1488-25-1Relevant articles and documents
The Mystery of the Benzene-Oxide/Oxepin Equilibrium—Heavy-Atom Tunneling Reversed by Solvent Interactions
Prado Merini, Melania,Sander, Wolfram,Schleif, Tim
supporting information, p. 20318 - 20322 (2020/10/02)
The equilibrium between benzene oxide (1) and oxepin (2) is of large importance for understanding the degradation of benzene in biological systems and in the troposphere. Our studies reveal that at cryogenic temperatures, this equilibration is governed by rare heavy-atom tunneling. In solid argon at 3 K, 1 rearranges to 2 via tunneling with a rate constant of approximately 5.3×10?5 s?1. Thus, in a nonpolar environment, 2 is slightly more stable than 1, in agreement with calculations at the CCSD(T) level of theory. However, if the argon is doped with 1 % of H2O or CF3I as typical hydrogen or halogen bond donors, respectively, weak complexes of 1 and 2 are formed, and now 2 is tunneling back to form 1. Thus, by forming non-covalent complexes, 1 becomes slightly more stable than 2 and the direction of the heavy-atom tunneling is reversed.
Synthesis and Desymmetrization of meso Tricyclic Systems Derived from Benzene Oxide
Matías, Desirée M.,Johnson, Jeffrey S.
, p. 4859 - 4866 (2018/04/26)
Ozonolysis of the Diels-Alder adducts derived from benzene oxides and N-alkylmaleimides resulted in fully substituted, meso bicyclic systems bearing six contiguous stereocenters, isolated as diols upon reductive workup with NaBH4. Variation in the workup allowed for isolation of two different diastereoisomers, through double epimerization of the imide stereocenters. Desymmetrization of the resulting meso diols via asymmetric nucleophilic epoxide opening and acylation reactions provided access to highly substituted, enantioenriched fused rings.
Is benzene oxide homoaromatic? A microcalorimetric study
Jia,Brandt,Thibblin
, p. 10147 - 10152 (2007/10/03)
Rate constants and heats of reaction for the aromatization of benzene oxide (1) and the acid-catalyzed aromatization of benzene hydrate (2) in highly aqueous solution giving phenol and benzene, respectively, have been measured by heat-flow microcalorimetry. The measured heat of reaction of benzene oxide, ΔH = -57.0 kcal mol-1, is much larger than that of benzene hydrate, ΔH = -38.7 kcal mol-1, despite an unusually low reactivity of benzene oxide, rate ratio 0.08. The measured enthalpies agree with those calculated using the B3LYP hybrid functional corrected with solvation energies derived from semiempirical AM1/SM2 calculations. Comparison with the measured enthalpies of the corresponding reactions of the structurally related 1,3-cyclohexadiene oxide (3) and 2-cyclohexenol (4) of ΔH = -24.9 kcal mol-1 (includes a small calculated correction of - 1.2 kcal mol-1) and ΔH ～ 0 kcal mol-1, respectively, gives a smaller aromatization energy for the benzene oxide than for the benzene hydrate reaction (ΔΔΔH = 6.6 kcal mol-l). This suggests that benzene oxide is unusually stabilized by a significant amount of homoaromatization as has been proposed previously (J. Am. Chem. Soc. 1993, 115, 5458). This unusual stability accounts for more than half of the ～107 times lower than expected reactivity of benzene oxide toward acid-catalyzed isomerization. The rest is suggested to originate from an unusually high energy of the carbocation-forming transition state.
