Kinetische Analyse zur Umwandlung von Oxirenen oder Thiirenen und ihren offenkettigen Valenzisomeren / Kinetic Analysis for the Conversion of Oxirenes or Thiirenes and their Open-Chain Valence Isomers

1980 ◽  
Vol 35 (8) ◽  
pp. 1040-1048 ◽  
Author(s):  
Herbert Meier ◽  
Heinz Kolshorn
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ring Opening ◽  
Product Distribution ◽  
Ring Closure ◽  
Quantitative Interpretation ◽  
Open Chain ◽  
Energy Profiles ◽  
Ring Opening Reactions ◽  
Kinetische Analyse

Abstract Ring closure and ring opening reactions possess an outstanding significance for the formation and reactivity of antiaromatic heterocycles like oxirenes and thiirenes. The valence isomerisations 2 ⇆ 1 ⇆ 2' can be controlled by the product distribution 2 → P/2' → P'. A quantitative interpretation of many experimental data, published in the last years, is given on the basis of a few kinetic models, which consider thermal and photochemical pathways. Possible energy profiles of single hypersurfaces (S0 or S1) and the transition between different hypersurfaces (S1 → S0) are the most important features of these models.

Intermediates from ring-opening reactions. Reactions of 2-chloro-5-nitropyridine and 2-chloro-3-nitropyridine with deuteroxide ion in selected solvents

1984 ◽  
Vol 62 (6) ◽  
pp. 1120-1123 ◽  
Author(s):  
John D. Reinheimer ◽  
Nicolas Sourbatis ◽  
Robert L. Lavallee ◽  
Douglas Goodwin ◽  
George L. Gould
Keyword(s):  
Ring Opening ◽  
Pyridine Ring ◽  
Ring Closure ◽  
Polar Solvents ◽  
Open Chain ◽  
Decomposition Products ◽  
Aqueous Sodium ◽  
Ring Opening Reaction ◽  
Ring Opening Reactions ◽  
Kinetics Of

Open chain intermediates from the ring-opening reaction of aqueous sodium deuteroxide (2 mol) with 2-chloro-5-nitropyridine (1 mol) and 2-chloro-3-nitropyridine (1 mol) were isolated. These intermediates were purified, analyzed for elemental composition, and characterized by various spectrophotometric techniques. The intermediate formed from 2-chloro-5-nitropyridine and two equivalents of deuteroxide ion reacts with additional deuteroxide in D2O in various polar solvents to reclose the pyridine ring. The kinetics of the ring closure reaction are reported and are supplemented with observations of salt and solvent effects upon the rate of closure. In addition, a mechanism for the ring closure is presented. The intermediate formed from 2-chloro-3-nitropyridine did not undergo a similar ring closure when reacted with additional deuteroxide, but instead formed various decomposition products. A reason for the failure of this ring closure is suggested.

scholarly journals One-Pot Synthesis of Novel Dibenzoxanthenes, Diarylbutanes, and Calix[4]resorcinarenes via Consecutive Pyrrolidine Ring-Closure/Ring-Opening Reactions

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Andrey V. Smolobochkin ◽  
Almir S. Gazizov ◽  
Alexander R. Burilov ◽  
Michail A. Pudovik
Keyword(s):  
Ring Opening ◽  
Ring Closure ◽  
Acidic Media ◽  
Pyrrolidine Ring ◽  
One Pot ◽  
One Pot Synthesis ◽  
Ring Opening Reactions

Herein, we report the approach to the otherwise hardly accessible dibenzoxanthenes, diarylbutanes, and calix[4]resorcinarenes possessing urea moieties based on the reaction of N-(4,4-diethoxybutyl)ureas with electron-rich aromatics in strongly acidic media. Unlike the previously developed methods, the proposed approach benefits from one-pot procedure and allows to obtain the target compounds with much higher yields.

scholarly journals Synthetic and Theoretical Studies of Novel Ring Closure and Ring Opening Reactions

ChemInform ◽  
2006 ◽  
Vol 37 (40) ◽  
Author(s):  
Jose Sepulveda-Arques ◽  
M. Eugenia Gonzalez-Rosende
Keyword(s):  
Ring Opening ◽  
Ring Closure ◽  
Theoretical Studies ◽  
Ring Opening Reactions

scholarly journals Synthetic and theoretical studies of novel ring closure and ring opening reactions

ARKIVOC ◽  
2005 ◽  
Vol 2006 (7) ◽  
pp. 5-19
Author(s):  
José Sepúlveda-Arques ◽  
M. Eugenia González-Rosende
Keyword(s):  
Ring Opening ◽  
Ring Closure ◽  
Theoretical Studies ◽  
Ring Opening Reactions

THE Hg 6(3P1) PHOTOSENSITIZED DECOMPOSITION OF CYCLOHEXENE VAPOR

1965 ◽  
Vol 43 (5) ◽  
pp. 1329-1337 ◽  
Author(s):  
G. R. De Maré ◽  
O. P. Strausz ◽  
H. E. Gunning
Keyword(s):  
Triplet State ◽  
Rate Constant ◽  
Bond Cleavage ◽  
Product Distribution ◽  
Ring Closure ◽  
Rate Equations ◽  
Open Chain ◽  
Fragmentation Reactions ◽  
Triplet Biradicals ◽  
Kinetic Features

The reaction follows the pattern established for the triplet state reactions of olefins in general. The major products, ethylene, 1,3-butadiene, vinylcyclobutane, cyclohexane, various C12-compounds, and polymer, can best be accounted for by the allylic C—H and C—C bond cleavage of the primary triplet biradicals and the ring closure and fragmentation reactions of the resulting open chain biradicals. At least three types of triplet state species must be involved in the mechanism. The rate equations, developed on the assumed mechanism, satisfactorily describe the observed product distribution and kinetic features of the system and permit the estimation of the elementary rate constant values and the lifetimes of the various transient biradicals involved. Preliminary experiments with cycloheptene indicate that vinylcyclopentane is an important product.

Novel photosensitive polyurethanes based on photochromic dithienylethene monomers: synthesis, characterization and photophysical properties of a new film-building material for photonic applications

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Arthur Thomas Bens ◽  
Radu Comanici ◽  
Bianca Gabel ◽  
Carola Kryschi ◽  
Hans-Dieter Martin ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Building Material ◽  
Ring Opening ◽  
Photophysical Properties ◽  
Ring Closure ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Free Standing ◽  
Polymer Backbone ◽  
Ring Opening Reactions

Abstract The synthesis of a novel photochromic dithienylethene-based polyurethane and its characterization by optical spectroscopy and scanning tunneling microscopy are presented. This linear polyurethane builds up perfect free-standing films suited for photonic applications. Moreover it may be extruded to long mechanically stable fibers. The photochromic reactions of the polyurethane, as being the electrocyclic ring-closure and ring-opening reactions of the dithienylethene unit in the polymer backbone, occur in a completely reversible and highly efficient fashion.

Azabenzenes (azines) — The nitrogen derivatives of benzene with one to six N atoms: Stability, homodesmotic stabilization energy, electron distribution, and magnetic ring current; a computational study

2004 ◽  
Vol 82 (1) ◽  
pp. 50-69 ◽  
Author(s):  
Jürgen Fabian ◽  
E Lewars
Keyword(s):  
Ring Opening ◽  
Electron Distribution ◽  
Computational Study ◽  
Open Chain ◽  
Isolation Techniques ◽  
Ring Opening Reactions ◽  
The Stability ◽  
Magnetic Ring ◽  
Derivatives Of ◽  
Ab Initio Dft

The twelve azabenzenes — the species formed by replacing CH groups of benzene by N — were examined computationally (with emphasis on the six contiguous-nitrogen species). MP2(fc)/6-31G*, B3LYP/6-31G*, CCSD(T)/6-31G*//MP2(fc)/6-31G*, and G3(MP2) calculations were used to probe kinetic and thermodynamic stabilities, homodesmotic ring-opening energies, electron distribution (bond orders and lengths, Bird index), and NICS values, primarily to discern where the transition occurs from reasonably stable to highly fragile species. Some azabenzenes with three and those with four or more nitrogens are thermodynamically unstable, but kinetic stabilities indicated that, with the possible exception of hexaazabenzene, all the azabenzenes should be isolable, although some with four nitrogens might decompose at room temperature, and pentaazabenzene would require matrix isolation techniques. Although homodesmotic ring-opening reactions showed an almost monotonic decrease in the stability of the cyclic relative to the open-chain species (in appropriate ring-opening reactions) on going from benzene to hexaazabenzene, bond-order variation and NICS suggested this may be because of increasing destabilization by nitrogen lone pairs rather than because of a decrease in electron delocalization (in aromaticity). Key words: azines, azabenzenes, pentazine, hexazine, ab initio, DFT, aromaticity.

A New Adsorption Rate Equation in Batch Systems

2018 ◽  
Author(s):  
yongson hong ◽  
Kye-Ryong Sin ◽  
Jong-Su Pak ◽  
Chol-Min Pak
Keyword(s):  
Experimental Data ◽  
Kinetic Analysis ◽  
Adsorption Kinetics ◽  
Rate Equation ◽  
Kinetic Models ◽  
Adsorption Kinetic ◽  
Adsorption Rate ◽  
Batch Systems ◽  
New View

<p><b>In this paper, the deficiencies and cause of previous adsorption kinetic models were revealed, new adsorption rate equation has been proposed and its validities were verified by kinetic analysis of various experimental data.</b> <b>This work is a new view on the adsorption kinetics rather than a comment on the previous adsorption papers.</b></p>

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