• Title/Summary/Keyword: halides

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Theory of the Chemical Bond. Bond Ionicities and Bond Energies of Diatomic Molecules

  • Kang, Young-Kee
    • Bulletin of the Korean Chemical Society
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    • v.6 no.2
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    • pp.107-111
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    • 1985
  • A revised simple method is proposed to calculated the ionicities and bond energies of diatomic molecules including hydrogen halides, interhalogen compounds, alkali hydrides, and alkali halides. The relative nuclear quadrupole coupling constants are evaluated to check the further validity of this method. It is shown that calculated values are consistent with available experimental values.

A Facile Synthetic protocol fpr the Preparation of 4-Halobutyl Benzoates voa Carbon-Oxygen Bond Cleavage of THF

  • Gang, Jong Min;Kim, Seong Hoe
    • Bulletin of the Korean Chemical Society
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    • v.21 no.6
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    • pp.611-612
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    • 2000
  • A facile synthetic route for the preparation of 4-halobutyl benzoates has been developed. 4-Chloro-, bromo-and iodobutyl benzoates can be easily prepared from the reaction of benzoyl chloride and metal halides in THF under extremely mild conditions. 4-Halo groups were easily controlled by selecting suitable metal halides.

Comparative Studies on the Reactions of Carbamyl and Thiocarbamyl Halides with NH3 in the Gas Phase and in Aqueous Solution: A Theoretical Study

  • Kim, Chang-Kon;Han, In-Suk;Sohn, Chang-Kook;Yu, Yu-Hee;Su, Zhishan;Kim, Chan-Kyung
    • Bulletin of the Korean Chemical Society
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    • v.33 no.6
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    • pp.1955-1961
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    • 2012
  • In this work, the reactions of carbamyl and thiocarbamyl halides with $NH_3$ were studied in the gas phase at the MP2(FC)/6-31+G(d) level of theory. Single point calculations were performed at the QCISD/6-311+G(3df,2p) to refine the energetics. The reaction mechanisms were also studied in aqueous solution. The structures were fully optimized at the CPCM-MP2(FC)/6-31+G(d) and refined by a single point CPCM-QCISD/6-311+G(3df,2p) calculations. The reaction mechanisms for the title compounds were compared with those for the acetyl and thioacetyl halides. The lower reactivity of carbamyl (and thiocarbamyl) groups was explained by comparing the C=O and C=S ${\pi}$-bond strengths as well as resonance contributions in the ground state.

The Solvolytic Reaction Mechanism of p-Substituted Benzyl Bromides (파라-치환 브롬화 벤질의 가용매 분해반응 메카니즘)

  • Lee, Ik Chun;Eom, Tae Seop;Sung, Dae Dong;Lee, Jong Pal;Park, Hyeon Seok
    • Journal of the Korean Chemical Society
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    • v.34 no.1
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    • pp.10-18
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    • 1990
  • Solvolyses of p-substituted benzyl bromides have been studied in dimethylsulfoxide-water and N,N-dimethylformamide-water mixtures by kinetic method. To determine the ionizing power, Y and the nucleophilicity, $N_{BS}$, the solvolyses of 1-adamantyl halides, t-butyl halides, and methyl tosylate in the same solvent mixtures have been investigated. The solvatochromic parameters for each dimethylsulfoxide-water mixtures have been determined by substituting into the Taft's linear solvatochromic energy relationships with measured $ν_{max}$. The solvolyses of p-substituted benzyl bromides have been found to proceed by borderline mechanism in which bond formation is more advanced than bond cleavage in the transition state based on the m, l values and ${\beta},{\rho}_s$, values.

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Kinetics and Mechanism of the Aminolysis of Benzenesulfonyl, Benzoyl and Benzyl Halides

  • Byung Choon Lee;Dong Sook Sohn;Ji Hyun Yoon;Sun Mo Yang;Ikchoon Lee
    • Bulletin of the Korean Chemical Society
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    • v.14 no.5
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    • pp.621-625
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    • 1993
  • Kinetic studies are conducted for the reactions of Y-benzoyl, Y-benzenesulfonyl and Y-benzyl halides with X-anilines in acetonitrile, and the transition state (TS) structures and their variations with substituents X and Y are discussed. The magnitude of the cross-interaction constants, $\rho$xy, is the largest and the inverse secondary kinetic isotope effect (SKIE), $k_H/k_D$ < 1.0, with deuterated aniline nucleophiles is the smallest for benzoyl fluoride reflecting the tightest TS for this compound. The SKIEs for sulfonyl halides are relatively large due to a relatively large, diffuse nature of the reaction center, S, causing weaker steric hindrance to the vibrations of the two N-H(D) bonds. For benzoyl and sulfonyl halides, the trends in $k_H/k_D$ and $Ir_XI$ variations with $\sigma$Y contradict each other, which is rationalized by the negative charge accumulation on the reaction center, CO and SO$_2$, causing inefficient transfer for the substrate with an electron donating substituent.

Nickel-Catalyzed Coupling of Arenesulfonates with Primary Alkylmagnesium Halides

  • Cho, Chul-Hee;Sun, Myung-Chul;Park, Kwang-Yong
    • Bulletin of the Korean Chemical Society
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    • v.26 no.9
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    • pp.1410-1414
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    • 2005
  • Neopentyl arenesulfonates reacted with primary alkylmagnesium halides in the presence of $(PPh_3)_2NiCl_2$ to produce the corresponding alkylarenes. The efficiency of this coupling reaction considerably depends on the nature of catalyst and solvent. Highest yield was obtained by using three equivalents of Grignard reagent to a mixture of $(PPh_3)_2NiCl_2$ and arenesulfonate in refluxing $Et_2O$. This reaction represents a novel method allowing the efficient and creative substitution of sulfur-containing groups in aromatic compounds. It also shows that the alkyloxysulfonyl group might be a suitable alternative to halides and triflate in some circumstances.

A Versatile Synthesis of α-Keto (cyanomethylene)triphenylphosphorane Ylides from Alkyl Halides Utilizing a Noble Phenylsulfonyl Reagent

  • Lee, Kieseung;Hwang, Chan-Yeon
    • Bulletin of the Korean Chemical Society
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    • v.34 no.10
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    • pp.2953-2958
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    • 2013
  • A noble phenylsulfonyl reagent 8 having ${\alpha}$-oxo (cyanomethylene)triphenylphosphorane ylide subunit readily condensed with various alkyl halides under basic conditions to afford ${\beta}$-alkyl-${\alpha}$-oxo-${\beta}$-phenylsulfonyl (cyanomethylene)triphenylphosphorane ylides 9 in excellent yields. These sulfonyl ylides 9 were then reductively desulfonylated with $Na(Hg)/Na_2HPO_4$ in the presence of methanol to provide ${\alpha}$-keto (cyanomethylene)-triphenylphosphorane ylides 2' in good to excellent yields. Our new synthetic approach offers an expeditious access to various ${\alpha}$-keto (cyanomethylene)triphenylphosphorane ylides from alkyl halides utilizing a new phenylsulfonyl reagent as the key reagent under mild reaction conditions in good overall yields.

Hot Atom Chemistry of Aromatic Halides : Scavenger, Temperature and Oxygen Effect (芳香族할라이드의 Hot Atom Chemistry 스캐벤져, 溫度 및 酸素의 效果)

  • Choi, Jae-Ho;Park, Yong-Chan;Son, Mi-Ja
    • Journal of the Korean Chemical Society
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    • v.9 no.2
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    • pp.78-80
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    • 1965
  • The organic yields(i.e., fraction of nuclear events resulting in organic compound formation) of the radioactive neutron capture reactions of the halogens in purified aromatic halides have been determined in the liquid and solid state, in the presence of scavenger, elemental halogen for thermal atoms, and in the presence of oxygen. Among the important results are; (1) organic yields of the halides are due in part to hot processes and in part to thermal processes; (2) temperature (from liquid state to solid state); (3) the organic yield of chlorobenzene is the same in the solid phase as in the liquid phase whereas the yields of the bromo-and iodobenzene are higher in the solid.

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