• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3738-3742
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• 2013

The reaction mechanism of $SiF_2$ radical with HNCO has been investigated by the B3LYP method of density functional theory(DFT), while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/$6-311++G^{**}$ level. To obtain more precise energy result, stationary point energies were calculated at the CCSD(T)/$6-311++G^{**}$//B3LYP/$6-311++G^{**}$ level. $SiF_2+HNCO{\rightarrow}IM3{\rightarrow}TS5{\rightarrow}IM4{\rightarrow}TS6{\rightarrow}OSiF_2CNH(P3)$ was the main channel with low potential energy, $OSiF_2CNH$ was the main product. The analyses for the combining interaction between $SiF_2$ radical and HNCO with the atom-in-molecules theory (AIM) have been performed.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.729-730
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• 2009

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.911-912
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• 2007

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.680-684
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• 1994

Pilocarpine analogs were prepared by empoying a radical cyclization reaction as a key step for the five-membered ring formation.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.184-184
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• 2011

Using first-principles density-functional calculations, we investigate the chain reaction mechanism of allyl alcohol (ALA) molecules on the H-terminated Si(001)-2${\times}$1 surface. Recently, it was reported [1] that allyl mercaptan (ALM) molecules show a self-directed line growth across the dimer rows through a chain reaction involving several reaction processes: (i) The created radical at the C atom is transferred to the S atom, (ii) the resulting S-centered radical easily abstracts an H atom from the neighboring dimer row, and (iii) the generated S-H group further reacts with the neighboring dimer row to produce the Si-S bond on the neighboring dimer row, accompanying the associative desorption of H2. This H2-desorption process creates a new DB on the neighboring dimer row, setting off the chain reaction across the dimer rows. In the present study, we find that although the structure of ALA with -OH functional is analogous to that of ALM with -SH functional, ALA and ALM lines show a difference in their growth direction. We predict that ALA undergoes the chain reaction to show a line growth along the dimer row, contrasting with the ALM line growth across the Si dimer rows. Our analysis shows that the different growth direction of ALA is due to the strong instability of oxygen radical intermediate, which prevents from growing across the dimer rows. Thus, we demonstrate that the stability of the radical intermediate plays a crucial role in determining the direction of molecular line growth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.385-393
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• 2019

Potential fire, explosion and safety hazards exist in medium- or small-scale chemical plants using radical batch reaction processes due to the various conditions of materials, works or products. To minimize the potential damage, a study was conducted on qualitative hazard analysis using the HAZOP technique, which is a typical method for a qualitative risk assessment and analysis of the potential risks encountered in these chemical plants. For this purpose, a domestic chemical plant, which produces the acrylic resin by a radical batch reaction process, was selected and a risk assessment and analysis according to the procedure of HAZOP method was performed for the process. As the result of the study, to prevent the hazard, the input of inert gas and the installation of a pressure gauge were indispensable. In addition, the initiator and monomer should also be separated, and inhibiting substances and equipment are also necessary to prevent a runaway reaction.

• Bulletin of the Korean Chemical Society
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• v.6 no.6
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• pp.362-366
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• 1985

The hydrogen atom transfer reaction between substituted methane, $CH_3X,$ and its radical, $CH_2X(X=H,F,CH_3,CN,OH\;and\;NH_2$ was studied by MINDO/3 method. The transition state(TS) structure and energy barriers were determined and variation of the transition state and of the reactivity due to the change of X were analyzed based on the potential energy surface characteristics. It was found that the greater the radical stabilization energy. the looser the TS becomes; the TS occurs at about 15% stretch of the C-H bond, which becomes longer as the radical stabilization energy of $CH_2X$ increasers. The intrinsic barrier, ${\Delta}E*_{x.x},$ of the reaction with X was found to increase in the order $H The degree of bond stretch of the C-H bond stretch of the C-H bond at the TS also had the same order indicating that the homolytic bond cleavage of the C-H bond is rate-determining. Orbital interactions at the TS between LUMO of the fragment $C{\ldots}H{\ldots}C$ and the symmetry adapted pair of nonbonding, $n{\pm}(=n_1{\pm}n_2),$ or pi orbitals of the two X atoms were shown to be the dominant contribution in determining tightness or looseness of the TS. The Marcus equation was shown to apply to the MINDO/3 barriers and energy changes of the reaction.

• Journal of the Korean institute of surface engineering
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• v.21 no.3
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• pp.95-102
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• 1988

The anodic oxidation of aniline in aqueous sulfuric acid solution on a platinum was studied. To examine of mechanism of this reaction, the date were obtained during controlled potential electrolysis, aided by computer system. The reaction mechanism was assumed the electrochemical-chemical-electrochemical(ECE) mechanism. We obtained the result that the intial charge transfer step proceeds through a radical cation, and this radical cation were bound cation led to may type of dimer in which p-aminodiphenylamine was de-electronated again to give the polymer.

• Journal of the Korean Chemical Society
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• v.17 no.1
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• pp.1-9
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• 1973

The purpose of this paper is to investigate the mechanism of Diels-Alder reaction by assuming pseudo molecular complex (PMC) which has characters both of ionic and radical bonds. We treated this complex quantum-chemically as an intermediate between the configuration without charge transfer (radical bond character) and the configuration corresponding to the charge transfer from Diene (R) to Dienophile (S) (ionic bond character). The wave function for the complex could be expressed as: ${\psi}_{complex} = {\psi}(R,S) +{ \rho}{\psi}(R^+,S^-)$ where ${\rho}$ is the extent of charge transfer which is a constant to measure the ionic character of PMC. It has been noticed that${\rho}$is related to the difference between Fr + Fr' and Fs + Fs' in free valence (F) when R is united to S through atom r in R to atom s in S and atom r' in R to atom s' in S, That is, ${\rho}{\alpha}$ ${\Delta}F = (Fr + Fr') - (Fs + Fs')$. We have calculated ${\Delta}F$values for more than forty Diels-Alder reactions. The calculated values of ${\Delta}F$ is reversely proportional to the values of Brown's paralocalization energy (Lp) as well as Dewar's differences of delocalization energy$({\Delta}Edeloc.)$ with good linearity. This approach also presents a way of predicting the possibility and the easiness of diene synthesis between any two conjugate compounds. According to the considerations, it could be concluded that Diels-Alder reaction takes place through the united ionic-radical mechanism rather than the separated ionic or radical mechanism.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.320-320
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• 2006

The authors report the synthesis and radical ring-crossover polymerization of macrocycles with radically exchangeable dynamic covalent bonds. The macrocyclic compounds with alkoxyamine units were designed and synthesized by condensation from alkoxyamine-based diol and the corresponding acid chlorides in the presence of pyridine under high-dilution condition. The macrocycles can thermally polymerize by intermolecular radical crossover reaction. Furthermore, the poly(alkoxyamine)s depolymerized to the monomers principally by the intramolecular radical exchange process under high-dilution conditions.