Variable-Temperature Microelectrode Voltammetry:  Application to Diffusion Coefficients and Electrode Reaction Mechanisms

1999 ◽  
Vol 103 (15) ◽  
pp. 2963-2969 ◽  
Author(s):  
Sarah R. Jacob ◽  
Qi Hong ◽  
Barry A. Coles ◽  
Richard G. Compton

A general computational strategy is presented for the calculation of the chronoamperometric responses arising from potential-step experiments at rotating disc electrodes. The method is applicable to a wide range of electrode reaction mechanisms and theoretical results are given for single- and double-potential-step experiments for ECE, DISP1, DISP2, EC' and CE reactions. For the last, the treatment is extended to cover the case where reactants have grossly unequal diffusion coefficients. Steadystate behaviour is also deduced. The extent to which the various mechanistic pathways can be distinguished is identified and the necessary experiments defined.


1989 ◽  
Vol 93 (1) ◽  
pp. 1-18 ◽  
Author(s):  
C.D. Baer ◽  
T.F. Camaioni-Neto ◽  
D.A. Sweigart ◽  
A.M. Bond ◽  
T.F. Mann ◽  
...  

2019 ◽  
Vol 91 (19) ◽  
pp. 12220-12227 ◽  
Author(s):  
Gareth F. Kennedy ◽  
Jie Zhang ◽  
Alan M. Bond

1988 ◽  
Vol 33 (11) ◽  
pp. 1489-1492 ◽  
Author(s):  
Katsuo Takahashi ◽  
Yasuhiro Yamamoto ◽  
Kiyoshi Matsuda ◽  
Hiroshi Yamazaki

2016 ◽  
Vol 12 ◽  
pp. 716-724 ◽  
Author(s):  
Grzegorz Mlostoń ◽  
Paulina Pipiak ◽  
Heinz Heimgartner

Reactions of dihetaryl and aryl/hetaryl thioketones with 2-diazopropane, diazoethane, and (trimethylsilyl)diazomethane were studied at variable temperature. The experiments showed that reactions with 2-diazopropane carried out at –75 °C occur mainly via the initially formed, relatively stable 1,3,4-thiadiazolines as products of the [3 + 2]-cycloaddition of the diazo dipole onto the C=S bond. The latter decompose only at higher temperature (ca. −40 °C) to generate thiocarbonyl S-isopropanide. In the absence of the starting thioketone, the corresponding thiiranes and/or ethene derivatives, formed from them via spontaneous desulfurization, are the main products. In contrast, reactions with diazoethane occurred predominantly via initially formed diradicals, which in cascade processes gave sterically crowded 4,4,5,5-tetrahetaryl-1,3-dithiolanes as major products. Finally, the reaction of dihetaryl thioketones with (trimethylsilyl)diazomethane occur smoothly at −75 °C leading to the corresponding 4,4,5,5-tetrahetaryl-1,3-dithiolanes as the exclusive [3 + 2]-cycloadducts formed via a cascade of postulated diradicals. The presence of S or Se atoms in the hetaryl rings is of importance for stabilizing diradical intermediates. Remarkably, in no single case, the ‘head-to-head dimerization’ of aryl/hetaryl and dihetaryl substituted thiocarbonyl ylides was observed.


Sign in / Sign up

Export Citation Format

Share Document