Amines Research Articles

Not Everything is a Question of Reputation: Safety of Bacteriocinogenic Lab Isolated from Smoked Salmon

Total DNA extracted from bacteriocinogenic and potential probiotic lactic acid bacteria (LAB) (Lactobacillus curvatus ET06, ET30 and ET31, Lactobacillus fermentum ET35, Lactobacillus delbrueckii ET32, Pediococcus acidilactici ET34 and Enterococcus faecium ET05, ET12 and ET88), have been screened for presence of more than 50 genes related to production of biogenic amines (histidine decarboxylase, tyrosine decarboxylase and ornithine decarboxylase), virulence factors (sex pheromones, gelatinase, cytolisin, hyaluronidase, aggregation substance, enterococcal surface protein, endocarditis antigen, adhesion of collagen, integration factors) and antibiotic resistance (vancomycin, tetracycline, erythromycin, gentamicin, chloramphenicol, bacitracin). Tested strains presented low frequencies of presence for virulence genes. Only few genes were detected in some strains, indicating their safety for application in fermented food products. Besides all beneficial properties studied for various LAB, most considered as GRAS, a special attention need to be addressed on the possible presence of virulence factors, production of biogenic amines and antibiotic resistance. Results from appropriate biochemical tests and detected main genes associated to virulence factors and antibiotic resistance in LAB strains, could be considered as potential hazard of application of this organisms in food products. Moreover, additional in vitro and in vivo experiments must be designed in the system simulating GIT conditions in order to investigate deeper the possible expression of the present virulence genes.

Regioselective α-Amination of Ethers Using Stable N-Chloroimides and Lithium tert-Butoxide.

Herein we describe a metal-free regioselective α-amination of ethers mediated by N-chloroimides in ethereal solvents in the presence of lithium tert-butoxide. This reactivity of N-chloroimides leads to the synthesis of hemiaminal ethers in good to excellent yields at room temperature. This C-H functionalization is achieved without the use of a light, heat source, or external radical initiators. Initial mechanistic work indicates that the reaction proceeds through a radical pathway.

Comparison of CLR and SS Flexible Systems for Post-Combustion CO2 Removal in a NGCC Power Plant

Carbon dioxide is essential to life on Earth, however its concentration in the atmosphere has significantly increased since pre-industrial era, causing global warming and climate change. To reduce these effects, the Paris Climate Agreement has established greenhouse gas emissions reduction targets, which can be achieved by decarbonizing energy-intensive industries as electricity production. Post-combustion removal of carbon dioxide can be obtained by employing aqueous solutions of amines - in most of the cases MonoEthanolAmine (MEA) is used - which absorb this acid gas from the flue gas streams and are then regenerated and recycled. They are widely employed, though being characterized by several drawbacks, as the high energy requirement at the reboiler of the regeneration section. Therefore, though adding Carbon Capture & Storage (CCS) to a power plant makes the production of electricity more advantageous from an environmental point of view, its operation represents an economic loss for the plant. Possible ways of minimizing the economic disadvantages due to the carbon dioxide removal section include running this section in flexible mode, on the basis of the price of electricity which varies from hour to hour and from day to day. The Capture Level Reduction (CLR) and the Solvent Storage (SS) methods are two possible solutions for flexible operation. This work focuses on the purification of a flue gas stream from a power plant fed with natural gas and performs simulations and techno-economic analyses of the CLR and SS modes, taking into account also the possible application of a carbon tax. By analysing the obtained results a comparison between the two options is carried out, and the best operating mode is determined.

Electrochemically Enhanced Fenton’s Reaction

Fenton reaction is often used for the treatment of industrial wastewaters polluted by a toxic and difficult to remove compounds where other methods as emulsion breaking chemical precipitation, or advanced chemical processes fail. To this category belong phenols, polychlorinated aromatic hydrocarbons, amines, mercaptans, and stable chemical complexes containing heavy metals at different concentrations and sometimes even radioactive isotopes. These wastewaters can cause severe damage to the environment, so their removal has a high priority. The principle of Fenton’s reaction is based on radical oxidation of the difficult to remove compounds realised by the application of oxidising reagent catalysed by the addition of metallic cations as an oxidant is frequently used hydrogen peroxide, ozone, or chloride lime which allows production of the hydroxyl radicals. As a catalyst, Cu+, Ti3+ or Cr2+ can be successfully employed, but most commonly, Fe2+ cations are used.The contribution of this paper is an adding of Fe2+ ions by dissolution of the electrodes. The advantage of this method consists of indirect adding of Fe+2 from solid phase which eliminates the need of dosing of the Fe in the form of the solution (FeSO4, FeCl2, FeCl3, Fe2(SO4)3 …) causing secondary pollution and an increase of salinity. This technology avoids unnecessary salts addition essential in cases, with problems of high salinity of the wastewater. To realise this process in the industrial scale, profound knowledge of the electrocoagulation and/or electroflotation is indispensable, especially for scale-up. This paper brings knowledge about the electrochemical background and technological approach for successful design for required volume flow. Based on our results, some details of suitable reactor types and its scale-up is presented in brief overview revealing suitability for selected cases.

Construction of N-S and C-N Bonds from Reactions of Benzofuroxans with DMSO or THF.

Novel ring-opening reactions are achieved employing benzofuroxan as a new type of iminating or aminating reagent. These diverse transformations give access to three types of molecular scaffolds, N-aryl dimethylsulfoximines, methanesulfonamides, and hemiaminal ethers, which are important structural motifs in organic and medicinal chemistry. The procedures feature solvent-involved reactions, easily available starting materials, operational simplicity, high atom economy, and the potential further transformation of nitro group.

Problem of Regioselectivity in the Amination of 2-Fluoro-5-iodopyridine with Adamantylalkyl Amines

Problem of Regioselectivity in the Amination of 2-Fluoro-5-iodopyridine with Adamantylalkyl Amines

Progress in Co-Catalyzed C-H Amination

Progress in Co-Catalyzed C-H Amination

The impact of lemon juice on the marination of anchovy (Engraulis encrasicolus): Chemical, microbiological and sensory changes

This paper investigates the qualitative changes (physical, biochemical, microbiological and sensory) in anchovy fillets during the maturation process, in a marinade made from fresh lemon juice and olive oil with the addition of 0.5 and 1% acetic acid. Marination was carried out at 4°C and it required 7 days until sensory acceptability of the product was achieved (glassy-white colour, soft fillet texture, favourable effect in terms of odour and flavour). At marination end point, a pH value of 4.2, aw of 0.85 and NaCl content of 4% were measured for the products. Volatile and non-volatile amines were extracted from the marinated anchovy fillets, and the detected concentration implies that the accumulation of these components during processing was weak (>10 mg TVB-N/100g, <0.5 mg TMA/100 g, <30 mg biogenic amines/kg). The lemon juice showed good preservative effect, it reduced the count of total viable bacteria, psychrophilic bacteria and lactic acid bacteria in the products, while the addition of 0.5% acetic acid improved the overall acceptability of the product as well as its sensory attributes.

Homolytic pathway for the RuO4-oxidation of amines

Homolytic pathway for the RuO4-oxidation of amines

Absorption of Carbon Dioxide using Enzyme Activated Amine Solution in Columns with Random Packings

Packed columns with structured or random packings are widely used in gas cleaning processes. Especially columns filled with random packings cover a large part of such applications in industrial practice. However, most of the recent investigation on carbon dioxide absorption from flue gases or other gas sources containing carbon dioxide (CO2) has been performed in columns equipped with structured packings, mostly due to their low pressure drop compared to other internals. CO2 usually is absorbed from the gas stream by means of a solvent. Amongst others, amine mixtures have gained a major role as a chemical solvent in this context. Beside the absorption kinetics and capacity, the energy demand for the regeneration of the solvent is a key factor for the operating costs of CO2 absorption plants.In previous studies, enzyme activated amines have been studied in lab scale, in order to enhance the absorption kinetics and to reduce the energy demand for regeneration. Besides the small scale, these studies focused almost exclusively on columns with structured packings. Despite the known benefits of structured packings, they can be inferior to random packings for systems with solid content and systems with mass transfer resistance in the liquid phase. Therefore, this work investigates columns at significantly larger scale equipped with random packings and presents the results of an extensive experimental study using the enzyme activated amine solution for the absorption of CO2. In particular, the different random packings McPac (Mackowiak 2001) from stainless steel and ENVIPAC from plastic have been studied in a test plant with diameter of ?? ?? =600 mm. Fluid dynamics and mass transfer characteristics have been measured using various liquid and gas loads, packing height and column diameter using the CO2 inlet concentrations of = 15 vol%.The experimental results are used for the validation of a process model, implemented in Aspen Plus® simulation software. A good agreement between experimental results and the simulation of the complex, reactive absorption system is established.

Amino Acid Based Solvent Vs. Traditional Amine Solvent: a Comparison

There is an increase in the development of absorption of acid gases by chemical solvents from flue gases of power plants due to the growing attention paid to the capture and storage of CO2. With the aim of substituting traditional amines, which at present have many disadvantages such as high energy requirement, corrosion, and toxicity, innovative solvents are being studied. In the last few years, attention has been paid to solvents which form precipitate during the absorption phase. Amino acids belong to this category and, because of their characteristics, allow a further enhancement of the chemical absorption process. Thus, it is possible to perform the removal of CO2 in an amount similar to that of traditional amines, but with lower regeneration energy and costs. In this work, an amino acid solvent of potassium taurate solution (4M potassium hydroxide – 4M taurine) has been considered. The process has been simulated with the commercial software ASPEN Plus® to perform a rigorous calculation. The software had been user customized on the basis of the available experimental data in previous work. Our previous publications reported the modelling of the process and the evaluation of its performance applied to the purification of a flue gas stream. In this work, a techno-economic comparison between the amine scrubbing process and the potassium taurate process is presented, taking into account both the operating costs, mainly affected by the energy consumption, and the capital costs.

Metal Dependent Formation of Imidazolidine or Hemiaminal Ether Complexes from Multicomponent One‐pot Reactions

AbstractImidazolidinylpyridines, a new type of strictly face‐capping tridentate ligands, are reported as cheap and easily synthesizable alternates to well‐known crown and scorpionate ligands that are costly and cumbersome to be synthesized. The reported imidazolidinylpyridines have been made from the equimolar multicomponent mixture of N1,N2‐bis(substituted)ethane‐1,2‐diamine, pyridine‐2‐carboxaldehyde and MCl2, where M is Ni, Cu or Cd. The metal dependent formation of complexes of the expected imidazolidinylpyridine while using cadmium(II) ion and unexpected hemiaminal ethers when Ni(II)/Cu(II) was used are portrayed with the support of complete characterization including NMR spectroscopy, mass spectrometry and solid‐state structures.

Chemo-selective couplings of anilines and acroleins/enones under substrate control and condition control

Rh(III)-catalyzed C–H activation of N-protected anilines and chemo-divergent couplings with acroleins/enones have been realized for synthesis of three classes of heterocycles. The oxidative coupling of N-pyridylaniline afforded dihydroquinolones with the acrolein being a major hydrogen acceptor. When the directing group was replaced by pyrimidyl in the same system, redox-neutral coupling occurred to afford hemiaminal ethers. Oxidative annulation of N-pyridylanilines with enones using AgBF4 oxidant afforded atropisomeric quinolinium salts.

Tetranuclear nickel cubane cluster formed by the hydrolysis of nickel koneramine complex

Hydrolysis of a nickel(II) complex of a hemiaminal ether ligand yielded a tetranuclear Ni4(μ3-O)4 cubane cluster. The structural, electrochemical, thermal and physical properties of the cluster were studied and reported here.

A silver cleaver splits cyclic amines

Organic Chemistry Carbon-carbon single bonds are fairly unreactive when they are not strained in a tight ring. Roque et al. now report that a silver salt can cleave C–C bonds in unstrained cyclic amines such as pyrrolidines and piperidines. Paired with an electrophilic fluorine source in aqueous

Formal Carbene Insertion into C−O or C−N Bond: An Efficient Strategy for the Synthesis of 2‐Substituted 2H‐Chromene Derivatives from Chromene Acetals or Hemiaminal Ethers

AbstractWe report the palladium/Brønsted acid co‐catalyzed formal insertion of carbene into the C−O or C−N bond of 2H‐chromene acetals or hemiaminal ethers. This transformation was initiated by the Brønsted acid‐promoted cleavage of the C−O or C−N bond, followed by modification of the leaving alcohol or amino fragments with palladium carbenes, and reassembly of the modified fragments. A variety of C‐2 functionalized 2H‐chromene derivatives were obtained in moderate yield (43∼75%) with good to excellent diastereoselectivities (up to &gt;95:5 dr) under mild conditions.magnified image

An unprecedented 7-membered ring enamide cyclization through hypervalent iodine phenolic oxidation

An unprecedented 7-membered ring cyclization of an enamide to a phenol through hypervalent iodine phenolic oxidation was discovered. In the process a molecule of solvent is incorporated on the cycle forming an unusual and stable hemi-aminal ether.

Mixture of mea/2-mae for effective co2 capture from flue gas stream

The climate change and global warming are the main environmental concerns because of CO2 emission into the atmosphere. The main sources of CO2 is from power plants in the form of flue gas. Recently, the effective technology to capture CO2 is chemical absorption by using aqueous amine solutions. The commonly used amine solution is monoethanolamine (MEA). It has disadvantages like low capacity and high energy consumption. 2-methylaminoethanol (2-MAE) as a new solvent has been formulated to improve the performance of CO2 mitigation but the cost of this chemical is higher. The two amines are mixed together to obtain higher performance and to compensate the drawbacks of each solvents. The objective of this research is to measure the solubility of CO2 in a mixed solvent with 20 : 10 wt% of MEA and 2-MAE for CO2 capture from the flue gas stream at the temperature of 313.15 K and 353.15 K and CO2 partial pressures ranging from 5 to 100 kPa. The experimental results are compared with that of single solution of MEA and 2-MAE at the same conditions. From the results, it is reported that in term of cyclic capacity, the amine mixture provides a better performance, which is higher than that of MEA ranging from 2.35 % to 61.90 % but lower than that of 2- MAE from 8.76 % to 43.45 %. The rate of CO2 loading of mixed solution is relatively close to that of MEA but lower than that of 2-MAE. Therefore, in the future, the mixed solvent may be used as an alternative solution for CO2 capture instead of using single amine.

Unassisted formation of hemiaminal ether from 4-aminopyridine and o-vanillin - experimental and theoretical study

The reactions between o-vanillin and three isomeric aminopyridines lead to imines of diverse spatial conformation and reactivity. The direct products of these simple reactions carried out in methanol are either imine compounds formed in the reactions of 2-amino- and 3-aminopyridine with o-vanillin or the α-aminoether formed in the reaction of o-vanillin with 4-aminopyridine. The Schiff-type derivative of 4-aminopyridine and o-vanillin, which is described in this paper for the first time, is very reactive and can only be obtained indirectly from the α-aminoether in anhydrous conditions. All compounds are characterized by X-ray diffraction and FT-IR and NMR spectroscopies. The DFT calculations at all-electron BLYP/Q4ZP level of theory are utilized to explain the differences between the reactivity of isomeric aminopyridines and their imine derivatives.

Arenes and amines

Arenes and amines