• Title, Summary, Keyword: {\gamma})$반응

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Reactions of $\gamma$,$\gamma$,$\gamma$-Trichloroethylidene-m-Nitroacetophenone with Hydrazines ($\gamma$,$\gamma$,$\gamma$-Trichloroethylidene-m-Nitroacetophenone과 Hydrazine 들의 반응)

  • Youn Young Lee;Suk Zu Song
    • Journal of the Korean Chemical Society
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    • v.17 no.1
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    • pp.25-30
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    • 1973
  • 2,6-Disubstituted-3-pyridazinones were synthesized by the reactions of $\gamma$,$\gamma$,$\gamma$-trichloroethylidene-m-nitroacetophenone with phenylhydrazine and substituted phenylhydrazines, and hydrazone was isolated as an intermediate from the reaction with 2, 4-dinitrophenylhydrazine. From the reaction with hydrazine hydrate 3-(m-nitrophenyl)-5-trichloromethyl-2-pyrazoline was obtained in good yield. The effect of substituents on phenyl group in the reaction of $\gamma$,$\gamma$,$\gamma$-trichloroethylidene-m-nitroacetophenone with substituted phenylhydrazines was also discussed.

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Synthesis and Monomer Reactivity Ratio of PNIPAAM-PMMA Random Copolymer (PNIPAAM-PMMA Random Copolymer의 합성 및 단량체 반응성비 측정)

  • 이창배;조창기
    • Polymer Korea
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    • v.24 no.2
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    • pp.168-173
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    • 2000
  • Radical copolymerization of N-isopropylacrylamide (NIPAAM) with methyl methacrylate (MMA) was carried out in 1,4-dioxane using 2,2'-azobisisobutyronitrile (AIBN). To investigate the reactivity ratios of NIPAAM and MMA at different reaction temperatures, the copolymerization was allowed to proceed to low conversion (less than 10 wt%), and the reaction temperatures were 50, 60, and 7$0^{\circ}C$. The monomer reactivity ratios of NIPAAM and MMA were estimated by the graphical methods according to the Finemann-Ross equation. The ${\gamma}$$_1$ and ${\gamma}$$_2$ values for NIPAAM-MMA were 0.259 and 2.782 at 5$0^{\circ}C$, 0.271 and 2.819 at 6$0^{\circ}C$, and 0.286 and 2.915 at 7$0^{\circ}C$, respectively. As the reaction temperature increased, the ${\gamma}$$_1$ and ${\gamma}$$_2$ values increased. The activation energy difference was estimated by comparing the reactivity ratios at different reaction temperatures.

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Production of ${\gamma}$-Glutamylcysteine by Immobilized Mixed Microbial System of Recombinant E. coli and Yeast (재조합 대장균과 효모의 고정화 혼합세포계에 의한 ${\gamma}$-Glutamylcysteine 생산)

  • 김원근;구윤모
    • KSBB Journal
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    • v.10 no.3
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    • pp.249-256
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    • 1995
  • ${\gamma}$-Glutamylcysteine production by the immobilized microbial system of recombinant Escherichia coli and yeast was investigated. ${\gamma}$-Glutamylcysteine was synthesized from L-glutamic acid and L-cysteine in the presence of ATP by the reaction catalyzed by ${\gamma}$-glutamylcysteine synthetase. An immobilized microbial cell system was developed for the efficient ${\gamma}$-glutamylcysteine production. Recombinant Escherichia coli and yeast were immobilized by alginate. Production of ${\gamma}$-glutamylcysteine was better with the recombinant Escherichia coli for both the synthesis of ${\gamma}$-glutamylcysteine and the ATP regeneration than the mixed system of recombinant Escherichia coli and yeast. The proper radio of recombinant Escherichia coli to yeast was experimentary observed to be 1:4 in the mixed system. Although the immobi1ized system had the slower reaction rate, its reaction stability was increased by 10%.

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Formation of Cobalt Ferrit Epitaxial Iron Oxide and Their Magnetic Properties(I) (코발트 훼라이트 에피탁시얼 산화철의 생성과 자기특성(I))

  • 변태봉;김대영;이재영;손진군
    • Journal of the Korean Magnetics Society
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    • v.2 no.1
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    • pp.8-14
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    • 1992
  • To improve the coercivity of ${\gamma}-Fe_{2}O_{3}$ particles. We have made cobalt ferrite epitaxial ${\gamma}-Fe_{2}O_{3}$ particles by crystallizing cobalt ferrite on the surface of ${\gamma}-Fe_{2}O_{3}$ particles. The coercivity of $Co_{x}Fe_{3-x}O_{4}$ which is conform to coating layer showed the most superior characteristic when the value of x was 1. On the formation of cobalt epitaxial ${\gamma}-Fe_{2}O_{3}$ particles, controlling reaction atmosphere as oxidation at. mosphere after non-oxidation atmosphere was the optimum condition to prepare cobalt epitaxial ${\gamma}-Fe_{2}O_{3}$ particles with superior magnetic properties. Epitaxial growth of cobalt ferrite on the surface of ${\gamma}-Fe_{2}O_{3}$ particles was accomplished at $90^{\circ}C$ for 30 minutes.

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Studies on the Properties of E. coli ${\gamma}-Glutamylcysteine$ Synthetase in Relation to the Enzymatic Synthesis of Glutathione (글루타치온의 효소적 생합성에 관계되는 E.coli ${\gamma}-Glutamylcysteine$ Synthetase의 특성 연구)

  • Nam, Yong-Suk;Kwak, Joon-Hyeok;Lee, Se-Yong
    • Applied Biological Chemistry
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    • v.40 no.6
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    • pp.478-483
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    • 1997
  • ${\gamma}-Glutamylcysteine$ synthetase was purified from E. coli K-12 strain and its properties related to the in vitro synthesis of glutathione by enzymatic method were investigated. The activity of purified ${\gamma}-glutamylcysteine$ synthetase was increased with increasing concentration of L-glutamate up to 60 mM, while it was decreased by about 50% and 40% under 60 mM of L-cysteine and 45 mM of glycine, respectively. The enzyme activity was reduced not only by ADP, one of the reaction products, but also by the reduced form of glutathione. Therefore, because the reduced glutathione as well as glycine which is the substrate for glutathione synthetase inhibit the activity of ${\gamma}-glutamylcysteine$ synthetase, it is recommended to design a bioreactor system with two separate reactions for glutathione synthesis : one with ${\gamma}-glutamylcysteine$ synthetase reaction and the other glutathione synthetase reaction. In addition since ADP, resulted from these reactions, reduces the activity of ${\gamma}-glutamylcysteine$ synthetase, it is necessary to introduce an ATP regeneration system for glutathione synthesis.

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Activity and Selectivity in Low Temperature for Dibenzothiophene Hydrodesulfurization based Zeolite Support (제올라이트 담체상의 디벤조티오펜 수첨탈황반응에서 저온활성 및 선택성)

  • Kim, Moon-Chan
    • Applied Chemistry for Engineering
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    • v.9 no.1
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    • pp.101-106
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    • 1998
  • Two types of CoMo/zeolite as well as $NiMo/{\gamma}-Al_2O_3$ were prepared and their activities and selectivities of low-temperature dibenzothiophene(DBT) hydrodesulfurization(HDS) were studied in high pressure fixed bed reactor. The HDS activities of CoMo/zeolites were higher than that of $NiMo/{\gamma}-Al_2O_3$ at temperatures below $225^{\circ}C$ while they were lower than that of $NiMo/{\gamma}-Al_2O_3$ at temperatures higher than $275^{\circ}C$. The main products from $NiMo/{\gamma}-Al_2O_3$ were biphenyl and cyclohexylbenzene. The product distribution of CoMo/zeolite catalysts was different from that of $NiMo/{\gamma}-Al_2O_3$. It is speculated that DBT is converted to alkylcyclohexane over zeolite based catalysts through both alkylation and hydrogenation reactions. The crystal structure of molybdenum was $MoO_3$ in fresh zeolite support while mixtures of $MoO_3$ and $MoS_2$ were observed in the aged catalyst.

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Reaction Characteristics of SOx/NOx Removal Using CuO/γ-Al2O3 Sorbent/Catalyst (CuO/γ-Al2O3 흡수제/촉매를 이용한 SOx/NOx 제거 반응특성)

  • Yoo, Kyung Seun;Kim, Sang Done
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.4
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    • pp.671-678
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    • 2000
  • Reaction characteristics of simultaneous removal of SOx and NOx have been investigated in a thermogravimetric analyzer and tubular fixed bed reactor using the $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst. Sulfur removal capacity of $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst is largely enhanced above both the temperature of $450^{\circ}C$ and the loading of 6wt% due to the participation of alumina support in a sulfation reaction. The NO reduction efficiency of 8wt% $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst shows the maximum value at $370^{\circ}C$ and then decreases with the increase of reaction temperature due to the oxidation of $NH_3$ gas. The presence of sulfate on the surface of sorbent/catalyst enhances the optimum reaction temperature showing the maximum deNOx efficiency. In the simultaneous removal of SOx and NOx at $250^{\circ}C$. deNOx activity of $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst is rapidly decreased due to the formation of ammonium salts such as $NH_4HSO_4$. In the simultaneous removal reaction of SOx and NOx, the optimum temperature showing the maximum deNOx efficiency increases to $400^{\circ}C$ due to the presence of $SO_2$ gas.

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Synthesis and Exploratory Photochemistry of ${\beta},\;{\gamma}$-unsaturated Carboxylic Acid, Carboxamide and Nitrile Derivatives (${\beta},\;{\gamma}$-불포화카르복시산, 카르복시아미드와 니트릴 유도체의 합성과 이들의 광화학적 반응에 관한 연구)

  • Givens Richard S.;Woo Ki Chae
    • Journal of the Korean Chemical Society
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    • v.26 no.2
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    • pp.99-106
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    • 1982
  • The ketone chromophore of 1-Acetyl-1-methyl-2-cyclopentene (1) was replaced by nitrile, carboxylic acid and acetamide group, and their photochemical reactions were investigated. While the ${\beta},\;{\gamma}$-unsaturated ketone 1 afforded 1,2 ar 1,3-Acyl shift product, these replaced chromophores did not afford any monomeric rearranged products. 1-Cyano-1-methyl-2-cyclohexene also afforded no product anology of the 1,2-acyl shift reaction. The replacement of the ketone chromophore by nitrile, carboxylic acid and carboxamide has greatly altered the photochemistry of ${\beta},\;{\gamma}$-unsaturated ketones.

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Measurement of Energy Dependent Differential Neutron Capture Cross-section of Natural Sm by Using a Continuous Neutron Flux below (연속에너지 중성자에 대한 천연 Sm의 중성자 포획단면적 측정)

  • Yoon, Jungran
    • Journal of the Korean Society of Radiology
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    • v.10 no.5
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    • pp.337-341
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    • 2016
  • We measured the neutron capture cross-section of natural Sm(n,${\gamma}$) reaction in the energy regions from 0.003 to 10 eV. The 46-MeV electron linear accelerator of Research Reactor Institute, Kyoto University was used for generating a continuous neutron source. The neutron time-of-flight method was adopted for energy measurement. An assembly of BGO($Bi_4Ge_3O_{12}$) scintillators composed of 12 pieces of BGO crystals measured prompt gamma rays from Sm(n,${\gamma}$) reaction. The BGO assembly was located at a distance of $12.7{\pm}0.02m$ from the neutron source. In order to determine the neutron flux impinging on the Sm, the $^{10}B(n,{\alpha}{\gamma})^7Li$ standard cross-section were used. Natural Sm(n,${\gamma}$) reaction measurement result of the neutron capture cross-section was compared with the results of evaluation of the BROND-2.2 and the previous experimental data of J. C. Chou and V. N. Kononov.

Catalytic Decomposition of $SF_6$ by Hydrolysis and Oxidation over ${\gamma}-Al_2O_3$ (${\gamma}-Al_2O_3$ 촉매상에서 가수분해와 산화반응에 의한 $SF_6$ 촉매분해 특성)

  • Lee, Sun-Hwa;Park, No-Kuk;Yoon, Suk-Hoon;Chang, Won-Chul;Lee, Tae-Jin
    • Clean Technology
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    • v.15 no.4
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    • pp.273-279
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    • 2009
  • $SF_6$, which has a high global warming potential, can be decomposed to sulfur and fluorine compounds through hydrolysis by $H_2O$ or oxidation by $O_2$ over solid acid catalysts. In this study ${\gamma}-Al_2O_3$ was employed as the solid acid catalyst for the abatement of $SF_6$ and its catalytic activity was investigated with respect to the reaction temperature and the space velocity. The catalytic activity for $SF_6$ decomposition by the hydrolysis reached the maximum at and above 973 K with the space velocity of $20,000\;ml/g_{-cat}{\cdot}h$, exhibiting a conversion very close to 100%. When the space velocity was lower than $45,000\;ml/g_{-cat}{\cdot}h$, the conversion was maintained at the maximum value. On the other hand, the conversion of $SF_6$ by the oxidation was about 20% under the same conditions. The SEM and XRD analyses revealed that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ during the hydrolysis and to $AlF_3$ during the oxidation, respectively. The size of $AlF_3$ after the oxidation was over $20\;{\mu}m$, and its catalytic activity was low due to the low surface area. Therefore, it was concluded that the hydrolysis over ${\gamma}-Al_2O_3$ was much more favorable than the oxidation for the catalytic decomposition of $SF_6$.

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