T=200°C;

sodium L-ascorbate in methanol; water; acetone 5 h;

in 1,4-dioxane; water react. under N2 (deoxygenated solns.); addn. of CrSO4 in distd. H2O to a slight excess of Te-compd. in dioxane at room temp.; extn. of Te2R2 into diethyl ether, washing of green-coloured aq. layer with ether (several times), concn. under reduced pressure at 30°C until pptn. occurs, filtration, washing with H2O, drying over P2O5 in vac.; elem. anal.;

T=0°C;

2: Na2S View Scheme