Abstract: Preparation and detection by esr spectroscopy of radical anions (semitriones) derived from CaH5COCOCOCaHs, CHaCOCOCOOR, and ROCOCOCOOR are described. In basic solution vicinal tri-or tetraketones have a great tendency to undergo decarbonylation to yield the a-diketone or its radical anion. These semitriones can be prepared only in the absence of strong base. The same degradation was observed for ...