From Organic Tellurium Compounds

The classes of organic tellurium compounds mentioned above are prepared by interaction of nucleophilic or electrophilic tellurium species with different classes of organic compounds. Such species are generated from elemental tellurium or from diorganoditellurides 4, as will be discussed in the following sections. 

Table 1 Lithium Tellurolates from Organic Lithium Compounds and Tellurium...

Another group of polymeric organic tellurium compounds was obtained from diphenyl tellurium dichloride and disilver salts of dicarboxylic acids. 

The special nature of the Tellurium compounds forced a change of the set-up principle of the Supplemental Volumes of the 4 edition to some extent, but all classes of Tellurium compounds with at least one carbon atom, which must not necessarily be bonded to the Tellurium atom, will be described, and also esters of the different Te-containing acids. The set-up will be easily understood from the Table of Contents. Since the chemistry of the organic Tellurium compounds has grown tremendously during the past 35 years, there will be only few references to volume IX of 1955 therefore, volume El 2b stands more or less by itself. 

Tellurium is the fourth element of the VIA family of the periodic table, which starts with oxygen. Since tellurium exhibits an electronic configuration similar to that of selenium and sulphur, the chemical behaviour of these elements is obviously closely related. This similarity was a hindrance to the greater development of tellurium chemistry. During several decades, research was restricted to an extrapolation of well-established reactions for the preparation and use of organic sulphur compounds to selenium, and mainly from selenium to tellurium. 

Although over a quarter of a century ago it would not have been predicted that the importance of the VIA family of the periodic table would exceed that of its second element, sulphur, the development of organoselenium chemistry has been so explosive that little comment is necessary, as illustrated by the impressive number of papers as well as by several books on the field. Tellurium compounds have taken an even longer time to rise from being considered an exotic and perverse element to a useful tool in organic chemistry. 

Tellurium speciation has been described by Klin-kenberg et al. [40] using reversed-phase LC-ICP-MS for the analysis of tellurium in samples from a wastewater treatment plant. A method was developed for the separation of Te03 and HTe04 and, although at least 11 different organic Te compounds were detected, no attempt was made to identify them. This is essentially a problem with ICP detection since all structural information is lost by plasma sample decomposition. 

Tellurium speciation in water samples from a treatment plant has been performed by Klinkenberg et al. [29]. Te032 and HTe04 were separated along with 11 unidentified organic Te compounds. More structural information was not available as a result of complete decomposition of the compounds in the plasma. 

Tellurium species are also useful to remove several different types of substituents from organic compounds. In some cases, variation of the experimental conditions allows the reductive removal of a substituent to be performed selectively in the presence of other functional groups. Scheme 26109 113 shows the removal of different substituents mediated by nucleophilic tellurium species.6,11,12... 

Alkanetellurolates, that can be obtained from an organic lithium compound or a Grignard reagent and tellurium, are oxidized to dialkyl ditellurium compounds on contact with air. Di-t-butyl ditellurium, that is difficult to prepare by other routes, was obtained by this method in excellent yield1 2. The reaction of /-butyl magnesium chloride with tellurium proceeded in THF solution only in the presence of hexamethylphosphoric triamide2. 

Alkyl tellurium halides, RTeX, in general, have no importance as starting materials for the preparation of alkyl tellurium trihalides. The alkyl tellurium halides are synthesized from dialkyl ditellurium compounds and elemental halogens. When alkyl tellurium trihalides are the desired products, there is no reason to prepare the monohalides first. However, when the tellurium monohalide is formed during the introduction of tellurium into an organic molecule, the reaction of this primary product with halogens is the method of choice for the preparation of the tellurium trihalides. This situation is realized for 3-oxo-l-propen-l-yl tellurium halides2,3. 

The following cyclic tellurium compounds were prepared from sodium telluride in ethanolic solution and the appropriate organic dihalides ... 

Arenetellurolates, prepared from diaryl ditellurium compounds via reduction with sodium borohydride in organic media, interact with arenediazonium chlorides2 and arenediazonium tetrafluoroborates3 to produce unsymmetrical diaryl tellurium products in yields below 50%. The arenediazonium chlorides were added as aqueous solutions to the tellurolates. Arenediazonium tetrafluoroborates were used as solids. 

The following compounds were obtained from phenyl tellurium iodide or 4-methoxyphenyl tellurium bromide and organic lithium compounds ... 

Ferrocenyl organo tellurium derivatives were prepared from diferrocenyl ditellurium and organic lithium compounds with toluene or tetrahydrofuran as the solvent2. 

Bis[acylmethyl] tellurium dichlorides and aryl benzoylmethyl tellurium dichlorides lose the acylmethyl group under conditions generally used for the reduction of diorganyl tellurium dichlorides. However, these acylmethyl tellurium dichlorides were successfully reduced in a two-phase system consisting of dichloromethane and an aqueous solution of disodium disulfite. The acylmethyl tellurium compounds escape into the organic phase and are protected from further attack by the reducing agent1. 

---