Thermolysis of 3-alkyl-3-methyl-1,2-dioxetanes: activation parameters and chemiexcitation yields

✍ Scribed by Alfons L. Baumstark; Sean L. Anderson; Chariety J. Sapp; Pedro C. Vasquez

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 72 KB
• Volume: 12
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.1028

✦ Synopsis

Abstract

3‐Methyl‐3‐(3‐pentyl)‐1,2‐dioxetane 1 and 3‐methyl‐3‐(2,2‐dimethyl‐1‐propyl)‐1,2‐dioxetane 2 were synthesized in low yield by the α‐bromohydroperoxide method. The activation parameters were determined by the chemiluminescence method (for 1 ΔH‡ = 25.0 ± 0.3 kcal/mol, ΔS‡ = −1.0 entropy unit (e.u.), ΔG‡ = 25.3 kcal/mol, k~1~ (60°C) = 4.6 × 10^−4^s^−1^; for 2 ΔH‡ = 24.2 ± 0.2 kcal/mol, ΔS‡ = −2.0 e.u., ΔG‡ = 24.9 kcal/mol, k~1~ (60°C) = 9.2 × 10^−4^s^−1^. Thermolysis of 1–2 produced excited carbonyl fragments (direct production of high yields of triplets relative to excited singlets) (chemiexcitation yields for 1: ϕ^T^ = 0.02, ϕ^S^ ≤ 0.0005; for 2: ϕ^T^ = 0.02, ϕ^S^ ≤ 0.0004). The results are discussed in relation to a diradical‐like mechanism. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:176–179, 2001