Equivalents Of NaOH Research Articles

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides.

An eco-friendly selective hydrolysis of chain α-oxo ketene N,S-acetals in water for the switchable synthesis of β-keto thioesters and β-keto amides is reported. In refluxing water, the hydrolysis reactions of α-oxo ketene N,S-acetals in the presence of 1.0 equiv of dodecylbenzenesulfonic acid effectively afforded β-keto thioesters in excellent yield, while β-keto amides were successfully obtained in excellent yield when the hydrolysis reactions were carried out in the presence of 3.0 equiv of NaOH. The green approach to β-keto thioesters and β-keto amides avoids the use of harmful organic solvents, thiols and thiolacetates as well as amines, which could result in serious environmental and safety issues.

Production of Lactic Acid via Catalytic Transfer Dehydrogenation of Glycerol Catalyzed by Base Metal Salt Ferrous Chloride and Its NNN Pincer-Iron Complexes.

NNN-Bis(imino) pyridine-based pincer-Fe(II) complexes with an expected trigonal bipyramidal (TBP) geometry equilibrated to a rearranged ion pair of an octahedral dicationic Fe complex containing two bis(imino)pyridine ligands that are neutralized by a tetrahedral dianionic-[FeCl4]2-. Single-crystal X-ray diffraction (SCXRD), high-resolution mass spectrometry (HRMS), and UV-visible (UV-vis) studies suggested that the equilibrium was dictated by the sterics of the R group on the imine N, with the less-crowded groups tilting the equilibrium to the ion pair and the bulky ones favoring the TBP geometry. Electron paramagnetic resonance (EPR) and Evan's magnetic moment measurements indicated that the complexes were paramagnetic with Fe(II) in a high-spin state. In solution, over a period of 7 days, these Fe(II) complexes oxidized to a mixture of low-spin and high-spin Fe(III) species. These pincer-Fe(II) were found to be highly active toward the transformation of biodiesel waste glycerol to value-added lactic acid (LA). Particularly, (Ph2NNN)FeCl2 (0.1 mol %) gave 91% LA with a 99% selectivity at 140 °C using 1.2 equiv of NaOH. With 0.0001 mol % (Ph2NNN)FeCl2, very high turnovers (74% LA, 98% selectivity, 740 000 turnover number (TON) at 4405 turnovers per hour (TOs/h)) were obtained after 7 days. EPR indicated Fe(III) species to be the active catalyst, a few of which were detected by HRMS. Experiments with Hg are suggestive of the mostly homogeneous molecular nature of the catalyst with a minor contribution from heterogeneous Fe nanoparticles.

Synthesis of Substituted 1,2-Dihydroisoquinolines by Palladium-Catalyzed Cascade Cyclization-Coupling of Trisubstituted Allenamides with Arylboronic Acids.

1,2-Dihydroisoquinolines are important compounds due to their biological and medicinal activities, and numerous approaches to their synthesis have been reported. Recently, we reported a facile synthesis of trisubstituted allenamides via N-acetylation followed by DBU-promoted isomerization, where various substituted allenamides were conveniently synthesized from readily available propargylamines with high efficiency. In light of this research background, we focused on the utility of this methodology for the synthesis of substituted 1,2-dihydroisoquinolines. In this study, a palladium-catalyzed cascade cyclization-coupling of trisubstituted allenamides containing a bromoaryl moiety with arylboronic acids is described. When N-acetyl diphenyl-substituted trisubstituted allenamide and phenylboronic acid were treated with 10 mol% of Pd(OAc)2, 20 mol% of P(o-tolyl)3, and 5 equivalents of NaOH in dioxane/H2O (4/1) at 80 °C, the reaction proceeded to afford a substituted 1,2-dihydroisoquinoline. The reaction proceeded via intramolecular cyclization, followed by transmetallation with the arylboronic acid of the resulting allylpalladium intermediate. A variety of highly substituted 1,2-dihydroisoquinolines were concisely obtained using this methodology because the allenamides, as reaction substrates, were prepared from readily available propargylamines in one step.

Efficient net transfer-dehydrogenation of glycerol: NNN pincer-Mn and manganese chloride as a catalyst unlocks the effortless production of lactic acid and isopropanol.

Herein, a series of pincer-Mn complexes based on bis(imino)pyridine ligands of the type R2NNN (R = tBu, iPr, Cy and Ph) were synthesized and characterized using various spectroscopic techniques. SCXRD studies revealed a trigonal bipyramidal geometry around the metal center in all the complexes. EPR spectroscopy confirmed the presence of high-spin Mn(II) centers with the consistent observation of sextets in EPR spectra. Additionally, solution magnetic moment measurement exhibited values ranging from 5.8 to 6.2 BM for all the complexes, which are in accordance with the theoretical value of 5.92 BM. HRMS analysis complemented structural characterization, showing fragments corresponding to various solvent adducts and derivatives of the complexes. Subsequently, the synthesized complexes were investigated for their catalytic activity in the transfer dehydrogenation of glycerol to lactic acid in the presence of acetone. Among the considered complexes, the catalyst Ph2NNNMnCl2 was found to be highly efficient. Remarkably, a yield of 92% LA was observed with >99% selectivity at 0.5 mol% loading of Ph2NNNMnCl2 in the presence of 1 equivalent of NaOH at 140 °C in 24 h, surpassing the yield obtained from its precursor MnCl2·4H2O, where a yield of 72% LA was observed with 96% selectivity under similar reaction conditions. This catalytic system was further investigated with a range of acceptors, and good to moderate yields were observed in most cases. Moreover, several control experiments, including reaction with PPh3, CS2 and Hg, highlighted the major involvement of molecular species in the reaction medium. Deuterium labelling studies indicated the involvement of C-H bond activation in the catalytic cycle but not in the rate-determining step (RDS), with a secondary kinetic isotope effect (KIE) of 1.25.

NaOH promoted hydrolysis of α-oxo ketene-N, S-acetals: Effective synthesis of β-keto amides

An effective and novel synthesis of β-keto amides had been developed by NaOH promoted hydrolysis of α-oxo ketene-N, S-acetals. It was found that the hydrolysis of α-oxo ketene-N, S-acetals in the presence of 2 equivalent of NaOH in refluxing EtOH (95%) gave β-keto amides in excellent yields. The uses of toxic and harmful amines as well as the prepurification of these nucleophilic reagents were not required in the hydrolysis reaction. The method can extend to gram scale.

Supramolecular and base-induced singlet oxygen generation enhancement of a water-soluble phthalocyanine

Investigation into the reactive oxygen species (ROS) generating abilities of photosensitizers outside of in-vitro/vivo conditions is a crucial element in the wider study of photodynamic therapy (PDT) in clinical settings. Zinc(II) phthalocyanine tetrasulfonic acid (ZnPcTS) is a water-soluble photosensitizer that can generate ROS as singlet oxygen (SO) under irradiation in the red and far-red region of the electromagnetic spectrum. The incorporation of ZnPcTS into nano-fibers of a bis-imidazolium hydrogel was demonstrated and the material was characterized with photophysical, rheological, and microscopy techniques. This supramolecular material containing ZnPcTS (named ZnPcTS_nEqBase@Gels) was found to significantly enhance the SO generation rate with respect to that of ZnPcTS in an aqueous solution. The effect is attributed mainly to reduced aggregation within the gel microenvironment compared with a solution. Furthermore, the preparation of ZnPcTS_nEqBase@Gels was carried out in the presence of varying amounts (0, 1, 2, 3, 4 eq.) of NaOH to improve the dissolution of ZnPcTSby ensuring full deprotonation of the sulfonate. The gel material containing 4 equivalents of NaOH per phthalocyanine was found to have a significantly greater SO-generating ability than the corresponding material containing no base. This phenomenon was shown to be partially a consequence of reduced aggregation as observed in the spectroscopic characterization. The enhancement in SO generation induced by this type of hybrid material makes it an attractive candidate to be used in different applications when efficient SO production is required.

Influence of Ca/P ratio on the catalytic performance of hydroxyapatite for decarboxylation of itaconic acid to methacrylic acid

Methacrylic acid, an important organic chemical, is commercially manufactured starting from fossil feedstock. The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid. In view of the problems existing in the researches on this route such as use of noble metal catalyst, harsh reaction conditions and low desired-product yield, we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance. The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity. The highest yield of MAA up to 61.2% was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH, 2 MPa of N2, 250 ℃, and 2 h. On this basis, a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established. With the aid of catalyst characterization using X-ray powder diffraction, NH3/CO2 temperature-programmed desorption, N2 physisorption, inductively coupled plasma optical emission spectrometry, and scanning electron microscopy, we found that the distribution of surface acid sites and basic sites, crystal growth orientation, texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio. Furthermore, the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.

Acidity-Driven Bidirectional Room-Temperature Spin-State Switch and Fluorescence Modulation of a Mononuclear Fe(II) Complex

Room-temperature switchable materials showing multiple responses toward external stimuli are highly desired. Herein, we report bidirectional spin-state switch and fluorescence modulation of an Fe(I...

Synthesis of 2,2′-dibenzoylaminodiphenyl disulfide based on Aspen Plus simulation and the development of green synthesis processes

AbstractThe rubber peptizer 2,2′-dibenzoylaminodiphenyl disulfide is typically synthesized from C7H5NS, NaOH, H2SO4, and H2O2, but these reactants were replaced with C6H4ClNO2, C2H6O, Na2S, S, and N2H4·H2O, and these raw materials effectively improved the synthesis yield, reduced the number of synthetic steps, and made the synthetic process greener. Although the catalyst is difficult to recover, it effectively avoids using ethanol as a volatile organic solvent. The Aspen Plus method was used to simulate the key processes in the synthesis in the experimental conditions as the boundary conditions. The simulation results show that the feed ratio of C7H5NS, H2O2, and C7H5ClO directly determines the yield of the reaction, and the equivalents of NaOH, H2SO4, and Na2CO3 indirectly affect the yield of the reaction by changing the reaction environment and controlling the formation of byproducts. The temperature of the ring-opening reaction and the acylation reaction should be maintained within 110–120°C to maximize the yield. The oxidation reaction temperature also directly affects the reaction yield and should be kept below 40°C. The simulation results are consistent with practical industrial production conditions. Based on the developed green synthesis process and the optimal process parameters obtained from the simulation, the industrial-scale production of 10,000 tons of 2,2′-di benzoyl amino diphenyl disulfide was carried out. Compared with that of o-nitrochlorobenzene, the yield of 2,2′-dibenzoylaminodiphenyl disulfide increased from approximately 72% to more than 90%. Using this method instead of the original synthesis method avoids the use of o-nitrochlorobenzene, which is neurotoxic; Raney nickel as the metal catalyst, which is difficult to recycle with existing environmental protection technologies; and ethanol as the organic solvent, which is associated with environmental problems. The amine tail gas that is easily generated in the original synthesis method is not generated in this system, and the drying step is eliminated.

Synthesis and characterisation of Co(iii) complexes of N-formyl hydroxylamines and antibacterial activity of a Co(iii) peptide deformylase inhibitor complex.

The X-ray crystal structure and pKa values of GSK322, a well-known and effective peptide deformylase inhibitor and antibacterial drug candidate, are reported. The first examples of Co(iii) complexes of N-formyl hydroxylamines are reported. Reaction of N-hydroxy-N-phenylformamide (HFA) with [Co(tren)Cl2]Cl and [Co(tpa)Cl2]Cl (where tren = tris(2-aminoethyl)amine, tpa = tris(2-pyridylmethyl)amine) with one equivalent of NaOH in H2O afforded [Co(tren)(HFA-1H)](PF6)1.5Cl0.5 (1) and [Co(tpa)(HFA-1H)]Cl2 (2), respectively. X-ray crystal structures of both complexes revealed that the N-formyl hydroxylamine group acts as a bidentate ligand, coordinating the Co(iii) centres via the carbonyl oxygen and deprotonated hydroxy group (O,O'), a coordination mode typically observed for closely related mono-deprotonated hydroxamic acids. Reaction of the N-formyl hydroxylamine-based GSK322 with [Co(tpa)Cl2]Cl afforded the corresponding Co(iii) chaperone complex of the peptide deformylase inhibitor, [Co(tpa)(GSK322-1H)](PF6)2. GSK322 and [Co(tpa)(GSK322-1H)](PF6)2 exhibited better Gram-positive activity than Gram-negative, where low MICs (1.56-6.25 μM) were determined for S. aureus strains, independent of their antibiotic susceptibility.

Dicyclohexyl(sulfanylidene)-λ5-phosphanyl]methanol

The title compound, [dicyclohexyl(sulfanylidene)-λ5-phosphanyl]methanol, Cy2P(=S)CH2OH (1), was obtained from the reaction between [Cy2P(CH2OH)2]Cl with one molar equivalent of NaOH and an excess of elemental sulfur (powdered). Characterization was by a single-crystal X-ray structure determination as well as IR, and 1D-NMR (1H, 13C{1H}, 31P{1H}), and 2D-NMR (DEPT-135 and HSQC) spectroscopy, ESI mass spectrometry, and elemental analysis. X-ray crystallography on Compound 1 shows the phosphorus atom to be tetrahedrally coordinated within a non-symmetric C3S donor set but with relatively minor distortions from the ideal geometry. In the molecular packing, hydroxyl-O–H⋯S(thione) hydrogen bonds led to supramolecular helical chains along the b-axis direction.

Feasible selective synthesis of 3-Acetylindoles and 3-Acetoacetylindoles from β-ethylthio-β-indoly α, β-unsaturated ketones

An efficient and selective synthesis of 3-acetyl free(N-H)/N-substituded indoles and 3-acetoacetyl free(N-H)/N-substituded indoles has been developed via the hydrolysis reaction of β-ethylthio-β-indoly α, β-unsaturated ketones in the presence of 3 equivalent of NaOH and 5 mol% of H2SO4, respectively. The procedure features easy operation, excellent yields, and high selectivity, compatibility and practicability.

Au/Al2O3 – Efficient catalyst for 5-hydroxymethylfurfural oxidation to 2,5-furandicarboxylic acid

The catalytic activity of a simple Au/Al2O3 catalytic system prepared by the direct anionic exchange (DAE) method was evaluated in the selective 5-hydroxymethylfurfural (HMF) oxidation under mild conditions, using molecular oxygen as the oxidant. The influence of the HMF/NaOH ratio and reaction time on product yield and distribution were studied and discussed in detail. Extremely high activity and selectivity were observed in mild conditions, with 99% of 2,5-furandicarboxylic acid (FDCA) production at full HMF conversion after 4 h with the use of only 4 equivalents of NaOH at 70 °C. Catalyst viability and stability were verified by repeating the cycle up to five times. Changes in the nature of the support were also contemplated by introducing some ceria fraction, i.e. 20 wt%.

Cell-instructive and stimuli-responsive injectable alginate hydrogels

Event Abstract Back to Event Cell-instructive and stimuli-responsive injectable alginate hydrogels Tianxin Miao1 and Rachael A. Oldinski1 1 University of Vermont, School of Engineering, United States Introduction: Injectable hydrogels with shear-shinning properties have emerged as promising biomaterials due to their permeability, biocompatibility, and ease-of-use through minimally-invasive procedures. Strain-responsive hydrogels provide a convenient and effective approach to administer a wide variety of bioactive agents such as genes, proteins, drugs, and living cells. The goal of this study was to develop a dual- responsive, injectable alginate hydrogel based on the supramolecular complex formation between β-cyclodextrin (β-CD, grafted onto the alginate repeat unit) and the poly(propylene glycol) (PPG) component of Pluronic® F108. The conjugation of cysteine-arginine-glycine-aspartic acid-serine (CRGDS) onto the alginate backbone was investigated to construct a 3-D, cell-instructive hydrogel. Materials and Methods: ρ-toluenesulfonyl (TosCl) chloride, dissolved in acentontrile, was added to aqueous β-CD solution at 4˚C to synthesize β-CD-TosCl. A 3:1 equivalent of NaOH was added drop-wise and stirred for 30 min at RT. The product was washed with ice water and acetone and dried under vacuum[1]. β-CD-TosCl was mixed with ethylenediamine (EDA) under N2 at 60˚C and reacted for 12 h. Alg-g-CD-CRGDS was synthesized from alginate and β-CD-EDA via carbodiimide chemistry[2]. Hydrogels were prepared from Alg-g-CD solutions mixed with Pluronic® F108 powder[3]. Shear-thinning experiments were performed on an AR2000 (TA Instruments) to test the reversibility of the hydrogel structure and thus mechanical properties; experiments started with low radial strain (0.5%) and then increased to a high radial strain (250%); each cycle was repeated 2x at 37 °C, 1 Hz. Storage (G’) and loss (G”) moduli were recorded during a temperature sweep at a heating rate of 0.5°C/min at 1 Hz frequency. Human lung cancer cells (A549 ATCC® CCL-185™) were mixed with 4% (w/v) Alg-g-CD-CRGDS and Pluronic® F108 (1:8 molar ratio) solutions, and ejected from an 18G needle at a concentration of 1 million cells/mL. The 3-D cell constructs were cultured at 37˚C, 5% CO2, stained with Live/Dead® overnight, and imaged using confocal laser scanning microscopy. Results: Figure 1 illustrates in situ hydrogel formation between Alg-g-CD-CRGDS and Pluronic® F108. The formation of the supramolecular inclusion complex was confirmed by rheometry. Figure 2A showed the chemistry synthesis of Alg-g-CD-CRGDS Figure 2B shows stacked 1H-NMR spectra for alginate (red), Alg-g-CD (green) and Alg-g-CD-CRGDS (blue), indicating the successful conjugation of β-CD and CRGDS onto the alginate backbone. Figure 3A demonstrates the dynamic relationship between shear stress and shear rate for Alg-C. Figure 3B demonstrates a self-curing and repeatable ability to deform and re-assemble upon loading and un-loading. Figure 3C illustrates the thermo-response of Alg-g-CD-CRGDS:F108 hydrogels and Figure 3D displays shear storage moduli (G’) for Alg-CD:F108 hydrogels at 25°C (white bars) and 37°C (black bars). A significant difference in G’ was observed between 25 and 37˚C within the same sample group. Figure 3E/3F demonstrates A549 cell distribution in the 3-D injectable hydrogel. Cells were alive and homogenously distributed throughout the hydrogel structure. Conclusion: The multi-stimuli responsive alginate-based hydrogels, with covalently attached cell instructive peptides (i.e., CRGDS) and tunable mechanical properties, warrant further investigation for biomedical applications such as drug delivery and cell transplantation in vivo. The authors would love to thank Dr. Monka. Ivancic for the help in 1H-NMR spectra.

Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters.

Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H4L have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca(THF)2(H2L(1)), Ca2(THF)2(μ-THF)(L(1)), and Ca2(THF)4(L(2)), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca2(py)5(L(3)). The mononuclear calcium complex Ca(THF)2(H2L(1)) reacts with various equivalents of LiN(SiMe3)2 to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca2(THF)2(μ-THF)(L(1)), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations.

ChemInform Abstract: Efficient and Benign One‐Pot Conversion of N‐Tosyl‐1,4,5,6‐tetrahydropyrimidines to Pyrimidines via Tandem β‐Elimination and Aromatization.

Abstract An efficient, mild, benign, and practical method for one-pot conversion of N-tosyl-1,4,5,6-tetrahydropyrimidines into pyrimidines is discussed in detail. In this method, N-tosyl-1,4,5,6-tetrahydropyrimidines are first prepared via N-tosylation of tetrahydropyrimidines with TsCl and then treated with 1.5 equivalents of NaOH in dimethylsulfoxide (DMSO) under air at 60 °C to afford corresponding pyrimidines in 70–95% yields via cascade β-elimination and aromatization. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]

Efficient and Benign One-Pot Conversion of N-Tosyl-1,4,5,6-tetrahydropyrimidines to Pyrimidines via Tandem β-Elimination and Aromatization

An efficient, mild, benign, and practical method for one-pot conversion of N-tosyl-1,4,5,6-tetrahydropyrimidines into pyrimidines is discussed in detail. In this method, N-tosyl-1,4,5,6-tetrahydropyrimidines are first prepared via N-tosylation of tetrahydropyrimidines with TsCl and then treated with 1.5 equivalents of NaOH in dimethylsulfoxide (DMSO) under air at 60 °C to afford corresponding pyrimidines in 70–95% yields via cascade β-elimination and aromatization. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]

Sodium Hydroxide Catalyzed N-Alkylation of (Hetero) Aromatic Primary Amines and N1,C5-Dialkylation of 4-Phenyl-2-aminothiazoles with Benzyl Alcohols

In the presence of a catalytic amount of NaOH, the selective N-alkylation of various heteroaromatic primary amines is reported. With 1 equiv of NaOH, N1,C5-dialkylation of 4-phenyl-2-aminothiazoles has been investigated. Reaction of in situ generated aldehyde with amine yields the N-alkylated and N1,C5-dialkylated products through hydride ion transformation from alcohol.

Polyfluorene Nanoparticles and Quantum Dot Hybrids via Miniemulsion Polymerization.

Suzuki-Miyaura polycondensation of 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-7-bromo-9,9-dioctylfluorene in aqueous miniemulsion with only two equivalents of NaOH as a base yields colloidally stable nanoparticles of polyfluorene with Mn ca. 2 × 104 g mol-1 and particle sizes of 40-85 nm, depending on the surfactant concentration. Polymerization in the presence of CdSe/CdS core/shell quantum dots affords hybrid nanoparticles of nonaggregated quantum dots, in particular nanoparticles composed of a single quantum dot embedded in a polyfluorene shell. Microphotoluminescence spectroscopy on single hybrid particles reveals an enhanced photostability of the quantum dots and indicates an efficient Förster energy transfer from the polyfluorene shell to the quantum dot.

Optimization of the Selective Monohydrolysis of Diethyl 4-Aryl-4H-pyran-3,5-dicarboxylates

A simple, efficient and eco-friendly procedure for the selective monohydrolysis of diethyl 2,6-dimethyl-4-aryl-4H-pyran-3,5-dicarboxylates under quaternary ammonium salt catalysis conditions is presented. The catalytic activities of various quaternary ammonium salts were investigated using different molar ratios of NaOH and water-organic solvent mixtures. The results indicate that the combination of 1.0 equivalent of tetraethyl-ammonium bromide (TEAB) with 1.2 equivalents of NaOH in a 10% water-ethanol media at 40 °C displays remarkable selectivity for the monohydrolysis of diethyl 2,6-dimethyl-4-aryl-4H-pyran-3,5-dicarboxylates. The utility of this process is demonstrated by the monohydrolysis of a series of 4-aryl-4H-pyran-3,5-dicarboxylate esters to afford the corresponding monoesters in 20–80% yields under the optimized conditions.