• 제목/요약/키워드: Chemical reactions

검색결과 2,729건 처리시간 0.029초

Chemistry of persulfates for the oxidation of organic contaminants in water

  • Lee, Changha;Kim, Hak-Hyeon;Park, Noh-Back
    • Membrane and Water Treatment
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    • 제9권6호
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    • pp.405-419
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    • 2018
  • Persulfates (i.e., peroxymonosulfate and peroxydisulfate) are capable of oxidizing a wide range of organic compounds via direct reactions, as well as by indirect reactions by the radical intermediates. In aqueous solution, persulfates undergo self-decomposition, which is accelerated by thermal, photochemical and metal-catalyzed methods, which usually involve the generation of various radical species. The chemistry of persulfates has been studied since the early twentieth century. However, its environmental application has recently gained attention, as persulfates show promise in in situ chemical oxidation (ISCO) for soil and groundwater remediation. Persulfates are known to have both reactivity and persistence in the subsurface, which can provide advantages over other oxidants inclined toward either of the two properties. Besides the ISCO applications, recent studies have shown that the persulfate oxidation also has the potential for wastewater treatment and disinfection. This article reviews the chemistry regarding the hydrolysis, photolysis and catalysis of persulfates and the reactions of persulfates with organic compounds in aqueous solution. This article is intended to provide insight into interpreting the behaviors of the contaminant oxidation by persulfates, as well as developing new persulfate-based oxidation technologies.

Some Reactions of 3-Methyl-5-oxo-1-phenyl-Δ2-pyrazoline-4-thiocarbohydrazide

  • Kandeel, Maymona M.;Abbady, Mohamed S.;Youssef, Mohamed Salah K.
    • Bulletin of the Korean Chemical Society
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    • 제23권1호
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    • pp.41-47
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    • 2002
  • The reactions of 3-methyl-1-phenyl-5-oxo-${\Delta}^2$-pyrazoline-4-thiocarbohydrazide towards phenyl isothiocyanate, sodium nitrite, cyclohexanone, aromatic aldehydes, and carbon disulphide has been studied. The Vilsmeier-Haack reaction has been applied on 4-substituted pyrazolone derivatives.

A Study of the Diastereoselectivity of Diels-Alder Reactions on the Ce-SiO2 as Support

  • Ziarani, Ghodsi Mohammadi;Badiei, Alireza;Miralami, Azam
    • Bulletin of the Korean Chemical Society
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    • 제29권1호
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    • pp.47-50
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    • 2008
  • The diastereoselectivity of Diels-Alder reactions were studied on the silica surface supported with different concentrations of cerium ion as efficient Lewis acid catalysts under solvent-free conditions. The results showed that the diastereoselectivity of reaction was highly improved in these conditions. The cerium ion was grafted on silica surface by using ion exchange method.

Long Chain Dicationic Phase Transfer Catalysts in the Condensation Reactions of Aromatic Aldehydes in Water Under Ultrasonic Effect

  • Esen, Ilker;Yolacan, Cigdem;Aydogan, Feray
    • Bulletin of the Korean Chemical Society
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    • 제31권8호
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    • pp.2289-2292
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    • 2010
  • Long chain dicationic ammonium salts were used successfully as phase transfer catalyst in the condensation reactions of aromatic aldehydes in water under ultrasonic irradiation for the first time. The quaternary salt having longer distance between the cation centers was more effective than the mono- and dicationic ones having short chain.

순수 산소계의 주간 및 야간 광화학반응 (Daytime and Nighttime Photochemical Reactions of the Pure Oxygen System)

  • 윤광식
    • 대한화학회지
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    • 제13권4호
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    • pp.249-261
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    • 1969
  • Studies of photochemical reactions of the pure oxygen atmosphere are made using reaction rate constants and atmospheric data available in the latest literature. The daytime and nighttime variations in atomic oxygen and ozone are computed, based on three different conditions: 1) photochemical equilibrium, 2) direct integrations of the rate equations with modifications and approximation to the equations, and 3) by numerical integrations. The departure from the photochemical equilibrium concentrations during day and nighttime are discussed by comparing the results obtaind from the three conditions.

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One-Pot Synthesis of 2H-Pyrans by Indium(III) Chloride-Catalyzed Reactions.Efficient Synthesis of Pyranocoumarins, Pyranophenalenones, and Pyranoquinolinones

  • Lee, Yong-Rok;Kim, Do-Hoon;Shim, Jae-Jin;Kim, Seog K.;Park, Jung-Hag;Cha, Jin-Soon;Lee, Chong-Soon
    • Bulletin of the Korean Chemical Society
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    • 제23권7호
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    • pp.998-1002
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    • 2002
  • An efficient synthesis of 2H-pyrans is achieved by indium (III) chloride-catalyzed reactions of 1,3-dicarbonyl compounds with a variety of $\alpha\beta-unsaturated$, aldehydes in moderate yields. This method has been applied to the synthesis of pyranocoumar ins, pyranophenalenones, and pyranoquinolinone alkaloids.

Zinc Mediated Barbier Type Allylation of Cyclic Imides and Subsequent Coupling Reactions with Carbon Nucleophiles

  • Kang, Seok-Won;Heo, Eun-Young;Jun, Jong-Gab;Kim, Sung-Hoon
    • Bulletin of the Korean Chemical Society
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    • 제25권12호
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    • pp.1924-1928
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    • 2004
  • Allylations of N-benzyl and N-methyl cyclic imides were accomplished successfully under mild Barbier type conditions using zinc metal, allyl bromide and catalytic amount of $PbBr_2$. Subsequent coupling reactions with some carbon nucleophiles afforded 1,2- and 1,4-addition products in moderate to high yields.

Point Particle Approximation for Single and Two Species Diffusion-Influenced Reactions

  • Kim, Hyojoon
    • Bulletin of the Korean Chemical Society
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    • 제34권5호
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    • pp.1454-1456
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    • 2013
  • The fluctuations in concentrations of reactants dominate the long-time dynamics of the single (A + A ${\rightarrow}$ 0) and two species (A + B ${\rightarrow}$ 0) diffusion-influenced annihilation reactions. Although hierarchical Smoluchowski approaches can provide a systematic and flexible framework to deal with the fluctuation effects, their results are too complicated to be analytically solved. For the efficient numerical calculation of the complicated fluctuation effect terms, we show that the presented point particle approximation is not only practical but also quite accurate for most conditions in diffusion-influenced reaction systems.