Two-pot Procedure Research Articles

Copper nitride/silver nanostructures synthesized via wet chemical reduction method for the oxygen reduction reaction

This work presents attempts to synthesize silver-doped copper nitride nanostructures using chemical solution methods. Copper(II) nitrate and silver(I) nitrate were used as precursors and the oleylamine as a reducing and capping agent. Homogeneous Cu3N/Ag nanostructures with a diameter of ~ 20 nm were obtained in a one-pot synthesis by the addition of the copper(II) salt precursor to the already-synthesized silver nanoparticles (Ag NPs). Synthesis in a two-pot procedure performed by adding Ag NPs to the reaction medium of the Cu3N synthesis resulted in the formation of a Cu3N@Ag nanocomposite, in which Ag NPs are uniformly distributed in the Cu3N matrix. The morphology, structure, and chemical composition of the obtained specimens were studied by TEM, XRD, XPS, and FT-IR methods, while optical properties using UV–Vis spectroscopy and spectrofluorimetry. The band gap energy decreased for Cu3N/Ag (Eg = 2.1 eV), in relation to pure Cu3N (Eg = 2.4. eV), suggesting the insertion of Ag atoms into the Cu3N crystal lattice. Additionally, Cu3N and Cu3N/Ag nanostructures were loaded on graphene (GNP) and tested as a catalyst in the oxygen reduction reaction (ORR) by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The Cu3N/Ag-modified GNP hybrid material revealed catalytic activity superior to that of Cu3N-based GNP hybrid material and pure GNP, comparable to that of a commercial Pt/C electrode.Graphical

Facile and scalable synthesis of baphicacanthin A by a two-pot procedure

Facile two-pot total synthesis of baphicacanthin A, a natural phenoxazinone alkaloid isolated from the roots of Baphicacanthus cusia which has been utilized as a traditional chinese medicine to effectively treat disease caused by coronavirus, has been developed from simple and commercially available starting materials. Catalytic aerobic oxidative cross-cyclocondensation of equimolar 2-aminophenol and 3-methoxy-2-hydroxylphenol in water was used to construct the key molecular skeleton 2-hydroxy-3H-phenoxazin-3-one. Gram scale synthesis was realized in 80% overall yield with practical convenience.

Reproducible nanostructuration of the superconducting κ-(BEDT-TTF)2Cu(NCS)2 phase

The synthesis of the superconductor κ-(BEDT-TTF)2Cu(NCS)2 is optimized following a two-pot procedure to obtain high quality nanoparticles This leads to homogeneous sized-nanoparticles, 30 nm diameter, which are further characterized by XRD and Raman spectroscopy. SQUID measurements confirm the occurrence of the superconducting transition at 9.1 K.

Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin.

A fast, protecting-group-free synthesis of dihydropyridinones has been developed. Starting from commercially available aldehydes, a novel one-pot amidoallylation gave access to diene compounds in good yields. Ring-closing metathesis conditions were then employed to produce the target dihydropyridinones efficiently and in high yields.

One and Two-Carbon Homologation of Primary and Secondary Alcohols to Corresponding Carboxylic Esters Using β-Carbonyl BT Sulfones as a Common Intermediate.

Herein we report the efficient one- and two-carbon homologation of 1° and 2° alcohols to their corresponding homologated esters via the Mitsunobu reaction using β-carbonyl benzothiazole (BT) sulfone intermediates. The one-carbon homologation approach uses standard Mitsunobu C-S bond formation, oxidation and subsequent alkylation, while the two-carbon homologation uses a less common C-C bond forming Mitsunobu reaction. In this latter case, the use of β-BT sulfone bearing esters lowers the p Ka sufficiently enough for the substrate to be used as a carbon-based nucleophile and deliver the homologated β-BT sulfone ester, and this superfluous sulfone group can then be cleaved. In this paper we describe several methods for the effective desulfonylation of BT sulfones and have developed methodology for one-pot alkylation-desulfonylation sequences. As such, overall, a one-carbon homologation sequence can be achieved in a two-pot (four step) procedure and the two-carbon homologation in a two-pot (three step) procedure (three-pot; four step when C-acid synthesis is included). This methodology has been applied to a wide variety of functionality (esters, silyl ethers, benzyls, heteroaryls, ketones, olefins and alkynes) and are all tolerated well providing good to very good overall yields. The power of our method was demonstrated in site-selective ingenol C20 allylic alcohol two-carbon homologation.

Synthesis of highly substituted 2-spiropiperidines.

2-Spiropiperidines are a highly desirable, yet under represented structure in drug discovery. 2-Spiropiperidines were synthesised in either a two-pot or one-pot reaction. In the two-pot reaction, the addition of a Weiler dianion to N-Boc imines, followed by deprotection and in situ condensation with a cyclic ketone generated functionalised 2-spiropiperidines in good to excellent yields. In the one-pot reaction, the addition of Chan's diene to N-Boc imines under Maitland-Japp conditions, followed by the addition of sodium bicarbonate and a cyclic ketone formed functionalised 2-spiropiperidines in moderate to good yields.

Pd(0)-Mediated 11C-Carbonylation of Aryl(mesityl)iodonium Salts as a Route to [11C]Arylcarboxylic Acids and Derivatives.

Pd(0)-mediated 11C-carbonylation of aryl(mesityl)iodonium salts followed by suitable quench provides a rapid room-temperature two-pot procedure for labeling arylcarboxylic acids and amide derivatives with the short-lived positron emitter carbon-11 (t1/2 = 20.4 min) in generally good to high yields (up to 71%). High product ring selectivity (≥13) was achieved when using mesityl as a spectator group in the diaryliodonium salt precursors. This process has potential for preparing new radiotracers for molecular imaging with positron emission tomography.

Visible-light-driven methane formation from CO2 with a molecular iron catalyst.

Converting CO2 into fuel or chemical feedstock compounds could in principle reduce fossil fuel consumption and climate-changing CO2 emissions. One strategy aims for electrochemical conversions powered by electricity from renewable sources, but photochemical approaches driven by sunlight are also conceivable. A considerable challenge in both approaches is the development of efficient and selective catalysts, ideally based on cheap and Earth-abundant elements rather than expensive precious metals. Of the molecular photo- and electrocatalysts reported, only a few catalysts are stable and selective for CO2 reduction; moreover, these catalysts produce primarily CO or HCOOH, and catalysts capable of generating even low to moderate yields of highly reduced hydrocarbons remain rare. Here we show that an iron tetraphenylporphyrin complex functionalized with trimethylammonio groups, which is the most efficient and selective molecular electro- catalyst for converting CO2 to CO known, can also catalyse the eight-electron reduction of CO2 to methane upon visible light irradiation at ambient temperature and pressure. We find that the catalytic system, operated in an acetonitrile solution containing a photosensitizer and sacrificial electron donor, operates stably over several days. CO is the main product of the direct CO2 photoreduction reaction, but a two-pot procedure that first reduces CO2 and then reduces CO generates methane with a selectivity of up to 82 per cent and a quantum yield (light-to-product efficiency) of 0.18 per cent. However, we anticipate that the operating principles of our system may aid the development of other molecular catalysts for the production of solar fuels from CO2 under mild conditions.

(18)F]Fluoroethyl Triazole Substituted PSMA Inhibitor Exhibiting Rapid Normal Organ Clearance.

Prostate-specific membrane antigen (PSMA) is overexpressed in the epithelium of prostate cancer and nonprostate solid tumor neovasculature. PSMA is increasingly utilized as a target for cancer imaging and therapy. Here, we report the synthesis and in vivo biodistribution of a low-molecular-weight PSMA-based imaging agent, 2-[3-(1-carboxy-5-{3-[1-(2-[(18)F]fluoroethyl)-1H-1,2,3-triazol-yl]propanamido}pentyl)ureido]pentanedioic acid ([(18)F]YC-88), containing an [(18)F]fluoroethyl triazole moiety. [(18)F]YC-88 was synthesized from 2-[(18)F]fluoroethyl azide and the corresponding alkyne precursor in two steps using either a one- or two-pot procedure. Biodistribution and positron emission tomography (PET) imaging were performed in immunocompromised mice using isogenic PSMA(+) PC3 PIP and PSMA(-) PC3 flu xenografts. YC-88 exhibited high affinity for PSMA as evidenced by a Ki value of 12.9 nM. The non-decay corrected radiochemical yields of [(18)F]YC-88 averaged 14 ± 1% (n = 5). Specific radioactivities ranged from 320 to 2,460 Ci/mmol (12-91 GBq/μmol) with an average of 940 Ci/mmol (35 GBq/μmol, n = 5). In an immunocompromised mouse model, [(18)F]YC-88 clearly delineated PSMA(+) PC3 PIP prostate tumor xenografts on imaging with PET. At 1 h postinjection, 47.58 ± 5.19% injected dose per gram of tissue (% ID/g) was evident within the PSMA(+) PC3 PIP tumor, with a ratio of 170:1 of uptake within PSMA(+) PC3 PIP to PSMA(-) PC3 flu tumor placed in the opposite flank. The tumor-to-kidney ratio at 2 h postinjection was 4:1. At or after 30 min postinjection, minimal nontarget tissue uptake of [(18)F]YC-88 was observed. Compared to [(18)F]DCFPyL, which is currently in clinical trials, the uptake of [(18)F]YC-88 within the kidney, liver, and spleen was significantly lower at all time-points studied. At 30 min and 1 h postinjection, salivary gland uptake of [(18)F]YC-88 was significantly less than that of [(18)F]DCFPyL. [(18)F]YC-88 is a new PSMA-targeted PET agent synthesized utilizing click chemistry that demonstrates high PSMA(+) tumor uptake in a xenograft model. Because of its low uptake in the kidney, rapid clearance from nontarget organs, and relatively simple one-pot, two-step radiosynthesis, [(18)F]YC-88 is a viable new PET radiotracer for imaging PSMA-expressing lesions.

Facile synthesis of para-[(18)F]fluorohippurate via iodonium ylide-mediated radiofluorination for PET renography.

para-[(18)F]fluorohippurate ([(18)F]PFH) is a renal tubular agent suitable for conducting positron emission tomography (PET) renography. [(18)F]PFH is currently synthesized by a four-step two-pot procedure utilizing a classical prosthetic group, N-succinimidyl-4-[(18)F]fluorobenzoate, followed by glycine conjugation. Considering the short half-life of fluorine-18 (110min), it is important to reduce the number of synthetic steps and overall production time for successful translation of any fluorine-18 radiopharmaceutical in to clinical practice. Here, we report a new two-step one-pot procedure using a novel spirocyclic iodonium ylide precursor for producing a dose of [(18)F]PFH suitable for human use in 45min including HPLC purification with an overall decay-corrected radiochemical yield of 46.4±2.9% (n=3) and radiochemical purity of >99%.

ChemInform Abstract: A Facile Synthesis of 3‐Trifluoromethyl‐1,2,4‐oxadiazoles from Cyanamides.

Abstract A safe and facile method for the formation of 3-trifluoromethyl-5-amino-1,2,4-oxadiazoles, via a reversed addition of hydroxylamine to cyanamides, is reported. This two-pot procedure is suitable to scale-up and avoids the hazards associated with trifluoromethyl amidoxime synthesis.

A facile synthesis of 3-trifluoromethyl-1,2,4-oxadiazoles from cyanamides

A safe and facile method for the formation of 3-trifluoromethyl-5-amino-1,2,4-oxadiazoles, via a reversed addition of hydroxylamine to cyanamides, is reported. This two-pot procedure is suitable to scale-up and avoids the hazards associated with trifluoromethyl amidoxime synthesis.

ChemInform Abstract: Two‐Pot Synthesis of N,N‐Disubstituted 4H‐3,1‐Benzothiazin‐2‐amines from Aryl(2‐isothiocyanatophenyl)methanones and Secondary Amines.

A convenient synthesis of N,N-disubstituted 4H-3,1-benzothiazin-2-amines from aryl(2-isothiocyanatophenyl)methanones using a two-pot procedure has been developed. Thus, treatment of these isothiocyanato ketones with secondary amines gave the corresponding keto thioureas, which were allowed to react with sodium borohydride or methylmagnesium bromide to afford 1,1-dialkyl-3-{2-[aryl(hydroxy)methyl]phenyl}thioureas or 1,1-dialkyl-3-[2-(1-aryl-1-hydroxyethyl)phenyl]thioureas, respectively, in one pot. Hydrobromic acid-mediated cyclization of these hydroxy thiourea precursors provided the desired 4H-3,1-benzothiazin-2-amines.

Two-pot synthesis of N, N-disubstituted 4 H-3,1-benzothiazin-2-amines from aryl(2-isothiocyanatophenyl)methanones and secondary amines

A convenient synthesis of N, N-disubstituted 4 H-3,1-benzothiazin-2-amines from aryl(2-isothiocyanatophenyl)methanones using a two-pot procedure has been developed. Thus, treatment of these isothiocyanato ketones with secondary amines gave the corresponding keto thioureas, which were allowed to react with sodium borohydride or methylmagnesium bromide to afford 1,1-dialkyl-3-{2-[aryl(hydroxy)methyl]phenyl}thioureas or 1,1-dialkyl-3-[2-(1-aryl-1-hydroxyethyl)phenyl]thioureas, respectively, in one pot. Hydrobromic acid-mediated cyclization of these hydroxy thiourea precursors provided the desired 4 H-3,1-benzothiazin-2-amines.

Proton conductivity and stability of low-IEC sulfonated block copolyimide membrane

The proton conductivity and membrane stability of sulfonated block copolyimide membranes with a low ion exchange capacity (IEC) synthesized by chemical imidization using a two-pot procedure were investigated. The proton conductivity of the low-IEC block copolyimide membrane at 80 °C and 98% relative humidity was 16 times larger than that measured for the low-IEC random copolyimide membrane, while that of the high-IEC block copolyimide membrane at the humidity was 4 times than that of the high-IEC random copolyimide membrane, suggesting that the protons in the low-IEC block copolyimide membrane were effectively transported. In addition, the hydrolytic and oxidative stabilities of the low-IEC sulfonated block copolyimide membranes were estimated in detail from FT-IR and 1H NMR. These stabilities of the low-IEC membranes were significantly enhanced compared to those of the high-IEC membranes. The oxidative stability problem in the low-IEC block copolyimide membranes was found to be primarily caused by a decrease in the sulfonic acid groups rather than by polyimide chain scission. These findings indicate that a sulfonated block copolymer consisted of a small amount of sulfonic acid groups is desirable for the development of proton exchange membranes, when considering the balance between the proton conductivity and membrane stability of the proton exchange membranes.

Gas permeation properties of 6FDA-2,4-DAT/mPDA copolyimides

A series of novel fluorinated copolyimides were synthesised with various diamine compositions by chemical imidisation in a two-pot procedure. The gas permeation behaviour of 2,2´-bis(3,4´-dicarboxyphenyl) hexafluoropropane dianhydride(6FDA)-2,4-diamine toluene(DAT)/1,3- phenylenediamine(mPDA) polyimides was investigated. The gas permeatility coefficients decreased with increasing mPDA content; however, the permselectivity of gas pairs such as H2/N2, O2/N2 and CO2/CH4 was enhanced with the incorporation of mPDA moiety. The permeability coefficients of H2, O2, N2, CO2 and CH4 were found to decrease with the increasing order of kinetic diameters of the penetrant gases. Moreover, all of the copolyimides studied in this work exhibited performance near, lying on or above the existing upper bound trade-off line between permselectivity and permeability.

Convergent synthesis of stereodefined exo-alkylidene-gamma-lactams from beta-halo allylic alcohols.

A convergent process for the assembly of stereodefined mono- and bicyclic exo-alkylidene-gamma-lactams is described that proceeds through the union of beta-halo allylic alcohols, aromatic imines, and CO. Overall, regio- and stereoselective Ti-mediated reductive cross-coupling, followed by Pd-catalyzed carbonylation, can be performed in a one- or two-pot procedure, defining a highly selective three-component coupling process for heterocycle synthesis.

Synthesis, characterization, and gas permeation properties of 6FDA-2,6-DAT/mPDA copolyimides

The goal of this work is to explore new polyimide materials that exhibit both high permeability and high selectivity for specific gases. Copolyimides offer the possibility of preparing membranes with gas permeabilities and selectivities not obtainable with homopolyimides. A series of novel fluorinated copolyimides were synthesized with various diamine compositions by chemical imidization in a two-pot procedure. Polyamic acids were prepared by stoichiometric addition of solid dianhydride in portions to the diamine(s). The gas permeation behavior of 2,2′-bis(3,4′-dicarboxyphenyl) hexafluoropropane dianhydride(6FDA)-2,6-diamine toluene (2,6-DAT)/1,3-phenylenediamine (mPDA) polyimides was investigated. The physical properties of the copolyimides were characterized by IR, DSC and TGA. The glass transition temperature increased with increase in 2,6-DAT content. All the copolyimides were soluble in most of the common solvents. The gas permeability coefficients decreased with increasing mPDA content. However, the permselectivity of gas pairs such as H2/N2, O2/N2, and CO2/CH4 was enhanced with the incorporation of mPDA moiety. The permeability coefficients of H2, O2, N2, CO2 and CH4 were found to decrease with the increasing order of kinetic diameters of the penetrant gases. 6FDA-2,6-DAT/mPDA (3:1) copolyimide and 6FDA-2,6-DAT polyimide had high separation properties for H2/N2, O2/N2, CO2/CH4. Their H2, O2 and CO2 permeability coefficients were 64.99 Barrer, 5.22 Barrer, 23.87 Barrer and 81.96 Barrer, 8.83 Barrer, 39.59 Barrer, respectively, at 35°C and 0.2 MPa (1 Barrer = 10−10 cm3 (STP)·cm·cm−2·s−1·cmHg−1) and their ideal permselectivities of H2/N2, O2/N2 and CO2/CH4 were 69.61, 6.09, 63.92 and 53.45, 5.76, 57.41, respectively. Moreover, all of the copolyimides studied in this work exhibited similar performance, lying on or above the existing upper bound trade-off lines between permselectivity and permeability. They may be utilized for commercial gas separation membrane materials.

Benzoxazines with tolyl, p-hydroxyphenyl or p-carboxyphenyl linkage and the structure–property relationship of resulting thermosets

Three benzoxazines (7–9) with a tolyl, p-hydroxyphenyl or p-carboxyphenyl structure, respectively, were successfully synthesized by a three-pot or two-pot procedure. In the three-pot approach, the first step is the condensation of 2-hydroxybenzaldehyde with p-toluidine, 4-aminophenol and 4-aminobenzoic acid, respectively, forming intermediates (1–3) with an imine linkage. The second step is the addition of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) on the imine linkage, resulting in intermediates (4–6) with a secondary amine linkage. The last step is the ring closure condensation of (4–6), leading to benzoxazines (7–9). In the simplified two-pot approach, the first two steps-the condensation and imine reduction were carried out in one reactor, so the yield of (4–6) was increased. The structures of monomers (1–9) were characterized and confirmed by 1D and 2D NMR spectra. The synthesized benzoxazines were thermally self-cured or copolymerized with a commercial benzoxazine, bis(3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)methane (F-a). IR analysis was utilized to monitor the ring-opening reaction of (7–9) and to propose the structures of P(7–9). The microstructure and the structure–property relationship of the resulting homopolymers and copolymers are studied.

SYNTHESIS,CHARACTERIZATION,AND GAS PERMEATION PROPERTIES OF COPOLYIMIDES

The goal of this work is to explore new polyimide materials that exhibit both a high permeability and a high selectivity for specific gases. copolyimides offer the possibility of preparing membranes with gas permeabilities and selectivities not obtainable with homopolyimides. a series novel fluorinated copolyimides were synthesized with various diamine compositions by chemical imidization in a two-pot procedure. polyamic acids were prepared by stoichiometric addition of solid dianhydride in portion wise to the diamine ( s) the gas permeation behavior of 2,2'-bis ( 3, 4'-dicarboxyphenyl) hexafluoropropane dianhydride ( 6fda)-2, 6-diamine toluene ( dat)/1, 3-phenylenediamine ( mpda) polyimides were investigated. the physical properties of the copolyimides were characterized by ir, dsc, and tga. glass transition temperature increased with increase in dat content. all the copolyimides were soluble in most of the common solvents. the gas permeabilities coefficients decreased with increasing mpda content; however, the permselectivity of gas pairs such as h-2/n-2, o-2/n-2, and co2/ch4 was enhanced with the incorporation of mpda moiety. the permeability coefficients of h-2, o-2, n-2, co2 and ch4 were found to decrease with the increasing order of kinetic diameters of the penetrant gases. 6fda-2,6-dat/mpda (3 : 1) copolyimide and 6fda-2,6-dat polymide had high separation properties for h-2/n-2, o-2/n-2 co2/ch4. the h-2, o-2 and co2 permealtilities were 64.99 barrer, 5.22 barrer, 23. 87 barrer and 81.96 barrer, 8.83 barrer, 39.59 barrer respectively at 35 degrees c and 0.2 mpa ( 1 barrer = 7.5 x 10(-14) cm(3) (stp)center dot cm center dot cm-2 center dot s(-1)center dot pa-1); and the ideal selectivities of h-2/n-2, o-2/n-2 and co2/ch4 were 69.61, 6.09, 63.92 and 53.45, 5.76, 57.41, respectively. moreover, all of the copolyimides studied in this work exhibited performance near, lying on or above the existing upper bound trade-off line between permselectivity and permeability. it may be utilized as commercial gas separation membrane material.