. Charge delocalization in DESs is the main reason behind the low melting points then of the individual constituents. The Hydrogen bonds play a significant role in the more effective binding of CO2 molecules by DESs compared to that of Ionic Liquids(ILs). In this work, different types of amine and glycol-based deep eutectic solvents were synthesized and the effect of water addition on CO2 solubility is studied. Tetrabutylammonium bromide was used as a hydrogen bond acceptor and different hydrogen bond donors were used. DESs were further analyzed by adding 10 wt. %, 20 wt. %,30 wt% of water. For measuring the CO2 solubility pressure drop method was used where a fixed amount of solvent is charged to the high-pressure equilibrium cell and a decrease in the pressure is monitored at regular intervals of time. The results showed that the synthesized DESs can absorb CO2. In general, amine-based solvents have shown higher CO2 absorption as compared to glycol-based solvents. Further, the addition of water has a different effect on glycol and amine-based DESs.

Amine Structure-Foam Behavior Relationship and Its Predictive Foam Model Used for Amine Selection for Design of Amine-based Carbon Dioxide (CO2) Capture Process

Background: The use of an amine solution to capture CO2 from flue gases is one of the methods applied commercially to clean up the exhaust gas stream of a power plant. One of the issues in this process is foaming which should be known in order to select a suitable amine for design. Objectives: In this work, all possible types of amines used for CO2 capture, namely, alkanolamines, sterically hindered alkanolamines, multi-alkylamines and cyclic amines, were investigated to elucidate their chemical structure–foaming relationships. Methods: Foam volume produced by each type of 2M amine solution with its equilibrium CO2 loading was measured at 40°C using 94 mL/min of N2 flow. Results: Amines with a higher number or a longer chain of the alkyl group exhibited higher foam volume because of alkyl group’s ability to decrease the surface tension while increasing the viscosity of the solution. An increase in the number of hydroxyl or amino groups in the amine led to the reduction of foam formation due to the increase in surface tension and a decrease in viscosity of the solution. The predictive foam models for non-cyclic and cyclic-amines developed based on the structural variations, surface tension and viscosity of 29 amines predicted the foam volume very well with average absolute deviations (AAD) of 12.7 and 0.001%, respectively. The model accurately predicted the foam volume of BDEA, which was not used in model development with 13.3 %AD. Conclusion: This foam model is, therefore, indispensable in selecting a suitable amine for an amine-based CO2 capture plant design and operation.

Solar and visible-light active nano Ni/g-C3N4 photocatalyst for carbon monoxide (CO) and ligand-free carbonylation reactions

In this study, we investigate the amino and alkoxycarbonylation reaction between various substituted aryl halides, benzyl iodides, and iodocyclohexane with different types of amines and alcohols in the absence of carbon monoxide gas and ligands.

DETA impregnated attapulgite hybrid ZIF-8 composite as an adsorbent for the adsorption of aspirin and ibuprofen in aqueous solution

The diethylenetriamine (DETA) impregnated modified attapulgite hybrid ZIF-8 composite is a new type of amine impregnated hybrid MOF adsorbent, which has an excellent ability to remove aspirin and ibuprofen from aqueous solution.

Nanotheranostic Application of Fluorescent Protein-Gold Nanocluster Hybrid Materials: A Mini-review.

The gold nanoclusters (Au NCs) are a special kind of gold nanomaterial containing several gold atoms. Because of their small size and large surface area, Au NCs possess macroscopic quantum tunneling and dielectric domain effects. Furthermore, Au NCs fluorescent materials have longer luminous time and better photobleaching resistance compared with other fluorescent materials. The synthetic process of traditional Au NCs is complicated. Traditional Au NCs are prepared mainly by using polyamide amine type dendrites, and sixteen alkyl trimethylamine bromide or sulfhydryl small molecule as stabilizers. They are consequently synthesized by the reduction of strong reducing agents such as sodium borohydride. Notably, these materials are toxic and environmental-unfriendly. Therefore, there is an urgent need to develop more effective methods for synthesizing Au NCs via a green approach. On the other hand, the self-assembly of protein gold cluster-based materials, and their biomedical applications have become research hotspots in this field. We have been working on the synthesis, assembly and application of protein conjugated gold clusters for a long time. In this review, the synthesis and assembly of protein-gold nanoclusters and their usage in cell imaging and other medical research are discussed.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ МОЛЕКУЛЯРНОЙ МАССЫ ЭПОКСИДНЫХ ОЛИГОМЕРОВ И ОТВЕРДИТЕЛЕЙ НА ЭКСПЛУАТАЦИОННЫЕ СВОЙСТВА ЛАКОКРАСОЧНЫХ ПОКРЫТИЙ

The paper provides the results of studies of lacquer coatings made on the basis of epoxy oligomers of different molecular mass hardened by the amine type hardeners. Thermal resistance, erosion resistance, strength and deformation characteristics of free lacquer films, as well as their physical and mechanical properties have been examined. It has been determined that the properties of epoxy lacquer coatings are significantly influenced by the molecular mass of the oligomer and hardener used to produce these coatings. It is shown that with the increase in the molecular mass used to obtain coatings epoxy oligomers improve their operational properties, such as heat resistance, erosion resistance, physical and mechanical properties.

Rapid Cycle Temperature Swing Adsorption Process Using Solid Structured Sorbent for CO2 capture from Cement Flue Gas

Concrete is the most widely used man-made material in the world. The production process of cement, a key component of concrete, contributes significantly to CO2 emissions. Every year, over 4 billion tonnes of cement are produced, releasing approximately 7%-8% of global CO2 emissions [1]. Cement flue gas, processes and raw materials, contain around 16% CO2 and 7-10% O2 and NOX /SOX (100-300 ppm), contingent on the fuel type. High amounts of NOX/SOX are a significant challenge for any carbon capture system. The presence of high O2 concentration in the emitted gas stream can chemically degrade typical amines via production of amides or other oxide derivatives. Therefore, it is crucial to conduct preliminary studies at a pilot scale using real cement flue gas conditions to develop a viable technology and accurate techno-economic analysis for large plants (1 million+ tonnes of captured CO2 per year). Svante (formerly Inventys) has a strong patent portfolio on Rapid Cycle Temperature Swing Adsorption (RC-TSA) processes using structured adsorbents, steam-assisted direct regeneration with fast kinetics (< 1.5 mins cycle time) as an alternative to traditional liquid amine technologies. This project utilized scaled up CALF-20 sorbent, one of the first Metal Organic Frameworks (MOFs) used in an industrial CO2 capture project. This MOF is robust with regards to steam, O2 and acidic contaminant gases (such a NOX/SOX) which make it an ideal candidate for the cement CO2 capture application. This article discusses efforts to scale up the CALF-20 MOF sorbent from lab scale to ton scale. A review of CALF-20 performance after 2300 hrs of VeloxoTherm™ capture process results on a boiler flue gas doped with CO2 and Air to simulate Cement kiln flue gas at 0.1 TPD capacity is presented. Also included are results from Phase 1 of the cement project related to NOX/SOX stability tests on CALF-20 sorbent.

Aminosilane-grafted bismuth-alumina adsorbents: Role of amine loading and bismuth content in iodine immobilization from aqueous solutions

Development of adsorbent materials that can efficiently remove radioactive species, in particular, iodine from aqueous waste streams is of great importance to prevent the discharge of these highly toxic chemicals into waterways, while providing a means for a safe disposal of nuclear wastes. In this study, we present a detailed investigation of the performance of a series of bismuth-loaded alumina adsorbents (Bi/Al) grafted with three different aminosilanes including 3-Aminopropyl-triethoxysilane (APS), N-methylaminopropyl-trimethoxysilane (MAPS), and 3-N,N-dimethylaminopropyl-trimeth-oxysilane (DMAPS), in the removal of iodine from aqueous solutions. Specifically, we studied the effects of bismuth loading, amine type and content, as well as iodine concentration and capture temperature to determine the best performing material and removal conditions for iodine immobilization from caustic scrubber solutions. Our results indicated that amine grafting can enhance the iodine removal performance of Bi-Al, with DMAPS giving rise to highest capacity. It was also found that iodine capture over amine-grafted Bi/Al changes dramatically with amine content. Among the materials investigated, Bi5/Al-DMAPS with an amine content of 60 wt% exhibited the highest iodine capture capacity of 215.7 mg/g at 50 °C. Moreover, amine grafting improved the retention of adsorbed iodine species within the adsorbent over time with no degree of leaching after 24 h, unlike Bi/Al2O3 analogue.

The Effects of Amine Type and Lean Amine Temperature on Gas Sweetening Processes

In the North Gas Company (NGC) in Kirkuk, Iraq, sour gas stream is loaded with considerable amounts of H2S and CO2 of 2.95% and 2.54%, respectively. A DEA amine system is currently used to reduce these sour component concentrations below 5 ppm and 2% for H2S and CO2, respectively. This study used Bryan Research and Engineering’s ProMax® process simulation software to optimize this amine sweetening system by adopting other amine types and blends, such as methyldiethanolamine (MDEA). It could be argued that a 50 wt% MDEA solution circulated at 414 m3/h was determined to be the optimum operating conditions. This design met sweet gas specifications and minimized the reboiler duty to 38 MW, 30.9% reduction in steam consumption. The experimental simulation work is also examined the effects of lean solvent temperature on the gas sweetening process efficiency and performance and find out that the lean amine temperature within the range of 43–48°C in all sceneries give acceptable sweetening results.

Self-reducible copper complex inks with two amines for copper conductive films via calcination below 100 °C

Herein is described a new method for the fabrication of copper conductive films at temperatures of less than 100 °C. This method uses self-reducible copper complex inks and two types of amines. Copper complex inks with only 3-butylpyridine are capable of self-reducing at temperatures below 100 °C, but the process is accompanied by the formation of cracks that results in metallic copper films that are highly resistive. The combination of 3-butylpyridine and dipropylamine in self-reducible copper complex inks prevents the generation of cracks via the connection of self-reduced copper particles in the film, which results in low volume resistivity.

Heterocyclic amine intake along with high fat diet may trigger predisposition to atherosclerosis

Background and Aims: The potential effects of polycyclic aromatic hydrocarbons on cardiovascular disease are well known. Despite their structural similarities; different types of heterocyclic aromatic amines are not considered enough on the basis of cardiovascular disease. Therefore, we aimed to investigate the effects of various heterocyclic aromatic amines exposure via diet on lipid profile and atherosclerosis.

Electrochemical Behaviour of Steel in Aqueous Alkanolamines for CO2 capture

Carbon dioxide capture using absorption-desorption by alkanolamines can mitigate carbon dioxide emissions, but corrosion of the steel reactor systems remains a limitation that depends on the amine type. The primary amine, monoethanolamine (MEA), a commonly used solvent for this process, forms carbamate ions (CH2CH2OHNHCOO-)when it absorbs CO2 and has been reported to corrode carbon steel. CO2 absorption in another popular solvent, the tertiary amine, methyldiethanolamine (MDEA), does not form carbamate, but rather hydrogen carbonate ions (HCO3 -), which facilitate FeCO3 formation on steel surfaces (Fig.1), limiting their corrosion rates.The surface reactions on iron in CO2-aqueous alkanolamine solutions were investigated by measuring current transients at an applied potential of -0.350 V vs. SHE at temperatures of 25 – 80 °C, concentrations of 5 and 3 M and various pHs. In aqueous 5 M MDEA solutions, an electrically resistive film formed on iron, evidenced from the sharp decrease in current density to ca. zero (Fig.2); similar behaviour was exhibited in 3 M MDEA(aq). By contrast, current transients measured in aqueous MEA solutions did not decrease sharply. Ex-situ surface characterisation by SEM and EDX detected FeCO3 (Fig.1) on the iron exposed to MDEA, but not on the iron sample exposed to MEA.We shall explain the formation mechanisms of films, if present, and report impedance spectra used to define conditions corresponding to electrically resistive, stable film formation that could be used to inhibit steel corrosion in carbon capture plants. Figure 1

Heterogeneous Aza-Michael Addition Reaction by the Copper-Based Metal–Organic Framework (CuBTC)

The copper benzene-1, 3, 5-tricarboxylate metal–organic framework (CuBTC) was found to be an effective heterogeneous catalyst for the aza-Michael addition reaction of the four types of amines to electron deficient alkenes at room temperature. The catalytic protocol showed high product yields and outstanding chemo selectivity. The cyclic amines (piperidine and pyrrolidine) and aliphatic amines (n-dibutylamine) provided aza-Michael addition with a high yield of product (⁓98%) within shorter reaction period (2 h) at room temperature under mild reaction conditions using CuBTC. However, it was observed that the aza-Michael reaction proceeded more slowly, giving 62% yield of product after 24 h in the case of aromatic amine (aniline) with n-butyl acrylate in the presence of CuBTC under identical reaction conditions. The catalyst could be reused four recycles without losing its initial catalytic activity and selectivity. XRD and SEM analysis further confirmed that the crystallinity of catalyst was retained during the reaction. A reaction mechanism is proposed for the aza-Michael addition reaction over heterogeneous CuBTC catalyst.

Theoretical insights into the synthesis reaction mechanism of 1,2,3-triazole based on sakai reaction

Abstract Sakai reaction is an important method to synthetize 1,2,3-triazole by the addition of α, α-dichlorotosylhydrazones and amines. However, the difficulty of introducing the 1,2,3-triazole ring is often affected by the type of amine reagent. More calculation results and detailed mechanisms are used to screen which amine is more suitable for the Sakai reaction. In this study, the DFT calculations were carried out to study the reaction mechanism of Sakai reaction. Depending on the type of amines, two different paths for Sakai reaction were revealed by our calculations. For the triazolamine, an H atom must transfer from the amines to the diazine synchronously when the new C–N bond is formed. The transformation from trans- to cis- is necessary for the intermediate vinyldiazine. For aniline, the amine molecule can combine with trans-vinyldiazine directly without an H transfer due to the formation of a structure that is similar to NH4+ ion.

Operation of a Pilot-Scale CO2 Capture Process with a New Energy-Efficient Polyamine Solvent

A new blending recipe of a polyamine-based solvent for capturing post-combustion CO2 was proposed, and its performance and characteristics were investigated using a pilot-scale carbon capture process (PCCP). The proposed solvent is a blend of three types of amines and was designed to separate the solvent roles into those of a main amine, auxiliary amine, and reaction-rate-enhancing amine. Polyamine 3,3′-iminobis (N, N-dimethylpropylamine) was selected as the main amine given its ability to capture large amounts of CO2. 2-Amino-2-methyl-1-propanol was used as the auxiliary amine, with piperazine added as the reaction-rate-enhancing amine. This solvent was tested in a PCCP that can handle 150 Nm3/h of flue gas. The proposed solvent was found to operate stably while consuming substantially lower reboiler duty than the monoethanolamine (MEA) 30 mass% solvent.

Synthesis of β-Diamine Building Blocks by Photocatalytic Hydroamination of Enecarbamates with Amines, Ammonia and N-H Heterocycles.

3‐Amino‐substituted saturated nitrogen heterocycles are an important subclass of β‐diamines, appearing in a number of clinical agents. Herein, we report a unified approach to these products based upon the regioselective photoredox‐mediated hydroamination of enecarbamates. The amine coupling partner can encompass diverse amine types under a single set of reaction conditions, including primary alkyl amines, ammonia, aryl and heteroaryl amines, and N−H heterocycles. The method enables the synthesis of a wide range of pharmaceutically relevant building blocks.

Diamine versus amines blend for CO2 chemical absorption

AbstractPresent work analyses the behavior of aqueous solutions of N,N‐dimethylethylenediamine as chemical solvent for carbon dioxide separation by gas–liquid absorption. The interest of this molecule is centered on the presence of different types of amino centers that confer it the capability to act as a solvent based on amines blend. For this reason, a comparison between diamine and amines blend solvent has been carried out in order to understand the differences between these solvents using absorption and nuclear magnetic resonance studies. This experimental work analyses the influence of amine type, concentration, and ratio between different amines. Also, the effect of gas flow rate used in the bubble column reactor upon the absorption kinetics has been analyzed.