Arrays of very small electrodes were constructed from nonconductive epoxy and reticulated vitreous carbon (RVC), polished to give a smooth two-dimensional surface. The resulting electrodes yield nearly steady-state currents at convenient rates of potential scan. Comparison of current densities with those at a normal glassy carbon electrode Indicates that on the time scale of seconds, nonlinear diffusion Is the predominant mode of mass transport to the electrode surface. The approach to steady-state current is related to the ratio of boundary length to surface area for the various arrays. Equivalent radii calculated from the boundary densities as if the carbon structures on the electrode surface were disks agree well with equivalent radii calculated from experimental data using the ratio of the forward and reverse currents.
was filtered off and washed with pentane, giving 14.4 mg (0.091 mmol) of orange 1,2-naphthoquinone, sintered 125 °C, mp ca. 133-139 °C dec. Melting points between 121 and 146 °C are cited in the literature.19 The IR spectrum (Nujol mull) matched a published one except for a small systematic shift in the wavelengths.22For quantitation, 90 /uL of 0.425 M 2-naphthol in ether was injected into 1.05 mL of 0.15 1 in hexane. After 5 min, the mixture was diluted to 4.0 mL. This solution showed Xmiu 536 nm (abs = 0.28), and the absorbance at 800 nm was 0.034. A 0.0162 M solution of the quinone in ether showed XmM 536 nm (abs = 0.578). From these data and c = 4.7 at 800 nm for 1 (in cyclohexane), we calculated that 4.1 mol of 1 was consumed per mole of the quinone produced, assuming that the e values were unchanged by the slight differences in solvent.
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