MODIFICATION OF POLYBUTADIENE RUBBER: A REVIEW

2021 ◽  
Author(s):  
Parashiva Prabhu C. ◽  
Subhra Mohanty ◽  
Virendra Kumar Gupta
Keyword(s):  
Chain Length ◽  
Industrial Applications ◽  
Global Market ◽  
Specific Method ◽  
Reactivity Ratios ◽  
Reaction Conditions ◽  
Commercial Products ◽  
Polybutadiene Rubber ◽  
Metal Catalyzed

ABSTRACT Developments in modification of polybutadiene rubber (PBR) using various reagents and catalysts have been reviewed. Hydrogenation and functionalization occurring at the site of unsaturation along chain length are discussed. Hydrogenation involving various metal catalyzed processes is discussed. Suitable conditions that are effective during hydrogenation and functionalization are mentioned in this article. Reactivity ratios associated with microstructures of polybutadiene rubber and possible mechanisms involved are described in the review. The importance of reaction conditions during reactivity and their impact on product properties are highlighted. A specific method that needs to be adopted in order to achieve expected product properties is discussed. Various industrial applications of modified PBR and their commercial products in the global market are discussed.

Microbial Bioconversion: A Regio-specific Method for Novel Drug Design and Toxicological Study of Metabolites

2019 ◽  
Vol 20 (14) ◽  
pp. 1156-1162
Author(s):  
Maria Yousuf ◽  
Waqas Jamil ◽  
Khayala Mammadova
Keyword(s):  
Microbial Transformation ◽  
Specific Method ◽  
Reaction Conditions ◽  
Small Organic Molecules ◽  
Toxicological Studies ◽  
Drug Designing ◽  
Transformation Methods ◽  
Novel Drug

The methods of chemical structural alteration of small organic molecules by using microbes (fungi, bacteria, yeast, etc.) are gaining tremendous attention to obtain structurally novel and therapeutically potential leads. The regiospecific mild environmental friendly reaction conditions with the ability of novel chemical structural modification in compounds categorize this technique; a distinguished and unique way to obtain medicinally important drugs and their in vivo mimic metabolites with costeffective and timely manner. This review article shortly addresses the immense pharmaceutical importance of microbial transformation methods in drug designing and development as well as the role of CYP450 enzymes in fungi to obtain in vivo drug metabolites for toxicological studies.

scholarly journals The COOL-Process—A Selective Approach for Recycling Lithium Batteries

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 259
Author(s):  
Sandra Pavón ◽  
Doreen Kaiser ◽  
Robert Mende ◽  
Martin Bertau
Keyword(s):  
Lithium Ion ◽  
Global Market ◽  
Raw Material ◽  
Mass Ratio ◽  
Reaction Conditions ◽  
Cool Process ◽  
Secondary Sources ◽  
Selective Approach ◽  
Valuable Metals ◽  
Housing Materials

The global market of lithium-ion batteries (LIB) has been growing in recent years, mainly owed to electromobility. The global LIB market is forecasted to amount to $129.3 billion in 2027. Considering the global reserves needed to produce these batteries and their limited lifetime, efficient recycling processes for secondary sources are mandatory. A selective process for Li recycling from LIB black mass is described. Depending on the process parameters Li was recovered almost quantitatively by the COOL-Process making use of the selective leaching properties of supercritical CO2/water. Optimization of this direct carbonization process was carried out by a design of experiments (DOE) using a 33 Box-Behnken design. Optimal reaction conditions were 230 °C, 4 h, and a water:black mass ratio of 90 mL/g, yielding 98.6 ± 0.19 wt.% Li. Almost quantitative yield (99.05 ± 0.64 wt.%), yet at the expense of higher energy consumption, was obtained with 230 °C, 4 h, and a water:black mass ratio of 120 mL/g. Mainly Li and Al were mobilized, which allows for selectively precipitating Li2CO3 in battery grade-quality (>99.8 wt.%) without the need for further refining. Valuable metals, such as Co, Cu, Fe, Ni, and Mn, remained in the solid residue (97.7 wt.%), from where they are recovered by established processes. Housing materials were separated mechanically, thus recycling LIB without residues. This holistic zero waste-approach allows for recovering the critical raw material Li from both primary and secondary sources.

scholarly journals Synthesis and Antitumor Activity of a Series of Novel 1-Oxa-4-azaspiro[4,5]deca-6,9-diene-3,8-dione Derivatives

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 936
Author(s):  
Ze Yang ◽  
Qiu Zhong ◽  
Shilong Zheng ◽  
Guangdi Wang ◽  
Ling He
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cancer Cell Lines ◽  
Oxidative Cyclization ◽  
Human Lung Cancer ◽  
Reaction Conditions ◽  
Promising Candidate ◽  
Metal Catalyzed ◽  
Further Development

A series of novel 1-oxa-4-azaspiro[4.5]deca-6,9-diene-3,8-diones were designed and synthesized by using 4-aminophenol and α-glycolic acid or lactic acid as starting materials in three or four steps. The key step is the metal-catalyzed oxidative cyclization of the amide to 1-oxa-4-azaspiro[4.5]deca-6,9-diene-3,8-diones (10a and 10b), the reaction conditions of which are investigated and optimized. The anticancer activity of 17 1-oxa-4-azaspiro[4.5]deca-6,9-diene-3,8-dione derivatives was evaluated. Preliminary results showed that 15 compounds have moderate to potent activity against human lung cancer A549, human breast cancer MDA-MB-231, and human cervical cancer HeLa cancer cell lines. Among them, compounds 11b and 11h were the most potent against A549 cell line with 0.18 and 0.19 µM of IC50, respectively; compounds 11d, 11h, and 11k showed the most potent cytotoxicity against MDA-MB-231 cell line with 0.08, 0.08, and 0.09 µM of IC50, respectively, while the activities of 11h, 11k, and 12c against HeLa cell line were the most potent with 0.15, 0.14, and 0.14 µM of IC50, respectively. Compound 11h is a promising candidate for further development, which emerged as the most effective compound overall against the three tested cancer cell lines.

scholarly journals Recent Advances in Homogeneous Metal-Catalyzed Aerobic C–H Oxidation of Benzylic Compounds

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 640 ◽  
Author(s):  
Garazi Urgoitia ◽  
Raul SanMartin ◽  
María Herrero ◽  
Esther Domínguez
Keyword(s):  
Molecular Oxygen ◽  
Aerobic Oxidation ◽  
Key Factors ◽  
Reaction Conditions ◽  
Aromatic Ketones ◽  
Recent Advances ◽  
Metal Catalyzed

Csp3–H oxidation of benzylic methylene compounds is an established strategy for the synthesis of aromatic ketones, esters, and amides. The need for more sustainable oxidizers has encouraged researchers to explore the use of molecular oxygen. In particular, homogeneous metal-catalyzed aerobic oxidation of benzylic methylenes has attracted much attention. This account summarizes the development of this oxidative strategy in the last two decades, examining key factors such as reaction yields, substrate:catalyst ratio, substrate scope, selectivity over other oxidation byproducts, and reaction conditions including solvents and temperature. Finally, several mechanistic proposals to explain the observed results will be discussed.

scholarly journals Enzymatic Biotransformation of Balloon Flower Root Saponins into Bioactive Platycodin D by Deglucosylation with Caldicellulosiruptor bescii β-Glucosidase

2019 ◽  
Vol 20 (16) ◽  
pp. 3854 ◽  
Author(s):  
Tae-Geun Kil ◽  
Su-Hwan Kang ◽  
Tae-Hun Kim ◽  
Kyung-Chul Shin ◽  
Deok-Kun Oh
Keyword(s):  
Pharmacological Activity ◽  
Plant Root ◽  
Industrial Applications ◽  
The Other ◽  
Root Extract ◽  
Reaction Conditions ◽  
Platycodin D ◽  
Caldicellulosiruptor Bescii ◽  
Platycodi Radix ◽  
Biotransformation Process

Platycodin D (PD), a major saponin (platycoside) in Platycodi radix (balloon flower root), has higher pharmacological activity than the other major platycosides; however, its content in the plant root is only approximately 10% (w/w) and the productivities of PD by several enzymes are still too low for industrial applications. To rapidly increase the total PD content, the β-glucosidase from Caldicellulosiruptor bescii was used for the deglucosylation of the PD precursors platycoside E (PE) and platycodin D3 (PD3) in the root extract into PD. Under the optimized reaction conditions, the enzyme completely converted the PD precursors into PD with the highest productivity reported so far, increasing the total PD content to 48% (w/w). In the biotransformation process, the platycosides in Platycodi radix were hydrolyzed by four pathways: deapiosylated (deapi)-PE → deapi-PD3 → deapi-PD, PE → PD3 → PD, polygalacin D3 → polygalacin D, and 3″-O-acetyl polygalacin D3 → 3″-O-acetyl polygalacin D.

The Reaction of Thiols and α,ω-Dithiols With Triphenylphosphine and Diisopropyl Azodicarboxylate

1990 ◽  
Vol 43 (1) ◽  
pp. 161 ◽  
Author(s):  
D Camp ◽  
ID Jenkins
Keyword(s):  
Chain Length ◽  
Disulfide Bond ◽  
Alkyl Chain ◽  
Bond Formation ◽  
Product Distribution ◽  
Alkyl Chain Length ◽  
Disulfide Bond Formation ◽  
Reaction Conditions ◽  
Mitsunobu Reactions

α,ω-Dithiols in the presence of triphenylphosphine and diisopropyl azodicarboxylate are converted into a mixture of monomeric and polymeric disulfides. The product distribution is dependent on the alkyl chain length and the reaction conditions. In contrast to normal Mitsunobu reactions, disulfide bond formation is achieved with regeneration of triphenylphosphine. The mechanism of this reaction is discussed.

Novel Templated Polyphenol for Ionic Conductivity

2001 ◽  
Vol 702 ◽  
Author(s):  
Ferdinando F. Bruno ◽  
Ramaswamy Nagarajan ◽  
Jayant Kumar ◽  
Lynne A. Samuelson
Keyword(s):  
Molecular Weight ◽  
Ionic Conductivity ◽  
High Molecular Weight ◽  
Polyethylene Oxide ◽  
Phenol Formaldehyde ◽  
Industrial Applications ◽  
Water Soluble ◽  
Reaction Conditions ◽  
Water Solvent ◽  
Potential Use

ABSTRACTPhenolic polymers and phenol formaldehyde resins are of great interest for a number of electronic and industrial applications. Unfortunately, the toxic nature of the starting materials (formaldehyde) and harsh reaction conditions required for the synthesis of these polymers have severely limited their use in today’s markets. We present here an alternative, biocatalytic approach where the enzyme horseradish peroxidase is used to polymerize phenol in the presence of a template such as polyethylene oxide. Here the template serves as a surfactant that can both emulsify the phenol and polyphenol chains during polymerization and maintain water/solvent solubility of the final polyphenol/template complex. The reactants and the reaction conditions of this approach are mild and result in high molecular weight, electrically and optically active, water-soluble complexes of polyphenol and the template used. High molecular weight water-soluble polyphenol/polyethylene oxide complexes were formed. The ionic conductivity and potential use of these polymers as polyelectrolytes for battery and solution cell applications will be discussed.

scholarly journals Metal-catalyzed organic reactions by Resonant Acoustic Mixing

2021 ◽  
Author(s):  
Lori Gonnet ◽  
Cameron Lennox ◽  
Jean-Louis Do ◽  
Ivani Malvestiti ◽  
Stefan Koenig ◽  
...  
Keyword(s):  
Ball Milling ◽  
Organic Synthesis ◽  
Mechanochemical Synthesis ◽  
Catalytic Synthesis ◽  
Antidiabetic Drug ◽  
Ring Closing Metathesis ◽  
Reaction Conditions ◽  
Metal Catalyzed ◽  
Resonant Acoustic Mixing ◽  
Model Reactions

We introduce catalytic organic synthesis by Resonant Acoustic Mixing (RAM): a mechanochemical methodology that does not require bulk solvent or milling media. Using as model reactions ruthenium-catalyzed ring-closing metathesis, ene-yne metathesis and copper-catalyzed sulfonamide-isocyanate coupling, we demonstrate RAM-based mechanochemical synthesis that is faster and operationally simpler than conventional ball milling. Moreover, the method can be readily scaled-up, as demonstrated by straightforward catalytic synthesis of the antidiabetic drug Tolbutamide from hundreds of milligrams to at least 10 grams, without any significant changes in reaction conditions.

scholarly journals Comparative Studies of Pectinase Production byBacillus subtilis strain Btk 27in Submerged and Solid-State Fermentations

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Oliyad Jeilu Oumer ◽  
Dawit Abate
Keyword(s):  
Solid State ◽  
Wheat Bran ◽  
Solid State Fermentation ◽  
Submerged Fermentation ◽  
Industrial Applications ◽  
Global Market ◽  
Subtilis Strain ◽  
Fast Pace ◽  
Initial Ph ◽  
Pectinase Production

The request for enzymes in the global market is expected to rise at a fast pace in recent years. With this regard, there has been a great increase in industrial applications of pectinase owing to their significant biotechnological uses. This study was undertaken with main objectives of meeting the growing industrial demands of pectinase, by improving the yield without increasing the cost of production. In addition, this research highlights the underestimated potential of agroresidues for the production of biotechnologically important products. In this study, the maximum pectinase production attained was using wheat bran, among the tested agroresidues. The production of pectinase was improved from 10.1 ± 1.4 U/ml to 66.3 ± 1.2 U/ml in submerged fermentation whereas it was in solid state fermentation from 800.0 ± 16.2 U/g to 1272.4 ± 25.5 U/g. The maximum pectinase production was observed using YEP (submerged fermentation) and wheat bran (solid state fermentation) at initial pH of 6.5, at 37°C and by supplementing the medium with 3 mM MgSO4.7H2O.

Sonochemistry in Transition Metal Catalyzed Cross-coupling Reactions: Recent Developments

2020 ◽  
Vol 23 (28) ◽  
pp. 3137-3153 ◽  
Author(s):  
Sankuviruthiyil M. Ujwaldev ◽  
K. R. Rohit ◽  
Sankaran Radhika ◽  
Gopinathan Anilkumar
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Reaction Rates ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Recent Developments ◽  
Ultrasound Assisted ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

: Transition metal catalyzed cross-coupling reactions have always been very important in synthetic organic chemistry due to their versatility in forming all sorts of carbon-carbon and carbon-hetero atom bonds. Incorporation of ultrasound assistance to these protocols resulted in milder reaction conditions, faster reaction rates, etc. This review focuses on the contributions made by ultrasound-assisted protocols towards transition metal catalyzed crosscoupling reactions.

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