δ-過氧內酯化合物A 在溶液中, 進行光分解反應,主要產物為化合物A-1,
化合物A-2 及化合物A-3其結構業經IR.MS.NMR鑑定以HPLC 追蹤且定量分
析發現,化合物A 照光分解量子產率及產物分佈, 受溶劑極性,照光反應溫
度,照光光源波長及添加敏光劑與否所影響隨著溶劑極性增大, 化合物A
照光分解量子產率有些許增加,顯示中間體a.b 稍具極性性質照光反應溫
度越高,分解量子產率越高,可能熱能對反應的影響不可忽視加入參態敏光
劑benzophenone或benzil 行光敏化照光後,化合物A-2 增多,化合物A-1
減少,推測化合物A-1在激發單態產生,而化合物A-2 在參態生成而溶劑極
性越大,化合物A-2 越多, 表示系統間穿越效率增強,必有一較靠近參態T(
close lying triplet)存在低溫(77K )及室溫(296K)下照光,發現室溫照
光時,化合物A-2比低溫照光來得多, 可能化合物A-2 於低溫下進行二次分
解所致 同時,使用不同波長光源(253.7nm,313nm,366nm)照光,照光波長越
短,化合物A-2 越多,顯示高電振能階( upper vibronic energy state)
支配著本光化學反應而嘗試捕捉中間體a, b沒有成功,立體障礙太大,生命
期太短,可能是主因 另一方面, 化合物A 之UV 吸收及螢光放射,隨溶劑極
性增大而呈紅位移 (red shift),表示第一激發單態S為(π,π*) .

Delta-Peroxylactone A proceeds photodecomposition reac- tion in
solution. The major products of the reaction are compound A-1,
A-2, and A-3. The structures of them were identified by means
of IR, MS, NMR.The photodecomposition reaction was monitored by
HPLC analysis. We found that the quantum efficiency of the
photodecomposition and product distribution were changed with
solvent polarity, temperature , wavelength of light source, and
the addition of sensi- tizers. The relative quantum efficiency
of the photodecompo- sition of compound A increased as solvent
polarity incr- eased. It appeals that diradical intermediates
a, b show partial polarity. The thermal energy can't be
ignored from temperature dependence of the reaction. When
the reaction was carried out in presence of triplet sensi-
tizers benzophenone and benzil, the yield of compound A- 2
increased and compound A-1 decreased. Compound A-1 is
produced from excited singlet state of compound A and
compound A-2 is from excited triplet state. On the other hand,
compound A-2 increased and compound A-1 decreased as solvent
polarity increases; this implies that the efficiency of
intersystem crossing increases with incre- asing solvent
polarity. So there must be a close lying triplet T.
Irradiation of compound A at 296K produced higher yield of
compound A-2 than at 77K, compound A-2 proceeds secondary
decomposition reaction at 77K probably. Shorter wavelength of
light source elevates the ratio of quantum yield of compound
A-2 to compound A-1, higher vibronic energy states control
the photochemistry. UV absorbance and fluorescence emission of
compound A show red shift as solvent polarity increases; these
results indicate that the first excited singlet is (π,π).
Delta-Peroxylactone A proceeds photodecomposition reac- tion in