scholarly journals A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

2015 ◽  
Vol 11 ◽  
pp. 1767-1780 ◽  
Author(s):  
Albert Poater ◽  
Luigi Cavallo
Keyword(s):  
Dft Calculations ◽  
Olefin Metathesis ◽  
Second Generation ◽  
Phosphine Ligands ◽  
Grubbs Catalyst ◽  
Heterocyclic Ligand ◽  
Grubbs Catalysts ◽  
Wide Range ◽  
First And Second Generation ◽  
Comprehensive Study

During a Ru-catalyzed reaction of an olefin with an alkylidene moiety that leads to a metallacycle intermediate, the cis insertion of the olefin can occur from two different directions, namely side and bottom with respect to the phosphine or N-heterocyclic ligand (NHC), depending on the first or second generation Grubbs catalyst. Here, DFT calculations unravel to which extent the bottom coordination of olefins with respect is favored over the side coordination through screening a wide range of catalysts, including first and second generation Grubbs catalysts as well as the subsequent Hoveyda derivatives. The equilibrium between bottom and side coordination is influenced by sterics, electronics, and polarity of the solvent. The side attack is favored for sterically less demanding NHC and/or alkylidene ligands. Moreover the generation of a 14-electron species is also discussed, with either pyridine or phosphine ligands to dissociate.

Application of Amine-based Ru Compounds in the Olefin Metathesis of Methyl Eugenol: A Comparison with Grubbs Catalysts

2020 ◽  
Vol 17 (8) ◽  
pp. 596-602
Author(s):  
Denise A. Sousa ◽  
Paulo S. Meneses ◽  
Patrik D.S. Gois ◽  
Eliada A. Silva ◽  
Valdemiro P.C. Junior ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Methyl Eugenol ◽  
Grubbs Catalyst ◽  
Catalytic Activities ◽  
2Nd Generation ◽  
Grubbs Catalysts ◽  
Ru Complexes

Methyl eugenol olefin metathesis was conducted with non-carbene Ru-complexes ([RuCl2(PPh3)2amine]) in the absence and presence of SnCl2 or CuCl2 as additives and their catalytic activities were compared with that of a commercial Grubbs catalyst 2nd Generation (G2).

A Brief Overview of Wireless Systems and Standards

2009 ◽  
pp. 965-971
Author(s):  
Sundar G. Sankaran
Keyword(s):  
Switched Systems ◽  
Wireless Lan ◽  
Second Generation ◽  
Wireless Systems ◽  
Data Rate ◽  
Third Generation ◽  
Data Traffic ◽  
Wide Range ◽  
Voice Service ◽  
First And Second Generation

This chapter provides a brief overview of wireless systems and standards. The evolution of wireless systems from voice-centric circuit-switched systems to data-centric packet-switched systems is discussed. The first- and second-generation wireless systems were designed primarily for voice service. The data rate supported by these systems is very limited. The 2.5G systems were developed to retrofit second-generation systems to support higher data rate applications. The third-generation systems are designed to meet the demands of the Internet era. A wide range of IP-based services is provided using these systems. IEEE 802.16 standard-based systems, commonly referred to as WiMAX, are being proposed as an alternative to third-generation systems for carrying data traffic. Popular wireless LAN and wireless PAN standards are also discussed.

A Brief Overview of Wireless Systems and Standards

2011 ◽  
pp. 1-7
Author(s):  
Sundar G. Sankaran
Keyword(s):  
Switched Systems ◽  
Wireless Lan ◽  
Second Generation ◽  
Wireless Systems ◽  
Data Rate ◽  
Third Generation ◽  
Data Traffic ◽  
Wide Range ◽  
Voice Service ◽  
First And Second Generation

This chapter provides a brief overview of wireless systems and standards. The evolution of wireless systems from voice-centric circuit-switched systems to data-centric packet-switched systems is discussed. The first- and second-generation wireless systems were designed primarily for voice service. The data rate supported by these systems is very limited. The 2.5G systems were developed to retrofit second-generation systems to support higher data rate applications. The third-generation systems are designed to meet the demands of the Internet era. A wide range of IP-based services is provided using these systems. IEEE 802.16 standard-based systems, commonly referred to as WiMAX, are being proposed as an alternative to third-generation systems for carrying data traffic. Popular wireless LAN and wireless PAN standards are also discussed.

Olefin metathesis, p‐Cresol and the Second Generation Grubbs Catalyst:  Fitting the Pieces

2021 ◽  
Author(s):  
Marthinus Rudi Swart ◽  
Linette Twigge ◽  
Elizabeth Erasmus ◽  
Charlene Marais ◽  
Barend Christiaan Bezuidenhoudt
Keyword(s):  
Olefin Metathesis ◽  
Second Generation ◽  
Grubbs Catalyst

A Brief Overview of Wireless Systems and Standards

2011 ◽  
pp. 148-154
Author(s):  
Sundar G. Sankaran
Keyword(s):  
Switched Systems ◽  
Wireless Lan ◽  
Second Generation ◽  
Wireless Systems ◽  
Data Rate ◽  
Third Generation ◽  
Data Traffic ◽  
Wide Range ◽  
Voice Service ◽  
First And Second Generation

This chapter provides a brief overview of wireless systems and standards. The evolution of wireless systems from voice-centric circuit-switched systems to data-centric packet-switched systems is discussed. The first- and second-generation wireless systems were designed primarily for voice service. The data rate supported by these systems is very limited. The 2.5G systems were developed to retrofit second-generation systems to support higher data rate applications. The third-generation systems are designed to meet the demands of the Internet era. A wide range of IP-based services is provided using these systems. IEEE 802.16 standard-based systems, commonly referred to as WiMAX, are being proposed as an alternative to third-generation systems for carrying data traffic. Popular wireless LAN and wireless PAN standards are also discussed.

Second generation logarithmic estimates of single-pool variable volume Kt/V: an analysis of error.

1993 ◽  
Vol 4 (5) ◽  
pp. 1205-1213
Author(s):  
J T Daugirdas
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Total Error ◽  
Absolute Value ◽  
Variable Volume ◽  
Wide Range ◽  
First And Second Generation ◽  
New Formula ◽  
Analysis Of Error ◽  
Original Formula

The original formula proposed to estimate variable-volume single-pool (VVSP) Kt/V was Kt/V = -In(R - 0.008 * t - f * UF/W), where in the Kt/V range of 0.7 to 1.3, f = 1.0 (* denotes multiplication). This formula tends to overestimate Kt/V as the Kt/V increases above 1.3. Because higher Kt/V values are now commonly delivered, the validity of both the urea generation term (0.008 * f) and correction for UF/W were explored by solving VVSP equations for simulated hemodialysis situations, with Kt/V ranging from 0.6 to 2.6. The analysis led to the development of a second-generation formula, namely: Kt/V = -In(R - 0.008 * t) + (4-3.5 * R) * UF/W. The first and second generation formulas were then used to estimate the modeled VVSP Kt/V in 500 modeling sessions in which the Kt/V ranged widely from 0.7 to 2.1. An analysis of error showed that this second-generation formula eliminated the overestimation of Kt/V in the high ranges found with the first-generation formula. Also, total error (absolute value percent error + 2 SD) was reduced with the second-generation formula. These results led to the proposal of a new formula that can be used for a very wide range of delivered Kt/V.

Amine-Mediated Degradation in Olefin Metathesis Reactions that Employ the Second-Generation Grubbs Catalyst

ChemCatChem ◽  
2014 ◽  
Vol 6 (2) ◽  
pp. 459-463 ◽  
Author(s):  
Justin A. M. Lummiss ◽  
Benjamin J. Ireland ◽  
Jacob M. Sommers ◽  
Deryn E. Fogg
Keyword(s):  
Olefin Metathesis ◽  
Second Generation ◽  
Grubbs Catalyst ◽  
Metathesis Reactions

Theoretical characterization of first and second generation Grubbs catalysts in styrene cross-metathesis reactions: insights from conceptual DFT

2016 ◽  
Vol 6 (3) ◽  
pp. 755-766 ◽  
Author(s):  
Katherine Paredes-Gil ◽  
Pablo Jaque
Keyword(s):  
Second Generation ◽  
Reorganization Energy ◽  
Conceptual Dft ◽  
Reactivity Descriptors ◽  
Cross Metathesis ◽  
Grubbs Catalysts ◽  
Metathesis Reactions ◽  
Theoretical Characterization ◽  
First And Second Generation

Reorganization energy and DFT-based reactivity descriptors revealed important issues regarding the performance of Grubbs catalysts.

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