Chemistry Reference
In-Depth Information
radical intermediates selectively. Accordingly,
platinum anodes are most suitable for Kolbe
electrolysis. It should be noted that when a
carbon anode is used in a solution containing
LiClO
4
, collapse of the electrode surface often
takes place due to the oxidation of binder such
as coal tar pitch in the carbon electrode. In
sharp contrast, glassy carbon (GC) electrodes
have enough durability for anodic oxidation,
and anode passivation does not occur, which is
quite different from other carbon electrodes.
However, GC electrodes are costly, as are
platinum electrodes. Although
non-precious-metal electrodes are not suitable
for anode materials, Mg, Zn, Al and Cu are
often used as reactive electrodes or sacrificial
anodes, as explained in section 3.1.
The following points should be noted when
organic electrosynthesis is carried out. In
contrast to electrochemical measurements,
electrochemical synthesis requires a relatively
large current of 10-100 mA (
∼
10 mA cm
−2
)
even on a laboratory scale. The use of a larger
electrode surface area is therefore
recommended to complete the electrolysis in a
shorter time. As working electrode shape, plate,
candy stick (baculiform) and mesh type are
commonly used. The surface area of the counter
electrode should be same as that of the working
electrode. Depending on the kind of electrodes,
pre-treatment of the electrode surface differs,
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