Ketone Oxime Research Articles

The synthesis and research of a novel organosilicon-modified waterborne blocked polyisocyanate crosslinker with a semi-interpenetrating network structure

The organosilicon intermediate containing hydrophilic tertiary amines was synthesized from N-Methylmonoethanolamine (MEA) and (3-glycidyloxypropyl) trimethoxy silane (GPTMS), followed by neutralization with acetic acid (Ac). Meanwhile, a polyurethane (PU) prepolymer was prepared by sequentially polymerizing hexamethylene diisocyanate trimer (HT-100) with polyethylene glycol (PEG-600) and methoxy polyethylene glycol (MPEG), and then chain extended by the intermediate. Ultimately, methyl ethyl ketone oxime (MEKO) was selected to block the remaining NCO group, forming a branched polyisocyanate crosslinker. Subsequently, a linear polyisocyanate crosslinker was prepared in the same system by polymerizing hexamethylene diisocyanate (HDI) with the intermediate. Consequently, an organosilicon-modified waterborne blocked polyisocyanate crosslinker with a semi-interpenetrating network structure was obtained and further processed through hydrolysis to obtain the corresponding crosslinker containing silanol groups. The structure and thermal properties of the crosslinkers were analyzed using 1H NMR, FT-IR, TG, and DTG. Furthermore, the comprehensive mechanical properties of the cured films were investigated. The results indicate that the crosslinker system containing silanol groups exhibits superior performance. When the films' maximum adhesion and the wiping resistance were optimized at 1.97 MPa and 72 times, respectively, the impact resistance still maintained above 85 cm.

Bis[μ-bis-(pyridin-2-yl)methanone oxime-κ3N:,N',N'']bis-[di-acetato-κ2O,O';κO-zinc(II)

The structure of the title complex, [Zn2(C2H3O2)4(C11H9N3O)2], is triclinic containing half of the mol-ecule in the asymmetric unit. Each zinc atom is coordinated to a pyridyl and oxime nitro-gen from one di-2-pyridyl ketone oxime (dpko) ligand and a third nitro-gen from the other dpko pyridyl ring. Additionally, each zinc is coordinated to two acetato anions, one of which is bidentate and the other monodentate. The uncoordinated oxygen of the monodentate acetato group is involved in a hydrogen bond with the oxime hydrogen. The packing in the crystal is assisted by weak C-H⋯O inter-actions between acetato groups and neighboring pyridyl rings.

Reactions of Cadmium(II) Halides and Di-2-Pyridyl Ketone Oxime: One-Dimensional Coordination Polymers.

The coordination chemistry of 2-pyridyl ketoximes continues to attract the interest of many inorganic chemistry groups around the world for a variety of reasons. Cadmium(II) complexes of such ligands have provided models of solvent extraction of this toxic metal ion from aqueous environments using 2-pyridyl ketoxime extractants. Di-2-pyridyl ketone oxime (dpkoxH) is a unique member of this family of ligands because its substituent on the oxime carbon bears another potential donor site, i.e., a second 2-pyridyl group. The goal of this study was to investigate the reactions of cadmium(II) halides and dpkoxH in order to assess the structural role (if any) of the halogeno ligand and compare the products with their zinc(II) analogs. The synthetic studies provided access to complexes {[CdCl2(dpkoxH)∙2H2O]}n (1∙2H2O), {[CdBr2(dpkoxH)]}n (2) and {[CdI2(dpkoxH)]}n (3) in 50-60% yields. The structures of the complexes were determined by single-crystal X-ray crystallography. The compounds consist of structurally similar 1D zigzag chains, but only 2 and 3 are strictly isomorphous. Neighboring CdII atoms are alternately doubly bridged by halogeno and dpkoxH ligands, the latter adopting the η1:η1:η1:μ (or 2.0111 using Harris notation) coordination mode. A terminal halogeno group completes distorted octahedral coordination at each metal ion, and the coordination sphere of the CdII atoms is {CdII(η1 - X)(μ - X)2(Npyridyl)2(Noxime)} (X = Cl, Br, I). The trans-donor-atom pairs in 1∙2H2O are Clterminal/Noxime and two Clbridging/Npyridyl; on the contrary, these donor-atom pairs are Xterminal/Npyridyl, Xbridging/Noxime, and Xbridging/Npyridyl (X = Br, I). There are intrachain H-bonding interactions in the structures. The packing of the chains in 1∙2H2O is achieved via π-π stacking interactions, while the 3D architecture of the isomorphous 2 and 3 is built via C-H∙∙∙Cg (Cg is the centroid of one pyridyl ring) and π-π overlaps. The molecular structures of 1∙2H2O and 2 are different compared with their [ZnX2(dpkoxH)] (X = Cl, Br) analogs. The polymeric compounds were characterized by IR and Raman spectroscopies in the solid state, and the data were interpreted in terms of the known molecular structures. The solid-state structures of the complexes are not retained in DMSO, as proven via NMR (1H, 13C, and 113Cd NMR) spectroscopy and molar conductivity data. The complexes completely release the coordinated dpkoxH molecule, and the dominant species in solution seem to be [Cd(DMSO)6]2+ in the case of the chloro and bromo complexes and [CdI2(DMSO)4].

Rongalite/iodine-mediated C(sp3)-H bond oximation and thiomethylation reaction of methyl ketones using copper nitrate as the [NO] reagent: synthesis of thiohydroximic acids.

In this work, a highly efficient rongalite/iodine-mediated oxime formation reaction for the preparation of thiohydroximic acids from methyl ketones by employing copper nitrate as the [NO] reagent has been developed. Notably, copper nitrate participated as both a catalyst and the mild oximation reagent in the transformation. This reaction is highly efficient and facile, with a broad substrate scope, especially for fused ring skeleton substrates, heterocyclic skeleton substrates, and acetyl-substituted natural products. Mechanistic studies revealed that copper nitrate might be converted into a NO2 radical or the NO2 radical dimeric forms as an ion-pair equivalent to participate in the transformation.

Experimental Investigations of the Thermal Safety of Methyl Ethyl Ketone Oxime Hydrochloride Based on the Flask Method, Thermal Analysis, and GC-MS

Chemical safety accidents caused by the thermal runaway of materials occur frequently around the world, seriously hindering the sustainable development of the chemical industry. Therefore, studies related to the thermal safety of materials are very important for chemical production. In order to ensure the safety of methyl tris (methyl ethyl ketone oxime) silane (MOS), the thermal safety of its accident-prone by-product, methyl ethyl ketone oxime hydrochloride (MEKOH), was analyzed in the study. Temperature changes of MEKOH dissolved in 5%, 10% and 15% deionized water were measured with the flask method. Thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) were applied to comprehensively analyze the thermal stability of MEKOH in different reaction states. The thermal decomposition products of MEKOH were detected with gas chromatography-mass spectrometry (GC-MS). The results show that the temperature of MEKOH dissolved in deionized water at room temperature (28 °C) increases by about 5 °C, and finally stabilizes at 33 °C. MEKOH has good thermal safety during this process. When the temperature rises to 50 °C, MEKOH starts to decompose violently, and no longer exhibits significant weight loss at 145 °C. From 50 °C to 100 °C, MEKOH releases heat, ranging from 29.65 to 45.86 J/g, during thermal decomposition, generating a large amount of flammable substances. The thermal decomposition products were detected, including pyrrolidine, heptane, MEKO, and other substances, but no MEKOH was detected. Overall, the study provides a theoretical basis for preventing the thermal runaway of MEKOH.

Highly stretchable dual‐cure photosensitive resin for digital light processing printing

AbstractThe two‐stage curing approach is one of the promising strategies to achieve the 3D printing of high‐performance elastomers. Herein, a novel resin formulation that is composed of a photocurable acrylic resin and a mixture of thermocurable isocyanate oligomer/diamine is evaluated by digital light processing technology. Such resin possesses a satisfying viscosity for printing, especially at ambient temperature. For first curing stage, that is, photocurable stage, precisely architectural components with the required shape can be fabricated by a free‐radical photopolymerization. Methyl ethyl ketone oxime that serves as a blocking agent, was employed to ensure the stability of isocyanate resin during this stage. Consecutively, a thermally activated deblocking process is carried out and accompanied by isocyanate/diamine copolymerization, which is the second curing stage. An interpenetrating polymer networks structure in designing resin (25 wt% photocurable resin and 75 wt% thermocurable resin) was formed after thermal curing, which is of significance for achieving excellently comprehensive mechanical properties. Contributed by special structures, it is capable of reaching a 4.67 MPa of tensile strength at 100% strain, while yielding favorable tensile strength of 7.51 MPa as well a maximum elongation at break of 745.3%, which is nearly identical to the initial mechanical performances of pure polyurethane elastomer.

Access to 4-Trifluoromethyl Quinolines via Cu-Catalyzed Annulation Reaction of Ketone Oxime Acetates with ortho-Trifluoroacetyl Anilines under Redox-Neutral Conditions.

An efficient Cu-catalyzed annulation reaction of ketone oxime acetates with ortho-trifluoroacetyl anilines has been disclosed. With the developed protocol, a series of 4-trifluoromethyl quinolines were obtained in good to excellent yields (58-99%) under redox-neutral conditions. The protocol also could be extended to ferrocene-based ketone oxime acetates for the construction of ferrocene-substituted fluorine-containing quinolines.

Visible-Light Photoredox-Catalyzed Dicarbofunctionalization of Styrenes with Oxime Esters and CO2: Multicomponent Reactions toward Cyanocarboxylic Acids and γ-Keto Acids.

A photoredox-catalyzed dicarbofunctionalization of styrenes with oxime esters and CO2 has been achieved. Notably, a series of four-, five-, or six-membered cyclic ketone oximes worked well to furnish a wide range of ε-, ζ-, and η-cyanocarboxylic acids in good yields. Furthermore, a series of γ-keto acids also could be obtained by employing acyclic ketone oxime esters as the carbonyl radical precursor. It provides convergent access to diverse biologically important cyanocarboxylic and γ-keto acids.

Chemodivergent Synthesis of Oxazoles and Oxime Ethers Initiated by Selective C-N/C-O Formation of Oximes and Diazo Esters.

Chemodivergent reactions of oximes and diazo esters involving Rh-catalyzed [3+2] annulation and photodriven O-H insertion have been developed to generate oxazoles and oxime ethers. A range of aldehyde and ketone oximes reacted with α-diazocarbonyl compounds in a controllable manner in which functional groups, including ketone, ester, amide, ether, thiol ether, silane, alkene, allene, and alkyne groups, were well tolerated.

Exchange coupling in a thiocyanato-bridged copper(II) chain: Computational approach to magnetostructural correlations

In this article we report the synthesis and magneto-structural characterization of two new copper(II) compounds with thiocyanato and methyl(2-pyridil) ketone oxime (mpkOH), namely [Cu(NCS)(mpkO)(mpkOH)] (1) and [Cu(µ-NCS)(NCS)(mpkOH)]n (2). Compound 1 is a mononuclear complex that crystallizes as discrete units. Conversely, compound 2 is a single equatorial-axial end-to-end thiocyanato bridged polymeric chain of Cu(II) with the oxime as a co-ligand. The coordination geometry around the Cu(II) centers is distorted square pyramidal for 1 and 2. The magnetic susceptibility data for 2 reveal weak intrachain antiferromagnetic coupling, with J value −0.74(3) cm−1 and g = 2.10(1). The application of computational tools to a binuclear model of 2 allowed us to unveil the structural basis that modulates the magnetic behavior of this type of thiocyanato-bridged Cu(II) chains. The results suggest that although small values of J are expected, the strongest ferromagnetic interactions can be obtained by including co-ligands that trigger a squared-based pyramidal-to-trigonal bipyramidal distortion of the coordination polyhedra.

Visible Light Driven and Copper-Catalyzed C(sp3)-H Functionalization of O-Pentafluorobenzoyl Ketone Oximes.

The C(sp3)-H functionalization of O-pentafluorobenzoyl ketone oximes was implemented under visible light irradiation with copper complexes as catalysts. The reactions involve iminyl-radical-mediated intramolecular hydrogen atom transfer as the key step, with the iminyl radicals being generated via copper-effected N-O cleavage. The reaction afforded 3,4-dihydro-2H-pyrroles under the conditions of [Cu(DPEphos)(bcp)]PF6 and DABCO, while γ-pentafluorobenzoyloxy ketones were produced predominantly when [Cu(dpp)2]PF6 and InCl3·4H2O were used as catalysts.

Multi-objective optimization of a clean, high-efficiency synthesis process of methyl-ethyl-ketone oxime from ammoximation

The ammoximation of ketones is an important chemical reaction, as oximes have a wide range of industrial applications. In this study, the process of preparing methyl ethyl ketone oxime by ammoximation of methyl ethyl ketone was studied. The modeling of the reaction unit was based on the kinetic data, and the reaction conditions were analyzed. Based on the total annual cost, an economic evaluation of the process was carried out, and a sequential iterative optimization algorithm integrating the reaction conditions was used to complete the process optimization. The minimum annual total cost was 2.41 × 107 USD/yr. The exergy of methyl ethyl ketone ammoximation to methyl ethyl ketone oxime process was analyzed, and the unit with the largest exergy loss was determined. The exergy loss rate was 65% for the minimum annual total cost. Considering exergy and annual total cost as the two optimization objectives, the process was comprehensively optimized by a multi-objective optimization algorithm. The annual total cost after multi-objective optimization was 2.55 × 107 USD/yr, which is 5.8% higher than minimum total annual cost, and the exergy loss rate was 64%, which is 1.54% lower than maximum exergy-loss rate. Compared with single-objective optimization, multi-objective optimization has a better comprehensive performance.

Synthesis of 1-Benzyl-, 1-Alkoxyl-, and 1-Aminoisoquinolines via Rhodium(III)-Catalyzed Aryl C-H Activation and Alkyne Annulation.

One-pot syntheses of 1-benzyl-, 1-alkoxyl-, and 1-alkylamino- isoquinolines through automatic directing group (DGauto)-assisted, rhodium(III)-catalyzed aryl C-H activation and annulation with internal alkynes were developed. The reactions affording 1-benzylisoquinolines involve a cascade oximation of diarylacetylenes with hydroxylamine, forming aryl benzyl ketone oxime, and oxime-assisted rhodium(III)-catalyzed aryl C-H activation and followed annulation with another molecule of diarylacetylene in a one-pot manner. The formation of 1-alkoxyl/amino isoquinolines includes the addition of nucleophilic alcohols or amines to aryl nitriles, imine-assisted rhodium-catalyzed aryl C-H activation, and subsequent alkyne annulation.

Evaporation‐Induced Self‐Assembly Method Route to TiO2−SiO2 Catalysts with Hierarchical Pores and Their Oximation of Ketones and Aldehydes

AbstractHierarchical porous titanosilicates with titanium species as high as 6 wt.% were successfully prepared by evaporation‐induced self‐assembly method with the CTAB and TPAOH as two templates in this paper. The physical and chemical properties for the prepared materials were characterized by many techniques such as XRD, N2 sorption, SEM, TEM, ICP, XPS, DR‐UV and FT‐IR etc., and the catalytic performance in the oximation of different ketones and aldehydes was also investigated. Based on the characterization results, the CTAB template is essential to the formation of the ordered mesopores resulting that above 85 % of titanium species can be incorporated into the titanosilicates. The 0.15 C‐0.06TS catalyst with uniform titanium species distribution shows higher catalytic performance than classical TS‐1 zeolite in the ketones and aldehydes oximation, and it showed high catalytic stability in the cycloheptanone oximation even after reused for five times. The results provide a valuable reference for the potential industrial application in the oximation of ketone.

Application of blocked isocyanate in preparation of polyurethane(urea) elastomers

AbstractHigh‐performance casting polyurethane elastomers (CPUe) were successfully synthesized by the reaction of polyurethane prepolymer (PUP) blocked by methyl ethyl ketone oxime (MEKO) with diamine chain extenders. The effects of blocking agent were systematically studied on the structures, thermal stabilities, mechanical properties, and processability of polyurethane. The addition of MEKO significantly improved the tensile strength and toughness. The maximum tensile strength was 35.6 MPa, and the maximum elongation at break was 1065%. The high strength and toughness were attributed to the fact that under mild reaction conditions, the reaction tended to extend the molecular chains, which indicated that the formation of long chains was conducive to the extension and self‐reinforcement of chain segments. Crystallization and strong hydrogen bonds between molecules also led to low loss factor. This deblocking polymerization strategy solves the gel problem in the polymerization process, and provides a new idea for the preparation of CPU.

면섬유 고정제를 위한 양이온 수용성 폴리우레탄의 합성 및 응용

The traditional reactive dyeing of cotton has the disadvantage of poor fastness. In order to improve the fastness, a novel environment-friendly cationic waterborne polyurethane (CWPU) was successfully synthesized via step-by-step polymerization. The CWPU was prepared from isophorone diisocyanate (IPDI), polypropylene glycol (PPG-1000), methyl ethyl ketone oxime and hydrophilic monomer (EGDEA). The chemical structure of CWPU was characterized by Fourier transform infrared spectroscopy. Effects of n (IPDI/PPG-1000), EGDEA dosage, and the neutralizational degree on the properties of the waterborne polyurethane emulsion and the fastness of the treated dyed cotton fabrics were investigated. Particle size and zeta potential were tested to evaluate the emulsion stability. Scanning electron microscope showed that CWPU had been successfully finished on the fabric. Compared with the untreated cotton fabric, the dry and wet rubbing fastness of the treated cotton fabric dyed with reactive dyes increase 0~0.5 and 0.5~1 level, respectively, and the wash fastness increases 0.5~1 level.

Synthesis, characterization and anti-inflammatory properties of karanjin (Pongamia pinnata seed) and its derivatives

Karanja (Pongamia pinnata) is a medicinal tree used in the Indian traditional ayurvedic system for treating several ailments. The seeds contain a unique furano-flavonoid karanjin, which has shown to possess many medicinal properties. Its usage at the clinical level is affected due to poor solubility and absorption. In the present investigation, molecular modifications of karanjin were attempted and evaluated their effect on anti-inflammatory activity. Firstly, Karanja ketone was obtained from karanjin by hydrolysis, and it was converted into karanja ketone oxime. The oxime undergoes Beckmann rearrangement and cyclized to yield furano benzoxazole (karanja oxazole). The new derivatives were purified with >95% purity (HPLC) and spectrally characterized (HR-MS, FTIR, and NMR). Among the test compounds, karanja ketone oxime exhibited higher antioxidant activity with an IC50 value of 360 µg/ml (DPPH). Soy lipoxygenase-1 (LOX-1) inhibitory activity of oxime was higher (IC50 = 65.4 µM) than other compounds. Fluorescence studies showed that oxime had higher quenching capacity with a Qmax of 76.3% and a binding constant of 0.9 × 105 M−1 for soy LOX-1. In-silico interaction studies showed that karanja ketone oxime had the least binding energy of −5.76 kcal/mol with LOX-1 by forming two hydrogen bonds with hydrophobic amino acids Leu 390 and Gly 392. The compounds were evaluated for their acute anti-inflammatory activity by the paw and ear edema in the rat model. Karanjin inhibits paw edema and ear edema by 34.13% and 51.13%, respectively, whereas the derivatives inhibited by 45–57 % and 70–76.8%. This study reports a rational approach to synthesize karanjin derivatives with considerable anti-inflammatory properties, both in-vitro and in-vivo.

I2-Catalyzed Oxidative Coupling of Ketone Oximes and Dialkyl/Diarylphosphine Oxides

AbstractA new protocol for the oxidative coupling of ketone oximes with dialkyl/diarylphosphine oxides to synthesize O-(dialkylphosphinyl)ketone oximes has been developed. Hydrogen peroxide is used as a green oxidizing agent, and molecular iodine is used as a nonmetal catalyst. The reaction has a high atom economy, with water as the only byproduct. O-(Dialkylphosphinyl)ketone oximes with 26 examples have been obtained with high yields. Furthermore, the product may be transformed into other molecules, i.e., by reduction.

Efficient Inhibition of Re‐blocking During the Deblocking of Blocked Isocyanates

Abstract3‐Silylpropanols bearing allyl or aryl groups on the silicon atom were found to act as isocyanate blocking agents that can allow to deblock with efficient inhibition of re‐blocking. As a result of the inhibition, the isocyanates blocked by 3‐silylpropanols showed an exceptional lower deblocking temperature than by a conventional aliphatic alcohol. The inhibition is based upon the decomposition reaction of 3‐silylpropanols to a 5‐membered cyclic silane and propylene or arene, where β‐silyl cation intermediates may play a key role. The new blocked isocyanates can tolerate water, whereas previously well‐known low‐temperature‐deblockable agents, such as methylethyl ketone oxime (MEKO), are not generally compatible with water.

Transition-Metal-Free Coupling of 1,3-Dipoles and Boronic Acids as a Sustainable Approach to C-C Bond Formation.

The need for alternative, complementary approaches to enable C−C bond formation within organic chemistry is an on‐going challenge in the area. Of particular relevance are transformations that proceed in the absence of transition‐metal reagents. In the current study, we report a comprehensive investigation of the coupling of nitrile imines and aryl boronic acids as an approach towards sustainable C−C bond formation. In situ generation of the highly reactive 1,3‐dipole facilitates a Petasis–Mannich‐type coupling via a nucleophilic boronate complex. The introduction of hydrazonyl chlorides as a complementary nitrile imine source to the 2,5‐tetrazoles previously reported by our laboratory further broadens the scope of the approach. Additionally, we exemplify for the first time the extension of this protocol into another 1,3‐dipole, through the synthesis of aryl ketone oximes from aryl boronic acids and nitrile N‐oxides.