Modification of Lipase with Various Synthetic Polymers and Their Catalytic Activities in Organic Solvent

1994 ◽  
Vol 10 (4) ◽  
pp. 398-402 ◽  
Author(s):  
Yoshihiro Ito ◽  
Hajime Fujii ◽  
Yukio Imanishi
Keyword(s):  
Organic Solvent ◽  
Synthetic Polymers ◽  
Catalytic Activities

scholarly journals Synthesis and Catalytic Activities of 3-Decyl-β-proline for Michael Reactions in Water without an Organic Solvent

ACS Omega ◽  
2021 ◽  
Author(s):  
Kazuhiro Nagata ◽  
Chihiro Nakagawa ◽  
Wakana Yokoyama ◽  
Haruka Usui ◽  
Rikako Mochizuki ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Catalytic Activities ◽  
Michael Reactions

scholarly journals Synthesis of C3-Symmetric Cinchona-Based Organocatalysts and Their Application in Asymmetric Michael and Friedel–Crafts Reactions

2021 ◽  
Author(s):  
Péter Kisszékelyi ◽  
Zsuzsanna Fehér ◽  
Sándor Nagy ◽  
Péter Bagi ◽  
Petra Kozma ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Asymmetric Catalysis ◽  
Michael Reaction ◽  
Supported Catalyst ◽  
Catalyst Recovery ◽  
Catalytic Activities ◽  
Symmetric Structure ◽  
Organic Solvent Nanofiltration ◽  
Positive Effect

In this work, anchoring of cinchona derivatives to trifunctional cores (hub approach) was demonstrated to obtain size-enlarged organocatalysts. By modifying the cinchona skeleton in different positions, we prepared four C3-symmetric size-enlarged cinchona derivatives (hub-cinchonas), which were tested as organocatalysts and their catalytic activities were compared with the parent cinchona (hydroquinine) catalyst. We showed that in the hydroxyalkylation reaction of indole, hydroquinine provides good enantioselectivities (up to 73% ee), while the four new size-enlarged derivatives gave significantly lower values (up to 29% ee) in this reaction. Anchoring cinchonas to trifunctional cores was found to facilitate nanofiltration-supported catalyst recovery using PolarClean alternative solvent. The C3-symmetric size-enlarged organocatalysts were completely rejected by all the applied membranes, whereas the separation of hydroquinine was found to be insufficient using organic solvent nanofiltration. Furthermore, the asymmetric catalysis was successfully demonstrated in the case of Michael reaction of 1,3-diketones and trans-β-nitrostyrene using Hub3-cinchona (up to 96% ee) as a result of the positive effect of the C3-symmetric structure using a bulkier substrate. This means an increased selectivity of the catalyst in comparison to hydroquinine in the latter Michael reaction.

scholarly journals Synthesis of C3-Symmetric Cinchona-Based Organocatalysts and Their Applications in Asymmetric Michael and Friedel–Crafts Reactions

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 521
Author(s):  
Péter Kisszékelyi ◽  
Zsuzsanna Fehér ◽  
Sándor Nagy ◽  
Péter Bagi ◽  
Petra Kozma ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Asymmetric Catalysis ◽  
Michael Reaction ◽  
Supported Catalyst ◽  
Catalyst Recovery ◽  
Catalytic Activities ◽  
Symmetric Structure ◽  
Organic Solvent Nanofiltration ◽  
Positive Effect ◽  
The Michael Reaction

In this work, anchoring of cinchona derivatives to trifunctional cores (hub approach) was demonstrated to obtain size-enlarged organocatalysts. By modifying the cinchona skeleton in different positions, we prepared four C3-symmetric size-enlarged cinchona derivatives (hub-cinchonas), which were tested as organocatalysts and their catalytic activities were compared with the parent cinchona (hydroquinine) catalyst. We showed that in the hydroxyalkylation reaction of indole, hydroquinine provides good enantioselectivities (up to 73% ee), while the four new size-enlarged derivatives resulted in significantly lower values (up to 29% ee) in this reaction. Anchoring cinchonas to trifunctional cores was found to facilitate nanofiltration-supported catalyst recovery using the PolarClean alternative solvent. The C3-symmetric size-enlarged organocatalysts were completely rejected by all the applied membranes, whereas the separation of hydroquinine was found to be insufficient when using organic solvent nanofiltration. Furthermore, the asymmetric catalysis was successfully demonstrated in the case of the Michael reaction of 1,3-diketones and trans-β-nitrostyrene using Hub3-cinchona (up to 96% ee) as a result of the positive effect of the C3-symmetric structure using a bulkier substrate. This equates to an increased selectivity of the catalyst in comparison to hydroquinine in the latter Michael reaction.

Evolution of Synthetic Polymers with Enzyme-like Catalytic Activities

2006 ◽  
pp. 63-88 ◽  
Author(s):  
Irving M. Klotz ◽  
Junghun Suh
Keyword(s):  
Synthetic Polymers ◽  
Catalytic Activities

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

STUDIES ON A NON-MELATONIN PINEAL ANTI-GONADOTROPHIN

1972 ◽  
Vol 69 (2) ◽  
pp. 257-266 ◽  
Author(s):  
Bryant Benson ◽  
Mary Jane Matthews ◽  
Alvin E. Rodin
Keyword(s):  
Solvent Extraction ◽  
Organic Solvent ◽  
Pineal Gland ◽  
Gel Filtration ◽  
Test System ◽  
Pineal Body ◽  
Physiological Effects ◽  
Organic Solvent Extraction ◽  
Gland Function

ABSTRACT Continuing investigation of pineal gland function indicates that the anti-gonadotrophic activity of this organ cannot be attributed solely to the postulated hormone melatonin, the concentration of which is negligible in the pineal body compared to quantities required to produce unequivocal physiological effects. A non-melatonin antigonadotrophic substance recently isolated from bovine pineal glands was further purified by organic solvent extraction, ultrafiltration and gel filtration. Studies of partial blockage of compensatory ovarian hypertrophy in unilaterally ovariectomized Charles River CD-1 mice indicated that this substance is significantly more potent than melatonin in this test system.

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