Recent Progress in Synthesizing Polyethers via Organocatalysts

Synlett ◽  
2021 ◽  
Author(s):  
Yao-Yao Zhang ◽  
Guan-Wen Yang ◽  
Guang-Peng Wu
Keyword(s):  
Molecular Weight ◽  
Recent Progress ◽  
Raw Materials ◽  
Catalytic Efficiency ◽  
Cost Effective ◽  
Catalytic Performance ◽  
Excellent Performance ◽  
Metallic Compounds ◽  
High Yields ◽  
Performance And Mechanism

Aliphatic polyethers are one of the most widely used polymers, whose synthesis is largely dependent on metallic compounds. Recent development of organocatalysts may break the limits of this long-standing field and infuse vitality into polyether production. In this Synpacts article, the recent advances of organocatalysts for polyether production is introduced in aspects of catalytic performance and mechanism. Moreover, attentions are paid to the latest contributions of bifunctional organoboron catalysts which can be prepared with high yields from cost-effective raw materials in two facile reactions and show excellent performance in the polyether production with remarkable catalytic efficiency, controllability on molecular weight, and explicit polymerization mechanism. Based on these advances, it is envisioned that new discoveries using organocatalysts will continue in the previsible future.

scholarly journals Ag2O–MnO2/Graphene Oxide Nanocomposite

2020 ◽  
Author(s):  
Farooq Syed ◽  
Mujeeb Khan ◽  
Mohammed Rafi Shaik ◽  
Mufsir Kuniyil ◽  
M Rafiq Siddiqui ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Specific Activity ◽  
Catalytic Efficiency ◽  
Cost Effective ◽  
Catalytic Performance ◽  
Industrial Applications ◽  
Recoverable Catalyst ◽  
Aerial Oxidation ◽  
Milling Method ◽  
State Mixing

In this study, we reported the eco-friendly fabrication of Ag2O–MnO2/GRO nanocomposites by the solid-state mixing of separately prepared GRO and Ag2O–MnO2 NPs using ball milling method, a mechanochemical approach. The prepared material was studied for the catalytic effect of GRO in the system for the aerial oxidation of a variety of alcohols. It was found that the (1%)Ag2O–MnO2/(5 wt.%)GRO nanocatalyst demonstrated a high conversion ability (~100%) and excellent selectivity in the presence of O2 as a clean oxidant. The higher catalytic properties of the nanocomposite were attributed to the presence of GRO, which exhibited extraordinary catalytic properties like improved surface area, excellent chemical compatibility, and stability, as well as the introduction of several defects in the obtained nanocomposite that enhance the catalytic performance. The specific activity of 13.3 mmol·g−1·h−1 is obtained for the catalyst i.e. (1%)Ag2O–MnO2/(5 wt.%)GRO, which is reportedly superior to the various other catalysts previously reported in the literature for the same conversion reaction. Our catalytic strategy was highly selective, producing only desired products with no over-oxygenation to carboxylic acids. The merits of our catalytic methodology were: (a) facile process, (b) inexpensive and clean oxidant, (c) no surfactants or nitrogenous bases were required, (d) mild catalytic conditions, (e) cost-effective recoverable catalyst, (f) complete convertibility, (g) full selectivity, (h) rapid process, and (i) applicable to virtually all types of alcohols. So, these highlights made this catalytic strategy to be highly applicable in the industrial applications for manufacturing of carbonyls. To the best of our knowledge, this was the first study of utilizing Ag2O–MnO2/GRO composite as a catalyst for the oxidation of alcohols, highlighting the catalytic efficiency of GRO.

scholarly journals Synthesis and process optimization of Boscalid by catalyst Pd-PEPPSI-IPrDtBu-An

2021 ◽  
pp. 3-3
Author(s):  
Jian Xu ◽  
Xiao-Bing Lan ◽  
Lin-Jian Xia ◽  
Yi Yang ◽  
Gao Cao
Keyword(s):  
Raw Materials ◽  
Condensation Reaction ◽  
Suzuki Reaction ◽  
Coupling Reaction ◽  
Catalytic Efficiency ◽  
Catalytic Performance ◽  
Synthesis Process ◽  
Reaction Conditions ◽  
Cross Coupling Reaction ◽  
Optimal Reaction

The purpose of this research was to reduce the amount of noble metal palladium catalyst and improve the catalytic performance in the Suzuki-Miyaura cross-coupling reaction, which is the key step in the synthesis of Boscalid. Taking o-bromonitrobenzene and p-chlorophenylboronic acid as raw materials, three kinds of Pd-PEPPSI-IPr catalysts were synthesized and employed in the Suzuki reaction, and then the biaryl product was subjected to reduction and condensation reaction to prepare Boscalid. Under optimal reaction conditions, the result showed that the catalytic system exhibits highest catalytic efficiency under aerobic conditions, giving the 2-(4-chlorophenyl)nitrobenzene over 99 % yield. Moreover, the Pd-PEPPSI-IPrDtBu-An catalyst was minimized to 0.01mol%. The synthesis process was mild, the post-treatment was simple, and the production cost was reduced which makes it suitable for industrial production.

Analyzing the Mechanism and Effect of Acid Protease in Wet blue Bating Process for Leather Production

2020 ◽  
Vol 115 (1) ◽  
pp. 10-15
Author(s):  
Hao Li ◽  
Deyi Zhu ◽  
Yanchun Li ◽  
Shan Cao ◽  
Jing Xiao
Keyword(s):  
Molecular Weight ◽  
Raw Materials ◽  
Collagen Fibers ◽  
Acid Protease ◽  
Excellent Performance ◽  
Functional Protein ◽  
Essential Step ◽  
Production Safety ◽  
Chromium Tolerance ◽  
Chromium Resistance

In recent years, in order to reduce the pollution produced in beam-house and tanning sections, more and more tanneries purchase wet blue from other factories in other regions directly used as raw materials for finished leather production thereby those polluted preliminary steps can be eliminated. Therefore, the wet blue bating process is an essential step to minimize the differences of wet blue which are purchased from different regions. In this study, the properties of different acid protease are analyzed for selecting suitable protease used for wet blue bating. The analysis of chromium tolerance of different acid proteases reveals that, L1 and L4 produced from Aspergillus have higher chromium resistance than that of produced from Bacillus. The effect of L1 and L4 on wet blue and collagen shows that the L1 has more excellent performance, in which the molecular weight of functional protein is 48 KD. By SEM and MCT analysis, L1 can successfully disperse the collagen fibers of wet blue. Furthermore, the biodegradation rates of collagen and elastin were 0.006‰ and 0.5‰, respectively. It indicates that the acid protease mainly degraded elastin but not collagen in bating process thereby ensuring production safety. This paper provides the importance references for the application and the basis for the development of mechanism of acid protease in bating process. 

Ligand Migration in the Reaction of Titanium Complexes with AlMe3

2007 ◽  
Vol 72 (4) ◽  
pp. 541-559 ◽  
Author(s):  
Michał J. Kobyłka ◽  
Lucjan B. Jerzykiewicz ◽  
Jasson T. Patton ◽  
Szymon Przybylak ◽  
Józef Utko ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Catalytic Performance ◽  
Active Species ◽  
Titanium Complexes ◽  
Propene Polymerization ◽  
Ligand Migration ◽  
High Yields ◽  
Titanium Compounds ◽  
Insight Into ◽  
Gaining Insight

Five different titanium compounds cis-[Ti(η2-hbo)2(OEt)2]·0.5toluene (1), cis-[TiCl2(η2-thp)2] (2), [TiCl2(edbp)2] (3), [Ti2(μ-OMe)2(edbp)2(Me)2] (6), [Ti2(μ-OMe)2(edbp)2(OMe)2] (7) (Hhbo = 2-(2-hydroxyfenyl)benzoxazole, Hthp = tetrahydropyran-2-methanol, H2edbp = 2,2'-ethylidenebis(4,6-di-tert-butylphenol)), have been prepared and tested in combination with MAO as catalysts for propene polymerization and ethene and oct-1-ene copolymerization with the aim of gaining insight into the structure of the active species. Investigation of the 1/AlMe3 or 2/AlMe3 systems resulted in isolation of [Al(η2-hbo)2(Me)] (4) and [Al2(μ2-η2-thp)2(Me)4] (5) in high yields. This indicates that the trimethylaluminum contained in MAO abstracts ligands from 1 or 2, affecting thus the catalytic performance of the 1,2/MAO catalysts. In contrast, compound 3 reacted with MAO affording methylated product 6. Accordingly, the 3/MAO catalyst differed from the above ones, furnishing at 70 °C e.g., narrow molecular weight polypropylene (Mn = 454 000; Mw/Mn = 2.49; Tm = 158.2 °C).

Upgrading of Pyrolysis Bio-Oil to Fuel over Supported Nanomaterials - A Review

2014 ◽  
Vol 625 ◽  
pp. 357-360 ◽  
Author(s):  
Madiha Yasir ◽  
Sujan Chowdhury ◽  
Nurlidia Mansor ◽  
Norani Muti Mohamed ◽  
Yoshimitsu Uemura
Keyword(s):  
Active Sites ◽  
Earth Metal ◽  
Catalytic Efficiency ◽  
Cost Effective ◽  
Active Phase ◽  
Catalytic Performance ◽  
Transportation Fuel ◽  
Support Materials ◽  
Highly Active ◽  
Bio Oil

Upgrading of bio-oil obtained from pyrolysis of biomass is one the most attractive way to produce fuel both in technological and economical aspect. Development of cost-effective, long life and highly active catalyst is a major challenge in this concern. Addition of support material to the nanocatalyst not only increases the life span of the catalyst but also offers more active sites as well as reduces the cost by lowering the amount of active metal used. Moreover, selection of appropriate support favors efficient dispersion of the active phase. The main focus of this review article is to look into the development of supported nanocatalysts in the past few decades, comparing catalytic performance and deactivation rate of catalysts in the upgrading of bio-oil to produce a value-aided and efficient transportation fuel. Overall, appreciable work has been done to improve the hydrodeoxygenation reaction using different nanosized rare earth metal support materials with enhanced catalytic efficiency and finally need to be implemented in industries for upgrading of pyrolysis bio-oil.

Antithrombotic Therapy for DVT/PE

1997 ◽  
Vol 17 (03) ◽  
pp. 161-162
Author(s):  
Thomas Hyers
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Oral Anticoagulants ◽  
Cost Effective ◽  
Therapeutic Agents ◽  
Great Promise ◽  
Term Therapy ◽  
Low Molecular Weight ◽  
Long Term Therapy

SummaryProblems with unfractionated heparin as an antithrombotic have led to the development of new therapeutic agents. Of these, low molecular weight heparin shows great promise and has led to out-patient therapy of DVT/PE in selected patients. Oral anticoagulants remain the choice for long-term therapy. More cost-effective ways to give oral anticoagulants are needed.

scholarly journals End-of-Life Alternatives of Glass Reinforced Polyester Boat Hulls Compared by LCA

2018 ◽  
Vol 27 (4) ◽  
pp. 096369351802700 ◽  
Author(s):  
Mehmet Önal ◽  
Gökdeniz Neşer
Keyword(s):  
End Of Life ◽  
Environmental Impacts ◽  
Raw Materials ◽  
Weight Ratio ◽  
Cost Effective ◽  
Raw Material ◽  
Photochemical Oxidation ◽  
Human Toxicity ◽  
Vacuum Infusion ◽  
Infusion Method

Glass reinforced polyester (GRP), as a thermoset polymer composites, dominates boat building industry with its several advantages such as high strength/weight ratio, cohesiveness, good resistance to environment. However, proper recovering and recycling of GRP boats is became a current environmental requirement that should be met by the related industry. In this study, to propose in a cost effective and environmentally friendly way, Life Cycle Assessment (LCA) has been carried out for six scenarios include two moulding methods (namely Hand Lay-up Method, HLM and Vacuum Infusion Method, VIM) and three End-of-Life (EoL) alternatives(namely Extruding, Incineration and Landfill) for a recreational boat's GRP hulls. A case study from raw materials purchasing phase to disposal/recycling stages has been established taking 11 m length GRP boat hull as the functional unit. Analysis show that in the production phase, the impacts are mainly due to the use of energy (electricity), transport and raw material manufacture. Largest differences between the methods considered (HLM and VIM) can be observed in the factors of marine aquatic ecotoxicity and eutrophication while the closest ones are abiotic depletion, ozon layer depletion and photochemical oxidation. The environmental impact of VIM is much higher than HLM due to its higher energy consumption while vacuum infusion method has lower risk than hand lay-up method in terms of occupational health by using less raw material (resin) in a closed mold. In the comparison of the three EoL techniques, the mechanical way of recycling (granule extruding) shows better environmental impacts except terrestrial ecotoxicity, photochemical oxidation and acidification. Among the EoL alternatives, landfill has the highest environmental impacts except ‘global warming potential’ and ‘human toxicity’ which are the highest in extrusion. The main cause of the impacts of landfill is the transportation needs between the EoL boats and the licenced landfill site. Although it has the higher impact on human toxicity, incineration is the second cleaner alternative of EoL techniques considered in this study. In fact that the similar trend has been observed both in production and EoL phases of the boat. It is obvious that using much more renewable energy mix and greener transportation alternative can reduce the overall impact of the all phases considerably.

scholarly journals Electrochemical multicomponent synthesis of 4-selanylpyrazoles under catalyst- and chemical-oxidant-free conditions

2021 ◽  
Author(s):  
Yan Wu ◽  
Jin-Yang Chen ◽  
Jing Ning ◽  
Xue Jiang ◽  
Jie Deng ◽  
...  
Keyword(s):  
Multicomponent Reaction ◽  
Raw Materials ◽  
Multicomponent Synthesis ◽  
Mild Conditions ◽  
Simple Protocol ◽  
High Yields

An electrochemical multicomponent reaction was established under catalyst-, chemical-oxidant-free and mild conditions, which provides an eco-friendly and simple protocol for constructing 4-selanylpyrazoles from easily available raw materials with high yields.

scholarly journals Novel Cs2HfCl6 Crystal Scintillator: Recent Progress and Perspectives

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 320-351
Author(s):  
Serge Nagorny
Keyword(s):  
Recent Progress ◽  
Raw Materials ◽  
Light Output ◽  
Light Yield ◽  
Thermal Conditions ◽  
Pulse Shape Discrimination ◽  
Main Element ◽  
High Quality ◽  
Crystal Sample ◽  
Discrimination Ability

Recent progress in Cs2HfCl6 (CHC) crystal production achieved within the last five years is presented. Various aspects have been analyzed, including the chemical purity of raw materials, purification methods, optimization of the growth and thermal conditions, crystal characterization, defect structure, and internal radioactive background. Large volume, crack-free, and high quality CHC crystals with an ultimate scintillating performance were produced as a result of such extensive research and development (R & D) program. For example, the CHC crystal sample with dimensions ∅23 × 30 mm3 demonstrates energy resolution of 3.2% FWHM at 662 keV, the relative light output at the level of 30,000 ph/MeV and excellent linearity down to 20 keV. Additionally, this material exhibits excellent pulse shape discrimination ability and low internal background of less than 1 Bq/kg. Furthermore, attempts to produce a high quality CHC crystal resulted in research on this material optimization by constitution of either alkali ions (Cs to Tl), or main element (Hf to Zr), or halogen ions (Cl to Br, I, or their mixture in different ratio), as well as doping with various active ions (Te4+, Ce3+, Eu3+, etc.). This leads to a range of new established scintillating materials, such as Tl2HfCl6, Tl2ZrCl6, Cs2HfCl4Br2, Cs2HfCl3Br3, Cs2ZrCl6, and Cs2HfI6. To exploit the whole potential of these compounds, detailed studies of the material’s fundamental properties, and understanding of the variety of the luminescence mechanisms are required. This will help to understand the origin of the high light yield and possible paths to further extend it. Perspectives of CHC crystals and related materials as detectors for rare nuclear processes are also discussed.

Sign in / Sign up

Export Citation Format

Share Document