Regioselective Multicomponent Sequential Synthesis of Oxa-Aza[3.3.3]propellanes

2014 ◽  
Vol 67 (6) ◽  
pp. 949 ◽  
Author(s):  
Abdolali Alizadeh ◽  
Fahimeh Bayat ◽  
Long-Guan Zhu
Keyword(s):  
Column Chromatography ◽  
Inert Atmosphere ◽  
Metal Catalyst ◽  
Component Approach ◽  
Aryl Isothiocyanates

A concise and efficient sequential four-component approach to oxa-aza[3.3.3]propellanes has been developed by reaction of aryl isothiocyanates, malonate compounds, ninhydrin, and malononitrile in the presence of NaH in DMF. The value of this method lies in its regioselectivity, good yields, lack of a metal-catalyst, ease of handling, and creating five new bonds in one operation. No inert atmosphere or separation by column chromatography is necessary.

Copper-Catalyzed Tandem Multi-Component Approach to 1,3-Oxazines at Room Temperature by Cross-Dehydrogenative Coupling Using Methanol as C1 Feedstock

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1171-1175 ◽  
Author(s):  
Paran Borpatra ◽  
Mohit Deb ◽  
Pranjal Baruah
Keyword(s):  
Carbon Source ◽  
Room Temperature ◽  
Inert Atmosphere ◽  
Environmentally Benign ◽  
Metal Catalyst ◽  
Methylene Carbon ◽  
One Pot ◽  
Dehydrogenative Coupling ◽  
Tert Butyl Hydroperoxide ◽  
Component Approach

A copper(II)-catalyzed multi-component one-pot approach for the synthesis of 1,3-oxazines at room temperature is reported here. Methanol is used as the solvent as well as the carbon source. The methylene carbon of the oxazine product comes from methanol via formaldehyde. tert-Butyl hydroperoxide is used as the oxidant. The reaction uses an environmentally benign metal catalyst and oxidant. No inert atmosphere or precaution is required for the reaction. Most importantly, the reaction avoids the use of carcinogenic formaldehyde.

Design, synthesis via a one-pot approach and molecular docking studies of novel pyrrolo[2,1-a]isoquinoline derivatives

2022 ◽  
Author(s):  
Dhruba Jyoti Boruah ◽  
Devarajan Kathirvelan ◽  
Satheesh Borra ◽  
Ram Awatar Maurya ◽  
Panneerselvam Yuvaraj
Keyword(s):  
Molecular Docking ◽  
Stereoselective Synthesis ◽  
Docking Studies ◽  
Metal Catalyst ◽  
One Pot ◽  
Design Synthesis ◽  
Molecular Docking Studies ◽  
Component Approach ◽  
Isoquinoline Derivatives

This new investigation describes an efficient three-component approach for the stereoselective synthesis of pyrrolo[2,1-a]isoquinolines from readily available isatins, chalcones and 1,2,3,4-tetrahydroisoquinoline without using any metal catalyst or additive.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Elemental Distribution in Pt-Re:Al2O3 Naphtha Reforming Catalysts

1980 ◽  
Vol 38 ◽  
pp. 200-201
Author(s):  
R. L. Freed ◽  
M. J. Kelley
Keyword(s):  
Bimetallic Catalyst ◽  
Supported Catalysts ◽  
Coke Formation ◽  
Materials Characterization ◽  
Metal Catalyst ◽  
Elemental Distribution ◽  
Exact Nature ◽  
Naphtha Reforming ◽  
Reforming Catalysts ◽  
Commercial Introduction

The commercial introduction of Pt-Re supported catalysts to replace Pt alone on Al2O3 has brought improvements to naphtha reforming. The bimetallic catalyst can be operated continuously under conditions which lead to deactivation of the single metal catalyst by coke formation. Much disagreement still exists as to the exact nature of the bimetallic catalyst at a microscopic level and how it functions in the process so successfully. The overall purpose of this study was to develop the materials characterization tools necessary to study supported catalysts. Specifically with the Pt-Re:Al2O3 catalyst, we sought to elucidate the elemental distribution on the catalyst.

Heparin Excretion in Intact and Hepatectomized Rats

1981 ◽  
Vol 45 (02) ◽  
pp. 146-149
Author(s):  
Ray Losito ◽  
Harry Gattiker ◽  
Ginette Bilodeau
Keyword(s):  
Column Chromatography ◽  
Normal Values ◽  
Anticoagulant Activity ◽  
Biliary Fistula ◽  
Kinetics Of ◽  
Intact Rats

SummaryMetabolism and kinetics of 3H-heparin were compared in intact and hepatectomized rats. Rats were divided into three groups: 1) intact rats with biliary fistulas and cystostomies 2) intact rats with only cystostomies and 3) hepatectomized rats with cystostomies. Radioactivity in blood, bile and urine besides anticoagulant activity in blood and urine were examined. In addition, column chromatography of urine was used to isolate possible metabolites. Seventy percent and 80% of the radioactive dose was found in the urine of intact rats at 24 hr and 48 hr. Close to 5% of the radioactivity was found in bile or rats with a biliary fistula after 48 hr. The APTT declined to near normal values at 1 hr whether rats had a biliary fistula or not. In contrast, only 25 % of the radioactivity could be excreted into the urine of hepatectomized rats in 24 hr; the APTT did not decline as fast and at 5 hr, it was still 100 seconds. Only one radioactive component could be isolated on chromatography from all urines of these animals and appears to be similar to the original heparin. Thus, the liver has an important role to play in regulating the anticoagulant effects and excretion of heparin.

VANILLINSÄURE ALS ENDPRODUKT DES STOFFWECHSELS VON ADRENALIN UND NORADRENALIN. II.

1963 ◽  
Vol 44 (1) ◽  
pp. 101-106 ◽  
Author(s):  
Wilhelm Dirscherl ◽  
Helmut Thomas
Keyword(s):  
Rat Liver ◽  
Paper Chromatography ◽  
Column Chromatography ◽  
Vanillic Acid ◽  
Hippuric Acid ◽  
Single Spot ◽  
Solvent Systems ◽  
Perfusion Experiment ◽  
Kinetics Of

ABSTRACT Perfusion of rat liver with vanillic acid yielded only one metabolite. In paper chromatography with three different solvent systems, the substance showed the same RF-values as vanillyolglycine (3-methoxy-4-hydroxyhippuric acid) and in mixed chromatograms there was only one single spot. After separation by column chromatography, the UV- and IRspectra of the reaction product were identical with those of 3-methoxy4-hydroxy-hippuric acid. During the perfusion experiment, the kinetics of the conjugation were investigated.

DIE ZUSAMMENSETZUNG DER JODHALTIGEN VERBINDUNGEN UND IHRE BEZIEHUNG ZUM JODUMSATZ IN EUTHYREOTEN STRUMEN

1962 ◽  
Vol 41 (4) ◽  
pp. 584-594 ◽  
Author(s):  
Dankwart Reinwein ◽  
Erich Klein
Keyword(s):  
Column Chromatography ◽  
Iodine Content ◽  
High Plasma ◽  
Secretion Rate ◽  
Total Iodine ◽  
Iodine Compound ◽  
Hormonal Secretion ◽  
Carrier Free ◽  
Iodine Metabolism ◽  
Diffuse Goiter

ABSTRACT The iodine metabolism was investigated in 29 patients with euthyroid non-endemic diffuse goiter. 1 to 14 days before thyroidectomy the patients received carrier-free 131I. The chemical iodine fractions (PBI, BEI and iodide) of the thyroid and the labelled iodine compound were analyzed by means of paper- and column chromatography. In one gland the total iodine content varied only by ± 19.6% of the average, the relative shares of PBI, BEI and iodide as well as that of the iodoamino acids being equal. Monoiodotyrosine, diiodotyrosine and thyroxine were found in the thyroid homogenate without hydrolysis. The homogenate after hydrolysis contained more iodotyrosines at the expense of iodothyronines than do normal glands. 17 goiters with normal 131I-uptake showed a high total iodine content (14.2 ± 5.0 mg) whilst 9 goiters with an increased 131I-uptake had low values (3.58 ± 0.6 mg). The opposite was found for the relative shares of BEI with the chromatographically isolated iodothyronines thyroxine, triiodothyronine and an unidentified iodine compound. Goiters with »high plasma PB131I« were characterized by a faster transfer of 131I into the more heavily iodinated compounds than is found in glands with a normal hormonal secretion rate. The highest values for the iodothyronines were found in goiters with increased 131I-uptake together with a high hormonal secretion rate. From this study it appears that the changes in the iodine-poor glands are due to a defective exo- or endogenous iodine supply. The observed alterations in iodine-rich glands are probably induced by a faulty iodine utilization characterized by an incomplete iodotyrosyl-coupling defect.

Fabrication of Carbon Nanotube Triode Using Helicon Plasma Cvd with Electroplated Nico Catalyst

2003 ◽  
Vol 772 ◽  
Author(s):  
Masakazu Muroyama ◽  
Kazuto Kimura ◽  
Takao Yagi ◽  
Ichiro Saito
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Metal Catalyst ◽  
Ni Catalyst ◽  
Plasma Cvd ◽  
Helicon Plasma ◽  
Plasma Enhanced Cvd ◽  
Turn On ◽  
Aligned Carbon Nanotubes ◽  
Vertically Aligned

AbstractA carbon nanotube triode using Helicon Plasma-enhanced CVD with electroplated NiCo catalyst has been successfully fabricated. Isolated NiCo based metal catalyst was deposited at the bottom of the cathode wells by electroplating methods to control the density of carbon nanotubes and also reduce the activation energy of its growth. Helicon Plasma-enhanced CVD (HPECVD) has been used to deposit nanotubes at 400°C. Vertically aligned carbon nanotubes were then grown selectively on the electroplated Ni catalyst. Field emission measurements were performed with a triode structure. At a cathode to anode gap of 1.1mm, the turn on voltage for the gate was 170V.

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