• 자원리싸이클링
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• 제30권3호
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• pp.41-46
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• 2021

메탄술폰산은 우수한 물리화학적 특성을 지니고 있어 금속의 침출에 효과적이다. 분자구조 및 코발트와 니켈 금속의 침출자료를 이용하여 메탄술폰산과 황산의 화학적 반응성을 비교하였다. 유발과 공명효과는 두 산의 반응성에 큰 영향을 미쳤다. 동일한 침출조건에서 코발트와 니켈의 침출률은 메탄술폰산보다 황산에서 높았다. 메탄술폰산의 강한 산도와 금속염의 높은 용해도를 고려하면 메탄술폰산을 금속회수시 침출제로 이용하는 것이 가능하다.

• Bulletin of the Korean Chemical Society
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• 제15권6호
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• pp.424-427
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• 1994

Effects of iron compounds in known biomimetic oxidation systems (Gif IV and GoAgg II) have been studied on activity and ketone/alcohol selectivity of cyclohexane oxidation. Both ketone/alcohol ratio and cyclohexane conversion were affected by counter-ion Z of iron compounds Z-Fe. When Z has a more electron withdrawing property, the reactivity is increased and the formation of ketone is favored. From these experimental results, a new mechanism is proposed for the biomimetic oxidation system.

• Bulletin of the Korean Chemical Society
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• 제24권9호
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• pp.1251-1255
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• 2003

Second-order rate constants have been determined spectrophotometrically for the reaction of phenyl 4-nitrophenyl carbonate with a series of primary amines in $H_2O$ containing 20 mol % DMSO at 25.0 ${\circ}$C. The Bronsted-type plot is linear with a ${\beta}_{nuc}\;0.69 {\pm} 0.04$, which is slightly smaller than the ${\beta}_{nuc}$ values for the reactions of 4-nitrophenyl acetate ( $\beta_{nuc}= 0.82 {\pm} 0.03$) and benzoate ( $\beta_{nuc} = 0.76 {\pm} 0.01$), indicating that the reaction proceeds through a tetrahedral zwitterionic intermediate $T^{\pm}$. The carbonate is more reactive than the corresponding acetate and benzoate. The changing Me (or Ph) to PhO has resulted in a decrease in the ${\beta}_{nuc}$ value without changing the reaction mechanism but an increase in the reactivity. The electronic effect of the substituent in the nonleaving group appears to be responsible for the enhanced reactivity of the carbonate compared with the corresponding acetate and benzoate.

• 대한화학회지
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• 제29권3호
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• pp.287-294
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• 1985

Acrylamide, N-alkyl substituted acrylamides and N,N-diethylacrylamide를 트리에틸아민과 palladium acetate-triorthotolyl phosphine 촉매 존재하에서 브롬화 방향족화합물들과 비닐화 반응을 실시하여 여러 기능기로 치환된 aryl conjugated enamides를 합성하였다. 이들 반응은 모두 선택적으로 진행되어 (E)-이성질체의 aryl conjugated enamides를 생성하였다. N-alkyl substituted acrylamides는 브롬화 방향족화합물들과의 반응에서 acrylamide와 N,N-diethylacrylamide보다 더 좋은 반응성을 나타내어 생성물들을 높은 수득율로 얻을 수 있었다. 또한 브롬화 방향족화합물이 전자받기 기능기로 치환된 경우에 좋은 반응성을 나타냈으며 전자 주기 기능기를 갖는 경우 acrylamide와 N,N-diethylacrylamide와의 반응에서는 반응이 전혀 진행되지 않거나 낮은 반응성을 나타냈다.

• 한국수소및신에너지학회논문집
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• 제19권6호
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• pp.520-528
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• 2008

2-step methane reforming, consisting of syn-gas production and water splitting step, was carried out over Cu-ferrite/$ZrO_2$. To improve the reactivity over Cu-ferrite/$ZrO_2$ presenting low reactivity in 2-step methane reforming, the addition of Ni was considered. As the results, the added Ni to Cu-ferrite/$ZrO_2$ improved the reactivity in syn-gas production step. However, (Cu, Ni) ferrite/$ZrO_2$ showed carbon deposition in syn-gas production step when an excess Ni was added. Furthermore, (Cu, Ni) ferrite/$ZrO_2$ showed the high durability without the deactivation of the medium during repeated ten cycles, although it showed more deposited carbon than the medium without Ni.

• Bulletin of the Korean Chemical Society
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• 제24권2호
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• pp.197-204
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• 2003

The intracluster ion-molecule reactions of $Ti^+(H_2O)_n,\;Ti^+(CH_3OCH_3)_n,\;and\;Ti^+(CH_3OD)_n$ complexes produced by the mixing of the laser-vaporized plasma and the pulsed supersonic beam were studied using a reflectron time-of-flight mass spectrometer. The reactions of $Ti^+$ with water clusters were dominated by the dehydrogenation reaction, which produces $TiO^+(H_2O)_n$ clusters. The mass spectra resulting from the reactions of $Ti^+\;with\;CH_3OCH_3$ clusters exhibit a major sequence of $Ti^+(OCH_3)_m(CH_3OCH_3)_n$ cluster ions, which is attributed to the insertion of $Ti^+$ ion into C-O bond of $CH_3OCH_3$ followed by $CH_3$ elimination. The prevalence of $Ti^+(OCH_3)_m(CH_3OD)_n$ ions in the reaction of $Ti^+\;with\;CH_3OD$ clusters suggests that D elimination via O-D bond insertion is the preferred decomposition pathway. In addition, the results indicate that consecutive insertion reactions by the $Ti^+$ ion occur for up to three precursor molecules. Thus, examination of $Ti^+$ insertion into three different molecules establishes the reactivity order: O-H > C-O > C-H. The experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by cluster size and argon stagnation pressure. The reaction energetics and formation mechanisms of the observed heterocluster ions are also discussed.

• 한국수소및신에너지학회논문집
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• 제18권2호
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• pp.140-150
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• 2007

Thermochemical 2-step methane reforming, involving the reduction of metal oxide with methane to produce syngas and the oxidation of the reduced metal oxide with water to produce pure hydrogen, was investigated on ferrite-based metal oxide mediums. The mediums, CoFZ, CuFZ, or MnFZ, were composed of the mixture of M(M=Co, Cu or Mn)-substituted ferrite as an active component and $ZrO_2$ as a binder, respectively. The WZ medium, composed of the mixture of $WO_3$ and $ZrO_2$, was also prepared to compare. With an addition of $ZrO_2$, the surface area of the mediums was slightly increased and the sintering of active components was greatly suppressed during the reduction. The higher reactivity of the reduced mediums for water splitting was confirmed by the temperature programmed reaction. From the results of the thermochemical 2-step methane reforming, the reactivity of $CH_4$ reduction and water splitting with ferrite-based metal oxide mediums was relatively higher than that with WZ, and the order of reactivity of the mediums was MnFZ>CoFZ>CuFZ>WZ.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4130-4136
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• 2021

By polymerization of gadolinium methacrylate (Gd (MAA)₃), lead methacrylate (Pb(MAA)₂) and methyl methacrylate (MMA), Gd and Pb were chemically bonded into polymers. The X-ray shielding performance was evaluated by Monte Carlo simulation method, and the results showed that the more metal functional organic monomer, the better the shielding performance of terpolymers. When the X-ray energy is 65 keV, Gd (MAA)₃-containing polymers have better shielding performance than Pb(MAA)₂-containing polymers. Gd could compensate for the weak absorption region of Pb. Therefore, polymers containing both Gd and Pb enhanced shielding efficiency against X-ray in various low-energy ranges. For obtaining terpolymers with uniform monomer compositions, the relationship between the monomer composition of the terpolymers and the conversion level was optimized by calculating the reactivity ratios. The value of reactivity ratios of r (Gd (MAA)₃/Pb(MAA)₂), r (Pb(MAA)₂/Gd (MAA)₃), r (Gd (MAA)₃/MMA), r (MMA/Gd (MAA)₃), r (Pb(MAA)₂/MMA) and r (MMA/Pb(MAA)₂) was 0.483, 0.004, 0.338, 2.508, 0.255, 0.029. The terpolymers with uniform monomer composition could be obtained by controlling the monomer compositions or conversion levels. The results can provide new radiation protection materials and contribute to the improvement in nuclear safety.

• 대한화학회지
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• 제40권8호
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• pp.34-585
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• 1996

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1177-1180
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• 2002