Indole, 1-methyl-, electrochemical

For the indole, methyl sustitution at the 2-position (i.e. 71) appears to sterically block C—C annulation vs C—N annulation (Scheme 46)126a. Note also that electrochemical methods are only useful for the substituted vinylindoles, as unsubstituted indoles passivate the working electrode. The results of cycloadditions of substituted enamines 66 and 69 to vinylindoles 65 and 71 are summarized in Tables 7 and 8. 

Phenalene, methyl- and dimethylphenalene, and benzanthracene levels were studied in various diesel fuel distillates [171]. Baseline separation was adiieved in <20 min when a C g column (electrochemical detector, -t-0.6V) and an isocratic 85/15 methanol/water (0.33 M sodium nitrate) mobile phase were used. Detection limits of lOmg/L and a working concentration range of up to 40mg/L were reported. The pH of the mobile phase had a strong effect on the sensitivity of the method. As the pH increased from 1.2 to 9.0 so did the detector response. Unfortunately, the response from interferents (indoles and carbazoles) increased faster than did that of the PAHs. Therefore, the use of a protic buffers was avoided and the sodium nitrate electrolyte was used instead. 

The oxidation of a number of catecholamines including adrenaline, noradrenaline, a-methylnoiadrenaline, dopamine and isoprenaline has been studied by electrochemical techniques [106, 107]. In 1 m sulphuric acid, adrenaline was reversibly oxidised to adrenaline quinone (43) and it was shown by cyclic voltammetry that under these conditions negligible cyclisation to adrenochrome occurred [106]. At pH 3, however, there was considerable cyclisation, and, as well as the adrenaline-adrenaline quinone (43) couple, the leucoadrenochrome (13)-adrenochrome and the 5,6-dihydroxy-A-methyl-indole (44)-A-methylindole-5,6-quinone (45) couples could be detected and... 

Kelaidopoulou A, Kokkinidis G, Coutouli-Argyropoulou E (1998) Electrochemical behavior of N-methyl-N-(3-indol-l-yl-propyl)-4,4 -bipyridinium. Anodic polymerization and redox properties of the viologen unit of monomer and polymer film. Electrochim Acta 43 987-997... 

---