AbstractThe reactions of acetone with tellurium tetrachloride have been studied with the aid of proton, carbon‐13, and tellurium‐125 NMR spectroscopy. In the absence of a proton scavenger, such as sodium hydrogen carbonate, at ambient temperature, a 2 : 1 ratio of acetone to tellurium tetrachloride quickly forms mainly acetonyl tellurium trichloride. At higher temperatures and after longer periods, the initially formed acetonyl tellurium trichloride is converted to 2‐methyl‐4‐oxo‐2‐penten‐1‐yl tellurium trichloride through an acidcatalyzed aldol condensation. In the presence of sodium hydrogen carbonate, the condensation reaction is prevented, and an equilibrium mixture of acetonyl tellurium trichloride and bis(acetonyl) tellurium dic