Electrolytic Reductive Coupling

Abstract

ANALYSIS OF GOLDbecomes contaminated with anionic impurities, derived mainly from the side reactions of the KCN with water and air. Moreover, a comparison of the results of this work and those of a previous work (1) would indicate that electrolysis has an effect on the relative concentrations of the H.COO-and CO3 = ions present within a KCN/KAu(CN)2 electroplating solution.The ratio of CO3 = ion to H.COO-ion in Table VIII is approximately 0.65. Yet, in an aqueous KCN solution maintained at 70~ and exposed to air (1), in which no electrolysis is being conducted, the ratio is closer to 0.2. The higher CO3=/H.COO -ratio observed for the used electroplating solution probably results from the electrolytic oxidation of the H.COOion at the anode to CO2 (8, 9), which is retained in the alkaline KCN solution. ConclusionDibasic ammonium citrate/KAu(CN)2 and KCN/ KAu(CN)2 electroplating solutions are both susceptible to metallic impurity contamination. These impurities do not plate out of the KCN/KAu (CN)2 solution with the gold as readily as they do from the dibasic ammonium citrate/KAu (CN) 2 solution. However, the H.COO-and CO3 = ionic impurities build up to a high concentration in the KCN/KAu(CN)2 electroplating solution, but are barely present in the dibasic ammonium citrate/KAu(CN)2 electroplating solution. FOILS FOR IMPURITIES 743There is evidence that some of the H.COO-ion is oxidized at the anode to CO2, which is retained in the alkaline electroplating solution.

Temperature Dependence of Ultra‐Exothermic Charge Recombinations

“…[21], and the reduction potential of FN from ref. [22]; the reorganization energies of the Py/FN system were calculated with r + = 3.7 for pyrene and r À = 2.8 for fumaronitrile (obtained from the Connolly surfaces of these species, as in ref. [15]).…”

Electron Transfer in Supercritical Carbon Dioxide: Ultraexothermic Charge Recombination at the End of the “Inverted Region”

“…Additionally, we employed only one electron acceptor, fumaronitrile (FN) (E red A = À1.36 eV versus SCE). [8] The choice of these systems was also guided by early work on fumaronitrile/aromatic hydrocarbons in benzene which showed that they form exciplexes with nanosecond lifetimes. [9][10][11] In this work we show that photoinduced charge separation from aromatic hydrocarbons to nitriles in supercritical Abstract: Charge-recombination rates in contact radical-ion pairs, formed between aromatic hydrocarbons and nitriles in supercritical CO 2 and heptane, decrease with the exothermicity of the reactions until they reach À70 kcal mol…”

“…Only two systems revealed sufficiently intense exciplex fluorescence in THF to be characterised, but the trend in their lifetimes is similar to [7,8] [b] The exciplex emission overlaps with the tail of the perylene emission. 0.005 [c] 0.00213 [b] [a] Errors are less than 5 %.…”

“…In this case the average frequency is the frequency of the maximum emission. By using such frequencies in Equation (8), the dipole moments given in Table 1, and the radiative rates given in Table 3, we obtain V = 880, 270, 620, and 580 cm À1 for Py/FN, Np/FN, p-X/FN, and o-X/FN, respectively, in heptane. This method to extract V is open to criticism.…”

Electrochemical Studies of Some Activated Olefinic Double Bonds in Nonaqueous Medium

“…The IR spectra (KBr disk) were recorded on a Pye Unicam SP-1100 spectrophotometer, 1 H NMR spectra were measured in CDCl 3 on a Varian EM-360 90-MHz spectrometer and chemical shifts are expressed in d units and elemental analyses were performed by the Microanalytical Center, University of Cairo.…”