• Title/Summary/Keyword: NBD-Cl

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Synthesis and Solution Chemistry of Metal Hydrides from Cationic Rhodium(I) Catalyst Precursors [(L-L)Rh(NBD)]$ClO_4 (L-L=Fe({\eta}^5-C_5H_4PBu^t\;_2)_2,\;Fe{\eta}^5-C_5H_4PPhBu^t)_2)$

  • Tae-Jeong Kim
    • Bulletin of the Korean Chemical Society
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    • v.11 no.2
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    • pp.134-139
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    • 1990
  • The hydrogenation catalyst precursors $[(L-L)Rh(NBD)]ClO_4\;(L-L=Fe({\eta}^5-C_5H_4PBu^t\;_2)_2,\;Fe({\eta}^5-C_5H_4PPhBu^t)_2$; NBD = norbornadiene) react with $H_2(1\;atm,\;30^{\circ}C$, MeOH) to yield $[(L-L)HRh({\mu}-H)_3RhH(L-L)]ClO_4$. These hydrido species are fluxional, and variable temperature NMR studies show the existence of a number of equilibria involving both fluxional and non-fluxional species. The synthesis, solution structures, and fluxional behaviors of these hydrides are described.

Enantiomer Separation of α-Amino Acid Esters as Nitrobenzoxadiazole Derivatives Using Chiral Columns (키랄 컬럼을 사용한 아미노산 에스테르의 니트로벤조옥사디아졸 유도체의 광학분리)

  • Yun, Won Nam;Kim, Ji Yeon;Lee, Wonjae
    • KSBB Journal
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    • v.28 no.6
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    • pp.423-427
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    • 2013
  • A new convenient derivatization method of ${\alpha}$-amino acid esters as nitrobenzoxadiazole (NBD) derivatives for chiral resolution was introduced and the enantiomer separation of ${\alpha}$-amino acid esters as NBD derivatives was performed by normal HPLC using chiral columns based on polysaccharide derivatives. The NBD derivatives were readily prepared by stirring NBD-Cl and ${\alpha}$-amino acid methyl ester HCl with $NaHCO_3$ in ethanol. The performance of Chiralpak IA was superior to the other chiral stationary phases for enantiomer resolution of NBD derivatives of several ${\alpha}$-amino acid methyl esters. Owing to fluorescence detection as well as strong UV absorption, it is expected that the convenient analytical method developed in this study will be very useful for enantiomer separation of ${\alpha}$-amino acid esters as NBD derivatives on polysaccharide-derived chiral columns.

Laser Induced Fluorimetry IV. Determination of N-Methylcarbamates by 7-Chloro-4-Nitrosobenz-2-Oxa-1,3-Diazole

  • Park, Chan-Seung;Hwang, Kil-Nam;Kim, Ha-Suck;Koh, Won-Yong
    • Bulletin of the Korean Chemical Society
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    • v.10 no.5
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    • pp.411-414
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    • 1989
  • A new sensitive fluorimetric method for the determination of N-methylcarbamates, a class of well known insecticides, based on the derivatization with 7-chloro-4-nitrosobenz-2-oxa-1,3-diazole (NBD-Cl) has been developed. Unreacted NBD-Cl was eluted ahead of derivatized carbamates from C-18 bonded column. An argon ion laser was used as an excitation source of chromatographic eluents and its fluorescence signal was monitored with optical multichannel analyzer. The detection limits of various carbamates were about 100 pg range and the working curves were linear to $10^4-10^5$ nanogram ranges.

Spectrofluorometric quantification of Clozapine in pharmaceutical formulations and human plasma

  • Mohammed, Ali Fahim;Alshirifi, AN;Kadhim, Kasim Hassan
    • Analytical Science and Technology
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    • v.35 no.1
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    • pp.24-31
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    • 2022
  • Herein, we present a simple, precise, accurate, and ultra-sensitive spectrofluorimetric method for estimation of clozapine (CLZ) in tablets and human plasma was developed and then validated. A highly fluorescent brown-yellowish fluorophore was formed (λex=469 nm, λemi=540 nm) as a nucleophilic substitution reaction occurred between CLZ and 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in alkaline mcllavine buffer (pH 9.0). Optimum values of experimental parameters were carefully determined and optimized. The calibration curve was rectilinear over the concentration range of 80-900 ng mL-1 with a linear correlation coefficient (r=0.9984). The LOD and LOQ were determined to be 14 ng mL-1 and 42 ng mL-1, respectively. The proposed approach has been used successfully to quantification of Clozapine in its commercial formulations and human plasma.

Promoting Effect of AlCl_3 on the Fe-catalyzed Dimerization of Bicyclo[2.2.1]hepta-2,5-diene

  • Nguyen, Mai Dao;Nguyen, Ly Vinh;Lee, Je-Seung;Han, Jeong-Sik;Jeong, Byung-Hun;Cheong, Min-Serk;Kim, Hoon-Sik;Kang, Ho-Jung
    • Bulletin of the Korean Chemical Society
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    • v.29 no.7
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    • pp.1364-1368
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    • 2008
  • The activity of the catalytic system composed of Fe$(acetylacetonate)_3$ (Fe$(acac)_3$), triphenylphosphine, and diethylaluminum chloride for the dimerization of bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene, NBD) to produce hexacyclic endo-endo dimer (hexacyclo[$7.2.1.0^{2,8}.1^{3,7}.1^{5,13}.0^{4,6}$]tetradec-10-ene, Hnn) was significantly enhanced by the presence of $AlCl_3$, especially at the molar ratios of NBD/Fe$(acac)_3$ of 500. XPS analysis of the catalytic systems clearly demonstrates that $AlCl_3$ facilitates the reduction of Fe$(acac)_3$ to form active species, Fe(II) and Fe(0) species. The layer separation was observed when [BMIm]Cl was used along with $AlCl_3$, but catalyst recycle was not very successful.

Rhodium(I) Complexes of 1,1$^\prime$-Bis(diphenylphosphino)-ferrocene as Efficient Catalysts in Regioselective Hydrogenation of Polynuclear Heteroaromatic Compounds

  • Kim, Tae-Jeong;Lee, Kyu-Chul
    • Bulletin of the Korean Chemical Society
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    • v.10 no.3
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    • pp.279-282
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    • 1989
  • Two rhodium(I) complexes of the types [Rh(BPPF)(NBD)]$ClO_4$ (10) and [Rh(BPPF)$Cl]_2$ (11) (BPPF = 1,1'-bis(diphenylphosphino)-ferrocene) have been prepared and investigated as catalysts for the regioselective hydrogenation of polynuclear heteroaromatic nitrogen and sulfur compounds such as quinoline (1), acridine (2), phenanthridine (3), 7,8-benzoquinoline (4), benzothiophene (5), isoquinoline (6), indole (7), pyridine (8), and thiophene (9). Both complexes 10 and 11, except for the cases of indole (7) and mononuclear heteroaromatics 8-9, are very efficient in the selective reduction under quite mild hydrogenation conditions to give the corresponding saturated nitrogen and sulfur heterocyclic analogues of 1-6 in fast conversion rates and in excellent yields. Relative rate studies revealed that the reduction depends significantly on the steric and electronic effects of the substrates. Of the two complexes 10-11, the dimeric species 11 gives faster reaction rates in all cases studied.