From Aryl Tellurium Trichlorides

Aryl tellurium trichlorides treated with potassium 4-methylbenzenethiosulfonate in boiling methanol formed aryl 4-methylphenylthiosulfonato tellurium derivatives.  

4-Methylphenylthiosulfonato Phenyl Tellurium Phenyl tellurium trichloride is dissolved in dry ethyl acetate, 3 molar equivalents of potassium 4-methylbenzenethiosulfonate dissolved in methanol are added, and the mixture is heated under reflux. The hot mixture is filtered, the filtrate is concentrated to a volume of 5 to 10 ml, and cooled. The orange crystals are collected, recrystallized from methanol, dried, and stored under nitrogen m.p. 138°. 

4-Methoxyphenyl 4-methylphenylthiosulfonato tellurium (m. p. 124 ) and 4-methoxyphenyl me thy Ithiosulfon-ato tellurium (68% yield m.p. 107°) were similarly prepared. 

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Aryl tellurium tris[benzenethiolates] were prepared from aryl tellurium trichlorides and benzenethiol2. 

Aryl tellurium chlorides, generated from diaryl ditelluriums and chlorine and used in situ, reacted with A.iV-dichloroarenesulfonamides. Aryl tellurium trichlorides and aryl (chloro)tellurium arenesulfonimides were obtained9. 

Table 7 Aryl Tellurium Trichlorides from Tellurium Tetrachloride and Substituted...

The preparation of alkyl and aryl tellurium trichlorides from ditellurium compounds is more conveniently carried out with thionyl chloride or sulfuryl chloride instead of gaseous chlorine. 

Aryl tellurium trichlorides and tribromides react with terminal and internal linear olefins and with cycloalkenes to produce aryl 2-chloroalkyl tellurium dihalides. The halide ion and the aryldichlorotelluro group approach the olefin from opposite sides of the plane defined by the atoms bonded to the olefinic carbon atoms. These arm-additions yield threo-addition products from (Z)-olefins, and erythro-products from (E)-olefins4 6. 

Hexaphenyl dilead3, tetramethyl lead3, and triphenyl lead chloride4 donate phenyl groups to aryl tellurium trichlorides to produce aryl phenyl tellurium dichlorides in yields from 73 to 92%. The lead compounds are more reactive than the tin and silicon derivatives and even react at 20°. 

Most of the complexes have well defined melting points. They appear to be monomeric in solution . An interesting method for the preparation of thiazolidine-2-thione complexes of aryl tellurium trichlorides is the addition of the tellurium compound to a melt of the ligand kept at 110°. Complexes with 1 1, 1 2, and 1 4 stoichiometries (Te-compound ligand) were obtained after recrystallization from dry methanol. Phenyl tellurium trichloride complexes with thiourea appear to form only when an organic solvent is used as the reaction medium in aqueous media the trichloride is reduced to the monochloride that is isolated as the thiourea adduct . 

Organo tellurium trifluorides, trichlorides, tribromides, and triiodides are known. Aryl tellurium trihalides are generally more stable than alkyl tellurium trihalides. The sensitivity toward atmospheric agents decreases from the trichlorides to the triiodides. Very few organo tellurium trifluorides have been prepared and little is known about their reactivity. The general reactivity of aryl tellurium trihalides decreases from the chlorides to the iodides. 2-Chloroalkyl tellurium trichlorides, products of the addition of tellurium... 

The halogenolysis of dialkyl ditellurium compounds is a convenient method for the preparation of alkyl tellurium trihalides because dialkyl ditellurium compounds are easily accessible through alkylation of disodium ditelluride (p. 258). Diaryl ditellurium compounds generally obtained via reduction of organo tellurium trichlorides (p. 274), serve as starting materials for the syntheses of aryl tellurium tribromides and triiodides (Vol. IX, p. 1156) that are not obtainable from the hydrocarbons and tellurium telrabromide or tetraiodide. 

Aryl tellurium trihalides treated with water are converted to arenetellurinyl halides. The susceptibility to hydrolysis decreases from the trichlorides to the triiodides2,3. With basic aqueous solutions (sodium carbonate, sodium hydroxide) tellurinic acids or tellurinic acid anhydrides are formed2 5. 

Aryltellurium trichlorides 5 (R = aryl, X = Cl) are usually yellow, very stable crystalline solids, with a slight odor of hydrochloric acid, which probably arises from the reaction of 5 with the air moisture. Contact of 5 with metallic spatulas, with moist solvents, or prolonged exposure to light must be avoided. These compounds, however, can be handled in the air with no risk of decomposition. Aryltellurium tribromides (5, R = aryl, X = Br) are yellow crystalline solids, and the triiodides (5, R = aryl, X = 1) are dark red solids. The aryltellurium tribromides and triiodides were less explored for synthetic purposes, in contrast to the aryltellurium trichlorides, which were frequently used in several synthetic transformations. The aliphatic tellurium trihalides are less stable than the aromatic ones and were much less studied and used for preparative purposes. 

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