Eine neue Synthese zur Darstellung von organischen Tellurverbindungen unter Verwendung von elektrochemisch erzeugten Polytelluriden

Abstract

A Novel Synthesis of Organic Tellurium Compounds by the Use of Electrochemically Generated Polytelluride‐ions The cathodic polarisation of a tellurium electrode in aprotic solutions gives rise to polytelluride anions, which react with alkylhalides to the corresponding disubstituted ditellurides. By this method of electrosynthesis a number of organic ditellurides can be simply prepared and without danger. Dialkylditellurides of the general formula R‐Te‐Te‐R (2a–r) can be produced with high yields. The reaction with α,ω‐dihalides gives heterocycles, which involve one or two tellurium atoms in the ring (5a–d, 6–8). The electrochemical reduction of tellurium in the presence of methyliodid yields trimethyltelluroniumiodid (9).

Electrochemistry of Organic Selenium and Tellurium Compounds

“…The typical electrolysis of RX was performed in DMF using a cell with a diaphragm and some examples of the yields of the products and potentials applied are given in Table 1. Ditellurides RTeTeR (5) were prepared 11,12 (Table 1) using a similar cathode with tellurium fused upon platinum but with small modifications of the procedure. Namely, after electrochemical generation of polytelluride ions in anaerobic conditions, mainly of Te 4 2− , the electrolyte was cooled to 5-10 • C and then organic halide was added.…”

“…Namely, after electrochemical generation of polytelluride ions in anaerobic conditions, mainly of Te 4 2− , the electrolyte was cooled to 5-10 • C and then organic halide was added. The electroreduction in the presence of MeI resulted in the formation of trimethyltelluronium iodide Me 3 TeI (80%) 12 . The unsymmetrical telluride c-HexTeTeMe was obtained in 60% yield by the consecutive addition of c-HexCl to a cooled (5 • C) electrolyte, followed by MeI after 48 hours at room temperature.…”

“…Moreover, using α,ω-dihalides XRX (6), cyclic compounds 7 with two tellurium atoms in the ring were prepared according to reaction 4. However, 8 with only one Te atom in the ring was obtained 12 …”

“…X = Br with the exception of 3a, 3c and 5i where X = Cl and 5b where X = I. b Cathodic potential vs. SCE applied to the Se electrode 8 . The potential applied to the tellurium electrode was always -1.4 V vs. SCE 11,12 . c Obtained 8 by the addition of RX to a solution of Se n 2-ions after cooling to 0 • C.…”

1,2-Ditellurolane: A new synthetic method, structure and chemical reactions

“…This compound has found use in organic synthesis, for example, in the preparation of stable cross-linked cyclodextrins with selenium bridges with hydrophobic cavities which are able to form inclusion complexes [12], and also calixarenes containing selenium [13]. The preparation of 1,2-ditellurolane 1 was first reported in 1984 [14]. It was obtained by the reaction of 1,3-dibromopropane with polytelluride anions generated by electrochemical reduction of tellurium and was characterized by UV spectroscopy and mass spectrometry.…”