Facile synthesis of regio-isomeric naphthofurans and benzodifurans

Naphtho[1,2-b]furans 1a-f, naphtho[2,1-b]furans 2a-f, benzo[1,2-b:5,4-b′]difurans 3a-b, benzo[1,2-b:4,5-b′]difurans 4a-b, and benzo[1,2-b:4,3-b′]difurans 5a-b were synthesized by base-catalyzed cyclization reaction of the corresponding o-alkoxybenzoylarene derivatives. The o-alkoxybenzoylarenes were obtained from the etherification reaction of the o-hydroxybenzoylarenes, which were prepared either by the reaction of methoxyarenes with benzoyl chloride in the presence of aluminum chloride or by photo-Fries rearrangement of aryl benzoates.     

Electrochemical and chemical synthesis of new luminescent schiff base complexes

Bis-chelate complexes of zinc, cadmium, lead, and mercury with o-N-tosylbenzylidene imines containing the C₇H₁₅ and C₁₈H₃₇ substituents at the C=N group nitrogen atom were prepared by the methods of electrochemical and chemical syntheses. The structure of the azomethines and their complexes was established by the methods of heteronuclear ¹H, ¹³C NMR spectroscopy (multidimensional and multinuclear COSY, HETCOR and HETCOR_LONG techniques). The complexes, as demonstrated by the X-ray analysis for the zinc chelate, have strongly distorted octahedral structure formed by the four azomethine nitrogen atoms and two oxygen atoms of the tosyl fragments. The coordination compounds show fluorescence in the blue part of the spectrum in high quantum yields for the zinc chelates.     

Palladium-catalyzed double annulations to construct multisubstituted benzodifurans

Efficient synthetic routes to construct multisubstituted benzo[1,2-b:5,4-b']difurans and benzo[1,2-b:4,5-b']difurans from bis(allyloxy)bis(alkynyl)benzenes or bis(alkynyl)dihydroxybenzenes and allylic halides utilizing palladium-catalyzed double annulations is reported. By further applying a double ring-closing metathesis reaction, pentacyclic compounds were also prepared.     

Electrochemical synthesis of perfluoroalkylacetones

The interaction of electrochemically generated radicals in the electrolysis of the perfluorocarboxylic acids R_FCF₂COOH (I), where R_F=F (a), CF₃ (b), C₂F₅ (c), C₃F₇ (d), C₅F₁₁ (e), and C₇H₁₅ (f), with isopropenyl acetate (II) was studied. The dependence of the results of the electrolysis on the adsorption capacity of the anode permits the proposition that the interaction of (II) with the ECG-radicals occurs close to the surface of the electrode. The yield of the perfluoroalkylacetones comprised 30–37%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1578–1584, July, 1991.     

Electrochemical synthesis of perfluoroalkylchlorides

Electrooxidation of perfluorocarboxylic acids in the presence of Cl₂ yields perfluoroalkylchlorides R_FCl. It is suggested that anodic oxidation of perfluorocarboxylate ions is the determining electrochemical stage in this electrochemical version of the Borodin-Hundsdikker reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1841–1844, August, 1990.     

Electrochemical synthesis of pentamethylenediazirine

Electrochemical synthesis of pentamethylenediazirine at the Pt/Ti anode was conducted. The reaction is reversible. The rate constants of the direct and reverse processes were estimated. The product and current yields of the target compound approach to 100%. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1939–1941, November, 2006.     

Electrochemical synthesis of thiocarbamates

The possibility of indirect and direct electrosyntheses of thiocarbamates is studied. The indirect synthesis is based on producing monochloramines by the chlorination of an aqueous solution containing an amine and sodium chloride on a dimensionally stable anode (DSA) in diaphragm electrolysis and a subsequent interaction of monochloramines with potassium xanthate. Optimum synthesis conditions are found ensuring a current efficiency for thiocarbamates of 43-60%. These are:c _amine = 0.17-2 M, c_NaC1 = 4 M,j_a = 20-30 A dm^-2, electrolysis temperature 10‡C, the chloramine : potassium xanthate : amine molar ratio of 1 : 1.1 : 2, and the temperature of the reaction between chloramine and potassium xanthate of 8‡C. The direct synthesis of thiocarbamates is realized in diaphragm electrolysis when oxidizing an aqueous solution containing an amine, potassium xanthate, and sodium chloride on DSA. With the electrosynthesis of ethyl ester of methylthiocarbamic acid as an example, conditions are found that allow one to obtain a target product with a current efficiency of about 44%. However, the direct synthesis is accompanied by the destruction of the anode material.     

Electrochemical synthesis of niobium methylate

The formation of niobium(V) methylate in methanol against the background of lithium chloride is studied. It is found that, in the anodic dissolution of niobium in the diaphragmless electrolyzer, formed niobium(V) methylate is partially reduced to the four-valent state at the cathode. In order to suppress the reduction of Nb(V), an electrolyzer was designed, which enabled one to separate the anolyte from the catholyte using the difference between their densities. Niobium methylate was not found in the anolyte; however, it forms as a result of mixing the anolyte with the catholyte after completion of electrolysis. The current efficiency of niobium methylate of 96–97% was achieved. Possible mechanism of the process is discussed.     

Electrochemical synthesis of polyaniline nanoparticles

Polyaniline nanoparticles were prepared on a highly oriented pyrolytic graphite (HOPG) surface from dilute polyaniline acidic solution (1 mM aniline+1 M HClO₄) using a pulsed potentiostatic method. Electrochemistry, Fourier transform infrared external reflection spectroscopy (FT-IR-ERS), X-ray photoelectron spectroscopy (XPS) and tapping-mode atomic force microscopy (TMAFM) were used to characterize the composition and structure of the polyaniline nanoparticles. FT-IR-ERS and XPS results revealed that the polyaniline was in its emeraldine form. TMAFM measurement showed that the electropolymerized polyaniline nanoparticles dispersed on the HOPG surface with a coverage of about 10¹⁰ cm⁻². These nanoparticles were disk-shaped having a height of 10–30 Å and an apparent diameter varying from 200 to 600 Å. The particle dimensions increased with the electropolymerization charge (Q) over the interval from 5.7 to 19.3 μC cm⁻².     

Electrochemical synthesis of sodium hexamethoxyniobate

Anodic dissolution of niobium in anhydrous methanol in the presence of sodium methylate was studied. A method for recovery of niobium methylate from sodium hexamethoxyniobate by the reaction with ammonium chloride was developed.     

Electrochemical synthesis of organosilicon compounds

Electrochemical reduction of allyl, vinyl, and aryl halides in the presence of a silylating agent (Me₃SiCl, HMe₂SiCl, or PhMe₂SiCl) afforded the corresponding organosilicon compounds offering a valuable method for introduction of a silyl group into organic molecules.     

Electrochemical synthesis of 2,2,6,6-tetramethylpiperidine

A preparative method for the production of 2,2,6,6-tetramethylpiperidine based on the electrochemical reduction of 4-oxo-2,2,6,6-tetramethylpiperidine in 30% sulfuric acid on cadmium or lead electrodes was developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 358–359, March, 1984.     

Electrochemical synthesis of hafnium silicides

The method of cyclic voltammetry was used to study cathodic processes in a molten salt of NaCl-KCl-NaF (10 wt %)-K₂HfF₆-K₂SiF₆. The parameters of electrochemical synthesis allowing synthesizing hafnium silicides are determined and hafnium silicide HfSi₂ is obtained using galvanostatic electrolysis.     

Electrochemical synthesis of substituted trialkyl phosphates

The process of synthesis of tryalkyl phosphates, i.e., derivatives of methanol, butanol, and diethylene glycol, by anodic oxidation of dimethyl phosphite in the corresponding alcohol is studied. It is found that three alkyl phosphates corresponding to the three possible combinations of substituents bound to phosphorus in phosphate are formed. It is established that the cause for formation of two of the three oxidation products is reesterification of the initial dimethyl phosphite by the alcohol in the course of electrolysis. It is assumed that the process of reesterification is catalyzed by the acid formed in the anode layer.     

Electrochemical synthesis of nanostructured tellurium films

Direct templating of materials via lyotropic liquid crystalline mesophases of non-ionic surfactants provides an elegant and highly versatile route to the production of a wide range of nanostructured materials with well-defined mesoporous architectures of extended spatial periodicities. This technique has now been applied in the electrochemical synthesis of adherent nanostructured tellurium films. This represents an important step towards the synthesis of II–IV semiconductor compounds such as cadmium telluride. Low angle X-ray scattering and transmission electron microscopy (TEM) studies of the resulting tellurium films indicate the presence of a system of uniform cylindrical pores organized in an hexagonal array.