Wayne H. Smith

Electrochemical reactions of organic compounds in liquid ammonia: Part IV. Reduction of cyclooctatetraene

Abstract The electroreduction of COT in liquid ammonia at −38° and −65°C was investigated by cyclic voltammetric and controlled potential coulometric techniques. The results are interpreted by a two-step two-electron transfer reaction with strong ion-pairing of the COT dianion. Values for the heterogeneous electron transfer rate constants and the equilibrium constant of the disproportionation of the radical anion are estimated, based on a digital simulation of the cyclic voltammogram.

Electrochemistry of 2,2′‐Bipyridine Complexes of Cobalt in the Presence of Acrylonitrile

The previously claimed (1) catalysis of the electroreduction of acrylonitrile by means of a complex of Co(I) and 2,2′‐bipyridine is shown to be erroneous. The “catalytic currents” result instead from the two‐electron reduction of a mixed complex of Co(I) acrylonitrile and 2,2′‐bipyridine. The equilibrium and forward rate constants for the formation of the mixed complex have been estimated and its spectrum is given. The behavior of a number of other vinyl monomers, which mimic acrylonitrile, is described.

Electrochemical Behavior of Selected Imine Derivatives, Reductive Carboxylation, α‐Amino Acid Synthesis

The electrochemical behavior of six selected imine derivatives, where , phenyl, phenyl; phenyl, phenyl, phenyl; H, isobutyl, phenyl; H, phenyl, benzyl; phenyl, phenyl, benzyl; and H, isobutyl, benzyl, has been investigated in acetonitrile/0.1M tetraethylammonium perchlorate and liquid ammonia/0.1 M potassium iodide. In anhydrous media the radical anion species are highly reactive, yielding mostly polymeric and dimeric products with some saturated amine formation. Addition of weak proton donors leads to an increased yield of the saturated amine. If the reduction is carried out in the presence of a high yield of α‐amino acid is observed, but only if the imine is directly reducible. The reaction imines reducing at less negative potentials than that for the direct reduction of give high current efficiencies, while low current efficiencies characterize the reduction of imines whose potentials are approximately equal to or more negative than that for . Mechanistic aspects of the reaction are discussed.

Electrohydrodimerization Reactions V . Liquid Ammonia as a Solvent for Reductive Coupling of Diethyl Fumarate, Cinnamonitrile, and Acrylonitrile

Cyclic vo l tammet r ic (CV) and control led potent ia l coulometr ic inves t igations of the reduct ion of severa l ac t iva ted olefins in anhydrous l iquid ammonia containing e i ther 0.1M m e t h y l t r i n b u t y l a m m o n i u m iodide or 0.1M potass ium iodide as suppor t ing electrolytes are reported. Fo r d ie thyl fumara te and cinnamoni t r i l e the studies provide evidence for format ion of a rad ica l anion, which undergoes d imer iza t ion and polymer iza t ion reactions, and of dianion format ion at more negat ive potentials . The effect of adding isopropanol and glacial acetic acid was also invest igated. The reduct ion of ac t iva ted olefins in aprot ic media has been the subject of numerous invest igat ions [see (1, 2) and references there in] . Diact ivated olefins (R) react via format ion of the radical anion and produce, depending upon the ac idi ty of the medium, hyd ro d imer (R2H2), reduced monomer (RH2), and polymer . At more negat ive potent ials , where dianion is p ro duced, extens ive po lymer iza t ion appa ren t ly occurs, so tha t the second reduct ion waves observed in vo l t amm e t r y are f requen t ly much smal ler t han the f i r s t waves. We have prev ious ly shown tha t anhydrous l iquid ammonia is a useful med ium for studies of the e lec t roreduct ion of organic compounds (3, 4) and tha t s table dianions of benzophenone and ni t robenzene could be p repa red in this solvent. This s tab i l i ty of radical anions and dianions in ammonia can be a t t r ibu ted to the low acidi ty of the solvent, the possib i l i ty of p repar ing h igh ly pure solutions th rough the use of vacuum l ine techniques and solvent t r ea tmen t wi th sodium, and the fact tha t these studies are carr ied out at low tempera tures , decreasing the ra te of homogeneous chemical react ions fol lowing the e lec t ron t ransfe r steps. Previous studies of ama lgam reduct ions leading to hydrod imer iza t ion in l iquid ammonia have also been descr ibed (5). In this paper we descr ibe p re l imina ry cyclic vo l tammet r ic and coulometr ic exper i ments on the reduct ion of severa l ac t iva ted olefins in l iquid ammonia ; the s t ructures of the substances s tudied are shown be low

Direct Voltammetric Determination of the Equilibrium Isotope Effect in Naphthalene‐h8/d8, Anthracene‐h10/d10, and Benzophenone‐12CO/13CO

Measurable differences in the reduction potentials (ΔE) of naphthalene-h 8 νs. naphthalene-d 8 (−13±2 mV) and anthracene-h 10 νs. anthracene-d 10 (−12±2 mV) have been determined by cyclic voltammetry in 0.1 M tetra n-butyl ammonium fluorborate (TBABF 4 )-tetrahydrofuran (THF). These results corroborate earlier reports of the existence of a large equilibrium isotope effect for these deuterated polyacene molecules