Effect of reaction conditions on the activity of the WCl6 + (CH3)4Sn catalytic system in the metathesis of methyl 10-undecenoate

1985 ◽  
Vol 50 (12) ◽  
pp. 2665-2669 ◽  
Author(s):  
Hynek Balcar ◽  
Alena Dosedlová ◽  
Lidmila Petrusová ◽  
Bohumír Matyska
Keyword(s):  
Catalytic System ◽  
Good Yield ◽  
Catalyst Concentration ◽  
Published Data ◽  
Reaction Conditions ◽  
Active Centres

In contrast to published data, metathesis of methyl 10-undecenoate is found to proceed with a good yield even if the ester is present in a high excess with respect to the catalyst, if the former is first reacted with WCl6 to form a complex (owing to which the reaction mixture acquires red colour), and only then the metathesis is started by adding (CH3)4Sn. Moreover, satisfactory degrees of conversion are only attained if the catalyst concentration is low enough so that the deactivation of the active centres is slowed down.

Ionic liquid immobilized Cu(I)-Hydrazone-Triphenylphosphine Complex: An Easily recyclable Catalytic System for Suzuki and Heck Cross Couplings

2021 ◽  
Author(s):  
Dileep Ramakrishna
Keyword(s):  
Ionic Liquid ◽  
Catalytic System ◽  
Catalyst Concentration ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Ethyl Methyl ◽  
Triphenylphosphine Complex ◽  
Effects Of Temperature

A highly efficient, reusable catalytic system towards Heck and Suzuki cross-coupling reactions was observed for an inexpensive copper complex dispersed in ethyl-methyl imidazolium hexafluorophosphate medium, [EMIM] PF6. The reaction conditions were optimized by studying the effects of temperature, catalyst concentration, solvent and time. The method functions for a variety of substrates towards the cross coupling reactions. Most notably, the catalyst-ionic liquid mixture was easily recoverable and reused for six times without much loss in the catalytic activity, causing significantly a very low impact on the environment.

scholarly journals Chromium–Salen Complex / Nitroxyl Radical Cooperative Catalysis:A New Combination for Aerobic Intramolecular Dearomative Coupling of Phenols

2020 ◽  
Author(s):  
Shota Nagasawa ◽  
Shogo Fujiki ◽  
Yusuke Sasano ◽  
Yoshiharu Iwabuchi
Keyword(s):  
Electron Transfer ◽  
Catalytic System ◽  
Good Yield ◽  
Nitroxyl Radical ◽  
Reaction System ◽  
Coupling Reaction ◽  
New Combination ◽  
Mechanistic Study ◽  
Reaction Conditions ◽  
Salen Complex

Herein we describe an aerobic intramolecular dearomative coupling reaction of phenols using a catalytic system with the combination of a chromium–salen (Cr–salen) complex and a nitroxyl radical. This novel catalytic system enables the construction of a spirocyclic dienone product, which is a potentially useful intermediate for the synthesis of various natural products such as alkaloids and phenylpropanoids from bisphenol in good yield under mild reaction conditions (under O2 and ambient temperature). A preliminary mechanistic study suggests that this reaction system is promoted by a cooperative electron transfer between the Cr(III)–salen complex, nitroxyl radical and bisphenol substrate.

scholarly journals Chromium–Salen Complex / Nitroxyl Radical Cooperative Catalysis:A New Combination for Aerobic Intramolecular Dearomative Coupling of Phenols

2020 ◽  
Author(s):  
Shota Nagasawa ◽  
Shogo Fujiki ◽  
Yusuke Sasano ◽  
Yoshiharu Iwabuchi
Keyword(s):  
Electron Transfer ◽  
Catalytic System ◽  
Good Yield ◽  
Nitroxyl Radical ◽  
Reaction System ◽  
Coupling Reaction ◽  
New Combination ◽  
Mechanistic Study ◽  
Reaction Conditions ◽  
Salen Complex

Herein we describe an aerobic intramolecular dearomative coupling reaction of phenols using a catalytic system with the combination of a chromium–salen (Cr–salen) complex and a nitroxyl radical. This novel catalytic system enables the construction of a spirocyclic dienone product, which is a potentially useful intermediate for the synthesis of various natural products such as alkaloids and phenylpropanoids from bisphenol in good yield under mild reaction conditions (under O2 and ambient temperature). A preliminary mechanistic study suggests that this reaction system is promoted by a cooperative electron transfer between the Cr(III)–salen complex, nitroxyl radical and bisphenol substrate.

scholarly journals Ring-Opening Copolymerization of Cyclohexene Oxide and Cyclic Anhydrides Catalyzed by Bimetallic Scorpionate Zinc Catalysts

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1651
Author(s):  
Felipe de la Cruz-Martínez ◽  
Marc Martínez de Sarasa Buchaca ◽  
Almudena del Campo-Balguerías ◽  
Juan Fernández-Baeza ◽  
Luis F. Sánchez-Barba ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Mechanism ◽  
Catalytic System ◽  
Phthalic Anhydride ◽  
Ring Opening ◽  
High Selectivity ◽  
Zinc Complexes ◽  
Cyclohexene Oxide ◽  
Reaction Conditions ◽  
Cyclic Anhydrides

The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO2 as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts tested for the ROCOP of CHO and phthalic anhydride at different reaction conditions, the most active catalytic system was the combination of complex 3 with bis(triphenylphosphine)iminium as cocatalyst in toluene at 80 °C. Once the optimal catalytic system was determined, the scope in terms of other cyclic anhydrides was broadened. The catalytic system was capable of copolymerizing selectively and efficiently CHO with phthalic, maleic, succinic and naphthalic anhydrides to afford the corresponding polyester materials. The polyesters obtained were characterized by spectroscopic, spectrometric, and calorimetric techniques. Finally, the reaction mechanism of the catalytic system was proposed based on stoichiometric reactions.

Optimization of biodiesel synthesis under simultaneous ultrasound-microwave irradiation using response surface methodology (RSM)

2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Teymor Tavakoli Hashjin ◽  
Barat Ghobadian ◽  
Gholamhasan Najafi ◽  
Stefano Mantegna ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Microwave Irradiation ◽  
Response Surface ◽  
Palm Oil ◽  
Catalyst Concentration ◽  
Irradiation Time ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Biodiesel Synthesis

AbstractThis work investigates the effect of simultaneous ultrasound-microwave irradiation on palm oil transesterification and uncovers optimal operating conditions. Response surface methodology (RSM) has been used to analyze the influence of reaction conditions, including methanol/palm oil molar ratio, catalyst concentration, reaction temperature and irradiation time on biodiesel yield. RSM analyses indicate 136 s and 129 s as the optimal sonication and microwave irradiation times, respectively. Optimized parameters for full conversion (97.53%) are 1.09% catalyst concentration and a 7:3.1 methanol/oil molar ratio at 58.4°C. Simultaneous ultrasound-microwave irradiation dramatically accelerates the palm oil transesterification reaction. Pure biodiesel was obtained after only 2.2 min while the conventional method requires about 1 h.

Optimization of Esterification Reaction Conditions Through the Analysis of the Main Significant Variables

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Bruna Ricetti Margarida ◽  
Luana I. Flores ◽  
Luiz Fernando De Lima Luz Jr. ◽  
Marcelo Kaminski Lenzi
Keyword(s):  
Catalyst Concentration ◽  
Biodiesel Production ◽  
Major Influence ◽  
Esterification Reaction ◽  
Reaction Conditions ◽  
Reaction Behavior ◽  
Reaction Conversion ◽  
Depth Analysis ◽  
Hydrous Ethanol ◽  
Water Ratio

Biodiesel production from residual sources is gaining considerable attention nowadays. Consequently, many different studies with in-depth analysis concerning the influence of the transesterification reaction conditions are available in the literature. However, further evaluation of the esterification of fatty acids in the biodiesel industry is still needed. In this study, different parameters influencing the esterification reaction behavior using ethanol as the alcohol and lauric acid as the FFA are analyzed through factorial design and ANOVA methodologies to verify which ones are significant in the reaction. In total, four parameters were evaluated: temperature, catalyst concentration, ethanol/FFA ratio, and ethanol/water ratio. The temperature and ethanol/water ratio had a major influence on the reaction, as increasing these parameters greatly improved reaction conversion. It was also verified that using hydrous ethanol in the esterification reaction is possible in some conditions.

Rhodium-Catalyzed Asymmetric Addition of Arylboronic Acids to Glyoxylates: Access to Optically Active Substituted Mandelic Acid Esters

Synlett ◽  
2019 ◽  
Vol 30 (14) ◽  
pp. 1693-1697
Author(s):  
Diao Chen ◽  
Jian-Guo Liu ◽  
Xu Zhang ◽  
Ming-Hua Xu
Keyword(s):  
Catalytic System ◽  
Mandelic Acid ◽  
Optically Active ◽  
Antiplatelet Drug ◽  
Reaction Conditions ◽  
Formal Synthesis ◽  
Arylboronic Acids ◽  
Synthetic Utility ◽  
Enantioselective Addition ◽  
Acid Esters

A rhodium-catalyzed enantioselective addition of glyoxylates to arylboronic acids promoted by a simple chiral sulfinamide-based olefin ligand under mild reaction conditions is described. The reaction provides access to a variety of optically active substituted mandelic acid esters in good yields with up to 83% ee. The catalytic system is also applicable to pyruvate addition. The synthetic utility of this method is highlighted by a formal synthesis of the antiplatelet drug clopidogrel.

Selective aerobic allylic oxidation of α-pinene catalyzed by metalloporphyrins in the absence of solvents and additives

2019 ◽  
Vol 43 (9-10) ◽  
pp. 419-425 ◽  
Author(s):  
Huanhuan Dong ◽  
Shichao Xu ◽  
Jing Wang ◽  
Yuxiang Chen ◽  
Liangwu Bi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Time ◽  
Flow Rate ◽  
Catalyst Concentration ◽  
Aerobic Oxidation ◽  
Oxygen Flow Rate ◽  
Oxidation Products ◽  
Allylic Oxidation ◽  
Temperature Reaction ◽  
Reaction Conditions

Selective aerobic oxidation of α-pinene to high-value products is a major challenge in chemistry. Metalloporphyrins are proved to be selective catalysts for aerobic oxidation of simple hydrocarbons. Herein, we extend this method to more complex substrates using metallodeuteroporphyrins as model catalysts. It was found that the oxidation occurs mainly on the C=C and allylic C–H bonds of α-pinene influenced by the reaction temperature, reaction time, catalyst concentration, and oxygen flow rate. Allylic C–H oxidation products are obtained with a maximum selectivity value of 78.4% using the following reaction conditions: 105°C, 7 h, 5 ppm, and 60 mL/min. The influence of the metal nuclei of the metallodeuteroporphyrins on this reaction is also investigated. It was found that metallodeuteroporphyrins with Fe3+ as the metal nucleus exhibit the highest catalytic activity.

Palladium-Catalyzed Anti-Markovnikov Oxidation of Aromatic and Aliphatic Alkenes to Terminal Acetals and Aldehydes

Synthesis ◽  
2020 ◽  
Author(s):  
Yasuyuki Ura
Keyword(s):  
Organic Compounds ◽  
Catalytic System ◽  
Recent Progress ◽  
Short Review ◽  
Nucleophilic Attack ◽  
Reaction Conditions ◽  
Terminal Alkenes ◽  
Palladium Catalyzed ◽  
Substrate Addition ◽  
Cyclic Alkenes

AbstractCatalytic anti-Markovnikov (AM) oxidation of terminal alkenes can provide terminally oxyfunctionalized organic compounds. This short review mainly summarizes our recent progress on the Pd-catalyzed AM oxidations of aromatic and aliphatic terminal alkenes to give terminal acetals (oxidative acetalization) and aldehydes (Wacker-type oxidation), along with related reports. These reactions demonstrate the efficacy of the PdCl2(MeCN)2/CuCl/electron-deficient cyclic alkenes/O2 catalytic system. Notably, electron-deficient cyclic alkenes such as p-benzoquinones (BQs) and maleimides are key additives that facilitate nucleophilic attack of oxygen nucleophiles on coordinated terminal alkenes and enhance the AM selectivity. BQs also function to oxidize Pd(0) depending on the reaction conditions. Several other factors that improve the AM selectivity, such as the steric demand of the nucleo­philes, slow substrate addition, and halogen-directing groups, are also discussed.1 Introduction2 Anti-Markovnikov Oxidation of Aromatic Alkenes to Terminal Acetals­3 Anti-Markovnikov Oxidation of Aromatic Alkenes to Aldehydes4 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Terminal Acetals­5 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Aldehydes6 Conclusion

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