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    Nucleophilic addition of thiaproline to electrochemically derived o-quinone, application to the sensitive voltammetric detection of thiaproline

    , Article Electroanalysis ; Volume 18, Issue 22 , 2006 , Pages 2225-2231 ; 10400397 (ISSN) Shahrokhian, S ; Amiri, M ; Sharif University of Technology
    2006
    Abstract
    The mechanism of electrochemical behavior of catechol in the presence of thiaproline is investigated by cyclic voltammetry, controlled-potential coulometry and spectrophotometric tracing of the reaction coordinate. The results indicate that thiaproline participate in with an ECEC mechanism in a nucleophilic (Michael) addition to o-quinone. Effect of pH of buffer solution on reaction pathway is studied and showed that addition of thiaproline to the o-quinone is performed only in solutions with pHs higher than 5. These results indicate that the addition of thiaproline is occurred first from amine functional group. In the second step, the addition of carboxylate group of thiaproline to C-5 of... 

    Electrochemical oxidation of dopamine in the presence of sulfhydryl compounds: Application to the square-wave voltammetric detection of penicillamine and cysteine

    , Article Electrochimica Acta ; Volume 51, Issue 20 , 2006 , Pages 4271-4276 ; 00134686 (ISSN) Shahrokhian, S ; Bozorgzadeh, S ; Sharif University of Technology
    2006
    Abstract
    Electro-oxidation of dopamine at a glassy carbon electrode was investigated in the presence of some biologically important thiols (R-SH), e.g. cysteine and penicillamine. Results of cyclic voltammetric studies together with the spectrophotometric foundations via Ellman's test during the controlled-potential coulometry show a nucleophilic addition/reduction of thiol to the electrochemically generated dopaminoquinone by a 1 + 4 Michael addition. The resulting ring substituted substrate (as RS-form) is more easily oxidized leading to an increase in the anodic current of dopamine, which is proportional to the concentration of thiol. The square-wave voltammetry (SWV) were applied as a very... 

    Investigation of the electrochemical behavior of catechol and 4-methylcatechol in the presence of methyl mercapto thiadiazol as a nucleophile: application to electrochemical synthesis

    , Article Journal of Applied Electrochemistry ; Volume 40, Issue 1 , 2010 , Pages 115-122 ; 0021891X (ISSN) Shahrokhian, S ; Rastgar, S ; Sharif University of Technology
    Abstract
    The present study concerns the electrochemical behavior of catechol and 4-methylcatechol in the presence of 2-mercapto-5-methyl-1,3,4-thiadiazole (MMT) in aqueous medium on the surface of the glassy carbon electrode by means of cyclic voltammetry and controlled-potential coulometry. The oxidation mechanism was deduced from voltammetric and spectrophotometric data. The electro-generation of quinoid intermediates and their subsequent Michael-type reaction with MMT has been investigated as a clean and convenient strategy for the synthesis of corresponding reaction products. In addition, electro-synthesis of Michael addition products has been successfully accomplished by controlled-potential... 

    Mercaptotriazole as a nucleophile in addition to o-quinone electrochemically derived from catechol: Application to electrosynthesis of a new group of triazole compounds

    , Article Electrochemistry Communications ; Volume 7, Issue 1 , 2005 , Pages 68-73 ; 13882481 (ISSN) Shahrokhian, S ; Amiri, M ; Sharif University of Technology
    2005
    Abstract
    Electrochemical oxidation of catechol in the presence of 3-mercapto-1,2,4-triazole (MTA) as a nucleophile in aqueous buffered solutions was studied by cyclic voltammetry and controlled-potential coulometry. The mechanism of electrochemical reaction is confirmed by spectrophotometric tracing in various times of controlled-potential coulometry. The voltammetric and spectrophotometric foundations indicate that a 1,4 Michael addition of MTA from its thiol moiety to the electrochemically derived o-quinone is occurred. The electrochemical synthesis of Michael addition product has been successfully accomplished by controlled-potential coulometry in a divided H-type cell and the reaction product was...