Tertiary Aromatic Amines Research Articles

Iodonium sulfonates as high‐performance coinitiators and additives for CQ‐based systems: Toward aromatic amine‐free photoinitiating systems

ABSTRACTIodonium sulfonates are proposed here as a new class of high‐performance coinitiators for camphorquinone (CQ)‐based systems for the polymerization of methacrylates under blue light irradiation. When combined with CQ, the new proposed coinitiators present excellent polymerization performances and are excellent candidates for the replacement of tertiary aromatic amines subjected to toxicological concerns in the well‐established CQ/amine photoinitiating system (PIS). Remarkably, good bleaching properties are obtained after polymerization. The use of the new PIS for dental adhesives is also investigated. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1664–1669

Rational Design of Efficient Amine Reductant Initiators for Amine-Peroxide Redox Polymerization.

Amine-peroxide redox polymerization (APRP) has been highly prevalent in industrial and medical applications since the 1950s, yet the initiation mechanism of this radical polymerization process is poorly understood so that innovations in the field are largely empirically driven and incremental. Through a combination of computational prediction and experimental analysis, we elucidate the mechanism of this important redox reaction between amines and benzoyl peroxide for the ambient production of initiating radicals. Our calculations show that APRP proceeds through SN2 attack by the amine on the peroxide but that homolysis of the resulting intermediate is the rate-determining step. We demonstrate a correlation between the computationally predicted initiating rate and the experimentally measured polymerization rate with an R2 = 0.80. The new mechanistic understanding was then applied to computationally predict amine reductant initiators with faster initiating kinetics. This led to our discovery of N-(4-methoxyphenyl)pyrrolidine (MPP) as amine reductant, which we confirmed significantly outperforms current state-of-the-art tertiary aromatic amines by ∼20-fold, making it the most efficient amine-peroxide redox initiator to date. The application of amines with superior kinetics such as MPP in APRP could greatly accelerate existing industrial processes, facilitate new industrial manufacturing methods, and improve biocompatibility in biomedical applications conducted with reduced initiator concentrations yet higher overall efficiency.

Study on the performance of methyl methacrylate polymerization: Comparison of partially oxidized tri-n-butylborane and benzoyl peroxide with aromatic tertiary amines.

In this study, we examined the polymerization performance of methyl methacrylate (MMA) initiated with partially oxidized tri-nbutylborane (TBBO) compared to that initiated with benzoyl peroxide and aromatic tertiary amine (BPO/amine) system. In the bulk polymerization of MMA at 37°C, conversion initiated with TBBO after 3 h was nearly quantitative, whereas the conversion with the BPO/amine system was low (~20%). The number-averaged and weight-averaged molecular weight of the TBBO-initiated polymer was more than twice as high as that of the BPO/amine-initiated polymer. Electron spin resonance (ESR) analysis of MMA polymerization indicated that the TBBO-initiated system maintained its radical intensities for a longer period than the BPO/amine-initiated system. Furthermore, the radical fragments in the TBBO-initiated PMMA after 72 h were still active as a polymerization initiator for MMA. These findings suggest that the polymerization mechanism of MMA initiated by TBBO functions as a living-like polymerization initiator.

Palladium(II)-Catalyzed Remote meta-C-H Functionalization of Aromatic Tertiary Amines.

Pd(II)-catalyzed remote C-H olefination of aromatic tertiary amines was achieved with high meta selectivity. With the assistance of an elaborated template, C-H functionalization of unreactive aryl tertiary amines, hindered by the p-π conjugation between the lone-pair electrons of the nitrogen atom and the phenyl ring, was realized with high meta regioselectivity via a quaternary ammonium salt assembly. The results demonstrate that apart from the distance and geometry of the template, the conformation of the arene substrate also plays a crucial role in the templated-assisted remote C-H functionalization.

Preparation of PSSS‐grafted polysulfone microfiltration membrane and its rejection and removal properties towards heavy metal ions

3‐Hydroxy‐N,N‐diethylaniline (HDEA) as a tertiary aromatic amine was introduced onto the surface of chloromethylated polysulfone (CMPSF) microfiltration membrane through modification reaction, resulting in the modified membrane PSF‐DEA. A redox surface‐initiating system (DEA/APS) was constituted by the bonded tertiary aromatic amine group DEA and ammonium persulfate (APS) in aqueous solution, and so, the free radicals formed on the membrane initiated sodium p‐styrenesulfonate (SSS) as an anionic monomer to produce graft polymerization, getting the grafting‐type composite microfiltration membrane, PSF‐g‐PSSS membrane. Subsequently, the adsorption property of PSF‐g‐PSSS membrane for three heavy metal ions, Pb2+, Zn2+, and Hg2+ ions, was fully examined, and the rejection performance of PSF‐g‐PSSS membrane towards the three heavy metal ions was emphatically evaluated via permeation experiments. The experimental results show that by the initiating of the surface‐initiating system of DEA/APS, the graft polymerization can smoothly be carried out under mild conditions. PSF‐g‐PSSS membrane as a functional microfiltration membrane has strong adsorption ability for heavy metal ions by right of strong electrostatic interaction (or ion exchange action) between the anionic sulfonate ions on the membrane and heavy metal ions. The order of adsorption capacity is Pb2+ > Zn2+ > Hg2+, and the adsorption capacity of Pb2+ ion gets up to 2.18 μmol/cm2. As the volume of permeation solutions, in which the concentrations of the three metal ions are 0.2 mmol/L, are in a range of 50 to 70 mL, the rejection rate of PSF‐g‐PSSS membrane for the three heavy metal ions can reach a level of 95%, displaying a fine rejection and removing performance towards heavy metal ions.

Photoredox Catalysis for the Coupling Reaction of Nitrones with Aromatic Tertiary Amines

Photoredox Catalysis for the Coupling Reaction of Nitrones with Aromatic Tertiary Amines

Metal-Free Synthesis of α-Aminophosphonates from Tertiary Amines and P(O)H Compounds via a Cross-Dehydrogenative Coupling Reaction

The various α-aminophosphonates have been prepared from tertiary aromatic and aliphatic amines with P(O)H compounds via a tert-butyl hydroperoxide mediated cross-dehydrogenative coupling reaction, eliminating the need for transition-metal catalysts. The oxidation of tertiary amine by tert-butyl hydroperoxide generates an iminium cation intermediate. A further addition of P(O)H compound to iminium cation gives the desired product.

Cobalt-Catalyzed Oxidative C(sp3)-H Phosphonylation for α-Aminophosphonates via C(sp3)-H/P(O)-H Coupling.

The first oxidative C(sp3)-H phosphonylation of tertiary aliphatic amines has been developed. The use of cobalt acetate as a catalyst, N-hydroxyphthalimide as a cocatalyst, and air as an oxidant enabled the conversion of tertiary aromatic and aliphatic amines into α-aminophosphonates in moderate to excellent yields under mild conditions via a cross dehydrogenative coupling reaction.

Direct arylation of tertiary amines via aryne intermediates using diaryliodonium salts

With a strategy by using diaryliodonium salts as the precursors of benzynes, direct N-arylation of tertiary amines with diaryliodonium salts was reported. Thus, the desired aromatic tertiary amines with a wide range of substituents were synthesized in moderate to excellent yields of 55–91%.

Triblock copolymers functionalized with quaternary ammonium salts as dehydrating agents for heavy and extra-heavy crude oils

ABSTRACTBlock copolymers PEO-PPO-PEO α,ω-functionalized with tertiary aliphatic or aromatic amines were synthesized to obtain a new type of ammonium salt. The compounds were evaluated as demulsifying agents in extra-heavy and heavy Mexican crude oils, 7.5° and 17.8° API. The grafting at the copolymer ends with trioctylamine and quinoline demonstrated to be the best functionalization for increasing the demulsifying efficiency in both crude oils. It was evidenced, for copolymers functionalized with aliphatic amines, that the length of the alkyl chain of the amine plays an important role in the potential to remove emulsified water. Furthermore, it was observed that higher positive value of log P parameter has a strong correlation with the performance of block copolymers functionalized with aliphatic amines. In the case of aromatic amines, the atomic charge of nitrogen proved to be an important factor to provoke the coalescence of the water drops. Finally, the molecular mass of block copolymer was also evaluated, showing that copolymers with higher are more efficient to remove the water from crude oils with huge amounts of asphaltenes.

A Si-rhodamine-based near-infrared fluorescent probe for visualizing endogenous peroxynitrite in living cells, tissues, and animals.

Peroxynitrite (ONOO-) is an extremely powerful biological oxidant and it can react with a wide variety of molecular targets to result in a series of disease states, which has made ONOO- a central biological pathogenic factor. In order to disclose its various pathological events, a large number of fluorescent ONOO- probes have been developed in recent years. Nevertheless, some limitations still remain, such as short excitation and emission wavelengths, long fluorescence response times, and cross-interference caused by other reactive oxygen species (ROS). In this work, a new near-infrared (NIR) fluorescent probe, SiRTA, containing an aromatic tertiary amine functional group and a Si-rhodamine fluorophore, was developed for endogenous ONOO- detection and imaging. The probe exhibits not only a fast, sensitive, and specific fluorescence off-on response toward ONOO- in chemical systems but also excellent imaging ability for endogenous ONOO- in living cells. With the probe, the therapeutic effects of phenolic acid antioxidants in EA.hy926 endothelial cells suffering from ischemia-reperfusion injury and the pathogenesis of diabetes and diabetic nephropathy in pancreatic β-cells and diabetic rats have successfully been evaluated. These results indicate that SiRTA is a potentially outstanding imaging tool for studying the physiological and pathological events of ONOO- and relevant drug therapies.

The sustainable heterogeneous catalytic reductive amination of lignin models to produce aromatic tertiary amines

A sustainable and heterogeneous catalytic reductive amination process is developed in the presence of heterogeneous zirconium-based catalysts, in which N,N-dimethylformamide (DMF) is used as the solvent, the low-molecular-weight amine source, and the reductant.

Carbonylative Tertiary Amide Synthesis from Aryl Iodides and Tertiary Amines via Oxidant‐Free C−N Bond Cleavage Catalyzed by Palladium(II) Chloride in Polyethylene Glycol/Water

AbstractIn this work, we have described the carbonylative synthesis of amides from aryl iodides and tertiary amines as an aminal source via oxidant‐free C(sp3)−N bond cleavage using in situ formation of palladium(0) nanoparticles from palladium(II) chloride in polyethylene glycol 400/water. Notably, these reactions were performed under base‐free, ligand‐free conditions and do not require any oxidant for the C−N bond cleavage. The developed protocol offers the selective N‐dealkylation of tertiary amines in a polyethylene glycol/water solvent system. Numerous symmetrical and unsymmetrical aliphatic, alicyclic, benzyl, as well as aromatic tertiary amines with aryl iodides were well tolerated and afforded the desired products in good yields. Furthermore, the in situ generation of palladium(0) nanoparticles in the polyethylene glycol 400 was confirmed by TEM, FEG‐SEM, EDS and XRD techniques, which strongly indicate that the palladium nanoparticles are highly active species and the reaction proceeds through the classical palladium(0)/palladium(II) pathway. Additionally, the syntheses can be easily scaled up and the catalytic system can be recycled up to five times without loss of its catalytic activity and selectivity.magnified image

N-Butyllithium-mediated synthesis of N-aryl tertiary amines by reactions of fluoroarenes with secondary amines at room temperature

A simple and facile method for the synthesis of aromatic tertiary amines by amination of fluoroarenes with secondary amines in the presence of n-butyllithium at room temperature was reported.

Polymerization of vinyl monomers in the presence of the initiating catalytic complexes “oxopropylidene tertiary aromatic amines – benzoyl peroxide”

Initiator systems for radical polymerization, having in its composition of several functional groups of interest in terms of creating new methods to control the polymer chain growth in radical polymerization, as it gives the opportunity to influence the molecular-mass characteristics of the products, on the kinetic parameters of the process, and in some cases, the composition and structure of polymers. The work examines the process of polymerization of vinyl monomers in the presence of a new initiating complexes of N,N’-dioxaphosphorinanes aniline (DOPA) + benzoyl peroxide, N,N’-dioxaphosphorinanes toluidine (DОPT) + benzoyl peroxide) and identified the mechanism of interaction of the initiating agents in the formation of the catalytic complex. In experiments was used a dilatometric technique. The polymerization was carried out at different temperatures (60, 80, 100 °C for styrene and 40, 60, 80 °C for methyl methacrylate). Determination of molecular weight of the styrene and methyl methacrylate were produced on the basis of measurements of the intrinsic viscosity of its solutions in toluene. Analyzed kinetics of radical polymerization of styrene and methyl methacrylate in the presence of initiating agents, benzoyl peroxide and DOPA, benzoyl peroxide and DОPT. Determined kinetic parameters of the polymerization of vinyl monomers in the presence of new catalytic systems. The rate of polymerization significantly depends on the concentration of the initiating agents. At high amine concentrations that exceed the peroxide content, there is a rapid expenditure of benzoyl peroxide. Established that tertiary aromatic amines oxopropylidene affect the increase in the rate of initiation of radical polymerization at moderately low temperatures. The proposed mechanism of radical polymerization of vinyl monomers in the presence of initiating system benzoyl peroxide DOPT.

Cobalt(II)-Catalyzed Oxidative Coupling of Aromatic Tertiary Amines with Enol Silyl Ethers Leading to β-Aminoketone Derivatives

We demonstrated that a cobalt(II)-TBHP ( tert -butyl hydro­peroxide) oxidizing system efficiently catalyzes the coupling of aromatic tertiary amines with enol silyl ethers, producing the corresponding β-aminoketones.

Cobalt-catalyzed oxidative annulation of aromatic tertiary amines with electron-deficient maleimides leading to tetrahydroquinoline derivatives

Described herein is a CoCl2–TBHP (t-butyl hydroperoxide) system that efficiently catalyzes the oxidative annulation of aromatic tertiary amines with a typical electron-deficient alkene, N-substituted maleimides, producing the corresponding polycyclic tetrahydroquinoline derivatives. This oxidizing system could also be applied to the annulation of an electron-rich alkene.

Substrate-Controlled Selectivity Switch in the Three-Component Coupling Involving Arynes, Aromatic Tertiary Amines, and CO2.

The transition-metal-free multicomponent coupling involving arynes, aromatic tertiary amines, and CO2 is reported. The reaction exhibits switchable selectivity depending on the electronic nature of the aromatic amines used. With amines bearing electron-releasing/neutral groups as the nucleophilic trigger, the reaction afforded 2-arylamino benzoates via a nitrogen to oxygen alkyl group migration. Employing electron-deficient amines in the reaction furnished 2-aminoaryl benzoates proceeding via the aryl to aryl amino group migration resembling a Smiles rearrangement.

A new class of fast-response and highly selective fluorescent probes for visualizing peroxynitrite in live cells, subcellular organelles, and kidney tissue of diabetic rats

Peroxynitrite (ONOO(-)) is an extremely powerful oxidant in biological systems, and can react with a wide variety of molecular targets including proteins, lipids, and nucleic acids, eventually resulting in a series of disease states such as diabetes, Alzheimer's disease, cancer, arthritis, autoimmune, and other disorders. In this work, we present a new class of ONOO(-) fluorescent probes by exploiting the ONOO(-)-triggered N-oxidation and N-nitrosation reactions of aromatic tertiary amine for the first time. The as-obtained fluorescent probe A2 could detect ONOO(-) with quite fast fluorescence off-on response (within seconds), ultrasensitivity (detection limit: <2nM), and excellent selectivity over a series of biologically relevant reactive oxygen species as well as metal cations. With the probe, the endogenous ONOO(-) in activated RAW264.7 murine macrophage, EA.hy926 endothelial cells after oxygen glucose deprivation and reoxygenation (OGD/RO), and kidney tissue of diabetic rats has been successfully visualized. Based on the molecular platform of A2, we further develop its mitochondria- and lysosome-targetable fluorescent probes Mito-A2 and Lyso-A2 by installing the corresponding targeting groups to alkoxy unit of A2, and confirm their abilities to image ONOO(-) in mitochondria and lysosomes, respectively, by co-localization assays. It is greatly expected that these probes can serve as useful imaging tools for clarifying the distribution and pathophysiological functions of ONOO(-) in cells, subcellular organelles, and animal tissues.

Employing Arynes in Diels-Alder Reactions and Transition-Metal-Free Multicomponent Coupling and Arylation Reactions.

Arynes are highly reactive intermediates having several applications in organic synthesis for the construction of various ortho-disubstituted arenes. Traditionally, arynes are generated in solution from haloarenes under strongly basic conditions. However, the scopes of many of the aryne reactions are limited because of the harsh conditions used for their generation. The renaissance of interest in aryne chemistry is mainly due to the mild conditions for their generation by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates. This Account is focused on the Diels-Alder reaction of arynes and their transition-metal-free application in multicomponent couplings as well as arylation reactions. The Diels-Alder reaction of arynes is a powerful tool for constructing benzo-fused carbocycles and heterocycles. In 2012, we developed an efficient, broad-scope, and scalable Diels-Alder reaction of pentafulvenes with arynes affording benzonorbornadiene derivatives. Subsequently, we accomplished the Diels-Alder reaction of arynes with dienes such as 1,2-benzoquinones and tropones. Moreover, we uncovered a transition-metal-free protocol for the synthesis of 9,10-dihydrophenanthrenes by the reaction of arynes with styrenes that proceeds via a Diels-Alder/ene-reaction cascade. In addition, we demonstrated the reaction of arynes with indene/benzofurans, which proceeds via a tandem [4 + 2]/[2 + 2] sequence. Multicomponent coupling (MCC) involving arynes mainly comprises the initial addition of a nucleophile to the aryne followed by interception of the aryl anion intermediate with an electrophile (provided the nucleophilic and electrophilic moieties do not belong to the same molecule). We have disclosed aryne MCCs initiated by N-heterocycles such as (iso)quinoline, pyridine, and aziridines. When (iso)quinoline is used as the nucleophilic trigger and N-substituted isatin as the third component, the reaction affords spirooxazino(iso)quinolines via 1,4-dipolar intermediates. Unexpectedly, using pyridine affords indolin-2-ones, where the reaction proceeds via the pyridylidene intermediate. Additionally, we developed the phosphine-triggered aryne MCCs for the synthesis of functionalized benzooxaphospholes. In another phase of our work, we studied the synthetic utility of CO2 as a one-carbon synthon in aryne MCCs for the synthesis of phthalimides. Engaging arynes as an aryl source is one of the transition-metal-free methods for arylation reactions. We have demonstrated the N-arylation of aromatic tertiary amines and O-arylation of aliphatic alcohols using arynes. It is anticipated that the chemistry of arynes will continue to prosper and will lead to surprising developments for the synthesis of various 1,2-disubstituted arenes of molecular complexity and structural diversity. Future challenges in this area include the utility of arynes in enantioselective transformations and the synthesis and reactions of exotic heterocyclic arynes.