Reaction pathways and transition states of the C-C and C-H bond cleavage in the aromatic pyrenemolecule - A Density Functional study

Abstract

The activation and reaction energies of the CC and C-H bonds cleavage in pyrene molecule are calculated applying the Density Functional Theory and 6-311G Gaussian basis. Different values for the energies result for the different bonds, depending on the location of the bond and the structure of the corresponding transition states. The CC bond cleavage reactions include H atom migration, in many cases, leading to the formation of CH2 groups and H-C≡Cacetylenic fragments. The activation energy values of the CC reactions are greater than 190.00 kcal/mol for all bonds, those for the C-H bonds are greater than 160.00 kcal/mol. The reaction energy values for the CC bonds range between 56.497 to 191.503 kcal/mol. As for the C-H cleavage reactions the activation energies range from 163.535 to 165.116 kcal/mol, the reaction energies are nearly constant, 117.500kcal/mol. The geometries of the transition states and reaction products are discussed too.

Reactivity of O-Drug Bond in some Suggested Voltarine Carriers: Semiempirical and ab Initio Methods

“…The biological activity was calculated in water as a solvent. The calculated quantum chemical descriptors included; the highest occupied molecular orbital energy (E HOMO ), lowest unoccupied molecular orbital energy (E LUMO ), ionization energy (IE), electron affinity (EA), energy gap (E GAP ), absolute hardness (η), absolute softness (S), optical softness (So), absolute electronegativity (χ), chemical potential (CP), electrophilicity index (ω), nucleophilicity index (N), additional electronic charges (N Max ), polarizability (α), the first hyperpolarizability (β o ) and dipole moment (µ), Equations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Urea was used as a standard in determination of NLO properties (17)(18)(19).…”

C-C and C-H bond cleavage reactions in the chrysene and perylene aromatic molecules: An ab-initio density functional theory study

“…The ab-initio DFT study for the C-H bond cleavage reaction of both molecules, similar to those of the formerly calculated molecules [1][2][3][4][5][6][7], shows common features, for both chrysene and perylene which might be concluded in the following statements; (i) All these reactions pass through planar S, TS's, (ii) They show common reaction energy, for the S and T products, of ~116-117 kcal/mol (iii) They show different values for the activation energy, Tables 1 and 2.…”

“…In former reports, we described the application of the abinitio DFT, quantum mechanical method, for the estimation of the structures and energies of the transition states (TS) and reaction products (RP) of the C-C and C-H bond cleavage reactions for a series of polyaromatic hydrocarbon (PAH) molecules [1][2][3][4][5][6][7]. The following properties of the C-C bond cleavage reactions could be concluded;…”

C-C and C-H bond cleavage reactions in acenaphthylene aromatic molecule, an ab-initio density functional theory study

“…Due to their industrial importance, the study of the thermal degradations of polycyclic aromatic hydrocarbons (PAH) had been a subject for numerous experimental and theoretical investigations [1][2][3][4][5][6][7][8][9][10][11][12][13]. In previous papers, we reported quantum mechanically calculated structures and energies of the transition states (TS) and reaction products (RP) of the C-C and C-H bond cleavage reactions for a number of poly-aromatic hydrocarbon molecules [14][15][16][17][18][19][20][21]. We applied for these treatments the ab-initio Density Functional Theory (DFT) method [23][24][25][26][27].…”