From alkali tellurides and alkylating agents

Alkali tellurides, among which sodium telluride is the most widely employed, are powerful nucleophilic reagents and therefore react easily with alkylating agents. 

This method has been applied successfully to n- and -aUcyl halides. 

Dialkyl tellurides (generalprocedure) Elemental Te is added in 0.5 g portions to a well-stirred solution of Na in liquid NHj until the solution decolourizes, forming a colourless suspension (2 g-atom Na/1 g-atom Te). The quantities of the materials are chosen to give a suspension of -0.7 M. The alkylating agent is added dropwise in 10% excess to the suspension of NUjTe. The reaction mixture is stirred until the NHj evaporates. H2O is then added, the mixture extracted with ether and the ethereal solution worked up in the usual manner. 

When the alkylating agent is insoluble in liquid ammonia, as in the case of long-chain compounds, an organic solvent is added to the sodium telluride residue after evaporation of the ammonia. Some cyclic and steroidal tellurides have been prepared from sodium telluride in ethanol and the appropriate dihalides.  

Bis(2-phenyl-l,2-dioxolan-2-yl)melhyl telluride (R=Ph-C-CH2) (typical procedure). Finely powdered Te (0.30 g, 2.3 mmol) and Na (0.22 g, 9.6 mmol) are stirred under N2 in dry DMF (15 mL) at 110°C nntil all the Te has disappeared (15 min). 2-(Bromomethyl)-2-phenyl-l,3-dioxolane (1.15 g, 4.7 mmol) in dry THF (10 mL) is added to the resulting yellowish suspension. After 2.5 h at room temperatnre the reaction mixture is poured into H2O and extracted with ether. Chromatography on Si02 (elnent CH2Cl2/petroleum ether at 40-60°C, 1 1) furnishes the telluride (0.65 g (60%) recrystallized from EtOH, m.p. 67-68°C). 

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