Tunneling in isolated resonance unimolecular reaction theory

1988 ◽  
Vol 92 (26) ◽  
pp. 7257-7259
Author(s):  
H. O. Pritchard
Keyword(s):  
Unimolecular Reaction ◽  
Reaction Theory

On the Unimolecular Decomposition of the tert-Butoxy Radical

1973 ◽  
Vol 51 (13) ◽  
pp. 2138-2140 ◽  
Author(s):  
C. K. Yip ◽  
H. O. Pritchard
Keyword(s):  
Pressure Dependence ◽  
Unimolecular Reaction ◽  
Unimolecular Decomposition ◽  
Reaction Theory ◽  
Butoxy Radical

It is argued that a large apparent pressure dependence in the rate of decomposition of the tert-butoxy radical should not be interpreted in terms of unimolecular reaction theory; the effect is probably heterogeneous in origin.

The commutative property of strong-transition rate matrices

1979 ◽  
Vol 57 (21) ◽  
pp. 2793-2797 ◽  
Author(s):  
Huw O. Pritchard ◽  
Arunachalam Lakshmi
Keyword(s):  
Transition Rate ◽  
Transition Probabilities ◽  
Boltzmann Distribution ◽  
Unimolecular Reaction ◽  
Infinite Time ◽  
Relaxation Matrix ◽  
Reaction Theory ◽  
Strong Transition ◽  
Commutative Property

The (n − 1)-fold degenerate set of transition probabilities used in our recent reformulation of unimolecular reaction theory is operationally equivalent to the set of effective strong-transition probabilities introduced recently by Nordholm. We have found that the relaxation matrix corresponding to these transition probabilities commutes with any other relaxation matrix which will drive the same system to a Boltzmann distribution at infinite time. Some useful results stemming from this commutative property are presented; we expect that these results will help to clarify further the nature of the assumptions underlying strong- and effective strong-collision theories.

Simple Test of Unimolecular Reaction Theory

1967 ◽  
Vol 46 (11) ◽  
pp. 4504-4508 ◽  
Author(s):  
Richard K. Lyon
Keyword(s):  
Unimolecular Reaction ◽  
Simple Test ◽  
Reaction Theory

Decomposition of Activated sec‐Butyl Radicals from Different Sources and Unimolecular Reaction Theory

1960 ◽  
Vol 33 (4) ◽  
pp. 1271-1272 ◽  
Author(s):  
R. E. Harrington ◽  
B. S. Rabinovitch ◽  
H. M. Frey
Keyword(s):  
Unimolecular Reaction ◽  
Reaction Theory ◽  
Different Sources

Nonequilibrium Effects in Unimolecular Reaction Theory

1966 ◽  
Vol 45 (11) ◽  
pp. 4280-4288 ◽  
Author(s):  
W. G. Valance ◽  
E. W. Schlag
Keyword(s):  
Unimolecular Reaction ◽  
Reaction Theory ◽  
Nonequilibrium Effects

An alternative view of unimolecular reaction theory

1977 ◽  
Vol 55 (2) ◽  
pp. 284-292 ◽  
Author(s):  
Huw Owen Pritchard
Keyword(s):  
Alternative View ◽  
Unimolecular Reaction ◽  
Matrix Elements ◽  
Stochastic Matrices ◽  
Total Rate ◽  
Primitive Form ◽  
Pressure Limit ◽  
The Matrix ◽  
Reaction Theory ◽  
Comparison Of The Results

A primitive form of unimolecular reaction theory is constructed, based on the master equation. Application of the theory depends upon the way in which eigenvalues of large stochastic matrices behave as certain of the matrix elements are varied. Some of the required eigenvalue properties have been deduced by numerical experiment, and others are available from earlier work on diatomic dissociation reactions. Comparison of the results from this primitive approach with those of existing theories of unimolecular reactions suggests some reinterpretation of parameters used in those theories: most interestingly, the number of effective oscillators occurring in Kassel theory (or its Slater-theory equivalent) appears to be the ratio, at infinite pressure, of the total rate to the rate of the only reaction channel which survives at the low-pressure limit.

Computational Study on the Kinetics and Mechanisms of Unimolecular Reactions of (Z)-(Z)-N-(λ5-phosphanylidene) Formohydrazonic Formic Anhydride: Intramolecular aza-Wittig Reaction in Competition with Mumm Rearrangement

2020 ◽  
Vol 17 (11) ◽  
pp. 884-889
Author(s):  
Somayeh Mirdoraghi ◽  
Hamed Douroudgari ◽  
Farideh Piri ◽  
Morteza Vahedpour
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Wittig Reaction ◽  
Computational Study ◽  
Single Step ◽  
Low Energy ◽  
Coupled Cluster ◽  
Unimolecular Reaction ◽  
Single Step Reaction ◽  
Good Agreement

For (Z)-(Z)-N-(λ5-phosphanylidene) formohydrazonic formic anhydride, Aza-Wittig reaction and Mumm rearrangement are studied using both density functional and coupled cluster theories. For this purpose, two different products starting from one substrate are considered that are competing with each other. The obtained products, P1 and P2, are thermodynamically favorable. The product of the aza-Wittig reaction, P1, is more stable than the product of Mumm rearrangement (P2). For the mentioned products, just one reliable pathway is separately proposed based on unimolecular reaction. Therefore, the rate constants based on RRKM theory in 300-600 K temperature range are calculated. Results show that the P1 generation pathway is a suitable path due to low energy barriers than the path P2. The first path has three steps with three transition states, TS1, TS2, and TS3. The P2 production path is a single-step reaction. In CCSD level, the computed barrier energies are 14.55, 2.196, and 10.67 kcal/mol for Aza-Wittig reaction and 42.41 kcal/mol for Mumm rearrangement in comparison with the corresponding complexes or reactants. For final products, the results of the computational study are in a good agreement with experimental predictions.

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