Kinetics and mechanism of the thermal decomposition of N-nitrosodiphenylmethylimine

1981 ◽  
Vol 59 (3) ◽  
pp. 559-562 ◽  
Author(s):  
Michael T.H. Liu ◽  
Toshikazu Ibata
Keyword(s):  
Thermal Decomposition ◽  
Transition State ◽  
Experimental Evidence ◽  
Kinetics And Mechanism ◽  
Ring Closure ◽  
Decomposition Products ◽  
Cyclic Transition ◽  
First Order ◽  
Closure Mechanism ◽  
Cyclic Transition State

The thermal decomposition of N-nitrosodiphenylmethylimine has been investigated in various solvents. The decomposition products are benzophenone and nitrogen. The ΔH†and ΔS† parameters for these first-order decompositions have been determined. The experimental evidence is consistent with the hypothesis that the thermolysis of N-nitrosodiphenylmethylimine involves the formation of a cyclic transition state via an electrocyclic ring closure mechanism.

Kinetic Studies of [4n+2]π-Thermal Cyclodimerization of 1-(3-Pyridazinyl)-3-oxidopyridinium Betaines

1992 ◽  
Vol 57 (9) ◽  
pp. 1951-1959 ◽  
Author(s):  
Madlene L. Iskander ◽  
Samia A. El-Abbady ◽  
Alyaa A. Shalaby ◽  
Ahmed H. Moustafa
Keyword(s):  
Energy Gap ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Cyclic Transition ◽  
Concerted Mechanism ◽  
First Order ◽  
Thermodynamic Activation Parameters ◽  
Cyclic Transition State ◽  
Complete Dissociation ◽  
Homo Lumo

The reactivity of the base induced cyclodimerization of 1-(6-arylpyridazin-3-yl)-3-oxidopyridinium chlorides in a pericyclic process have been investigated kinetically at λ 380 nm. The reaction was found to be second order with respect to the liberated betaine and zero order with respect to the base. On the other hand dedimerization (monomer formation) was found to be first order. It was shown that dimerization is favoured at low temperature, whereas dedimerization process is favoured at relatively high temperature (ca 70 °C). Solvent effects on the reaction rate have been found to follow the order ethanol > chloroform ≈ 1,2-dichloroethane. Complete dissociation was accomplished only in 1,2-dichloroethane at ca 70 °C. The thermodynamic activation parameters have been calculated by a standard method. Thus, ∆G# has been found to be independent on substituents and solvents. The high negative values of ∆S# supports the cyclic transition state which is in favour with the concerted mechanism. MO calculations using SCF-PPP approximation method indicated low HOMO-LUMO energy gap of the investigated betaines.

Divergent Reactivity of Stannane and Silane in the Trifluoromethylation of PdII: Cyclic Transition State versus Difluorocarbene Release

2018 ◽  
Vol 130 (46) ◽  
pp. 15301-15305 ◽  
Author(s):  
Maoping Pu ◽  
Italo A. Sanhueza ◽  
Erdem Senol ◽  
Franziska Schoenebeck
Keyword(s):  
Transition State ◽  
Cyclic Transition ◽  
Cyclic Transition State

ChemInform Abstract: A Cyclic Transition State for the Darzen Reaction.

ChemInform ◽  
2010 ◽  
Vol 28 (5) ◽  
pp. no-no
Author(s):  
A. YLINIEMELAE ◽  
G. BRUNOW ◽  
J. FLUEGGE ◽  
O. TELEMAN
Keyword(s):  
Transition State ◽  
Cyclic Transition ◽  
Cyclic Transition State

Theoretical Study of the Kinetics and Mechanism of the Thermal Decomposition of 3-Oxetanone in the Gas Phase

2017 ◽  
Vol 42 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Mohammad Khavani ◽  
Javad Karimi
Keyword(s):  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Ethylene Oxide ◽  
Gas Phase ◽  
Transition States ◽  
Decomposition Reaction ◽  
Kinetics And Mechanism ◽  
Methyl Radical ◽  
Decomposition Products ◽  
Concerted Mechanism

The kinetics and mechanism of the thermal decomposition reaction of 3-oxetanone in the gas phase were studied using quantum chemical calculations. The major products of this reaction are formaldehyde, ketene, carbon monoxide, ethylene oxide, ethylene and methyl radical. Formaldehyde, ketene, carbon monoxide and ethylene oxide are the initial decomposition products and other species are the products of ethylene oxide decomposition. The results of B3LYP and QCISD(T) calculations reveal that thermal decomposition of 3-oxetanone to ethylene oxide and carbon monoxide is more probable than to formaldehyde and ketene from an energy viewpoint. Moreover, quantum theory of atoms in molecules and natural bond orbital analysis indicate that 3-oxetanone decomposition to formaldehyde, ketene, carbon monoxide and ethylene occurs via a concerted mechanism and bonds that are involved in the transition states have a covalent character. Moreover, the calculated changes in bond lengths in the transition states reveal that bond breaking and new bond formation occur asynchronously in a concerted mechanism.

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