Aminolysis Products Research Articles

Green synthesis of δ-lactam from biomass-derived 4-hydroxy-6-methylpyridin-2(1H)-one

The sustainable route for δ-lactam (6-methylpiperidin-2-one: MPO) production has been demonstrated through transfer hydrogenation/hydrogenolysis of aminolysis product of biomass-derived triacetic acid lactone (TAL) with bimetallic Ni-Ru catalyst.

Mechano-chemical rubber reclamation using aminolysis products of waste flexible polyurethane foams as the devulcanizing agent

Rubber and polyurethane are polymers that are widely used but difficult to decompose in the natural environment. In this work, polyurethane aminolysis products (PAPs) are used to assist in the devulcanization of waste rubbers for the first time. The amine groups contained in PAPs can couple with the radicals generated by the scissions of crosslink bonds under the action of mechanical shear force, enhance the degree of devulcanization, and thus improve the mechanical properties of the reclaimed rubbers (RRs). The addition of PAPs can also shorten the optimum cure time of the RRs and improve the crosslink density and hardness of the RR re-vulcanizates. Using 1.8 phr of lower-layer PAPs prepared at 120 °C, the RR re-vulcanizate exhibit a tensile strength of 16.48 MPa, an elongation at break of 330.2%, and a tear strength of 48.5 MPa. This method realizes the dual high-value recycling of waste polyurethanes and rubbers, exhibiting bright application prospects.

Chemical conversion of waste PET to valued-added bis(2-hydroxyethyl) terephthalamide through aminolysis

Polyethylene terephthalate (PET) refers to a widely used thermoplastic polymer that is difficult to degrade naturally. Therefore, large amounts of waste PET need to be recycled. In this study, to achieve a green and efficient method to degrade and recycle waste PET for new functional chemicals, PET waste was first swelled with acetic acid. Then, it was degraded under atmospheric pressure at 70 °C for 4 h using ethanolamine as solvent. The degradation efficiency of PET was higher than conventional methods because of the swelling-induced pores caused by the acetic acid. The aminolysis product bis(2-hydroxyethyl) terephthalamide was confirmed by Fourier transform infrared and nuclear magnetic resonance characterization methods and could be readily separated and recovered from the solvent. Finally, the degradation mechanism was discussed. This research provides a feasible and efficient approach to realize the recycling of PET with high value.

Conversion of waste bottle PET to magnetic microparticles adsorbent for dye-simulated wastewater treatment

Mass production and consequent accumulation of plastic wastes in the environment urges the development of technologies for the efficient plastic wastes utilization and valorization to materials and products to support circular economy. Here, we report a novel conversion of PET plastic to a magnetic microparticles adsorbent prepared by co-precipitation of Fe3O4 nanoparticles with oligomeric products of PET aminolysis. The obtained adsorbent represents highly water-dispersible oligo(terephthalamide) particles of several tens μm size embedding magnetic nanoparticles randomly distributed in the organic matrix. The PET-derived magnetic adsorbent was used for the rapid and facile magnetic separation of an anionic dye (Congo Red, CR) from dye simulated water samples. The adsorbent containing plenty of amine groups showed superb adsorption capacity for CR of ca. 780 mg/g which is pH dependent and optimal at pH 6.5. Furthermore, the microparticular, non-aggregative state of the adsorbent coupled with its magnetic functionality provided rapid saturation of the adsorbent with dye by ca. 70% of the equilibrium adsorption capacity within 5 min and possibility of instantaneous removal from solution by a magnet. The proposed here material design addresses simultaneously the problem of plastic wastes utilization and preparation of cost-effective and efficient adsorbents for environmental cleaning purposes.

Aminolysis-assisted hydrothermal conversion of waste PET plastic to N-doped carbon dots with markedly enhanced fluorescence

While the possibility of waste bottles’ PET conversion to fluorescent materials has been recently demonstrated, optimization of the conversion protocol based on rational material design may greatly enhance key characteristics of the upcycled material. In this study, conversion of PET to fluorescent nanomaterials by means of hydrothermal (HT) treatment of PET and products of PET pyrolysis, glycolysis, and aminolysis in the presence and in the absence of an oxidizing agent was systematically investigated to compare fluorescent properties of HT products. Among studied conversion routes, the direct HT conversion of PET or a combination of the HT treatment with the PET pre-treatment by either pyrolysis or glycolysis resulted in non-fluorescent of weakly fluorescent products, whereas aminolysis of PET bottle plastics followed by the HT treatment of the aminolysis products increased dramatically, up to tens to hundreds fold, the fluorescence of the products. Admixing of several percent of an oxidant, H2O2, to HT mixture further enhanced the product fluorescence yielding fluorescent nanoparticles (nitrogen-doped carbon dots, NCDs) with 25.3% conversion yield and the quantum yield of 9.1%. Based on 1H and 13C NMR, FTIR, XPS, and Raman spectroscopy data, the mechanism of NCDs formation was proposed. The N-doped carbon dots obtained by waste PET upcycling were used for detection and quantification of Cu2+ ion at ppm and Fe3+ ion at ppb concentrations.

Asparaginyl Endopeptidase-Mediated Protein C-Terminal Hydrazinolysis for the Synthesis of Bioconjugates.

Asparaginyl endopeptidases (AEPs) are cysteinyl enzymes naturally catalyzing the hydrolysis and transpeptidation reactions at Asx-Xaa bonds. These reactions go by a common acyl-enzyme thioester intermediate, which is either attacked by water (for a protease-AEP) or by a peptidic amine nucleophile (for a ligase-AEP) to form the respective hydrolysis or aminolysis product. Herein, we show that hydrazine and hydroxylamine, two α-effect nucleophiles, are capable of resolving the thioester intermediate to yield peptide and protein products containing a C-terminal hydrazide and hydroxamic acid functionality, respectively. The hydrazinolysis reaction exhibits very high efficiency and can be completed in minutes at a low enzyme-to-substrate ratio. We further show the utility of the so-formed asparaginyl hydrazide in native chemical ligation and hydrazone conjugation. Using an EGFR-targeting affibody as a model protein, we have showcased our methodology in the preparation of a number of protein ligation or conjugation products, which are decorated with various functional moieties. The ZEGFR affibody-doxorubicin conjugate shows high selective binding and cytotoxicity toward the EGFR-positive A431 cells. Our results demonstrate the advantages of AEP-mediated protein hydrazinolysis as a simple and straightforward strategy for the precision manufacturing of protein bioconjugates.

Conversion of waste bottles’ PET to a hydrogel adsorbent via PET aminolysis

To ensure sustainable use of natural resources and circulation of materials, efficient methods of waste plastic conversion into value chemicals and scenarios for utilization of the latter are increasingly demanded. Here, we propose a method of waste PET bottles conversion to cross-linked hydrogels through PET aminolysis using tri- and tetraamines as a method of plastic waste valorization. Water-soluble oligomeric products of PET aminolysis were cross-linked in water using diglycidyl ether to get mechanically stable hydrogels that show typical polyelectrolyte behavior of polycations. PET-derived hydrogels abundant with amino groups and aromatic moieties were tested as adsorbents for an anionic dye such as Congo Red, and their absorption capacity towards dye was found to be ca. 500 mg/g. Beside demonstrated here application of PET-derived hydrogels for water cleaning from an industrial dye, utilization of such hydrogel materials in fields of environment, agriculture, separation, etc. are also anticipated.

Reactions of 4‐Nitrophenyl 5‐substituted Furan‐2‐carboxylates with R2NH/R2NH2+ in 20 mol% DMSO(aq): Effect of Aryl Group on the Acyl‐Transfer Reaction

Reactions of 4‐nitrophenyl 2‐furoates (1a–e) with R2NH/R2NH2+ in 20 mol% DMSO(aq) have been studied. The reactions produced aminolysis products and exhibited second‐order kinetics. The Brönsted plots were linear with βnuc values of 0.75–0.89, which remained nearly the same for all 5‐furyl substituents. The rate data showed excellent correlations on the Yukawa‐Tsuno plots with ρ(x) = 0.72–1.1, and r = 0.55–0.95, respectively. The ρ value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the CO bond and a decrease in the resonance contribution. The results have been interpreted with the addition–elimination mechanism in which the second step is the rds. By comparing with the data for ArC(O)OC6H4‐4‐NO2 (Ar = Ph, thienyl), the effect of the aryl group on the acyl transfer reaction was assessed.

Synthesis and characterization of isophorondiamine-based oligoamides: catalytic effect of amides during the curing of epoxy resins

The aminolysis products of PET could be applied in several fields. The purpose of this study was to explore their use as a dual-purpose component as cross-linkers and catalysts in epoxy curing. PET aminolysis was carried out with 1:1.5 and 1:2 PET/amine ratios to produce amides with different molecular weights. The reaction products were characterized with functional group analysis, NMR, FTIR, MALDI-TOF, and solution viscosimetry. The terephthalamides were dissolved in isophorondiamine and used as cross-linkers. Reaction kinetics studies with DSC, viscosimetry, and quantum chemical computational methods were used to characterize their accelerative effects. Our studies have shown that terephthalamides are active catalyst and their efficiency can be tuned with their molecular weight. The quantum chemical simulations suggested that the terephthalamides are in the same order of magnitude in effectiveness as phenolic accelerators. Consequently, terephthalamides are valued materials that can serve as double-purpose components in epoxy curing.

Effect of functional groups on the thermal degradation of phosphorus- and phosphorus/nitrogen-containing functional polymers

In the present study the thermal behavior of phosphorus- and phosphorus/nitrogen-containing functional polymers was studied. The polymers were synthesized via oxidative chlorophosphorylation reaction of butadiene rubber and were subsequently subjected to hydrolysis, aminolysis and/or alcoholysis in order to introduce appropriate functionalities. The successful modifications of the polymer and presences of the respective functional groups were determined using Fourier transform infrared spectroscopy. It was found that the product of hydrolysis of the modified butadiene rubber contains acidic groups in its structure while the products of aminolysis and alcoholysis contain both acidic and amine and/or alcohol-derived moieties. The kinetic analyses of the thermal decomposition reaction were evaluated using thermogravimetric analysis and subsequently Friedman and Ozawa–Flynn–Wall methods revealing three-stage degradation process. Calorimetric measurements were performed for the studied polymers, and mass spectrometric analyses were used to identify the decomposition products for phosphorus-containing polymer. The overall results allowed to reveal the influence of the attached phosphorus- and phosphorus/nitrogen-containing functional groups to the thermal degradation of the cross-linked polymers.

Composition and reactivity of aminolysis products of phenyl glycidyl ether with benzylamine

Composition of aminolysis products of phenyl glycidyl ether with benzylamine in various conditions was studied. The ratio of 1-(benzylamino)-3-phenoxypropan-2-ol and 1,1'-(benzylazanediyl)bis(3-phenoxypropan-2-ol) does not considerably depend on the nature of the solvent and is basically determined by ratio of initial reagents. 2,6-Bis(phenoxymethyl)morpholine was obtained by dehydration of aminodiol in conditions of Mitsunobu reaction with subsequent reductive debenzylation.

Reaction of 2-(nitroamino)pyrimidin-4(3H)-one derivatives with arylamines of low basicity in pivalic acid

Pivalic acid was used as a solvent for aminolysis of poly-substituted 2-(nitroamino)-pyrimidin-4(3Н)-one derivatives with arylamines of low basicity. The reaction did not occur in the other solvents or without solvent. Aminolysis products were obtained in 51–59% yields.

Design and Synthesis of Hydrolytically Stable N‐Nitrourea Explosives

AbstractA series of high energy density compounds (HEDCs) based on N‐nitrourea were designed and their theoretical performances were calculated using the Gaussian programs. The predicted values of the energy density of these compounds are in the range 1.848–1.93 g cm−3, and their calculated VODs are in the range 6700–8305 m s−1. Tetranitrodiglycoluril (TNDGU) (1) and tetranitrotriglycoluril (TNTGU) (2) were synthesized and characterized by NMR (1H, 13C) and IR spectroscopy as well as elemental analyses. The structure of the aminolysis product (7) of TNDGU was further confirmed by single‐crystal X‐ray diffraction, which indicated that the structure belongs to P21/c space group in the monoclinic system.

Synthesis of Pyrimidine‐Fused Benzazepines from 5‐Allyl‐4,6‐dichloropyrimidines

AbstractA detailed examination of the synthesis of functionalized 6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepines 4 is described. Base‐promoted aromatic nucleophilic substitution of 5‐allyl‐4,6‐dichloropyrimidines 1a–c with different N‐substituted anilines and indoline gave the corresponding aminolysis products 3a–p, which on acid‐promoted intramolecular Friedel–Crafts cyclization produced the target polysubstituted 6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepines 4a–p in moderate to very high yields.

Thermodynamically controlled chemoselectivity in lipase-catalyzed aza-Michael additions

Chemoselective synthesis of N-protected β-amino esters involving lipase-catalyzed aza-Michael additions and α,β-unsaturated precursors is mainly hampered by the two electrophilic sites present on these compounds. In order to control the chemoselectivity a solvent engineering strategy based on the thermodynamic behaviour of products in media of different polarity was designed. This strategy allowed to obtain aza-Michael adducts from benzylamine and different acrylates with high selectivity. In almost all reactions carried out in n-hexane, a non-polar solvent, aminolysis was avoided while the corresponding Michael adducts were exclusively synthesized in 53–78% yields. On the contrary, in reactions carried out in a polar solvent such as 2-methyl-2-butanol the aminolysis products were favoured. Thermodynamic analyses of these processes using the COSMO-RS method helped to understand some of the key factors affecting chemoselectivity and confirmed that a reliable estimation of the thermodynamic interactions of solutes and solvents allows an adequate selection of a reaction media that may lead to chemoselectivity.

Квантово-хімічне дослідження механізму реакції N-циклізації продуктів амінолізу епіхлоргідрину

The mechanism of intramolecular cyclization for products of epichlorohydrin aminolysis by secondary amines has been investigated at ab initio level of theory. By comparative analysis of energetic characteristics, which obtained in vacuo as well as in acetonitrile solution with the trace quantities of water as an «active» solvation partner of reaction, it has been shown a decisive role of solvent, which occurs mainly at the expense of the polarizable effects for nonspecific solvation. Indeed, the addition to the substrate of one water molecule have decreased corresponding EACT values only 24.1 kJ/mol, while the appearance of acetonitrile surroundings have the same influence ~42.0 kJ/mol. The results of calculations are in good agreement with that data, which have been obtained for such type modeling previously.

A Study on Aminolysis of Xianfeng Lignite by Ethanolamine and Characteristics of Aminolysis Products

A Xianfeng lignite was aminolyzed with a series of amines at 200°C within 1 h. Ethanolamine was found to be a superior solvent for lignite aminolysis under mild conditions. Up to ca. 77 wt% of a Xianfeng lignite could be dissociated with ethanolamine. Solvent-extraction components of aminolysis products of Xianfeng lignite with ethanolamine are mainly water insoluble fractions, water soluble fractions-acetone insoluble, and water soluble fractions-acetone soluble. Water insoluble, water soluble fractions-acetone soluble, and water soluble fractions-acetone insoluble mainly contain about 1 to 2 rings, 2 to 3 rings, and 1 to 4 rings aromatic structure, respectively.

From Aminolysis Product of Pet Waste to Value-Added Products of Polymer and Assistants

In this work, the aminolysis depolymerization of poly(ethylene terephthalate) PET was carried out with ethanolamine and several acetates as catalysts. The main product, bis(2-hydroxyethyl) terephthalamide (BHETA), was identified from FTIR and 1H NMR. It was found that PET depolymerization is favoured by increasing temperature, time and catalysts. Results shown that under present conditions of aminolysis, the conversion of PET was 100% and high yield of BHETA. Moreover, aminolysis products have the potential to undergo further reactions to yield secondary value-added product, such as unsaturated polyesters, polyurethanes, epoxy resin hardeners and non-ionic polymer surfactants.

Synthesis, Structure, and Electrochemistry of Fischer Alkoxy- and Aminocarbene Complexes of Tungsten: The Use of DFT To Predict and Understand Oxidation and Reduction Potentials

Reactions of Fischer alkoxycarbene complexes [W(CO)5{C(OEt)Ar}] (Ar = 2-thienyl (1), 2-furyl (2)) with ethylenediamine led to the formation of two different reaction products: an aminolysis product (5 or 6) where the ethoxy substituent of the carbene ligand is replaced by the ethylenediamine moiety and a chelated product where aminolysis and substitution of one carbonyl ligand had taken place, yielding 7 or 8. Aminolysis of 1 and 2 with cyclohexylamine (CHA) produced the aminocarbene complexes 3 (Ar = 2-thienyl) and 4 (Ar = 2-furyl). Complexes 1–8 have been electrochemically investigated by means of cyclic voltammetry. The relative shifts in the oxidation and reduction potentials are discussed and related to density functional theory (DFT) calculated energies. DFT calculations further show that the oxidation center is located on the metal and the carbonyl groups, while the reduction center is localized on the carbene moiety and is strongly influenced by the electronic properties of its substituents. Crystal structures of 1–4, 6, and 8 are reported.

Synthesis and characterization of novel nitroxide organometallic Fischer-type carbene complexes

Reactions of 4-amino TEMPO with alkynylmethoxy Fischer type carbene complexes lead to unknown transition organometallic nitroxide spin labels. According to the temperature and the nature of the aromatic group of the initial alkynyl carbene, Michael adducts and aminolysis products were obtained in various proportions. The reaction was extended to ferrocenyl carbene complexes to obtain novel organometallic spin systems containing two kinds of redox units. Their constitution is in agreement with IR, elemental analysis and mass spectrometry. Single X-ray diffraction has confirmed the molecular structure of the complexes and has showed the existence of intra and intermolecular hydrogen bonds. These air-stable paramagnetic carbenes have interesting redox behaviours and paramagnetic properties.