238. “Thermolysis and Chemiluminescence of Monocyclic 1,2,4-Trioxan-5-ones”
     Jefford, C.W.; Josso, M.C.; Vicente, M.d.G.H.; Hagemann, H.R.; Lovy, D.; Bill, H.
     Helv. Chim. Acta 1994, 77, 1851-1860.

The 3,6-substituted 1,2,4-trioxan-5-ones 11–14, on heating to 170–200°, underwent unimolecular thermolysis to generate electronically excited singlet ketones with an efficiency of ca. 0.2%. The chemiluminescence quantum yields (?oS_CL) depended on the nature of the 6-substitutents and increased linearly with temperature. The Arrhenius activation energies were obtained by measuring the rate of decay of luminescence and determined as 22.9, 30.4, 35.6, and 34.2 kcal/mol for 11–14, respectively. Step analysis of the chemiluminescence of 14 afforded an average activation energy of 44.3 kcal/mol. This latter result is explicable in terms of two decomposition paths, higher and lower in energy, leading to excited and ‘dark’ products, respectively. The thermolysis of trioxanones 12–14 lacking a H-atom at the 6-position is interpreted as involving successive rupture of the peroxide bond, excision of ketone at the 3-substituted end, and loss of CO₂, to finally produce ketone originating from the 6-position (see Scheme 4).

DOI : 10.1002/hlca.19940770716 

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