A Gaussian-2 molecular orbital study of the unimolecular reactions of acetyl cyanide

So, Suk Ping

doi:10.1016/s0009-2614(97)00367-9

Cited by 11 publications

(10 citation statements)

References 13 publications

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“…Thus, the activation barrier for the isomerization process is 53.6 kcal/mol in MP2 and 47.8 kcal/mol in DFT. A similar isomerization process has been reported by So [21] in acetyl cyanide from G2 theory with an activation barrier of 40.8 kcal/mol. The calculated values of the enthalpy difference between the higher energy isomer CNC(O)CN and the lower energy isomer NCC(O)CN in MP2/6-31G * and B3LYP/6-311+G * are 19.5 and 13.4 kcal/mol, respectively.…”

Section: Isomerization Studies In Carbonyl Cyanidesupporting

confidence: 82%

Quantum chemical study of mechanisms of dissociation and isomerization reactions in some molecules and radicals of astrophysical significance: Cyanides and related molecules

Gupta

Sharma

2006

Pramana - J Phys

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A theoretical study of the mechanism of photodecomposition in carbonyl cyanide, diethynyl ketone, acetyl cyanide and formyl cyanide has been conducted using density functional and MP2 theories. A complete analysis of the electronic spectra of these molecules in terms of nature, energy and intensity of electronic transitions has been provided by time-dependent density functional theory. Mixing coefficients and main configurations of the electronic states have been used to identify the states leading to the photodecomposition process. While the Rydberg state 1 (n,3s) is involved in the dissociation of formyl cyanide and acetyl cyanide, the π * CC /π * CN states are involved in the case of carbonyl cyanide and diethynyl ketone. In all cases, however, stepwise decomposition process is preferred over the concerted reaction process. Based on potential energy curves for bond dissociation and the transition state and IRC studies, it is found that besides the direct dissociation of carbonyl cyanide, a photoisomerization process through a nonplanar transition state may also occur resulting in the formation of a stable and planar isomer CNC(O)CN. A complete vibrational analysis of the higher energy isomer has been conducted and several new fundamental bands are predicted. Some of the earlier experimental results on the photodecomposition mechanism and energies of photofragments in carbonyl cyanide and acetyl cyanide have also been rationalized.

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Section: Isomerization Studies In Carbonyl Cyanidesupporting

confidence: 82%

Quantum chemical study of mechanisms of dissociation and isomerization reactions in some molecules and radicals of astrophysical significance: Cyanides and related molecules

Gupta

Sharma

2006

Pramana - J Phys

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“…A comparison of the results has been made with the earlier ab initio results reported for the HFCO, CH 3 COCl, CH 3 CHO, and HC(O)CN 7 decompositions. When this article was under preparation, we came across a recent study of So on the unimolecular reactions of acetyl cyanide. In his work, So has considered a few of the channels studied here, namely, 2A , 3A , 5A , 6A , 1B , and 2B formation and optimized the structures at the MP2/6-31G* level and computed energies at the G2 level.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on Unimolecular Reactions of Acetyl Cyanide and Acetyl Isocyanide

Sumathi

Nguyen

1998

J. Phys. Chem. A

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The potential energy surfaces of acetyl cyanide and its functional isomer acetyl isocyanide in their electronic ground state have been investigated using ab initio molecular orbital MP2(FU)/6-311G** and QCISD(T)/6-311G** calculations. The molecular eliminations of CH3COX (X = CN,NC) to CH3X + CO, HX + CH2CO, and CH2 + HCOX, the unimolecular rearrangements to CH3C−OX and CH3O−CX carbenes, 1,3-hydrogen migration to CH2C(OH)X, 1,3-methyl migration to CH3NCCO, and radical decompositions to X• + CH3CO and CH3 • + COX have been examined. Also the secondary decomposition processes of COCN and CONC radicals in their ground states and the secondary elimination of HX from CH2C(OH)X have been investigated. Cyanide−isocyanide isomerization is found to be the predominant channel in the unimolecular reactions of acetyl cyanide. Despite being exothermic, the decomposition of acetyl cyanide into CH3CN + CO is found to be kinetically unfavorable. Decomposition into HCN + CH2CO, the reverse reaction of CH3COCN synthesis, is found to be a preferred dissociation pathway and is expected to compete at high temperatures with the 1,3-hydrogen migration, yielding cyanovinyl alcohol. The barriers for the rearrangement processes to carbenes in acetyl isocyanide are quite high in contrast to those of acetaldehyde and fluoroformaldehyde. The large magnitude of the reverse barrier from the carbenes to acetyl cyanide suggests the stability of the carbenes. In the ground state of CH3COX, the CH3−C bond cleavage is found to be more facile compared to the C(O)−X bond cleavage. The secondary dissociation from CONC requires a rather small barrier, and both cyanide and isocyanide forms are found to have very similar potential energy surface.

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“…In the theoretical investigation for the isomerisation of acetyl isocyanide to acetyl cyanide, Sumathi and Nguyen [14], and So [15] reported that the barriers of the isomerisation were 26.7 and 28.2 kcal mol À1 , respectively, and they concluded that the isomerisation was possible at low temperatures. In our theoretical study, P b2 0 isomerises to P b2 via TS18 with a barrier of 26.3 kcal mol À1 , and we infer that the interconversions between cyclopentadienyl isocyanides and cyclopentadienyl cyanides are feasible.…”

Section: The Interconversions Between Cyclopentadienylmentioning

confidence: 99%

“…The reactivities of ketene (CH 2 CO) and its derivatives have been widely studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Sumathi and Nguyen [14] and So [15] studied the unimolecular reaction of acetyl cyanide and acetyl isocyanide in theory, and revealed the potential energy profile of the decomposition reactions of acetyl isocyanide to CH 2 CO and HNC and acetyl cyanide to CH 2 CO and HCN.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study on the mechanism for the reaction of pentafulvenone with HNC in singlet and triplet states, interconversions and solvation effect

et al. 2008

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2008) Theoretical study on the mechanism for the reaction of pentafulvenone with HNC in singlet and triplet states, interconversions and solvation effect,The mechanism for the reaction of pentafulvenone with HNC in singlet and triplet states is studied theoretically at MP2/6-311þG**//B3LYP/6-311þG** level. Eleven singlet and two triplet stable points, 21 singlet and 11 triplet transition states are found. The results show that the reaction has two attacking modes, which are HNC attacking carbon-oxygen and carbon-carbon double bond of pentafulvenone. The reaction is more favourable in singlet state, and the dominant pathway is to form cyclopentadienyl isocyanide P b1 0 via TS6. The structure of the most stable product is identified. The interconversions between cyclopentadienyl isocyanides and cyclopentadienyl cyanides are thoroughly studied in the singlet state. In aqueous solvent, the reaction of pentafulvenone with HNC are investigated using the PCM-UAHF model at the MP2 (PCM)/6-311þG**// B3LYP (PCM)/6-311þG** and MP2 (PCM)/6-311þG**//B3LYP/6-311þG** levels. The barrier of the transition state in the main pathway is decreased.

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A Gaussian-2 molecular orbital study of the unimolecular reactions of acetyl cyanide

Cited by 11 publications

References 13 publications

Quantum chemical study of mechanisms of dissociation and isomerization reactions in some molecules and radicals of astrophysical significance: Cyanides and related molecules

Quantum chemical study of mechanisms of dissociation and isomerization reactions in some molecules and radicals of astrophysical significance: Cyanides and related molecules

Theoretical Study on Unimolecular Reactions of Acetyl Cyanide and Acetyl Isocyanide

Theoretical study on the mechanism for the reaction of pentafulvenone with HNC in singlet and triplet states, interconversions and solvation effect

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