Agents For Amines Research Articles

Synthesis of γ-Amino Amides by Iridium-Catalyzed Enantioselective Hydroamination of Internal Alkenes Directed by an Amide.

Catalytic regio- and enantioselective hydroamination of less activated internal alkenes presents a challenge to synthetic chemists due to their low reactivity and the difficulty in simultaneously controlling regio- and enantioselectivities. Here, we report an iridium-catalyzed enantioselective hydroamination of internal alkenes directed by an amide. The amide group on the alkene effectively directs the catalyst to overcome the low reactivity and control the regioselectivity and the enantiotopic face selection. Phthalimide serves as the amination agent, which could be readily removed to afford a primary amine. This coordination assistance enables hydroamination to occur selectively at the remote position with up to 97% ee, delivering valuable enantio-enriched γ-amino acid derivatives that are otherwise challenging to access.

Increasing the Thermal Resistance of Water-Based Mud for Drilling Geothermal Wells

Energy demand and growing environmental concerns have fueled increased interest in geothermal drilling in recent decades. The high temperature and pressure in the boreholes present significant challenges to drilling, particularly in terms of the selection of suitable drilling mud, cement slurry, and drilling equipment. Drilling mud is regarded as one of the primary factors that affect the cost and success of geothermal drilling. This paper presents experimental studies aimed at assessing the thermal stability of drilling muds for geothermal drilling. Research on the antidegradation of polymers contained in drilling muds is presented. The thermal stability of drilling fluids was evaluated on the basis of changes in rheological and filtration parameters under the influence of a temperature of 160 °C. Attempts were made to increase the thermal resistance of drilling fluids by using antioxidants and glycol compounds. The effectiveness of increasing the thermal resistance of muds by adding synthetic polymers, nanomaterials, and graphite was tested. A new way of increasing the thermal resistance of drilling muds by using fatty amine compounds in combination with the amine agent ‘TEA’ was proposed. Tests showed that the addition of polyglycol and the antioxidant agent sodium ascorbate to the mud did not protect the polymers from decomposition at 160 °C. There was no effect of increasing the thermal conductivity on improving the thermal resistance of the scrubber. Based on the analysis of results from laboratory tests, a composition of a water-based drilling mud without bentonite was developed for drilling geothermal wells. The developed drilling mud is characterized by thermal resistance up to 160 °C, stable rheological parameters, low filtration, and appropriate thermal conductivity characteristics.

Azodicarboxylate as a comonomer for radical polymerization to incorporate nitrogen–nitrogen single bonds into the polymer chain

AbstractIn organic synthesis, azodicarboxylates are frequently used as an aza‐dienophile and electrophilic amination agent. To create carbon–nitrogen bonds, azodicarboxylates typically react with nucleophiles or radicals. This report explores its reactivity as a co‐monomer towards radical polymerization to introduce nitrogen–nitrogen single bonds into the polymer chain. Azodicarboxylates are capable of copolymerizing with styrenic monomers to achieve linear polymers with 40% feed.

Mechanism of Modified Ether Amine Agents in Petalite and Quartz Flotation Systems under Weak Alkaline Conditions

To investigate the flotation separation behavior of petalite and quartz, various methods were employed in this study. These included micro-flotation experiments, a contact angle analysis, zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) to explore the separation mechanism of a modified ether amine reagent (L0-503) for petalite and quartz under weakly alkaline conditions. The micro-flotation test results indicated that the modified ether amine collector had a higher collecting ability for quartz than for petalite, with a maximum recovery rate of 93.2% for quartz and a recovery rate consistently below 14% for petalite in the presence of L0-503. This indicates that the modified ether amine reagent can be used as a reverse flotation agent for separating petalite and quartz. The separation mechanism results showed that the modified ether amine reagent had a significantly higher adsorption capacity for quartz than for petalite due to a strong reaction between the quartz and the secondary amine (-NH=) on the modified ether amine collector. Additionally, the electrostatic force and hydrogen bonding between the reagent and quartz further enhanced the adsorption, while no reaction occurred between the reagent and petalite.

Preparation of a novel high-performance lignin-based anionic adsorption resin for efficient removal of Cr(VI) in aqueous solutions

To remove Cr(VI) in water, a novel lignin-based anionic adsorption resin epichlorohydrin cross-linking lignin grafted by diethylenetriamine (E-DAL) was prepared by the direct cross-linking and curing of alkali lignin grafted by diethylenetriamine in aqueous solutions. Under the determined optimum synthesis conditions, E-DAL with higher nitrogen (7.46%) and lignin (32.78%) contents was obtained. Structural and physicochemical measurement results showed E-DAL was a macroporous resin, having a regular connected pore structure with porosity of 67.48% and pore size of 615.6 nm, also strong hydrophilicity, excellent acid-alkaline resistance and thermal stability. Adsorption experiment results indicated the adsorption isotherm of E-DAL to Cr(VI) was well-described by Langmuir model. E-DAL showed a higher adsorption capacity to Cr(VI), and the fitted maximum adsorption capacity reached up to 775.2 mg/g. Pseudo-second-order model could fit this adsorption process well, suggesting its chemisorption characteristics. The calculated thermodynamic parameters indicated a spontaneous and endothermic adsorption of E-DAL to Cr(VI). Dynamic column adsorption results showed E-DAL could completely remove Cr(VI) in wastewater. This whole preparation process only used a very small amount of cheaper amination agent and was relatively low-cost. This work provided efficient technical supports for the structural design of high-performance lignin-based anionic adsorption materials in water treatment field.

Electronic structure and detonation property prediction of pentazolate derivatives: Aminopentazole, diaminopentazole cations, azopentazole, and 1,2-diazopentazole

In this study, various polynitrogen pentazolate derivatives: aminopentazole, diaminopentazole cations, azopentazole (N12), and 1,2-diazopentazole (N14), were designed and computed. Based on quantum chemistry calculations and wavefunction analyses, the equilibrium geometry, bond orders, atoms-in-molecules (AIM) analysis, atomic charges, electrostatic potential distribution, frontier molecular orbitals, and many indices to represent aromaticity were determined and represented. In addition, their densities, heats of formation, detonation properties, and impact sensitivities were calculated using thermodynamics methods. These polynitrogen pentazolate derivatives could exhibit high density (1.668–1.965 g·cm−3); high heat of formation (2.96–15.86 kJ·g−1); outstanding detonation performance (D: 9070–12,243 m·s−1, P: 34.8–70.0 GPa); in particular, N14 (D: 12,243 m·s−1, P: 70.0 GPa); acceptable thermostability and sensitivity (h50: 12–49 cm). The excellent energetic performance demonstrates that polynitrogen pentazolate derivatives are promising energetic materials. The synthesis of aminopentazole and diaminopentazole cations may be achieved via an amination agent and the synthesis of N12 and N14 using an oxidizing agent.

Cobalt phthalocyanine conjugated SBA-15 mesoporous silica via the Ugi four-component reaction: A potential heterogeneous catalytic nanocomposite for CO2 fixation reaction

Owing to the porosity, high hydrothermal and mechanical stability of SBA-15, this type of silica mesoporous has attracted significant attention from many researchers for catalytic systems design. Accordingly, SBA-15 was utilized in this work as eco-friendly support to synthesize an effective heterogeneous catalytic nanocomposite based on the conjugation or immobilization of metalophthalocyanines (MPcs). For this purpose, initially, SBA-15 was modified by (3-aminopropyl)triethoxysilane (APTES) as an amination agent to produce SBA-15-NH2 and then participated in a straightforward one-pot Ugi four-component reaction (Ugi-4CR) of cyclohexyl isocyanide, benzaldehyde, and cobalt (II) phthalocyanine tetracarboxylic acid (Co-PcTCA) as an acid component. Afterward, the catalytic activity of the cobalt (II) phthalocyanine immobilized via SBA-15-NH2 (Co-PcTCA/SBA-15-N) was examined in the CO2 fixation reaction for the preparation of cyclic carbonates in water as a green solvent. Interestingly, catalytic experiments revealed that SBA-15 as a porose support could considerably ameliorate the catalytical properties of the Co-PcTCA regarding the CO2 fixation reaction via high CO2 adsorbent capacity in the shortest reaction time.

Determination of Anthraquinone-Tagged Amines Using High-Performance Liquid Chromatography with Online UV Irradiation and Luminol Chemiluminescence Detection

Quinones are frequently used as derivatization reagents in HPLC analysis to improve detection sensitivity. In the present study, a simple, sensitive, and selective chemiluminescence (CL) derivatization strategy for biogenic amines, prior to their HPLC-CL analysis, was developed. The novel CL derivatization strategy was established based on using anthraquinone-2-carbonyl chloride as derivatizing agent for amines and then using the unique property of the quinones' moiety to generate reactive oxygen species (ROS) in response to UV irradiation. Typical amines such as tryptamine and phenethylamine were derivatized with anthraquinone-2-carbonyl chloride and then injected into an HPLC system equipped with an online photoreactor. The anthraquinone-tagged amines are separated and then UV-irradiated when they pass through a photoreactor to generate ROS from the quinone moiety of the derivative. Tryptamine and phenethylamine can be determined by measuring the chemiluminescence intensity produced by the reaction of the generated ROS with luminol. The chemiluminescence disappears when the photoreactor is turned off, suggesting that ROS are no longer generated from the quinone moiety in the absence of UV irradiation. This result indicates that the generation of ROS could be controlled by turning the photoreactor on and off. Under the optimized conditions, the limits of detection for tryptamine and phenethylamine were 124 and 84 nM, respectively. The developed method is successfully applied to determine the concentrations of tryptamine and phenethylamine in wine samples.

C1-symmetric aza-crown ethers as chiral shift agents for amines and amino acid derivatives

Reported herein is our recent research progress in the development of macrocyclic chiral recognition studies. Highly enantiopure C1-symmetric aza-crown ethers, which were prepared previously by our lab from catalytic enantioselective symmetry-breaking C (sp3)-H bond transformation of readily available and inexpensive aza-crown ethers, were useful 1H NMR chiral shift reagents to resolve racemic amines and amino acid derivatives, providing an easy and rapid NMR assay of enantiomeric purity of chiral compounds, especially chromophore-devoid ones that are not detected and quantified by colorimetric method.

A Robust Strategy for Photoinitiated Macromolecular Thiol‐Ene Radical Coupling Reaction with High‐Efficiency Based on a RAFT‐Generated Thiol‐Terminated PDPA Reactant

AbstractThiol‐ene radical coupling reaction exhibits high chemical selectivity and rapid kinetics. In particular, the experiment of photoinitiated reaction has the advantages of facile operation and short reaction time. However, there are few reports on its application in macromolecular thiol‐ene coupling reaction in the presence of polymeric chains containing amine moieties. On the one hand, an amine agent itself may be involved in photoreaction; and on the other hand, amine moieties can create an alkaline environment, which may retard thiol‐ene radical reaction. In this paper, a well‐defined A(B‐L)2 type miktoarm star copolymer unit is investigated and synthesized, together with further A(B‐L)2C type one, by employing macromolecular thiol‐ene radical coupling reactions. In two copolymers, A, B, and C are poly(ε‐caprolactone) (PCL), poly(2‐(diisopropylamino) ethyl methacrylate) (PDPA), and poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC) arms, respectively, and L is terpyridine (tpy) ligand group and locates at the end of B arm. Especially, the synthesis of A(B‐L)2 type molecular architecture involved that a PDPA reactant (tpy‐PDPA‐SH) contains both a thiol end‐group and pendant tertiary amine moieties. Herein, such a macromolecular thiol‐ene radical coupling reaction is investigated and a robust synthesis strategy is reported.

Palladium‐Catalyzed Sequential C−H Activation/Amination of 2‐Iodobiphenyls with Benzoisoxazoles for Synthesis of Carbazoles

AbstractA coupling reaction of 2‐iodobiphenyl with benzoisoxazole under the cooperative catalysis of Pd(CH3CN)2Cl2 and P(4‐F−Ph)3 is disclosed. The reaction proceeds via intramolecular C−H activation/N−O cleavage/migratory insertion sequence to give an array of N‐arylcarbazoles with an aldehyde or a ketone. The employment of benzoisoxazoles as an amination agent obviates the need for stoichiometric amount of oxidants.magnified image

Synthesis of Hydrofluoroolefin-Based Iodonium Reagent via Dyotropic Rearrangement and Its Utilization in Fluoroalkylation.

[1,2]‐shift of atoms in alkyl fragments belongs to the class of dyotropic rearrangements. Various atoms, including halogens can be involved in the migration, however participation of iodine is unprecedented. Herein, we report our experimental and DFT studies on the oxidation triggered dyotropic rearrangement of iodo and chloro functions via butterfly‐type transition state to demonstrate the migrating ability of λ3‐iodane centre. With the exploitation of dyotropic rearrangement we designed and synthesized a novel fluoroalkyl iodonium reagent from industrial feedstock gas HFO‐1234yf. We demonstrated that the hypervalent reagent serves as an excellent fluoroalkylation agent for various amines and nitrogen heterocycles.

Synthesis of Hydrofluoroolefin‐Based Iodonium Reagent via Dyotropic Rearrangement and Its Utilization in Fluoroalkylation

Abstract[1,2]‐shift of atoms in alkyl fragments belongs to the class of dyotropic rearrangements. Various atoms, including halogens can be involved in the migration, however participation of iodine is unprecedented. Herein, we report our experimental and DFT studies on the oxidation triggered dyotropic rearrangement of iodo and chloro functions via butterfly‐type transition state to demonstrate the migrating ability of λ3‐iodane centre. With the exploitation of dyotropic rearrangement we designed and synthesized a novel fluoroalkyl iodonium reagent from industrial feedstock gas HFO‐1234yf. We demonstrated that the hypervalent reagent serves as an excellent fluoroalkylation agent for various amines and nitrogen heterocycles.

Firm evidence for the detoxification of senecionine-induced hepatotoxicity via N-glucuronidation in UGT1A4–humanized transgenic mice

Uridine diphosphate glucuronosyltransferase (UGT)1A4 is responsible for N-glucuronidation of tertiary amines but is a pseudogene in commonly used rodent models in toxicity and safety assessment. As a continuation of our investigation into the toxicity and safety assessment of pyrrolizidine alkaloid (PA)-containing herbs, we generated a UGT1A4–humanized (hUGT1A4) transgenic mouse model to systematically study the toxicity, metabolism network, and toxicokinetic characteristics of senecionine (a representative toxic PA) and compared with that in the wide-type controls in parallel. As results, senecionine-induced toxicity was significantly decreased as approved by mortality, pathology, and biochemistry assays in hUGT1A4 mice and cultured primary hepatocytes. More importantly N-glucuronidation adduct was exclusively identified in all the hUGT1A4 mice, liver microsomes, and cultured primary hepatocytes, yet absent in the wide-type controls. The variation in toxicokinetic characters was also observed between hUGT1A4 mice and the wide-type controls with a notably inhibition of the toxification metabolites, i.e., pyrrole-protein adducts, in hUGT1A4 mice. Conclusively, UGT1A4 plays an important role in detoxification of senecionine and the hUGT1A4 mouse model is promising for the pre-clinical evaluation of the efficacy and toxicity of tertiary amine agents in drug development and safety assessment.

Nitrocellulose blister material as a source of N-nitrosamine contamination of pharmaceutical drug products

The recent focus of pharmaceutical regulatory authorities has been oriented towards the mitigation of carcinogenic N-nitrosamines in drug products and different sources of N-nitrosamines have been revealed. Within this work, the elucidation of a further source of N-nitrosamines in drug products is reported. A case was investigated where traces of N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were detected in a finished dosage form, whereas they were not found in the bulk drug product. This led to an in-depth study of blister material as a potential source, wherein nitrocellulose primer in a lidding foil was identified as a risk factor. Nitrocellulose acts as a nitrosating agent for secondary amines, present in printing inks, forming N-nitrosamines in lidding foil. Their formation was confirmed by the addition of printing ink containing dimethylamine and diethylamine, or diethylamine alone, to lidding foil containing nitrocellulose primer. Their transfer to drug product during the blistering operation was demonstrated by solid-phase microextraction sampling of N-nitrosamine vapors on two commonly used types of pharmaceutical blistering machines, operating with plate sealing or roller sealing technology. Higher vapor amounts were detected on plate sealing equipment, where N-nitrosamine contamination was additionally confirmed in film-coated tablets and blister cavities of the finished dosage form.

Preparation and structure tuning of CO2 adsorbent based on in-situ amine-functionalized hierarchical porous polymer

Amine-functionalized porous adsorbent is one kind of important materials in carbon dioxide capture due to its stability and efficiency. In this study, a copolymer (polyHIPE) with interconnected macropore networks, hierarchical porous structure and abundant branched amino groups was prepared by high internal phase emulsion (HIPE) strategy via copolymerization of styrene (St), divinylbenzene (DVB), tetraethyl orthosilicate (TEOS), and triethoxyvinylsilane (VTEO), and then a novel amine-functionalized CO 2 adsorbent was synthesized by in situ ring-opening grafting copolymerization of aziridine with the polyHIPE. The structure, morphology, and physicochemical properties of the polyHIPEs were characterized by FTIR, TEM, TGA, and SEM. The key roles of VTEO and TEOS in introducing active hydroxyl groups onto the surface of the inert polymer was evaluated, which was essential to improve the hydrophilicity of the polyHIPE and to provide reactive sites to combine with amine agents. The contact angle of the polyHIPE while copolymerized with TEOS and VTEO significantly was decreased from 144° to 72°. In order to further increase the specific surface area of the polyHIPEs, post crosslinking of polyHIPEs was implemented through a Friedel–Crafts reaction. The specific surface area of post-crosslinked polyHIPE could reach 513 m 2 /g, which was proven to be effective to enhance its CO 2 adsorption capacity. Finally, the abundant branched amino sites via aziridine grafting and high surface area greatly enhanced CO 2 adsorption capacity of the amino-modified polyHIPEs. The adsorption capacity of 2.40 and 3.25 mmol CO 2 /g could be achieved under dry and humid conditions in 0.1 atm partial pressure of CO 2 , respectively. • The hydroxyl groups modified monolithic was synthesized by one-step high inner phase emulsion copolymerization. • The post-crosslinking and in-situ grafting of amino obtained higher specific surface area and more CO 2 adsorption sites. • The polyHIPE-V 1 T 2 -HCP-NH monolithic exhibits obviously high CO 2 adsorption capacity and amino efficiency. • 3.25 mmol CO 2 /g-adsorbent and amine efficiency of 0.65 mmol CO 2 /mmol N could be achieved under humid conditions.

C1-Symmetric Aza-Crown Ethers as Chiral Shift Agents for Amines and Amino Acid Derivatives

C1-Symmetric Aza-Crown Ethers as Chiral Shift Agents for Amines and Amino Acid Derivatives

Preparation of the interfacial enhanced PA/APVC nanofiltration membrane based on the in-situ amination of substrate membrane

In this research, a novel interfacial enhanced thin film composite nanofiltration (TFC NF) membrane with nail-fixed like surface structure and wave line like cross-section structure, good permeability and superior interfacial stability was prepared by interfacial polymerization (IP) on one-step in-situ aminated polyvinyl chloride (APVC) support layer. The effects of amination agent (triethylenetetramine, TETA) content on the support layers and the effects of the support layers with different degrees of amination on the performance of the TFC NF membranes were studied comprehensively. Furthermore, the interfacial bonding strength of the TFC NF membrane was explored by the inverse permeation test. It was concluded from the results that higher TETA content in casting solution led to the APVC membrane to form macroporous surface structure, thinner top skin layer and larger mean pore size. Meanwhile, more TETA molecules were grafted onto the PVC chains through nucleophilic substitution to participate in IP in a synergistic manner. Accordingly, the corresponding TFC NF membrane formed a nail-fixed like surface structure similar to semi-free-standing polyamide (PA) layer and wave line like cross-section structure with thinner and denser active layer. The water flux of the TFC NF membrane prepared with the optimized APVC membrane as the substrate membrane was increased by 395% at 0.6 MPa compared with the TFC NF membrane prepared with PVC membrane as the substrate membrane, while Na2SO4 rejection did not sacrifice and increased by 3.48%, which manifested that unique structure was favorable to speed up the water transmission and effectively conquered the trade-off effect. Moreover, the representative TFC NF membrane prepared with optimized APVC membrane as the substrate membrane with strong covalent bond between support layer and active layer demonstrated superior interfacial stability in the short-term circulating inverse permeation test.

Copper-Catalyzed Electrophilic Amination of Diarylcadmium Reagents Utilizing Acetone O-(4- chlorophenylsulphonyl)oxime and Acetone O-(2-naphthylsulphonyl)oxime as Amination Agent

In this study, a CuCN catalyzed process of the diarylcadmium compounds by electrophilic amination method was developed using novel acetone O-(4-chlorophenylsulfonyl)oxime and acetone O-(2-naphthylsulfonyl)oxime. Herein, it has been demonstrated that primary arylamines can easily be obtained with good yields at room temperature by CuCN catalyzed amination of diarylcadmium reagents. It was settled down that the yield of primary arylamines depended strongly on the steric and electronic effects of organocadmium reagent and amination agent. In both amination reagents, meta-substituted arylamines were obtained in higher yields than para-substituted aryl amines. All reactions involving organocadmiums were carried out under an argon atmosphere by standard syringe/cannula methods. Amines as reaction products were separated from the reaction mixture as benzamide derivatives and purified and melting points, 1H NMR analysis determined their accuracy.

Room-temperature copper-catalyzed electrophilic amination of arylcadmium iodides with ketoximes

We started our study by preparation two ketoximes. Later, there were studies to reveal these ketoximes' effects in the electrophilic amination reaction with organocadmium reagents. Primarily, it was observed that arylcadmium iodides could not be reacted with ketoximes at room temperature in the absence of a catalyst. CuCN was a suitable catalyst for this electrophilic amination reaction of arylcadmium iodides and allowed the preparation of functionalized aniline derivatives in good yields under mild reaction conditions. We obtained the results indicated that the yield of primary arylamines was strongly dependent on the steric and electronic effects of organocadmium reagent and amination agent. In the case of both amination reagents, meta-substituted arylamines were obtained in higher yields than para-substituted arylamines. We observed that acetone O-(4-chlorophenylsulfonyl)oxime, 1, as an aminating agent, was more successful than acetone O-(2-Naphthylsulfonyl)oxime, 2, in the synthesis of functionalized arylamines by electrophilic amination of corresponding aryl cadmium iodides. In this method, there is no cadmium release to the environment.