Class Of Amines Research Articles

Use of p-methoxy cinnamaldehyde in label-assisted laser desorption/ionization mass spectrometry (LALDI-MS) for detection of different classes of primary amines, amino acids and neurotransmitters

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), useful for the detection of macromolecules, is generally not suitable for recording the mass spectrum of small molecules, especially within the range of m/z 500, because of the appearance of matrix cluster peaks in the small molecular weight range. To circumvent this problem, a matrix-free variant of MALDI-MS, namely Label-assisted laser desorption/ionization mass spectrometry (LALDI-MS) has been developed in recent years where analytes get covalently attached to a laser absorbing label which induces the desorption/ionization process thus facilitating the recording the mass spectra and avoiding the problem of formation of cluster peaks. In general, the probes used for such detections are all pyrene-based scaffolds which despite being a good laser-active chromophore have both reactivity and solubility problems. Inspired by the right chromophoric nature, we have undertaken a systematic study to design and optimize cinnamaldehyde derivatives and have found that p-methoxy cinnamaldehyde (PMC) as a simpler, cost-effective, less hydrophobic laser-active label, which can detect a series of primary amines, including the neurotransmitters and amino acids. The label PMC can also discriminate between aliphatic and aromatic primary amines.

Fischer-Tropsch Synthesis for the Production of Sustainable Aviation Fuel: Formation of Tertiary Amines from Ammonia Contaminants.

Fischer-Tropsch synthesis combined with product workup is a promising route toward synthetic aviation fuel from renewable hydrogen and carbon sources like biomass, CO2, and waste. Cost savings can be achieved by reducing the number of gas treatment steps in new plants, but the consequence of contaminants in the feed needs investigation. While feeding 2.6 ppmV ammonia to a Fischer-Tropsch reactor, it was shown that ammonia was predominantly chemically converted into organic amines, with most nitrogen found in the water phase (89%), followed by heavy wax (7%) and light wax (1%). The concentration difference between water and light wax was shown to be due to the post-condensation separation of amines on polarity. Amines up to a chain length of 120 were detected in the heavy wax with MALDI-FT-ICR-MS, which, in combination with the high nitrogen content, suggests that amines have a similar chain growth probability compared to the main hydrocarbon products. Detailed product analysis with three independent analytical techniques showed that tertiary N,N-dimethylalkylamines were by far the most abundant amine class. This suggests that ammonia is decomposed on the cobalt surface and, potentially as a dimethylamine fragment, incorporated in the growing chain. Further evidence was obtained from the abundance of trimethylamine and from the reconciled nitrogen product analysis up to C100, which showed that the amine product distribution followed from naphtha onward the same ASF kinetics as alkanes and oxygenates while being distinctively different from the alkene distribution. The presented findings provide further avenues for studies of the Fischer-Tropsch reaction mechanism and indicate the opportunity of cost saving on gas treatment, while further validation is required to assess the impact on hydrocracking and product quality.

Metabolomic profiling of Fiore Sardo cheese: Investigation of the influence of thermal treatment and ripening time using univariate and multivariate classification techniques

The effect of different sub-pasteurization heat treatments and different ripening times was investigated in this work. The metabolite profiles of 95 cheese samples were analyzed using GC–MS in order to determine the effects of thermal treatment (raw milk, 57 °C and 68 °C milk thermization) and ripening time (105 and 180 days). ANOVA test on GC–MS peaks complemented with false discovery rate correction was employed to identify the compounds whose levels significantly varied over different ripening times and thermal treatments. The univariate t-test classifier and Partial Least Square Discriminant Analysis (PLS-DA) provided acceptable classification results, with an overall accuracy in cross-validation of 76% for the univariate model and 72% from the PLS-DA. The metabolites that mostly changed with ripening time were amino acids and one endocannabinoid (i.e., arachidonoyl amide), while compounds belonging to the classes of biogenic amines and saccharides resulted in being strongly affected by the thermization process.

Electrochemical action on the flotation beneficiation of ordinary iron ore concentrate

One of the main challenges in processing fresh ferruginous quartzites is to obtain high-quality iron ore concentrates containing more than 70% total iron and less than 1.8% silica to produce DR pellets and hot Briquetted Iron (HBI). Currently, it is widely recognized that the most effective methods to achieve high-quality iron ore concentrates is through reverse flotation using cationic amine collectors in an alkaline medium. However, due to the very fine impregnation of magnetite in quartz, the insufficiently complete release of magnetite even with fine grinding, and the proximity of the flotation (surface) behavior of the separated minerals, high-quality concentrates are not always achievable in the flotation process. Consequently, exploring methods to enhance the efficiency of flotation separation of minerals and improve concentrate quality remains a pertinent issue. Historical studies have shown that electrochemical treatment can adjust the properties of reagents, enhance their effect on specific minerals, and thus control the flotation process. The efficiency of quartz and other silicates flotation by amines significantly depends on the ratio of ionic and molecular forms of the reagent in aqueous solutions of the collector and in the flotation pulp. Altering this ratio can impact the outcomes of reverse cationic flotation of iron ores. It is feasible to change the ratio of the amine forms through electrochemical oxidation or reduction of the reagent solution. Moreover, the electrochemical treatment facilitates the dispersion of the amine in the aqueous medium and its physical adsorption on minerals. Therefore, electrochemical pretreatment of amines can be considered a promising method for intensifying the reverse flotation of iron ore. This paper presents research results aimed at improving the quality of the oversize of the fine screening of ordinary magnetite concentrate from Mikhailovsky GOK, named after A.V. Varichev, through the use of electrochemically treated solutions of cationic amine class collectors in the process of reverse cationic flotation. The research findings confirmed the feasibility of using preliminary diaphragmless electrochemical treatment of reagents Tomamine RA-14 and Lilaflot 811M (esters of monoamine of different composition) for the targeted modification of their properties and for increasing the efficiency of reverse flotation. Consequently, the silica content in the flotation cell product decreased from 1.66–1.7% to 1.51–1.56, with the grade of total iron exceeding 70%.

Engineering the enantioselectivity of a novel imine reductase from Streptomyces viridochromogenes for the dynamic kinetic reductive amination of cyclic β-ketoester

N-substituted β-amino esters as an important class of chiral amines, are widely used as building blocks in pharmaceuticals. A novel imine reductase SvIRED was identified through gene mining from Streptomyces viridochromogenes with high enantioselectivity of > 99 % ee (1R, 2S), 95 % de (cis:trans), towards 2-oxocyclohexane-1-carboxylate and cyclopropylamine. SvIRED exhibited the highest activity at pH 7.0 and 40 °C. A variety of amine donors could be used by SvIRED and produce chiral N-substituted β-amino esters with different enantioselectivity. Employing methylamine (i) and pyrrolidine (n) as amine donors, SvIRED exhibited reversed enantioselectivity of 23 % ee (1S, 2R) and 79 % ee (1S, 2R) respectively. Through alanine scanning, M183 and H244 were identified with remarkable roles in governing enantioselectivity towards i and n. Compared with WT SvIRED, the enantioselectivity of M183A was inverted to ee value of >99 % (1R, 2S) and de value of >99 % (cis:trans) towards i, and the enantioselectivity of H244A was inverted to ee value of 88 % (1R, 2S) and de value of >99 % (cis:trans) towards n. Interaction analysis indicated the orientation of ester group was vital for manipulation of enantioselectivity. This study provides novel Imine reductase mutants for enantioselective synthesis of N-substituted β-amino esters with different amine donors.

Target-specific modification of diethylenetriamine with hydroxyalkyls: Efficient absorbents for CO2 capture

Chemical absorption of CO2 by amine solutions is an industrialized operation and currently represents the most practical technology worldwide. However, the development of amine absorbents with high efficiency and energy-saving benefits remains a major challenge. Here, we developed a novel class of amines through the target-specific modification of the secondary amine group in diethylenetriamine (DETA) with various hydroxyalkyls. The obtained amines present enhanced overall efficiency for CO2 capture, especially with regards to the absorption/desorption rates and recyclability. Significantly, the regeneration energy consumption for the developed amines can be reduced to a remarkable low value of 2.78 GJ t-1 CO2. Moreover, the CO2 absorption and desorption processes were closely monitored by nuclear magnetic resonance (NMR). Combined with density functional theory (DFT) calculations, the mechanism of the developed amine for CO2 capture was fully elucidated. This targeted modification strategy provides a new avenue for the development of efficient amine absorbents for practical CO2 capture.

Selective C–H activation of unprotected allylamines by control of catalyst speciation

An outstanding challenge in the Pd-catalyzed functionalization of allylamines is the control of stereochemistry. Terminal alkenes preferentially undergo Heck-type reactions, while internal alkenes may undergo a mixture of Heck and C-H activation reactions that give mixtures of stereochemical products. In the case of unprotected allylamines, the challenge in achieving C-H activation is that facile in situ formation of Pd nanoparticles leads to preferential formation of trans rather than cis-substituted products. In this study we have demonstrated the feasibility of using mono-protected amino acid (MPAA) ligands as metal protecting groups to prevent aggregation and reduction, allowing the selective synthesis of free cis-arylated allylamines. This method complements Heck-selective methods, allowing complete stereochemical control over the synthesis of cinnamylamines, an important class of amine that can serve as therapeutics directly or as advanced intermediates. To highlight the utility of the methodology, we have demonstrated rapid access to mu opioid receptor ligands.

Tetraphenylphosphonium Allyldithiocarbimates: A Novel Safe Amine Class of Morita–Baylis–Hillman-Derived NBR Vulcanization Accelerators

Tetraphenylphosphonium Allyldithiocarbimates: A Novel Safe Amine Class of Morita–Baylis–Hillman-Derived NBR Vulcanization Accelerators

Amine treatment application for carbon dioxide capturing from gas emissions of a hybrid power plant with a solid oxide fuel cell

The transition to alternative electrical and thermal energy sources has opened up many promising areas for the hydrogen-containing fuel study. When assessing the environmental prospects of using a solid oxide fuel cell, it was found that carbon dioxide is obtained as a by-product, which must be captured and disposed of. Carbon dioxide is captured by physical absorption, chemisorption, adsorption, catalytic hydrogenation, membranes, enzymes under the electricity action. In this work, an experiment was carried out on the carbon dioxide capture by absorption, namely, amine-containing substances. In the experiment, both single-component and multi-component solutions were tested. The experiment was carried out on a laboratory setup. Based on the data obtained, a conclusion was made on the carbon dioxide capture by various classes of amines. Recommendations have been made for industrial scale amine purification. Compliance with these requirements will achieve good results in industrial carbon capture.

Supercritical Fluid Nanospray Mass Spectrometry: II. Effects on Ionization.

Nanospraying supercritical fluids coupled to a mass spectrometer (nSF-MS) using a 90% supercritical fluid CO2 carrier (sCO2) has shown an enhanced desolvation compared to traditional liquid eluents. Capillaries of 25, 50, and 75 μm internal diameter (i.d.) with pulled emitter tips provided high MS detection sensitivity. Presented here is an evaluation of the effect of proton affinity, hydrophobicity, and nanoemitter tip size on the nSF-MS signal. This was done using a set of primary, secondary, tertiary, and quaternary amines with butyl, hexyl, octyl, and decyl chains as analytes. Each amine class was analyzed individually to evaluate hydrophobicity and proton affinity effects on signal intensity. The system has shown a mass sensitive detection on a linear dynamic range of 0.1-100 μM. Results indicate that hydrophobicity has a larger effect on the signal response than proton affinity. Nanospraying a mixture of all amine classes using the 75 μm emitter has shown a quaternary amine signal not suppressed by competing analytes. Competing ionization was observed for primary, secondary, and tertiary amines. The 75 and 50 μm emitters demonstrated increased signal with increasing hydrophobicity. Surprisingly, the 25 μm i.d. emitter yielded a signal decrease as the alkyl chain length increased, contrary to conventional understanding. Nanospraying the evaporative fluid in a sub-500 nm emitter likely resulted in differences in the ionization mechanism. Results suggest that 90% sCO2 with 9.99% methanol and 0.01% formic acid yielded fast desolvation, high ionization efficiency, and low matrix effect, which could benefit complex biological matrix analysis.

Analysis of genotoxic N-nitrosamines in active pharmaceutical ingredients and market authorized products in low abundance by means of liquid chromatography – tandem mass spectrometry

In 2018, high levels of the IARC class IIA carcinogen N-nitrosodimethylamine (NDMA) were analytically verified in the active pharmaceutical ingredient (API) valsartan, resulting in extensive regulatory action on angiotensin-II-receptor antagonists and recall of finished drug products by the pharmaceutical industry to ensure patient safety. The root cause of contamination was the unintended reaction of common reagents utilized during drug synthesis. This lead to serious effects on drug quality and immediate regulatory action. Thus, routine analysis of drug product contents are inevitable and necessitate thoroughly performed work up procedures of the product as well as adequate validated analytical methods. The nature of N-nitrosamines (NA), ranging from small, semi-volatile compounds up to highly polar molecules, effort sophisticated requirements in terms of instrumental analysis. Up today, gas as well as liquid chromatographic devices coupled to mass spectrometers are the most widespread systems for analysis. Gas chromatographic – mass spectrometric (GC-MS) systems, obviously superior towards liquid chromatography – mass spectrometry (LC-MS) for detecting small volatile compounds like NDMA, reach their limits for broadly designed studies including polar or acidic NA. In this study, a complementary and highly sensitive approach by means of liquid chromatography – tandem mass spectrometry (LC-MS/MS) is presented, including detection of 13 NA deduced from major classes of secondary amines. Thereby, the fully validated approach was performed in accordance to ICH and European Medicines Agency (EMA) guidelines. Quantitative proof-of-concept measurements with various APIs and market authorized tablets as representative drug formulations conclude applicability for further presumably contaminated substances. The approach employs organic or inorganic extraction steps with solid phase extraction (SPE). The limit of detection for the most prominent NA, NDMA and N-diethylnitrosamine (NDEA), were both 0.025 parts-per-billion (ppb) per matrix, respectively.

Copper‐Catalyzed Carbonylative Cross‐Coupling of Alkyl Iodides and Amines

A general copper-catalyzed carbonylative cross-coupling between amines and alkyl iodides is reported. Using a simple combination of catalytic amounts of copper(I) chloride and N , N , N' , N" , N" -pentamethyldiethylenetriamine in the presence of sodium hydroxide under carbon monoxide pressure, a broad range of alkyl iodides and amines can be efficiently coupled to the corresponding amides that are obtained in good to excellent yields. Notable features of this process - the first one relying on a base metal catalyst - include the availability and low cost of the catalytic system, its successful use with primary, secondary, tertiary alkyl iodides and all classes of amines - with no or limited competing nucleophilic substitution without CO incorporation - as well as its efficiency with complex alkyl iodides and amines . Mechanistic studies demonstrated that a radical pathway is operative and the key role of CO.

Amine-incorporated quinoxaline based fluorescent sensor for detection of trace water: Solvent influenced self-assembly

Polarity is a complex parameter, with important effect in chemistry and biology. In recent years, polarity exploration attracted more and more attention hence, it’s of great importance to exploit new methods for polarity determination. A novel class of long, coplanar, and amine incorporated electron-rich quinoxaline scaffold(L1) furnished maximum solvatochromic effect and large Stokes shift and was chosen to determine water content in organic solvents e.g. acetonitrile, THF, DMF, and methanol through fluorescence spectroscopy. Moreover, the probe was found to perform as an effective fluorescent sensor for the quantitative detection of low-level moisture content in four commonly-used organic solvents with low detection limits (0.018%, 0.027%, 0.012%, and 0.43% respectively). This study also describes the morphological transformation of L1 form a fibrous network to spherical aggregates upon increasing water content in several organic solvents. Real-life implementation of the probe was successfully employed for the detection of moisture content in commercial food products and building materials such as cement, sand, limestone, salt, wheat, and detergent powder. Furthermore, probe L1-immersed easy-to-prepare test strips provide a reliable approach for qualitative monitoring of water content in organic solvents by a simple color-changing method under UV irradiation via smartphone-assisted RGB analysis.

Synthesis of Secondary Amines with Long Chains Containing Ether Bonds

AbstractA novel class of secondary amines with long chains containing ether bonds were synthesized by a three-step protection–etherification–deprotection process from diethanolamine. The optimum reaction conditions were examined. This method has the advantages of simplicity, low cost, and high yield. Furthermore, some new downstream products (diglycolamides) were prepared from the ether-containing long-chain secondary amines as reactants, and their loading capacities in extractions of several metal ions were evaluated.

Computational screening methodology identifies effective solvents for CO2 capture

Carbon capture and storage technologies are projected to increasingly contribute to cleaner energy transitions by significantly reducing CO2 emissions from fossil fuel-driven power and industrial plants. The industry standard technology for CO2 capture is chemical absorption with aqueous alkanolamines, which are often being mixed with an activator, piperazine, to increase the overall CO2 absorption rate. Inefficiency of the process due to the parasitic energy required for thermal regeneration of the solvent drives the search for new tertiary amines with better kinetics. Improving the efficiency of experimental screening using computational tools is challenging due to the complex nature of chemical absorption. We have developed a novel computational approach that combines kinetic experiments, molecular simulations and machine learning for the in silico screening of hundreds of prospective candidates and identify a class of tertiary amines that absorbs CO2 faster than a typical commercial solvent when mixed with piperazine, which was confirmed experimentally.

Identification of the profile of volatile compounds in commercial kombucha added with hibiscus (Hibiscus rosa-sinensis) / Identificação do perfil de compostos voláteis em kombucha comercial adicionado de hibisco (Hibiscus rosa-sinensis)

Kombucha is a fermented drink from a symbiotic culture of bacteria and yeasts (SCOBY) and has been consumed due to its sensory and antioxidant characteristics that provide several health benefits, in addition to scientific evidence showing that there are variations in the chemistry of these kombucha. Therefore, this study aimed to investigate the profile of volatile compounds from kombucha commercials using the GC-MS-SPME technique. Five kombucha samples from commercial points on Rio de Janeiro City were analyzed. The profile of volatile compounds was evaluated using the SPME technique using a PDMS/DVB/CAR triple fiber. Volatiles were identified by comparing their mass spectra with a NIST and IRL. The results indicated that the profile of volatile compounds analyzed was constituted by nine classes of compounds, namely, esters, ketones, carboxylic acids, alcohols, aldehydes, amines, hydrocarbons, lactones and terpenes. Among them, the esters were the majority, ranging from 20.0 to 28.0 %, it was also possible to observe that 2-Octenal was the most abundant compound in all samples, ranging from 52.7 to 63.0 %. Thus, it is seen that the profile of volatile compounds in kombucha is found by a complex mixture of compounds belonging to different classes and which have the esters as the most representative due to the fermentation process that occurs during the production of kombucha.

Systematic Evaluation of HILIC Stationary Phases for Global Metabolomics of Human Plasma.

Polar hydrophilic metabolites have been identified as important actors in many biochemical pathways. Despite continuous improvement and refinement of hydrophilic interaction liquid chromatography (HILIC) platforms, its application in global polar metabolomics has been underutilized. In this study, we aimed to systematically evaluate polar stationary phases for untargeted metabolomics by using HILIC columns (neutral and zwitterionic) that have been exploited widely in targeted approaches. To do so, high-resolution mass spectrometry was applied to thoroughly investigate selectivity, repeatability and matrix effect at three pH conditions for 9 classes of polar compounds using 54 authentic standards and plasma matrix. The column performance for utilization in untargeted metabolomics was assessed using plasma samples with diverse phenotypes. Our results indicate that the ZIC-c HILIC column operated at neutral pH exhibited several advantages, including superior performance for different classes of compounds, better isomer separation, repeatability and high metabolic coverage. Regardless of the column type, the retention of inorganic ions in plasma leads to extensive adduct formation and co-elution with analytes, which results in ion-suppression as part of the overall plasma matrix effect. In ZIC-c HILIC, the sodium chloride ion effect was particularly observed for amino acids and amine classes. Successful performance of HILIC for separation of plasma samples with different phenotypes highlights this mode of separation as a valuable approach in global profiling of plasma sample and discovering the metabolic changes associated with health and disease.

Directed Evolution of Artificial Metalloenzymes in Whole Cells.

Artificial metalloenzymes (ArMs), created by introducing synthetic cofactors into protein scaffolds, are an emerging class of catalyst for non-natural reactions. Although many classes of ArMs are known, in vitro reconstitution of cofactors and proteins has been a limiting step in the high-throughput screening and directed evolution of ArMs because purification of individual host proteins is time-consuming. We describe the application of a platform to combine mutants of the P450 enzyme CYP119 and the cofactor Ir(Me)MPIX in vivo, by coexpression of the CYP119 mutants with the heme transporter encoded by the hug operon, to the directed evolution of ArMs containing Ir(Me)MPIX in whole cells. We applied this platform to the development an ArMs catalyzing the insertion of the acyclic carbene from α-diazopropanoate esters (Me-EDA) into the N-H bonds of N-alkyl anilines, a combination of carbene and amine classes for which mutant enzymes of natural hemoproteins previously reacted with low enantioselectivity. The mutants of the artificial metalloenzyme Ir(Me)CYP119 identified by an evolution campaign involving more than 4000 mutants are shown to catalyze the reaction of Me-EDA with N-methyl anilines to form chiral chiral amino esters with high TON and good enantioselectivity, thereby demonstrating that the directed evolution of ArMs can rival that of natural enzymes in vivo.

Directed Evolution of Artificial Metalloenzymes in Whole Cells

AbstractArtificial metalloenzymes (ArMs), created by introducing synthetic cofactors into protein scaffolds, are an emerging class of catalyst for non‐natural reactions. Although many classes of ArMs are known, in vitro reconstitution of cofactors and proteins has been a limiting step in the high‐throughput screening and directed evolution of ArMs because purification of individual host proteins is time‐consuming. We describe the application of a platform to combine mutants of the P450 enzyme CYP119 and the cofactor Ir(Me)MPIX in vivo, by coexpression of the CYP119 mutants with the heme transporter encoded by the hug operon, to the directed evolution of ArMs containing Ir(Me)MPIX in whole cells. We applied this platform to the development an ArMs catalyzing the insertion of the acyclic carbene from α‐diazopropanoate esters (Me‐EDA) into the N−H bonds of N‐alkyl anilines, a combination of carbene and amine classes for which mutant enzymes of natural hemoproteins previously reacted with low enantioselectivity. The mutants of the artificial metalloenzyme Ir(Me)CYP119 identified by an evolution campaign involving more than 4000 mutants are shown to catalyze the reaction of Me‐EDA with N‐methyl anilines to form chiral chiral amino esters with high TON and good enantioselectivity, thereby demonstrating that the directed evolution of ArMs can rival that of natural enzymes in vivo.

Recent developments in reductive N-methylation with base-metal catalysts

N-methylamines are an important class of amines that find increasing applications in chemical, pharmaceutical, agrochemical and material industries. For their preparation, reductive N-methylation reactions employing CO2, formic acid, and (para)formaldehyde as renewable C1 sources have shown outstanding advantages compared to traditional methylation reagents, on standpoint of sustainable chemical processes. In this respect, significant efforts have been made on the synthesis of N-methylamines by catalytic reductive aminations. In this review, we discuss the recent advancements toward the base metal-catalyzed reductive amination of amines and nitroarenes including nitriles using CO2, formic acid, and (para)formaldehyde for the synthesis of diverse N-methylated products.