Directed Electrosynthesis

The primary goal of the researchers has been to produce Q-dots possessing all of the attributes of the Q-dots prepared using liquid-phase synthetic methods (that is adjustability of the nanocrystal identity and diameter and size monodispersity) and also the technological utility of Q-dots prepared by MBE (specifically, the deposition of nanocrystals with a defined orientation and an electrical output contact). It was shown that the E/C-synthesized 5-CuI and CdS Q-dots were indeed epitaxial with narrow size distribution and strong photoluminescence tunable by the particle size. Qne of the advantages of the E/C method is that it can be made size selective. The key point is that the size as well as the size dispersion of product nanoparticles are directed actually by the corresponding properties of the metal nanoparticles therefore the first deposition step assumes special importance. 

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Rajeshwar K, de Tacconi NR, Chenthamarakshan CR (2004) Spatially directed electrosynthesis of semiconductors for photoelectrochemical applications. Curr Opin Solid State Mater Sci 8 173-182... 

Genders JD, Weinberg NL, Zawadzinski C (1991) The direct electrosynthesis of L-cysteine free base, Electroorg Synth (Manuel M Baizer Meml Symp) 1990, (Publ 1991) 273 Chem Abstr 116 (1992) 138606x... 

The direct electrosynthesis of S—N bonds from disulfides and amines has been shown to occur through a reaction of the amine with the oxidized disulfide being a strong electrophile. In contrast to the results, the cross-coupling of phthahmide (16) with disulfide does not proceed in a direct electrolysis. However, the electrosynthesis of sulfenimides (17) can be achieved by a [Br]" "-mediated cross-coupling reaction of imides with disulfides (Scheme 7). The electrolysis of a mixture of (16) and dicyclohexyl disulfide in an MeCN-NaBr-(Pt) system affords... 

The direct electrosynthesis of sulfen-imines (19) from a-aminoalkanoates (18) and diaryl disulfides proceeds in a CH2CI2-H20-MgBr2-(Pt) system in 70 96% yields (Scheme 8) [50]. Electrolysis of sulfenami-des (20) is considered to be the intermediates in the direct conversion of (18)— (19). 

The addition of carbanions, generated electrochemically by reduction of the carbon-halogen bond, to carbon dioxide has been examined under a variety of experimental conditions. Direct electrosynthesis of carboxylic acids in a divided cell using an aprotic solvent and a tetraalkylammonium salt as electrolyte is most sue-... 

The electrochemical dissolution of copper and other metals (see Sec. 3.4.2 on direct electrosynthesis), in solutions of tetramethylthiuram disulfide and its analogues in nonaqueous solutions of acetone and acetonitrile, was first carried out by Tuck and coworkers [619]. Complexes with a general formula given by M(R2NCS2) are formed with good yields under these conditions. The proposed mechanism... 

Recommendations on the synthesis of metal phthalocyanines. It is still difficult to evaluate real reaction mechanisms in each synthetic procedure applied. It is clear that the use of such polar protic solvents as alcohols contributes to higher yields of Pc from PN in the electrosynthesis conditions due to the ease of nucleophilic attack of the generated additional RO-. In the further steps of Pc formation from PN or 1,3-D, a solvent s nature has no significant importance. These data about the importance of, first of all, the initial stage correspond to those reported on UV irradiation [40] of PN solutions, where such a treatment is effective only at the beginning of the process. However, in the case of the use of urea and PA, a solvent must be completely inert (or be close to urea s nature) to carry out the one-step synthesis of metal phthalocyanines, in order to exclude any negative influence on the reaction course. The fact that the yields are almost always higher in the case of direct electrosynthesis could serve as an additional confirmation about the usefulness and necessity of this technique. 

In direct electrosynthesis, the desired product is formed by means of an electrochemical reaction. In indirect electrosynthesis, a redox couple is used as an electron carrier for the oxidation or reduction of another species in the system. In other words, the electrode is used to reconvert the redox reagent continuously to an oxidation state where it is able to react with another compound in a desirable, generally homogeneous redox reaction. Most suitable redox couples are inorganic whereas the desired product is typically organic. The final redox step may be carried out inside or outside the electrochemical cell. 

Tomilov and collaborators were the first to obtain trialkylphosphates by electrolysis of suspensions of phosphorus in alcohol + HCl [92]. This direct electrosynthesis of organophosphorus compounds using elementary phosphorus was further developed by the electrochemists in Kazan (joint pubUcatirMi [93]). It is worth mentioning that although Tomilov worked in a closed institute, he participated in many joint activities with electrochemists from open institutions... 

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