Reactions Affecting the Alkylidene Groups

6-Diphenyl-4-formylmethylidene-4H-tellurin was obtained by hydrolysis of the dimeth-yliminio derivative with aqueous sodium hydrogen carbonate.  

4-FormylaIkylidene-4//-telIurins condensed with 4-methylchalcogeninium salts to form trimethine dyes  

Mixing solutions of 4-(2,6-diorgano-4//-tellurin-4-ylidene)-2,6-diorgano-4/f-tellurin in dichloromethane with solutions of tetracyanoquinodimethane in acetonitrile caused 1 1, 1 2, and 2 3 complexes to form.  

Both tellurium atoms in 4-(2,6-diphenyl-4//-tellurin-4-ylidene)-2,6-diphenyl-4/f-tellurin were replaced by sulfur atoms when the tellurium compound and excess sulfur were refluxed in toluene.  

The reactions leading to 7e-dihalides, diacetates, and dihydroxides are discussed on pages 803, 809. 

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