Affecting the Nitrogen Atom

3-Benzotellurazoles react with hydrohalic acids to form 1,3-benzotellurazolium halides, which, upon treatment with aqueous solutions of ammonia or sodium hydrogen carbonate, are converted back to the benzotellurazoles.  

3-Benzotellurazoles react with alkyl trifluoromethanesulfonates in chlorinated hydrocarbons as reaction media to produce iV-alkyl-l,3-benzotellurazolium trifluoromethanesul-fonates  

3-Dimethyl-l,3-benzotellurazolium Trifluoromethanesulfonateh 10.5 g (43 mmol) 2-methylbenzotellura-zole are dissolved in 10 m/ dry dichloromethane. 7.5 g (45 mmol) freshly distilled methyl trifluorometh-anesulfonate are added. After a few min this exothermic reaction produces crystals, which are collected by filtration, washed with diethyl ether, and dried. The pale yellow powder is dissolved in 100 m/ acetone. Diethyl ether is added, until the solution becomes turbid. Colorless plates separate upon cooling the turbid solution yield 87% m.p. 160-162°. 

Naphthotellurazoles were similarly methylated by methyl trifluoromethanesulfonate . Equimolar amounts of 1,3-benzotellurazoles and trimethylene sulfate had to be heated for several hours at 80° to produce the zwitterionic 1,3-benzotellurazolium iV-(trimethylene-sulfate)  

The trifluoromethanesulfonate anion can be exchanged for iodide by treating the 1,3-benzotellurazolium salts with sodium iodide in acetone .  

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