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Cyclopolymerization Leading to Polycyclic Systems
Published in George B. Butler, Cyclopolymerization and Cyclocopolymerization, 2020
1,4-Pentadiene has been polymerized by Ziegler catalysts to give soluble polymers containing a small amount of residual unsaturation.57 Some main chain unsaturation as well as pendant group unsaturation was observed. The former was due to some isomerization of 1,4- to 1,3-pentadiene which then copolymerized with the 1,4-diene. The extent of isomerization varied with the catalyst system used. On the basis of an infrared examination of the CH2 stretching frequencies in the 2900 cm-1 region, it was concluded that the polymer did not contain a methylene-linked four-membered ring structure. Analogous to the results obtained on N,N-divinylaniline (4-13), a mechanism, leading to bicyclo[3.3.1]-nonane rings was proposed.1-89 The possibility of a five-membered ring structure was not considered.
Arene ruthenium, rhodium and iridium complexes containing N∩O chelating ligands: synthesis, antibacterial and antioxidant studies
Published in Journal of Coordination Chemistry, 2021
Agreeda Lapasam, Lathewdeipor Shadap, Deepak Kumar Tripathi, Krishna Mohan Poluri, Werner Kaminsky, Mohan Rao Kollipara
All reagents used in this work were purchased commercially and used without purification; 4-hydroxybenzhydrazide, 3-methoxybenzhydrazide, pentamethylcyclo-pentadiene, cyclopentadiene, and α-terpinene were purchased from Sigma Aldrich. The solvents were purified and dried according to standard procedures [34]. The starting precursor metal complexes [(p-cymene)RuCl2]2, [Cp*MCl2]2 (M = Rh/Ir) and [CpRu(PPh3)2Cl], were prepared according to literature methods [35–37]. The syntheses of all the complexes were performed at room temperature. Infrared (IR) spectra were recorded on a Bruker ALPHA II FTIR spectrometer as KBr pellets from 4000 to 400 cm−1. 1H NMR spectra were recorded on a Bruker Avance II 400 MHz spectrometer using deuterated chloroform and deuterated dimethyl sulfoxide as solvents, with TMS as internal references. UV–vis absorption spectra were obtained on a Perkin-Elmer Lambda 25 UV/Vis spectrophotometer in acetonitrile solution. Elemental analyses of the complexes were carried out on a Perkin-Elmer 2400 CHN analyzer.
Molecular magnetisabilities computed via finite fields: assessing alternatives to MP2 and revisiting magnetic exaltations in aromatic and antiaromatic species
Published in Molecular Physics, 2021
Tim Stauch, Brad Ganoe, Jonathan Wong, Joonho Lee, Adam Rettig, Jiashu Liang, Jie Li, Evgeny Epifanovsky, Teresa Head-Gordon, Martin Head-Gordon
We also consider cyclopentadiene , which was presented as an illustration against using out-of-plane magnetisability exaltation as an aromaticity criteria [94]. With our method, against both planar s-cis and trans isomers of 1,3-pentadiene, cyclopentadiene displays moderate negative exaltation, around 35–50% of benzene. This suggests that not all of the exaltation results from the ring current effect, as the aforementioned authors stated [94]; nonetheless, given the difference in magnitude, out-of-plane magnetisability exaltation remains to appear to be a useful gauge of aromaticity.
Analysis of laminar premixed flame structure of isooctane/2-methylfuran/air mixtures with a skeletal mechanism
Published in Combustion Theory and Modelling, 2021
In the present work, a skeletal chemical kinetic mechanism consisting of 238 species and 1156 reactions has been proposed for the simulation of premixed flames involving isooctane/2MF blends. Experimental data and detailed mechanisms from literature have been used for the validation of the proposed mechanism for individual fuel components (i.e. isooctane and 2MF) and their blends. The basic C1-C0 chemistry and NOx sub-mechanism incorporated in the present model have also been validated separately against a wide range of recent experimental data on laminar burning velocity and ignition delay time. Furthermore, it has been shown in the present work that the proposed mechanism can successfully predict the concentrations of gaseous soot precursors generated during the pyrolysis of 2MF molecule. It has been observed in this work that the likelihood of co-oxidation reactions among the species generated from the initial decomposition of the fuel molecules is minimised due to the following reasons: The formation of H2O2 as an intermediate resist the initial breakup of isooctane molecules in the low temperature part of the preheat zone in the flame. As a consequence of this resistance, isooctane and 2MF molecules decompose at different locations inside the premixed flame.The initial decomposition species generated from isooctane and 2MF (i.e. the isooctyl radicals, 2-furylmethyl, 1-oxo-1,3-butadiene and 3,4-pentadiene-1-one-2-yl) show their peaks at different locations of the flame. These locations are determined by the preferential diffusion.The peak mole fractions of the primary decomposition species of isooctane (i.e. the isooctyl radicals) and 2MF (i.e. 2-furylmethyl, 1-oxo-1,3-butadiene and 3,4-pentadiene-1-one-2-yl) also vary by several orders of magnitude.