• 제목/요약/키워드: S-chemistry

검색결과 8,330건 처리시간 0.039초

Anthocyanins Extracted from Grapes as Green Corrosion Inhibitors for Tin Metal in Citric Acid Solution

  • Mohamed, Mervate Mohamed;Alsaiari, Raiedhah;Al-Qadri, Fatima A.;Shedaiwa, Iman Mohammad;Alsaiari, Mabkhoot;Musa, Esraa Mohamed;Alkorbi, Faeza;Alkorbi, Ali S.
    • Corrosion Science and Technology
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    • 제21권5호
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    • pp.381-389
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    • 2022
  • Cyclic Voltammetry and weight loss measurements were used to investigate corrosion prevention of tin in a 0.5M citric acid solution containing Anthocyanins extracted from grapes at various concentrations and temperatures. Results showed that the investigated chemicals, Anthocyanins extracted from grapes, performed well as tin corrosion inhibitors in 0.5M citric acid. Increasing the concentration of Anthocyanins increased their corrosion inhibition efficiencies. When the temperature dropped, their inhibition efficiencies, increased indicating that higher temperature tin dissolution predominated the adsorption of Anthocyanins at the surface of tin metal. When inhibitor concentrations were increased, their inhibition efficiencies were also increased. These results revealed that corrosion of tin metal was inhibited by a mixed type of adsorption on the metal surface. The adsorption isotherm of Langmuir governed the adsorption of Anthocyanins. Thermodynamic parameters such as the enthalpy of adsorption, the entropy of adsorption, and Gibbs free energy and kinetic parameters such as activation energy, enthalpy of activation, and entropy of activation were computed and discussed in this study.

Synthesis of Chiral Azophenolic Pyridino-18-Crown-6 Ether and Its Enantiomeric Recognition toward Chiral Primary Amines

  • Kim, Jae-kon;Song, Su-Hee;Kim, Jae-Hong;Kim, Tae-Hyun;Kim, Ha-suck;Suh, Hong-Suk
    • Bulletin of the Korean Chemical Society
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    • 제27권10호
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    • pp.1577-1580
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    • 2006
  • The article reports the synthesis and enantiomeric recognition of a new chiral azophenolic pyridino-18-crown-6 ether, (S,S)-6, possessing diphenyl groups as chiral barriers. The association constants for the enantiomeric recognition of chiral primary amines (7-12) using chiral azophenolic pyridino-18-crown-6 ether, (S,S)-6, were determined by UV-visible titration method in acetonitrile at $25{^{\circ}C}$.

Facile Synthesis of 3-Thioxo-3H-benzo[f]chromen-2-yl methanone and 3H-Benzo[f]chromene-3-one Under Solvent Free Condition

  • Singh, Okram Mukherjee;Devi, Nepram Sushuma;Devi, Laishram Ronibala;Lim, Ki-Bum;Yoon, Yong-Jin;Lee, Sang-Geyong
    • Bulletin of the Korean Chemical Society
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    • 제32권1호
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    • pp.175-178
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    • 2011
  • A facile, convenient, efficient and high yielding synthesis of a combinatorial library of coumarins has been developed by the condensation of readily available $\beta$-oxodithioesters and S,S-acetal with 2-hydroxy-1-naphthaldehyde in the presence of catalytic amount of $CuCl_2$ under solvent free conditions.

Schiff Bases as Anticorrosive Additives for Mild Steel Corrosion in Acid Media

  • Abirami, M.;Sasikala, S.;Chitra, S.;Parameswari, K.;Selvaraj, A.
    • Corrosion Science and Technology
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    • 제8권1호
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    • pp.1-10
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    • 2009
  • The influence of Schiff bases on the corrosion inhibition of mild steel in 1 M $H_2SO_4$ have been investigated by weight loss, gasometry, impedance and polarization techniques. The results obtained reveal that these compounds act as good inhibitors. The inhibition efficiency of Schiff bases increased with concentration and synergistically increased on addition of chromate, sulphate and halide ions. Potentiodynamic polarization measurements clearly reveal that the investigated inhibitors are of mixed type but they are more cathodic in nature. The adsorption of these compounds on mild steel surface for both the acids were found to obey Langmuir adsorption isotherm. The surface morphology was studied by SEM and UV reflectance spectra.

노르후록사신-금속이온 착물의 물리화학적 성질 및 항균력 (Physiochemical Properties and Antibacterial Activities of Metal Complexes of Norfloxacin)

  • 박원봉;김경아;이명환;이동선;노동윤
    • 약학회지
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    • 제36권6호
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    • pp.577-581
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    • 1992
  • Norfloxacin complexes of $Fe^{2+}$, $Cu^{2+}$ and $Al^{3+}$ have been prepared as solids. The stoichiometry of the complexes has been established. IR investigation indicates the metal-ligating sites in norfloxacin. The bioactivities of complexes all lower than that of norfloxacin. The solubilities and partition coefficients have been measured as a function of temperature. The data are used to evaluate the thermodynamic parameters ${\Delta}G$, ${\Delta}H$, ${\Delta}S$ for the solute transfer process and compared with the parent quinolone, norfloxacin. The existence of such complexes is discussed in the light of quinolone mode-of-action theories.

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Reaction of Di-s-butoxyborane in Tetrahydrofuran with Selected Organic Compounds containing Representative Functional Groups. Catalytic Effect of Tetraalkoxyborate on the Reaction of Dialkoxyborane$^\dag$

  • Cha, Jin-Soon;Lee, Jae-Cheol;Kim, Jin-Euog;Lee, Kwang-Woo;Yoon, Mal-Sook
    • Bulletin of the Korean Chemical Society
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    • 제8권4호
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    • pp.304-310
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    • 1987
  • The approximate rate and stoichiometry of the reaction of excess di-s-butoxyborane with selected organic compounds containing representative functional groups under standardized conditions (tetrahydrofuran, $25^{\circ}C)$ were examined in order to define the characteristics of the reagent for selective reductions. And the catalytic effect of lithium tetra-s-butoxyborate on the reaction of di-s-butoxyborane was also studied in order to increase the utility of this reducing system. Di-s-butoxyborane reacts only with simple aldehydes. However the addition of 2.5 mole % of lithium tetra-s-butoxyborate shows the tremendous rate enhancement of reaction for aldehydes, ketones, anhydrides, acid chlorides, lactones, and epoxides. This catalytic effect is assumed to in situ formation of lithium trialkoxyborohydride.