Wolfgang H. H. Gunther

Methods in chalcogen chemistry : V. A new reagent for the synthesis of aromatic tellurium compounds

Abstract It has been discovered that the combination of tellurium tetrachloride with more than one molar equivalent of aluminium chloride constitute an efficient reagent for the introduction of tellurium into aromatic molecules. Kinetics control of the reaction with benzene (a substance inert to TeCl 4 alone) selectively yielded the products of successive substitution on tellurium as follows: diphenyl ditelluride (via reductive workup from phenyltellurium trichloride), diphenyltellurium dichloride and triphenyltelluronium chloride after evolution of 1,2 and 3 equivalent HCl, respectively. Extension of this simple reaction to the preparation of numerous other aromatic tellurium compounds appears feasible.

The synthesis and characterization of α- and β-1, 1-diiodo-3,4-benzo-1-telluracyclopentane, C8H8Tel2

Elemental Tellurium reacts with α,α′-dichloro- o -xylene and NaI in 2-methoxyethanol to form 1,1-diiodo-3,4-benzo-1-telluracyclopentane in 83% yield. C 8 H 8 TeI 2 is molecular in acetone, methylene chloride and methyl ethyl ketone, but ionic in DMF. Two crystalline modifications of the compound have been isolated from 2-methoxyethanol. The yellow-orange or α form is monoclinic, space group P 2 1 / c ; the orange-red or β form is also monoclinic, space group I 2/ c . Infrared, optical and mass spectral data, along with solution UV, NMR, molecular weight and conductivity data, suggest that the two crystalline modifications are plymorphs, possibly differing in the degree and type of heavy atom interaction. In 2-methoxyethanol the β form undergoes a solution phase transformation to the stable α form. Both forms are thermochromic.

METHODS IN SELENIUM CHEMISTRY IV. SYNTHETIC APPROACHES TO POLYDISELENIDES

The remarkable photoelectric properties of elemental selenium form the basis for the major industrial application of this element in xerographic photoreceptors. The physics of the photoexcitation and electrical charge transport phenomena has been the subject of numerous investigations, but little is known about the molecular basis of the photoelectric effect. Since the element consists of linear sequences of selenium atoms, variously assembled into cyclic structures and polymer chains, it seemed of interest to investigate model polymers that contained organic residues interspersed between short selenium chains. Such species might then combine various desirable properties of selenium with those of organic polymers. In this paper we shall discuss some synthetic approaches used to generate a variety of aliphatic, benzylic and aromatic oligomers and polymers with the general formula (RSe2). , all designated as polydiselenides and characterized by having a selenium-selenium bond per monomer unit as an integral part of the backbone. The discussion of polymer properties will be restricted to data incidental to their structural identification.

Novel synthesis of organic diselenides

Reaction of hydrogen selenide, aldehydes, and amines, followed by reduction with sodium borohydride, gives high yields of diselenides.