Tetramethyl triplet acetone formed from

The specificity of this reaction has been used to chemically titrate both the excited-singlet acetone and the triplet acetone produced through thermal decomposition of tetramethyl-I,2-dioxetane. (Cf. Section 7.6.4.) For this purpose the thermolysis was carried out in the presence of /ra/ii-l,2-dicy-anoethylene, and the quantities of singlet and triplet acetone formed were obtained from the yields of dioxetane and c/s-I,2-dicyanoethylene, respectively (Turro and Lechtken, 1972). 

Excitation appears to be general for this reaction but yields of excited products vary substantially with the substituent R. The highest yield reported is from tetramethyl-l,2-dioxetane [35856-82-7] (TMD) where the yield of triplet acetone is 50% of total acetone formed (18,19). Probably only one carbonyl of the two produced can be excited by the thermal decomposition, and TMD provides 100% of the possible yield of triplet acetone. Singlet excited acetone is also formed, but at the low yield of 0.1—0.3% (17—21). Other tetraaLkyldioxetanes behave similarly to TMD (22). 

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