Intermolecular orbital theory of the interaction between conjugated systems. I. General theory

Salem, Lionel

doi:10.1021/ja01005a001

Cited by 557 publications

(206 citation statements)

References 2 publications

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“…We have therefore chosen to re-determine the coefficients m and c for equation (I) using a more robust level of theory to calculate E SOMO and we have attempted to use all known experimental determinations of the value of rate constants of the reactions of NO or HO 2 with organic peroxy radicals. Information on frontier molecular orbital theory can be found in (Albright et al, 1985;Dewar and Dougherty, 1975;Fleming, 1996) and information on the correlation of frontier orbital energies with the logarithm of rate constants can be found in (King et al, 1999a;King et al, 1999b;King et al, 2001;Klopman, 1968;Marston et al, 1999;Salem, 1968a;Salem, 1968b).…”

Section: Introductionmentioning

confidence: 99%

Rate constants for the reaction of NO and HO2 with peroxy radicals formed from the reaction of OH, Cl or NO3 with alkenes, dienes and α,β-unsaturated carbonyls

King

Thompson

2003

Atmospheric Environment

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Rate constants for the reaction of NO and HO 2 with peroxy radicals formed from the reaction of OH, Cl or NO 3 with alkenes, dienes and α,β-unsaturated carbonyls. Atmospheric Environment 37 (32) 4517-4527.This is an author-produced version of a paper published in Atmospheric Environment (ISSN 1352(ISSN -2310. This version has been peer-reviewed but does not include the final publisher proof corrections, published layout or pagination.All articles available through Birkbeck ePrints are protected by intellectual property law, including copyright law. Any use made of the contents should comply with the relevant law. AbstractRate constants for the gas-phase reaction of NO and HO 2 radicals with 33 peroxy radicals are presented. The peroxy radicals are derived from the addition of either OH, Cl, or NO 3 radicals, followed by addition of O 2 , to a series of alkenes: tetrachloroethene, ethene, 1,2−dimethyl but−2−ene, butadiene, 2,3,4,5−tetramethyl hexa−1,3−diene, 1,1,2,3,4,4−hexachlorobutadiene but−1−ene−3−one (methyl vinyl ketone) and 2,3−dimethylpen−2−ene−4−one. The rate constants were predicted using a correlation between the singly occupied molecular orbital (SOMO) energy of the peroxy radical and the logarithm of the rate constant for reaction with NO or HO 2 . A discussion of the accuracy of the method and the trends in the reactivity of the titled peroxy radicals is given. Peroxy radicals derived from halogenated alkenes have larger values of rate constants for reaction with NO relative to reaction with HO 2 , indicating that they are more likely to react with NO, rather than HO 2 , in the atmosphere. The reverse is true for peroxy radicals derived from alkylated alkenes.

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Section: Introductionmentioning

confidence: 99%

Rate constants for the reaction of NO and HO2 with peroxy radicals formed from the reaction of OH, Cl or NO3 with alkenes, dienes and α,β-unsaturated carbonyls

King

Thompson

2003

Atmospheric Environment

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“…We used the General Theory of Perturbation Limited to the Frontier Molecular Orbitals. [34][35][36][37][38] The geometry of the 4-(4-chlorophenyl)pyrimidinium benzoyl methylide 5a (for the energetically most favoured geometry, the heat of formation is ∆H= 63.174 kcal/mol), the atomic charges, the coefficients of the atomic orbitals, and the values of the energies of the frontier molecular orbitals ( An analysis of the data from Table 2 leads to the following conclusions: -the ylide carbanion center, C-7, has a negative atomic charge, less than unity, but significant; -the ylide nitrogen atom, N-1, has a positive atomic charge, less than unity, significant but smaller (in absolute value) than the ylide carbanion; -the α-endocyclic carbon atoms, C-2 and C-6, have small negative atomic charges, both being less than unity. Table 2.…”

Section: Methodsmentioning

confidence: 99%

4-(4-Chloro-phenyl)-pyrimidinium ylides. 1. Structure, stability, reactivity

Moldoveanu¹,

Mangalagiu²,

Caprosu³

et al. 2004

Arkivoc

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In this paper we present a theoretical and experimental study concerning the structure, stability, and reactivity of 4-(4-chlorophenyl)pyrimidinium ylides. 4-(4-Chlorophenyl)-pyrimidinium ylides are relatively stable compounds, their stability varying with the nature of the ylide carbanion substituent. The stronger the electron-withdrawing effect of these substituents, the more the anionic charge is delocalized, and therefore the higher their stability. The experimental and quantum chemical calculations confirm this hypothesis and are in accordance with each other. The electronic absorption spectra of 4-(4-chlorophenyl)-pyrimidinium 4-X-benzoyl methylides can be assigned to an intramolecular charge transfer band. The quantum chemical calculations show the possibility to use pyrimidinium ylides as nucleophilic reagents as well as 1,3-dipoles in reaction with appropriate reagents. The influence of microwave irradiation for the synthesis of azinium salts was also studied. The reaction of 4-(4-chlorophenyl)pyrimidine with an organic haloalkane shows a remarkable rate acceleration under microwave irradiation and allows a general and facile synthesis of azinium salts. A comparative study of microwave and classical conditions (use of solvents) has been done.

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“…46 The studies on electrophilicity have shown that as one moves across the spectrum of S N 2 to S N 1 there are changes in site-selectivity (see panels C and D in Figure 5). 47 The Klopman-Salem 48,49 distinction between charge-controlled and orbital controlled reactions has been invoked (and seems reasonable) to explain these trends. However, recent evidence suggests that Markus theory might be superior in understanding site-selectivity in reactions with multiple nucleophilic centres.…”

Section: Mechanisms Of Nucleobase Modificationmentioning

confidence: 99%

Properties and reactivity of nucleic acids relevant to epigenomics, transcriptomics, and therapeutics

2016

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Developments in epigenomics, toxicology, and therapeutic nucleic acids all rely on a precise understanding of nucleic acid properties and chemical reactivity. In this review we discuss the properties and chemical reactivity of each nucleobase and attempt to provide some general principles for nucleic acid targeting or engineering. For adenine-thymine and guaninecytosine base pairs, we review recent quantum chemical estimates of their Watson-Crick interaction energy, - stacking energies, as well as the nuclear quantum effects on tautomerism. Reactions that target nucleobases have been crucial in the development of new sequencing technologies and we believe further developments in nucleic acid chemistry will be required to deconstruct the enormously complex transcriptome.

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Intermolecular orbital theory of the interaction between conjugated systems. I. General theory

Cited by 557 publications

References 2 publications

Rate constants for the reaction of NO and HO2 with peroxy radicals formed from the reaction of OH, Cl or NO3 with alkenes, dienes and α,β-unsaturated carbonyls

Rate constants for the reaction of NO and HO2 with peroxy radicals formed from the reaction of OH, Cl or NO3 with alkenes, dienes and α,β-unsaturated carbonyls

4-(4-Chloro-phenyl)-pyrimidinium ylides. 1. Structure, stability, reactivity

Properties and reactivity of nucleic acids relevant to epigenomics, transcriptomics, and therapeutics

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