Galvanostatic synthesis

In 2005, a diastereoselective synthesis of m-3-alkyl-l-benzyl-4-ethoxycarbonyl-[S-1 act a ms has been reported to be developed by galvanostatic electrolysis of a solution of acetonitrile containing a tetraalkylammonium salt, as supporting electrolyte and /V-(ethoxycarbonyl)methyl-/V-benzyl-2-bromoalkylcarboxamides [165]. The electrogenerated cyanomethyl anion, at room temperature and under a nitrogen atmosphere, caused the cyclization of the substituted carboxamides. High cis/trans ratios were observed with all the substrates exploited, (Scheme 68). 

In 2006, electrochemically induced synthesis of (3-lactams, by cyclization of haloamides, has been achieved in suitable solvent-supporting electrolyte solutions previously electrolyzed under galvanostatic control [166, 167]. The yields and the stereochemistry of the process were influenced by the nature of the R -R4 substituents, by the solvent-supporting electrolyte solutions, and by the electrolysis conditions (Scheme 69). 

Scheme 68 Synthesis of disubstituted [3-lactams by galvanostatic electrolysis...

Nanocrystalline cerium (IV) oxide powders with an average particle size of 10 -14 nm have been prepared by the cathodic base electrogeneration method.The nanocrystallinc CeO powders are prepared in the cathode compartment of a divided electrochemical cell. The cathode is a platinum wire and the anode is a platinum mesh electrode. The cathode compartment in the divided cell contained 0.5 mol T cerium (HI) nitrate and 0.5 moM ammonium niu-ate, and the anode compartment contained 0.5 mol I ammonium nitrate. The two compartments are separated with a medium porosity glass frit. The electrochemical synthesis is run in the galvanostatic mode at a current density of I A cm and the particle size is controlled by adjusting the solution temperature. 

Electrolyses at sacrificial electrodes allow direct synthesis of metal complexes from bare metal electrodes. Systematic studies have been reported and periodically reviewed.22-24 The sacrificial electrode may either be a cathode (Pb, Sn, Hg), or an anode (metals) which is the most usual configuration. The experiments are generally carried out under galvanostatic conditions (10-30 mA cm-2) and so a reference electrode and a potentiostat are not required. Different types of products have been obtained from the simplest complexes to clusters. 

Acetonitrile was also used as the solvent for the first successful synthesis of a PAn/PPy copolymer via galvanostatic (constant-current) electropolymerization of mixtures of aniline (0.5 M) and pyrrole (0.1-1.0 M) in acetonitrile solvent in the presence of CF3COOH as acid and tetraethylammonium tetrafluoroborate as supporting electrolyte. Differential scanning calorimetry and Fourier transform infrared (FTIR) measurements confirmed that the electrically conducting product was a mixture of PAn, PPy, and a random PAn/PPy copolymer.36... 

To achieve high conductivities, the polythiophene paradox must be overcome. The polymerization process and conductivity of the resultant material are influenced by the concentration of monomer used during polymerization116 because, if this is too low, the overoxidation reaction predominates, at least when galvanostatic polymerization is used. Synthesis at reduced temperatures will help avoid overoxidation and can be used to increase the conductivity of the resultant material.117... 

R = CH3 CH2CH3 CH(CH3)2 (CH2)3CH3 C-C5H9 c-CeH, Scheme 68 Synthesis of disubstituted fS lactams by galvanostatic electrolysis... 

H2PtCl6 (1 mM) PPY Single potential step, RSWP (0.1 Hz), galvanostatic reduction or cyclic voltammetry after PPY synthesis in presence of Me ions Pt depth profile dep. on deposition method 51,52, 132... 

P. Ocon, P. Herrasti, and S. Rojas, Galvanostatic and pulse potential synthesis of poly-3-methylthiophene. Pol3Tner as catalytic support. Polymer, 42, 2439-2448 (2001). 

ABSTRACT Synthesis of nanostructured LiCoOj and TiO via microwave assisted and conventional hydrothermal methods, respectively, is presented. The physical properties of the resulting material are characterised via X-ray powder diffraction and scanning electron microscopy. Cyclic voltammetry and Galvanostatic Intermittent Titration Technique are used to study differences of the electrochemical properties compared to bulk material. 

A working electrode made of a copper rod (5 mm diameter) and platinum disk (3 mm diameter) sealed in a Teflon holder using epoxy resin is realized. This electrode is polished with aqueous suspensions of alumina (1 pm) and then polarized at 1V vs. SCE. The polymerization medium is an aqueous solution containing the pyrrole monomer (0.5 M) and sodium salicylate (IM). PPy electrodeposition on copper is performed either potentiostatically (0.6 V) or galvanostatically (0.5 to 5 mA cm ) for 1 min. After the synthesis, the PPy film is rinsed with water and its electroactivity checked by cycling from —IV to -1-0.5 V in a monomer-free solution, with a pH adjusted to 6 by addition of salicylic acid or soda. 

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