Competing pathways in the [2+2] cycloadditions of cyclopentyne and benzyne. A DFT and ab initio study

2004-08-06
The [2 + 2] cycloadditions of cyclopentyne and benzyne to ethylene are explored at the B3LYP and CASSCF levels, supplemented by CCSD(T) and CAS-MP2 calculations at the stationary points. The biradical path in the benzyne system is computed to be about 4.1 kcal/mol lower than the concerted path, consistent with the experimentally observed loss of original stereochemistry in this cycloaddition. However, computations fail to confirm the 99% stereoretention in the corresponding reaction of cyclopentyne. The concerted and biradical paths in the latter reaction are found to involve nearly isoenergetic barriers, thus predicting only about 75% stereoretention. More sophisticated theoretical methods seem to be needed to resolve the issue in the cyclopentyne system.
JOURNAL OF ORGANIC CHEMISTRY

Suggestions

Combined Point-Mass and Particle Filter for Target Tracking
Orguner, Umut; Tornqvist, David; Gustafsson, Fredrik (2010-03-13)
This paper presents a combined Point Mass Filter (PMF) and Particle Filter (PF), which utilizes the support of the PMF and the high particle density in the PF close to the current estimate. The result is a filter robust to unexpected process events but still with low error covariance. This filter is especially useful for target tracking applications, where target maneuvers suddenly can change unpredictably.
Interaction of TNT and Aluminum - A DFT Treatment
Türker, Burhan Lemi (2015-02-01)
Within the constraints of density functional theory [UB3LYP/6-31G(d,p) and UB3LYP/6-31++G(d,p)], TNT/Al and TNT/2Al composites are investigated, considering various multiplicity states. Depending on the localization of aluminum atoms in space and multiplicity of the composite systems, the structure of TNT undergoes various degrees of perturbations. It was shown that the presence of aluminum atoms affects the bond lengths, electron population as well as the HOMO-LUMO energy gap of TNT. All these are thought ...
Enhancement of hydrogen storage properties of Ca3CH antiperovskite compound with hydrogen doping
Gencer, Ayşenur; Surucu, Gokhan (Wiley, 2020-01-01)
The doping effect of hydrogen on the Ca3CHx (x = 1, 4, 7, 9, and 10) antiperovskite compounds has been examined using density functional theory (DFT). The results of the structural optimizations show that all these compounds have negative formation energy implying the energetic stability and synthesizability. The band structures that are essential for the electronic properties have been determined along with the partial density of states (DOS) showing the metallic behavior of these compounds. In addition, t...
Comments on "Propagation Modeling Over Irregular Terrain by the Improved Two-Way Parabolic Equation Method"
Ozgun, Ozlem; Apaydin, Gokhan; Kuzuoğlu, Mustafa; Sevgi, Levent (2014-07-01)
The above paper [1] is about the two-way split-step parabolic equation method (2W-SSPE) over irregular terrain, and claims that they have developed the “improved” version of the 2W-SSPE approach that has been proposed and validated by us in literature [2]-[11]. The paper [1] claims to derive the 2W-PE directly from 2D Helmholtz equation. They do this by listing and explaining equations (1)-(9). The authors needed to state that this is quite different from the formulation given in Levy's book (reference [9] ...
Kinetic Model of Lipid Oxidation in Foods
Özilgen, Sibel; Özilgen, Mustafa (Wiley, 1990-3)
A general mathematical model in the same form with the logistic equation simulated lipid oxidation in food systems. Almost perfect agreement was found between the model and seventeen sets of data from the literature, obtained with egg yolk, restructured beef and pork nuggets, cooked pork meat, iced gutted dogfish, frozen mackerel fillets and ground raw poultry meat. A simple method was described for the evaluation of the numerical values of the model parameters. Variations of these numerical values were als...
Citation Formats
İ. Özkan, “Competing pathways in the [2+2] cycloadditions of cyclopentyne and benzyne. A DFT and ab initio study,” JOURNAL OF ORGANIC CHEMISTRY, pp. 5390–5394, 2004, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/31181.