• Title/Summary/Keyword: halides

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Reaction of Potassium Fluoride with Organic Halogen Compounds. (Part I) Reactions of Potassium Fluoride with Organic Halides, Acids, and Esters in presence of Dimethyl Formamide and their Pyrolytic Decaboxylation in presence of Potassium Fluoride (有機 할로겐 化合物과 弗化加里의 反應 (第1報) 有機 할라이드, 酸 및 에스테르와 弗化加里의 디메칠 호름아마이드 溶媒系反應 및 高溫-脫炭酸-熱分解反應)

  • You Sun Kim
    • Journal of the Korean Chemical Society
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    • v.7 no.3
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    • pp.189-196
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    • 1963

  • Reactions between potassium fluoride with organic halogen-containing carboxylic acids in dimethyl formamide solvent gave a decarboxylation reaction for the case of fluoro carboxylic acids of the type of $CF_3\;COOH,\;C_3F_7COOH,\;and\;C_2F_5COOH,$ whereas an additional partial fluorination together with dimerization reaction occurred for the chlorine containing acids of the type of $CH_2ClCOOH,\;CH_3CHClCOOH, \;CHCl_2COOH\;and\;o-Cl-C_6H_4-COOH.$ The phenyl halides showed no reactivity, but the halides with two electron attracting substituents on the benzene ring gave mainly dimerization reaction. The esters and alcohols gave an usual fluorination reaction. The same reactions in absence of the solvent at the elevated temperature increase the yield of the dimerized product and gave the cyclized product, fluorenone, in case of ο-chlorobenzoic acid. It was found that the fluorination usually precede the decarboxylation reaction by checking the stiochemical sequence of reaction. Catalytic influence of potassium fluoride were discussed and the mechanism of the reaction was considered.

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Synthesis and Antimicrobial Activity of Some New 1-Alkyl-2-alkylthio-1,2,4-triazolobenzimidazole Derivatives

  • Mohamed, Bahaa Gamal;Hussein, Mostafa Ahmed;Abdel-Alim, Abdel-Alim Mohamed;Hashem, Mohammed
    • Archives of Pharmacal Research
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    • v.29 no.1
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    • pp.26-33
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    • 2006

  • Some new derivatives of 1,2,4-triazolo[2,3-a]benzimidazoles were synthesized through the reaction of 1,2-diaminobenzimidazole with carbon disulfide. The resulting 1,2,4-triazolo-[2,3a]benzimidazole-2-thione intermediate was reacted with one equivalent of alkyl halides to give the corresponding 2-alkylthio derivatives, which were further alkylated through the reaction with another one equivalent of different alkyl halides to afford the target compounds; 1-alkyl-2alkylthio-1,2,4-traizolo[2,3-a]benzimidazoles. On the other hand, the 1,2-disubstituted derivatives with two identical alkyl substituents were prepared by the reaction of 1,2,4-triazolo[2,3-a]benzimidazole-2-thione with two equivalents of the alkyl halides. The structures of the new compounds were assigned by spectral and elemental methods of analyses. The synthesized compounds were tested for their antibacterial and antifungal activities. Most of the tested compounds proved comparable results with those of ampicillin and fluconazole reference drugs. The study indicated that, the antibacterial as well as the antifungal activities of the test compounds were improved with increase in the bulkiness of the introduced alkyl groups. Also, some active antibacterial compounds were tested for their antimycobacterial activity. All the test compounds showed equipotent antitubercular activity as that of INH as a reference drug.

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Theoretical Studies of the Gas-Phase Identity Nucleophilic Substitution Reactions of Cyclopentadienyl Halides

  • Lee, Ik-Choon;Li, Hong-Guang;Kim, Chang-Kon;Lee, Bon-Su;Kim, Chan-Kyung;Lee, Hai-Whang
    • Bulletin of the Korean Chemical Society
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    • v.24 no.5
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    • pp.583-592
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    • 2003

  • The gas phase identity nucleophilic substitution reactions of halide anions (X = F, Cl, Br) with cyclopentadienyl halides (1) are investigated at the B3LYP/6-311+G**, MP2/6-311+G** and G2(+)MP2 levels involving five reaction pathways: σ-attack $S_N2$, β-$S_N$2'-syn, β-$S_N$2'-anti, γ-$S_N$2'-syn and γ-$S_N$2'-anti paths. In addition, the halide exchange reactions at the saturated analogue, cyclopentyl halides (2), and the monohapto circumambulatory halide rearrangements in 1 are also studied at the same three levels of theory. In the σ-attack $S_N2$ transition state for 1 weak positive charge develops in the ring with X = F while negative charge develops with X = Cl and Br leading to a higher energy barrier with X = F but to lower energy barriers with X = Cl and Br than for the corresponding reactions of 2. The π-attack β-$S_N$2' transition states are stabilized by the strong $n_C-{\pi}^{*}_{C=C}$ charge transfer interactions, whereas the π-attack γ-$S_N$2' transition states are stabilized by the strong $n_C-{\sigma}^{*}_{C-X}$ interactions. For all types of reaction paths, the energy barriers are lower with X = F than Cl and Br due to the greater bond energy gain in the partial C-X bond formation with X = F. The β-$S_N$2' paths are favored over the γ-$S_N$2' paths only with X = F and the reverse holds with X = Cl and Br. The σ-attack $S_N2$ reaction provides the lowest energy barrier with X = Cl and Br, but that with X = F is the highest energy barrier path. Activation energies for the circumambulatory rearrangement processes are much higher (by more than 18 kcal $mol^{-1}$) than those for the corresponding $S_N2$ reaction path. Overall the gas-phase halide exchanges are predicted to proceed by the σ-attack $S_N2$ path with X = Cl and Br but by the β-$S_N$2'-anti path with X = F. The barriers to the gas-phase halide exchanges increase in the order X = F < Br < Cl, which is the same as that found for the gas-phase identity methyl transfer reactions.

  • https://doi.org/10.5012/bkcs.2003.24.5.583 인용 PDF KSCI