Chromium-Based Ethylene Tetramerization Catalysts Supported by Silicon-Bridged Diphosphine Ligands: Further Combination of High Activity and Selectivity

ChemCatChem ◽  
2016 ◽  
Vol 9 (1) ◽  
pp. 76-79 ◽  
Author(s):  
Le Zhang ◽  
Xuejiao Meng ◽  
Yanhui Chen ◽  
Chengang Cao ◽  
Tao Jiang
Keyword(s):  
High Activity ◽  
Diphosphine Ligands ◽  
Ethylene Tetramerization

Switchable Ethylene Tri-/Tetramerization with High Activity: Subtle Effect Presented by Backbone-Substituent of Carbon-Bridged Diphosphine Ligands

ACS Catalysis ◽  
2013 ◽  
Vol 3 (10) ◽  
pp. 2311-2317 ◽  
Author(s):  
Jun Zhang ◽  
Xiao Wang ◽  
Xuejun Zhang ◽  
Weijie Wu ◽  
Gengtao Zhang ◽  
...  
Keyword(s):  
High Activity ◽  
Diphosphine Ligands ◽  
Subtle Effect

Intermolecular Hydroacylation: High Activity Rhodium Catalysts Containing Small-Bite-Angle Diphosphine Ligands

2012 ◽  
Vol 134 (10) ◽  
pp. 4885-4897 ◽  
Author(s):  
Adrian B. Chaplin ◽  
Joel F. Hooper ◽  
Andrew S. Weller ◽  
Michael C. Willis
Keyword(s):  
High Activity ◽  
Diphosphine Ligands ◽  
Rhodium Catalysts ◽  
Bite Angle

ChemInform Abstract: High Activity Ethylene Trimerization Catalysts Based on Diphosphine Ligands.

ChemInform ◽  
2010 ◽  
Vol 33 (34) ◽  
pp. no-no
Author(s):  
Anthea Carter ◽  
Steven A. Cohen ◽  
Neil A. Cooley ◽  
Aden Murphy ◽  
James Scutt ◽  
...  
Keyword(s):  
High Activity ◽  
Diphosphine Ligands ◽  
Ethylene Trimerization

scholarly journals Preparation of Extremely Active Ethylene Tetramerization Catalyst [iPrN(PAr2)2−CrCl2]+[B(C6F5)4]– (Ar = −C6H4-p-SiR3)

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1122
Author(s):  
Jung Hyun Lee ◽  
Jun Won Baek ◽  
Dong Geun Lee ◽  
Ji Hyeong Ko ◽  
Dong Geun Lee ◽  
...  
Keyword(s):  
High Activity ◽  
Active Catalyst ◽  
Low Cost ◽  
Phosphine Ligands ◽  
Synthetic Method ◽  
Ethylene Tetramerization

Numerous efforts have been made to achieve “on-purpose” 1-octene production since Sasol discovered a Cr-based selective ethylene tetramerization catalyst in the early 2000s. By preparing a series of bis(phosphine) ligands iPrN(PAr2)2 where the Ar contains a bulky –SiR3 substituent (Ar = −C6H4-p-Si(nBu)3 (1), −C6H4-p-Si(1-hexyl)3 (2), −C6H4-p-Si(1-octyl)3 (3), −C6H4-p-Si(2-ethylhexyl)3 (4), −C6H4-p-Si(3,7-dimethyloctyl)3 (5)), we obtained an extremely active catalyst that meets the criteria for commercial utilization. The Cr complexes [iPrN(PAr2)2−CrCl2]+[B(C6F5)4]–, obtained by reacting ligands 1–5 with [(CH3CN)4CrCl2]+[B(C6F5)4]–, showed high activity exceeding 6000 kg/g-Cr/h, when combined with the inexpensive iBu3Al, thus avoiding the use of expensive modified methylaluminoxane (MMAO). The bulky –SiR3 substituents played a key role in the success of catalysis by blocking the formation of inactive species (Cr complexes coordinated by two iPrN(PAr2)2 ligands, that is, [(iPrN(PAr2)2)2−CrCl2]+[B(C6F5)4]–). Among the complexes prepared, [3−CrCl2]+[B(C6F5)4]– exhibited the highest activity (11,100 kg/g-Cr/h, 100 kg/g-catalyst) with high 1-octene selectivity (75 wt%) and, moreover, mitigated the generation of undesired > C10 fractions (10.7 wt%). A 10-g-scale synthesis of 3 was developed, as well as a facile and low-cost synthetic method for [(CH3CN)4CrCl2]+[B(C6F5)4]–.

ChemInform Abstract: Intermolecular Hydroacylation: High Activity Rhodium Catalysts Containing Small-Bite-Angle Diphosphine Ligands.

ChemInform ◽  
2012 ◽  
Vol 43 (33) ◽  
pp. no-no
Author(s):  
Adrian B. Chaplin ◽  
Joel F. Hooper ◽  
Andrew S. Weller ◽  
Michael C. Willis
Keyword(s):  
High Activity ◽  
Diphosphine Ligands ◽  
Rhodium Catalysts ◽  
Bite Angle

High-activity samarium-153-EDTMP therapy followed by autologous peripheral blood stem cell support in unresectable osteosarcoma

2001 ◽  
Vol 40 (06) ◽  
pp. 215-220 ◽  
Author(s):  
S. Bielack ◽  
S. Flege ◽  
J. Eckardt ◽  
J. Sciuk ◽  
H. Jürgens ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
High Activity ◽  
Peripheral Blood ◽  
Peripheral Blood Stem Cell ◽  
Blood Stem Cell ◽  
High Dose ◽  
External Radiotherapy ◽  
Primary Tumor Site ◽  
Hematopoietic Stem

Summary Purpose: Despite highly efficacious chemotherapy, patients with osteosarcomas still have a poor prognosis if adequate surgical control cannot be obtained. These patients may benefit from therapy with radiolabeled phosphonates. Patients and Methods: Six patients (three male, three female; seven to 41 years) with unresectable primary osteosarcoma (n = 3) or unresectable recurrent sites of osteosarcomas (n = 3) were treated with high-activity of Sm-153-EDTMP (150 MBq/kg BW). In all patients autologous peripheral blood stem cells had been collected before Sm-153-EDTMP therapy. Results: No immediate adverse reactions were observed in the patients. In one patient bone pain increased during the first 48 hrs after therapy. Three patients received pain relief. Autologous peripheral blood stem cell reinfusion was performed on day +12 to +27 in all patients to overcome potentially irreversible damage to the hematopoietic stem cells. In three patient external radiotherapy of the primary tumor site was performed after Sm-153-EDTMP therapy and in two of them polychemotherapy was continued. Thirty-six months later one of these patients is still free of progression. Two further patients are still alive. However, they have developed new metastases. The three patients who had no accompanying external radiotherapy, all died of disease progression five to 20 months after therapy. Conclusion: These preliminary results show that high-dose Sm-153-EDTMP therapy is feasible and warrants further evaluation of efficacy. The combination with external radiation and polychemotherapy seems to be most promising. Although osteosarcoma is believed to be relatively radioresistant, the total focal dose achieved may delay local progression or even achieve permanent local tumor control in patients with surgically inaccessible primary or relapsing tumors.

Gastric Fibrinolysis

1975 ◽  
Vol 34 (02) ◽  
pp. 409-418 ◽  
Author(s):  
I. M Nilsson ◽  
S.-E Bergentz ◽  
U Hedner ◽  
K Kullenberg
Keyword(s):  
Gastric Ulcer ◽  
Gastric Juice ◽  
High Activity ◽  
Fibrinolytic Activity ◽  
Duodenal Juice ◽  
Bleeding Tendency ◽  
Local Fibrinolysis ◽  
Heated Plates

SummaryGastric juice from 15 normals, 20 patients with gastric ulcer and 4 patients with erosive haemorrhagic gastroduodenitis was investigated in respect of its activity on unheated and heated fibrin plates and its content of FDP and plasminogen or plasmin with immunochemical methods. Gastric juice from normals showed no activity on unheated and heated fibrin plates, and no FDP or plasminogen could be demonstrated. In the patients with gastric ulcer the gastric juice showed little or no fibrinolytic activity on fibrin plates except in 2, who had regurgitation of duodenal juice and neutral pH of the juice. These patients had equally high activity on heated as on unheated plates and no plasmin could be demonstrated. It was shown that this activity was not due to fibrinolysis, but to non-specific proteolytic activity (probably trypsin). The patients with erosive haemorrhagic gastroduodenitis exhibited quite a different picture. The gastric juice from these patients showed extremely high activity on fibrin plates, the activity was higher on unheated than on heated plates. The activity was inhibited in vitro by addition of EACA and in vivo after administration of AMCA. The occurrence of plasmin could be demonstrated directly immunologically in the gastric juice. By comparison of plasmin and trypsin in various assays it could further be proved that the gastric juice in these cases contained plasminogen activator and plasmin. The patients with erosive haemorrhagic gastroduodenitis showed no increase in fibrinolysis in the blood, but low values for plasminogen and α2M, and the serum contained FDP. These findings in the blood and gastric juice were interpreted as signs of local fibrinolysis in the stomach and duodenum. There is reason to assume that this gastric fibrinolysis contributes substantially to the bleeding tendency. The effect of administration of AMCA on fibrinolytic activity and the haemorrhage lends support to the assumption of such a mechanism.

Separation of Heparin into Subtractions by DEAE-Cellulose Chromatography

1979 ◽  
Vol 42 (05) ◽  
pp. 1452-1459 ◽  
Author(s):  
Robert H Yue ◽  
Toby Starr ◽  
Menard M Gertler
Keyword(s):  
High Activity ◽  
Uronic Acid ◽  
Deae Cellulose ◽  
Exchange Chromatography ◽  
Net Charge ◽  
Uronic Acid Content ◽  
Successful Separation ◽  
Salt Gradient ◽  
Structure And Activity ◽  
Low Activity

SummaryCommercial porcine heparin can be separated into three distinct subtractions by using DEAE-cellulose chromatography and a stepped salt gradient. Gram quantities of heparin can be fractionated by this technique. All three heparin subtractions can accelerate the inhibition of thrombin by antithrombin III with different efficiency. The specific activities of the high activity heparin, intermediate activity heparin and low activity heparin are 228 units/mg, 142 units/mg and 95 units/mg, respectively. Both the uronic acid content and the quantity of N-SO4 for all three heparin subfractions have been evaluated. The high activity heparin has the lowest uronic acid and N-SO4 content. The successful separation of commercial heparin into three distinct subfractions by means of ion-exchange chromatography suggests that the net charge on these three heparin components will serve as a model system in the elucidation of the structure and activity relationship to the biological function of heparin.

Iridium-Catalyzed Silylation of C-H bonds in Unactivated Arenes: A Sterically-Encumbered Phenanthroline Ligand Accelerates Catalysis Enabling New Reactivity

2019 ◽  
Author(s):  
Caleb Karmel ◽  
Zhewei Chen ◽  
John Hartwig
Keyword(s):  
High Activity ◽  
Functional Group ◽  
Activity Analysis ◽  
High Reactivity ◽  
High Yield ◽  
Phen Ligand ◽  
Mechanistic Studies ◽  
Phenanthroline Ligand ◽  
First Time ◽  
New System

We report a new system for the silylation of aryl C-H bonds. The combination of [Ir(cod)(OMe)]<sub>2</sub> and 2,9-Me<sub>2</sub>-phenanthroline (2,9-Me<sub>2</sub>phen) catalyzes the silylation of arenes at lower temperatures and with faster rates than those reported previously, when the hydrogen byproduct is removed, and with high functional group tolerance and regioselectivity. Inhibition of reactions by the H<sub>2</sub> byproduct is shown to limit the silylation of aryl C-H bonds in the presence of the most active catalysts, thereby masking their high activity. Analysis of initial rates uncovered the high reactivity of the catalyst containing the sterically hindered 2,9-Me<sub>2</sub>phen ligand but accompanying rapid inhibition by hydrogen. With this catalyst, under a flow of nitrogen to remove hydrogen, electron-rich arenes, including those containing sensitive functional groups, undergo silylation in high yield for the first time, and arenes that underwent silylation with prior catalysts react over much shorter times with lower catalyst loadings. The synthetic value of this methodology is demonstrated by the preparation of key intermediates in the synthesis of medicinally important compounds in concise sequences comprising silylation and functionalization. Mechanistic studies demonstrate that the cleavage of the aryl C-H bond is reversible and that the higher rates observed with the 2,9-Me<sub>2</sub>phen ligand is due to a more thermodynamically favorable oxidative addition of aryl C-H bonds.

(A review) Green Data Book of the Bryansk region: plant communities that are in need of protection / Ed. A. D. Bulokhov. Bryansk, 2012. 144 p.

2013 ◽  
pp. 133-135
Author(s):  
L. G. Naumova ◽  
E. Z. Baisheva ◽  
V. B. Martynenko
Keyword(s):  
High Activity ◽  
Plant Communities ◽  
Subject Matter ◽  
Vegetation Communities ◽  
Data Book

Bryansk syntaxonomic center (Mirkin, Ermakov, 2010), which includes a group of researchers, students by prof. Bulahov A. D., characterized by high activity. Peer-reviewed monograph summarizes studies of the vegetation of the Bryansk region in the context of the choice of subject matter. In the text of the monograph a brief "Foreword", Chapter 2 theoretical and 3 parts, which is characterized by rare, reference and moss vegetation communities.

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