From Sodium or Piperidinium Tellurocarboxylates and Alkyl Iodides

From Sodium or Piperidinium Tellurocarboxylates and Alkyl Iodides 

The red, oily sodium tellurocarboxylates (p. 162) react with an excess of an alkyl iodide at temperatures between — 63 and — 30° to give alkyl tellurobenzoates, yellow to orange oils or crystals, that are relatively stable thermally and hydrolytically. They can be stored at — 20° under argon for weeks but they are very sensitive towards oxygen. The methyl tellurobenzoates are the least stable of the tellurobenzoates .  

R = C17H35, CH2-C6HS, CgHe R = CHs.CzHs.CHiCHslj.CtHg 

Methyl 2-Methoxy(tellurobenzoate) A solution of 0.171 g (1 mmol) 2-methoxybenzoyl chloride in Hml tetrahydrofuran is added to 0.174 g (1 mmol) of freshly prepared sodium telluride (liquid ammonia method). The mixture is stirred at 0° for 1 h and then filtered. The solvent is evaporated from the filtrate under reduced pressure. The red, oily residue is cooled to — 63° under nitrogen and mixed with 2 ml (32 mmol) iodomethane. The mixture is warmed to — 30° and stirred at this temperature for 2 h. The excess iodomethane is evaporated under reduced pressure below 0°. The residue is treated with 5 ml dichloromethane, the black mixture is filtered, and the filtrate evaporated under reduced pressure below 0° to give yellow crystals yield 84% m.p. 25°. 

2-naphthalene (tellurocarboxylate) phenylmethane (tellurocarboxylate) iso-propyl 2-methoxy(tellurobenzoateJ butyl 2-methoxy( tellurobenzoate ) 

---