scholarly journals Acetate Facilitated Nickel Catalyzed Coupling of Aryl Chlorides and Alkyl Thiols

2021 ◽  
Author(s):  
Regina M. Oechsner ◽  
J. Philipp Wagner ◽  
Ivana Fleischer
Keyword(s):  
Catalytic System ◽  
Room Temperature ◽  
Low Cost ◽  
Potassium Acetate ◽  
Addition Product ◽  
Catalytic Cycle ◽  
Nmr Studies ◽  
Aryl Chlorides ◽  
Wide Range ◽  
Tertiary Alkyl

We report a mild, fast and convenient catalytic system for the coupling of aryl chlorides with primary, secondary, as well as previously challenging tertiary alkyl thiols using an air-stable nickel(II) precatayst in combination with the low-cost base potassium acetate at room temperature. This new catalytic system tolerates a variety of functional groups and enables the generation of thioethers for a wide range of substrates, including pharmaceutical compounds in excellent yields. Chemoselec-tive functionalization of disubstituted substrates was demonstrated. Kinetic and NMR-studies, as well as DFT computations support a Ni(0)/Ni(II) catalytic cycle and identify the oxidative addition product as the resting state. Acetate coordination and subsequent acetate facilitated formation of a thiolate complex via internal deprotonation play a key role in the catalytic cycle.

μCHILL: a lightweight, modular system for handling crystalline samples at low temperatures under inert conditions

2018 ◽  
Vol 51 (2) ◽  
pp. 541-548 ◽  
Author(s):  
Michael Solar ◽  
Nils Trapp
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Low Cost ◽  
Three Dimensional ◽  
Modular System ◽  
Preparation Time ◽  
Stable Conditions ◽  
Wide Range ◽  
Single Operator ◽  
Cold Gas

A procedure for preparing and mounting crystals under inert conditions is demonstrated, using a specialized apparatus (μCHILL) to provide a cold gas stream fed from a liquid nitrogen (LN2) reservoir or an open bath heat exchanger. A second, dry gas stream at room temperature enwraps the cold gas, protecting the sample preparation zone from ambient moisture. The technique is extremely flexible, requiring only a single operator, little practice and almost no preparation time. The device enables operation in a wide temperature range (at least 213 K to room temperature), providing temperature control and very stable conditions with no icing for extended time periods. The flexible, modular and low-cost design is based on three-dimensional-printed parts and readily available standard components, potentially making the device available to a wide range of users and applications not limited to single-crystal studies.

scholarly journals Photochemically-Mediated Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamides

2020 ◽  
Author(s):  
Robert Simons ◽  
Georgia Scott ◽  
Anastasia Gant Kanegusuku ◽  
Jennifer Roizen
Keyword(s):  
Visible Light ◽  
Catalytic System ◽  
Visible Light Irradiation ◽  
Room Temperature ◽  
Iridium Complex ◽  
Aryl Chlorides ◽  
Coupling Methods ◽  
Aryl Bromides ◽  
Boronic Esters ◽  
General Method

A general method for the <i>N</i>-arylation of sulfamides with aryl bromides is described. The protocol leverates a dual-catalytic system of nickel and a photoexcitable iridium complex and proceeds at room temperature under visible light irradiation. Using these tactics, aryl boronic esters and aryl chlorides can be carried through the reaction untouched. Thereby, this method complements known Buchwald-Hartwig coupling methods for N-arylation of sulfamides.

‘On-water’ organic synthesis: a green, highly efficient, low cost and reusable catalyst system for biaryl synthesis under aerobic conditions at room temperature

RSC Advances ◽  
2015 ◽  
Vol 5 (63) ◽  
pp. 50655-50659 ◽  
Author(s):  
Bishwajit Saikia ◽  
Preeti Rekha Boruah ◽  
Abdul Aziz Ali ◽  
Diganta Sarma
Keyword(s):  
Organic Synthesis ◽  
Room Temperature ◽  
Low Cost ◽  
Suzuki Reaction ◽  
Catalyst System ◽  
Reusable Catalyst ◽  
Wide Range ◽  
Biaryl Synthesis ◽  
Phenylboronic Acids ◽  
Operational Simplicity

The PdCl2/sucrose/K2CO3/H2O system showed the superb catalytic activity towards the Suzuki reaction of a wide range of aryl/heteroaryl halides with diverse phenylboronic acids at room temperature with operational simplicity and shorter reaction time.

scholarly journals Photochemically-Mediated Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamides

2019 ◽  
Author(s):  
Robert Simons ◽  
Georgia Scott ◽  
Anastasia Gant Kanegusuku ◽  
Jennifer Roizen
Keyword(s):  
Visible Light ◽  
Catalytic System ◽  
Visible Light Irradiation ◽  
Room Temperature ◽  
Iridium Complex ◽  
Aryl Chlorides ◽  
Coupling Methods ◽  
Aryl Bromides ◽  
Boronic Esters ◽  
General Method

A general method for the <i>N</i>-arylation of sulfamides with aryl bromides is described. The protocol leverates a dual-catalytic system of nickel and a photoexcitable iridium complex and proceeds at room temperature under visible light irradiation. Using these tactics, aryl boronic esters and aryl chlorides can be carried through the reaction untouched. Thereby, this method complements known Buchwald-Hartwig coupling methods for N-arylation of sulfamides.

Systematic Precipitation of Magnesium Hydroxide Using NH4OH to Preparing MgO-PSZ Precursor Powder

2014 ◽  
Vol 805 ◽  
pp. 712-717
Author(s):  
Chieko Yamagata ◽  
Jose O.A. Paschoal
Keyword(s):  
Magnesium Hydroxide ◽  
Room Temperature ◽  
Low Cost ◽  
Zirconium Oxychloride ◽  
Precursor Powder ◽  
Molar Ratio ◽  
Ceramic Processing ◽  
Wide Range ◽  
High Molar Ratio ◽  
Co Precipitation

The wide range of applications of zirconia based ceramics is due to stabilization of its tetragonal and cubic structures at room temperature, by controlled adding of dopants such as yttria, magnesia, calcia, ceria and some rare earth oxides. The advantage of the use of magnesia as dopant is not only due to its low cost, but fact that by controlling its ceramic processing, it is possible to control a specific microstructure for the specific application. The precipitation of magnesium hydroxides, using NH4OH as a precipitant, presents some difficulties due to the formation of a variety of soluble complexes of ammonia with magnesium, which inhibits the total precipitation of magnesium. In the present work, the influence of precipitant and metals concentrations and pH on the magnesium hydroxide precipitation was investigated. Magnesium chloride, zirconium oxychloride and NH4OH were used as starting materials. The precipitation of magnesium hydroxide depends on concentrations of OH-, Cl- and Mg2+. To achieve specific precipitation yield, lower the concentration of Mg2+ high molar ratio of [OH-]/[Cl-] is required. The pH measure is not enough to control Mg (OH)2 precipitation. The use of molar ratio of [OH-]/[Cl-] = 4.4, resulted in 95 % of Mg (OH)2 precipitation. The co-precipitation of Zr and Mg hydroxides, using the optimized molar ratio of [OH-]/[Cl-], the precipitation of Mg (OH)2 achieved in range of 97.6 to 98.3 %.

scholarly journals Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors

2017 ◽  
Vol 13 ◽  
pp. 2385-2395 ◽  
Author(s):  
Mukta Shaw ◽  
Yogesh Kumar ◽  
Rima Thakur ◽  
Amit Kumar
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic System ◽  
Room Temperature ◽  
Pyridinium Salt ◽  
Pyridinium Salts ◽  
Thiourea Derivative ◽  
Reaction Conditions ◽  
Thiourea Derivatives ◽  
Wide Range

The glycosylation of O-glycosyl trichloroacetimidate donors using a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This transformation occurs under mild reaction conditions with a wide range of O-glycosyl trichloroacetimidate donors and glycosyl acceptors to afford the corresponding O-glycosides in moderate to good yields with predictable selectivity. In addition, the optimized method is also utilized for the regioselective O-glycosylation by using a partially protected acceptor.

scholarly journals Photochemically-Mediated Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamides

2020 ◽  
Author(s):  
Robert Simons ◽  
Georgia Scott ◽  
Anastasia Gant Kanegusuku ◽  
Jennifer Roizen
Keyword(s):  
Visible Light ◽  
Catalytic System ◽  
Visible Light Irradiation ◽  
Room Temperature ◽  
Iridium Complex ◽  
Aryl Chlorides ◽  
Coupling Methods ◽  
Aryl Bromides ◽  
Boronic Esters ◽  
General Method

A general method for the <i>N</i>-arylation of sulfamides with aryl bromides is described. The protocol leverates a dual-catalytic system of nickel and a photoexcitable iridium complex and proceeds at room temperature under visible light irradiation. Using these tactics, aryl boronic esters and aryl chlorides can be carried through the reaction untouched. Thereby, this method complements known Buchwald-Hartwig coupling methods for N-arylation of sulfamides.

scholarly journals A Novel Seedless TSV Process Based on Room Temperature Curing Silver Nanowires ECAs for MEMS Packaging

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 351 ◽  
Author(s):  
Meng ◽  
Cheng ◽  
Yang ◽  
Sun ◽  
Luo
Keyword(s):  
Room Temperature ◽  
Microelectromechanical Systems ◽  
Silver Nanowires ◽  
Low Cost ◽  
Mems Devices ◽  
Filling Process ◽  
Conductive Adhesives ◽  
Mems Packaging ◽  
Wide Range ◽  
High Efficient

The through-silicon-vias (TSVs) process is a vital technology in microelectromechanical systems (MEMS) packaging. The current via filling technique based on copper electroplating has many shortcomings, such as involving multi-step processes, requiring sophisticated equipment, low through-put and probably damaging the MEMS devices susceptible to mechanical polishing. Herein, a room temperature treatable, high-efficient and low-cost seedless TSV process was developed with a one-step filling process by using novel electrically conductive adhesives (ECAs) filled with silver nanowires. The as-prepared ECAs could be fully cured at room temperature and exhibited excellent conductivity due to combining the benefits of both polymethyl methacrylate (PMMA) and silver nanowires. Complete filling of TSVs with the as-prepared 30 wt% silver nanowires ECAs was realized, and the resistivity of a fully filled TSV was as low as 10−3 Ω·cm. Furthermore, the application of such novel TSV filling process could also be extended to a wide range of different substrates, showing great potential in MEMS packaging, flexible microsystems and many other applications.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

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