Hammett analysis of the palladium-catalyzed allyl-aryl coupling reaction has demonstrated that the rate of the coupling reaction is enhanced by electron-withdrawing groups on the aryl siloxane. The positive slope of the Hammett plot indicated involvement of a charged transition state in which negative charge on the aryl ring is stabilized inductively. This result is consistent with either transmetalation or reductive elimination being the rate-determining step in the coupling process. Furthermore, the influence of ligand on the metal site has been assessed from competition studies as a function of ligand type, cone angle, and electronic effects. From the relative ratios of coupling products produced in the Hammett study, it is possible to gather insight into the role of the electronic as well as the steric effects of ligands on the mechanism of the coupling reaction.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jo8010254 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Direct Observation of Hybridization Between Co 3d and S 2p Electronic Orbits: Moderating Sulfur Covalency to Pre-Activate Sulfur-Redox in Lithium-Sulfur Batteries.
Adv Sci (Weinh)
December 2024
Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin, Heilongjiang, 150025, China.
Lithium-sulfur batteries (LSBs) offer high energy density and environmental benefits hampered by the shuttle effect related to sluggish redox reactions of long-chain lithium polysulfides (LiPSs). However, the fashion modification of the d-band center in separators is still ineffective, wherein the mechanism understanding always relies on theoretical calculations. This study visibly probed the evolution of the Co 3d-band center during charge and discharge using advanced inverse photoemission spectroscopy/ultraviolet photoemission spectroscopy (IPES/UPS), which offers reliable evidence and are consistent well with theoretical calculations.
View Article and Find Full Text PDFEnhanced subtyping from stool samples using semi-nested barcode PCR: validation with an NGS-based approach.
Biotechniques
December 2024
Laboratorio de Parasitología Molecular, Vicerrectoría de Investigaciones, Universidad El Bosque, Bogotá, Colombia.
In 2006, a PCR method was introduced to subtype by Sanger sequencing of an ≈610 bp amplicon of the 18S rRNA gene. This method, known as barcoding-PCR, has become widespread, although the primer pair used can amplify non- sequences, which can result in false positives. Barcoding-PCR is most effective with DNA extracted from cultures, limiting its sensitivity when used directly with stool samples.
View Article and Find Full Text PDFHepatitis B virus impacts embryonic development and methylation of maternal genes in assisted reproductive technology patients.
J Assist Reprod Genet
December 2024
Department of Reproduction, Qingdao Municipal Hospital, 5 Donghaizhong Road, Qingdao, 266071, China.
Purpose: In China, the prevalence of hepatitis B virus (HBV) infection among infertile couples is a significant clinical problem. It is necessary to determine the effect of HBV infection on embryo development.
Methods: The 4301 fresh cycles and 5763 frozen embryo transfer (FET) cycles were grouped according to the couple with or without HBV infection.
Displacement and stress response of open-web girders under near field explosive loading.
Sci Rep
December 2024
Research Center of Space Structures, Guizhou University, Guiyang, 550025, China.
This study employed numerical simulation to investigate the dynamic response characteristics of open-web girders subjected to proximity blast loading and to compare these characteristics with those of solid-web girders. The research utilized the Coupled Eulerian-Lagrangian (CEL) method for simulation, effectively combining the advantages of both Eulerian and Lagrangian approaches. This method mitigated issues related to mesh distortion while accurately modeling the damage inflicted by blast loads on the structures.
View Article and Find Full Text PDFRatiometric fluorescent probe and smartphone-based visual recognition for HO and organophosphorus pesticide based on Ce/Ce cascade enzyme reaction.
Food Chem
December 2024
Laboratory of Functional Polymers, School of Materials Science and Engineering, Linyi University, Linyi 276005, China. Electronic address:
Organicphosphorus is a ubiquitous pesticide that has potential hazards to human health and environmental well-being. Therefore, the precise identification of residues of organophosphorus pesticides (OPs) emerges as an urgent necessity. A ratiometric fluorescent sensor for the detection of OPs by leveraging the catalytic activities of Ce and Ce on the two fluorescent substrates 4-Methylumbelliferyl phosphate (4-MUP) and o-phenylenediamine (OPD) correspondingly was designed.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!