Thermolysis and Chemiluminescence of Monocyclic 1,2,4-Trioxan-5-ones

✍ Scribed by Charles W. Jefford; Martin C. Josso; Maria da Graça H. Vicente; Hans R. Hagemann; Dominique Lovy; Hans Bill

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: German
• Weight: 495 KB
• Volume: 77
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19940770716

✦ Synopsis

Abstract

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 (ϕoS~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 CO~2~, to finally produce ketone originating from the 6‐position (see Scheme 4).