Anodic hydroxylation of 1-carbomethoxy-1,2,3,4-tetrahydrocarbazoles

Analysis of ECE-type electrode reactions by chronocoulometry: anodic hydroxylation of tetrahydrocarbazoles

“…Chemicals. 1-Carbomethoxy-(1) and 7-methoxy-l-carbomethoxy- (2) 1,2,3,4-tetrahydrocarbazoles were prepared as described previously (11). 1 was purified by distillation at reduced pressure; 2 was recrystallized 3 times from ethanol.…”

“…13C and 2D NMR and high-resolution MS confirmed that only the C-l position of each compound had been deuterated and that 1-D and 2-D were stable in acetonitrile-water mixtures for several days. Purity of all compounds and concentrations of stock solutions used for chronocoulometry were checked by HPLC (11). Since the crystalline compounds 2 and 2-D were obtained in higher purity than the viscous liquids 1 and 1-D, the most extensive quantitative studies were done with the former.…”

“…Acetonitrile and electrolytes were from the same sources as used previously (11). All solutions for chronocoulometry contained 0.2 M LÍCIO4.…”

“…Apparatus and Procedures. Three-electrode cells and electrodes were the same as described previously for voltammetric studies of these systems (11). The carbon paste working electrode had a geometric area of 0.08 cm2.…”

“…The method computes all necessary parameters directly from Q vs. t data. In this paper, we extend the regression method to the computation of chemical rate constants in ECE-type reactions from singlepotential-step data and provide guidelines for choosing experimental times that yield optimum precision in k. Using anodic hydroxylations of several 1-carbomethoxy-l,2,3,4tetrahydrocarbazoles as experimental examples (11), we also demonstrate the use of deviation pattern recognition to distinguish between a heterogeneous (ECE) THEORY Nonlinear regression models for ECE and DISP1 mechanisms in single-potential-step chronocoulometry were developed for planar electrodes and included edge-diffusion corrections. The initial potential of the working electrode is a value £¡ where no electrolysis takes place.…”