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Synthesis, Thermal Stability, and Chemiluminescence Properties of Bisdioxetanes Derived from p ‐Dioxines
Author(s) -
Adam Waldemar,
Platsch Herbert,
Schmidt Ernst
Publication year - 1985
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19851181110
Subject(s) - chemistry , dioxetane , methanol , thermal decomposition , thermal stability , acetic anhydride , singlet state , decane , medicinal chemistry , photochemistry , chemiluminescence , excited state , organic chemistry , catalysis , physics , nuclear physics
By elimination of methanol from 2,5‐dimethoxy‐1,4‐dioxanes and 2,3‐dihydro‐2‐methoxy‐1,4‐dioxines on treatment with p ‐toluenesulfonic acid in acetic anhydride, the new tetrakis(4‐methoxyphenyl)‐, tetrakis(4‐chlorophenyl)‐, tetra‐ p ‐tolyl‐, and 2,5‐dimethyl‐3,6‐diphenyl‐1,4‐dioxines ( 1 ) were prepared in good yields. Photosensitized singlet oxygenation of these 1,4‐dioxines 1 afforded the corresponding bisdioxetanes 2 , the 1,2‐diketones, and the enediol diesters 7 . Thermal decomposition of the bisdioxetanes 2 yielded the corresponding anhydrides 4 essentially quantitatively. During the thermolysis of 1,6‐dimethyl‐3,8‐diphenyl‐2,4,5,7,9,10‐hexaoxatricyclo[6.2.0.0 3,6 ]decane ( 2f ) appreciable amounts of (3 R ,4 S )‐3‐acetoxy‐4‐(benzoyloxy)‐4‐methyl‐3‐phenyl‐1,2‐dioxetane ( 3f ) were detected. The bisdioxetanes 2 and monodioxetane 3f exhibited similar thermal stabilities, the free energies of activation (ΔG ± ) at 298 K falling within 25.5 + 1.5 kcal/mol. The singlet excitation yields (Φ s ) ranged between 0.003 and 0.03% and the triplet excitation yields (Φ T ) between 9.5 and 71.5%. Despite the favorable energy balance, it is concluded that no higher excited states of anhydride 4f are produced during the thermolysis of bisdioxetane 2f . On thermal activation, the bisdioxetanes decompose by sequential cleavage of the two dioxetane rings.