The C6H5N energy surface. IV. Isotopic labelling studies in phenylnitrene isomerizations

1975 ◽  
Vol 28 (8) ◽  
pp. 1755 ◽  
Author(s):  
WD Crow ◽  
MN Paddon-Row
Keyword(s):  
Nitrogen Atom ◽  
Energy Level ◽  
Gas Phase ◽  
Energy Surface ◽  
Product Formation ◽  
Isotopic Labelling ◽  
Phenyl Azide ◽  
Ring Contraction ◽  
Isomerization Processes

Gas phase pyrolysis of phenyl azide gives rise to aniline, cyclopentadienecarbonitrile and pyridine as isomerization products from phenylnitrene. Isotopic labelling studies (14C, 13C) are used to examine the isomerization processes which occur in phenylnitrene prior to product formation. ��� At the lowest energy level of the intermediate little or no label randomization occurs and aniline evidently arises from hydrogen capture at this stage. Higher levels of the intermediate involve a cycloperambulatory motion of the nitrene nitrogen atom, followed by ring contraction to cyclo- pentadiene-1-carbonitrile. The pyridine formed possibly arises from a ring-expanded intermediate, which may not have undergone the cycloperambulation of the nitrene nitrogen atom. � The aniline and cyanocyclopentadiene derived from 5- pyridyltetrazole pyrolysis appear to exhibit very similar behaviour to those from phenyl azide as far as isotopic migration is concerned.

The C6H5N energy surface. III. Isomerization processes and intramolecular trapping in picolylcarbenes

1975 ◽  
Vol 28 (8) ◽  
pp. 1741 ◽  
Author(s):  
WD Crow ◽  
AN Khan ◽  
MN Paddon-Row
Keyword(s):  
Gas Phase ◽  
Energy Surface ◽  
Methyl Groups ◽  
Ring Contraction ◽  
Isomerization Process ◽  
Major Process ◽  
Isomerization Processes

The synthesis is reported of a series of 5-(methyl-2-, -3- and -4- pyridyl)tetrazoles from the corresponding picolinecarbonitriles. These compounds are used as gas phase generators for the corresponding picolylcarbenes at 600�/0.05 mm. The normal isomerization process in arylcarbenes are interrupted in some cases by intramolecular trapping by the methyl groups, resulting in the first reported syntheses of cyclobuta-[b] and -[c]pyridines. The major process competing with this is that of nitrogen-extrusion to give tolylnitrenes, which then undergo ring contraction to form methyl-cyclopentadienecarbonitriles. The relative yields from these and other processes are used to deduce the preferred isomerization pathways in picolylcarbenes. In methyl-2- pyridylcarbenes there is almost exclusive insertion into the 2,3-bond, leading to the tolylnitrenes. The 3- and 4-pyridylcarbenes, however, show a tendency for the carbene centre to oscillate over the 3-, 4- and 5-positions of the ring with slower leakage to the 2-position.

The C7H6 energy surface: phenylcarbene and 2-Methylene-3,5-cyclohexadienylidene - A duality of mechanism

1973 ◽  
Vol 26 (8) ◽  
pp. 1705 ◽  
Author(s):  
WD Crow ◽  
MN Paddon-Row
Keyword(s):  
Gas Phase ◽  
Energy Surface ◽  
Ring Contraction ◽  
Factors Affecting ◽  
Tracer Techniques ◽  
13C Tracer

The conversion of phenylcarbene (1) into fulvenallene (17) and ethynylcyclo-pentadiene (18) on gas-phase pyrolysis has been examined by 13C-tracer techniques. Complete randomization of all seven carbon atoms has been shown to precede ring contraction. The result is consistent with a pool of intermediates [cycloheptatrienylidene (19) and bicyclo[4,1,0]hepta-2,4,6-triene (21)], interconverting rapidly through tautomerism and concomitant H-shifts. Dimerization, intramolecular trapping, and ring contraction constitute the major exits from this pool. ��� Gas-phase thermolysis of indazole generates the same products (17)/(18) and in this case the mechanism has been investigated by the intramolecular trapping in 1-deutero-3-methylindazole to yield deuterostyrenes. Two pathways are revealed, proceeding respectively through phenylcarbene and 2-methylene-3,5-cyclohexadienyl-idene (36); factors affecting the latter pathway are discussed.

Gas phase pyrolysis of annelated pyrazoles: a duality of mechanism in aromatic ring contraction

1972 ◽  
Vol 13 (22) ◽  
pp. 2235-2238 ◽  
Author(s):  
W.D. Crow ◽  
A.R. Lea ◽  
M.N. Paddon-Row
Keyword(s):  
Gas Phase ◽  
Aromatic Ring ◽  
Ring Contraction

STRUCTURAL, ELECTRONIC AND QSAR PROPERTIES OF THE CYFLUTHRIN MOLECULE: A THEORETICAL AM1 AND PM3 TREATMENT

2006 ◽  
Vol 17 (10) ◽  
pp. 1391-1402 ◽  
Author(s):  
EMİNE DENİZ ÇALIŞIR ◽  
ŞAKİR ERKOÇ
Keyword(s):  
Energy Level ◽  
Gas Phase ◽  
Ground State ◽  
Heat Of Formation ◽  
Tobacco Budworm ◽  
Vibrational Modes ◽  
Lumo Energy ◽  
Deciduous Fruit ◽  
Semi Empirical ◽  
Homo Energy Level

Cyfluthrin is a synthetic cyano-containing pyrethroid insecticide that has both contact and stomach poison action. It is a nonsystemic chemical used to control cutworms, ants, silverfish, cockroaches, mosquitoes, tobacco budworm and many others. Its primary agricultural uses have been for control of chewing and sucking insects on crops such as cotton, turf, ornamentals, hops, cereal, corn, deciduous fruit, peanuts, potatoes, and other vegetables. Cyfluthrin is also used in public health situations and for structural pest control. The structural, vibrational, electronic and QSAR properties of the cyfluthrin molecule in gas phase have been investigated theoretically by performing molecular mechanics method by using MM+ force field, and semi-empirical molecular orbital AM1 and PM3 calculations. The geometry of the molecule has been optimized, infrared spectrum (vibrational modes and intensities) and the electronic properties of the molecule have been calculated in its ground state. According to PM3 calculation, heat of formation of cyfluthrin molecule is about -48.58 kcal/mol (exothermic), which shows that this molecule thermodynamically be stable. The HOMO energy level for this molecule is found to be -9.701 eV and the LUMO energy level is -0.660 eV giving rise to a gap of 9.041 eV, which also indicates that cyfluthrin is thermodynamically stable.

Kinetics and dynamics study of the OH + C2H6 → H2O + C2H5 reaction based on an analytical global potential energy surface

2020 ◽  
Vol 22 (26) ◽  
pp. 14796-14810 ◽  
Author(s):  
C. Rangel ◽  
M. Garcia-Chamorro ◽  
J. C. Corchado ◽  
J. Espinosa-Garcia
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Gas Phase ◽  
Energy Surface ◽  
Hydrogen Abstraction ◽  
Ethane Molecule ◽  
Abstraction Reaction ◽  
Kinetics And Dynamics ◽  
Oppenheimer Approximation ◽  
Hydrogen Abstraction Reaction

To describe the gas-phase hydrogen abstraction reaction between the hydroxyl radical and the ethane molecule, an analytical full-dimensional potential energy surface was developed within the Born–Oppenheimer approximation.

Interaction of the C = N Bond with the Cyclopropyl Ring

1981 ◽  
Vol 36 (7) ◽  
pp. 768-773 ◽  
Author(s):  
Shatha F. Al-Siaidi ◽  
Ibrahim T. Ibrahim ◽  
Keyword(s):  
Excited State ◽  
Nitrogen Atom ◽  
Gas Phase ◽  
Bathochromic Shift ◽  
Wave Number ◽  
Phase Spectra

Abstract The conjugative interaction of the C=N bond with the cyclopropylring is studied using UV-spectrophotometric technique. The observed small bathochromic shift in the n-n* bands, relative to the spectra of similar compounds but with no cyclopropylring, is attributed to the interaction of the internal Walsh MO with the nonbonded MO of the Nitrogen atom (Zlint-n interaction) in the bisected conformation of the molecule. The observed bathochromic shifts of the 71-71* bands are explained in terms of the A-n interaction. The gas phase spectra of the azomethine derivatives show vibronic structuring of the band which when analyzed yeld wave number differences be­ tween the successive vibronic peaks, of the magnitude 720—860 cm-1. They are attributed to to the wave number differences between the successive C—N=C deformed ion levels in the excited state. I n te r a c tio n o f th e C = N B o n d w ith th e C y c lo p r o p y l R in g

Full-dimensional analytical potential energy surface describing the gas-phase Cl + C2H6 reaction and kinetics study of rate constants and kinetic isotope effects

2018 ◽  
Vol 20 (6) ◽  
pp. 3925-3938 ◽  
Author(s):  
Cipriano Rangel ◽  
Joaquin Espinosa-Garcia
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Gas Phase ◽  
Energy Surface ◽  
Isotope Effects ◽  
Hydrogen Abstraction ◽  
System P ◽  
Abstraction Reaction ◽  
Analytical Potential ◽  
Oppenheimer Approximation

Within the Born–Oppenheimer approximation a full-dimensional analytical potential energy surface, PES-2017, was developed for the gas-phase hydrogen abstraction reaction between the chlorine atom and ethane, which is a nine body system.

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