Abstract
The conversion of adamantane to adamantanols mediated by ferrate (FeO42-), monoprotonated ferrate (HFeO4-), and diprotonated ferrate (H2FeO4) is discussed with the hybrid B3LYP density functional theory (DFT) method. Diprotonated ferrate is the best mediator for the activation of the C-H bonds of adamantane via two reaction pathways, in which 1-adamantanol is formed by the abstraction of a tertiary hydrogen atom (3°) and 2-adamantanol by the abstraction of a secondary hydrogen atom (2°). Each reaction pathway is initiated by a C-H bond cleavage via an H-atom abstraction that leads to a radical intermediate, followed by a C-O bond formation via an oxygen rebound step to lead to an adamantanol complex. The activation energies for the C-H cleavage step are 6.9 kcal/mol in the 1-adamantanol pathway and 8.4 kcal/mol in the 2-adamantanol pathway, respectively, at the B3LYP/6-311++G** level of theory, whereas those of the second reaction step corresponding to the rebound step are relatively small. Thus, the rate-determining step in the two pathways is the C-H bond dissociation step, which is relevant to the regioselectivity for adamantane hydroxylation. The relative rate constant (3°)/(2°) for the competing H-atom abstraction reactions is calculated to be 9.30 at 75 °C, which is fully consistent with an experimental value of 10.1.
| Original language | English |
|---|---|
| Pages (from-to) | 3958-3965 |
| Number of pages | 8 |
| Journal | Journal of Organic Chemistry |
| Volume | 68 |
| Issue number | 10 |
| Publication status | Published - May 16 2003 |
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All Science Journal Classification (ASJC) codes
- Organic Chemistry
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A theoretical study of reactivity and regioselectivity in the hydroxylation of adamantane by ferrate(VI). / Shiota, Yoshihito; Kihara, Naoki; Kamachi, Takashi; Yoshizawa, Kazunari.
In: Journal of Organic Chemistry, Vol. 68, No. 10, 16.05.2003, p. 3958-3965.Research output: Contribution to journal › Article
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TY - JOUR
T1 - A theoretical study of reactivity and regioselectivity in the hydroxylation of adamantane by ferrate(VI)
AU - Shiota, Yoshihito
AU - Kihara, Naoki
AU - Kamachi, Takashi
AU - Yoshizawa, Kazunari
PY - 2003/5/16
Y1 - 2003/5/16
N2 - The conversion of adamantane to adamantanols mediated by ferrate (FeO42-), monoprotonated ferrate (HFeO4-), and diprotonated ferrate (H2FeO4) is discussed with the hybrid B3LYP density functional theory (DFT) method. Diprotonated ferrate is the best mediator for the activation of the C-H bonds of adamantane via two reaction pathways, in which 1-adamantanol is formed by the abstraction of a tertiary hydrogen atom (3°) and 2-adamantanol by the abstraction of a secondary hydrogen atom (2°). Each reaction pathway is initiated by a C-H bond cleavage via an H-atom abstraction that leads to a radical intermediate, followed by a C-O bond formation via an oxygen rebound step to lead to an adamantanol complex. The activation energies for the C-H cleavage step are 6.9 kcal/mol in the 1-adamantanol pathway and 8.4 kcal/mol in the 2-adamantanol pathway, respectively, at the B3LYP/6-311++G** level of theory, whereas those of the second reaction step corresponding to the rebound step are relatively small. Thus, the rate-determining step in the two pathways is the C-H bond dissociation step, which is relevant to the regioselectivity for adamantane hydroxylation. The relative rate constant (3°)/(2°) for the competing H-atom abstraction reactions is calculated to be 9.30 at 75 °C, which is fully consistent with an experimental value of 10.1.
AB - The conversion of adamantane to adamantanols mediated by ferrate (FeO42-), monoprotonated ferrate (HFeO4-), and diprotonated ferrate (H2FeO4) is discussed with the hybrid B3LYP density functional theory (DFT) method. Diprotonated ferrate is the best mediator for the activation of the C-H bonds of adamantane via two reaction pathways, in which 1-adamantanol is formed by the abstraction of a tertiary hydrogen atom (3°) and 2-adamantanol by the abstraction of a secondary hydrogen atom (2°). Each reaction pathway is initiated by a C-H bond cleavage via an H-atom abstraction that leads to a radical intermediate, followed by a C-O bond formation via an oxygen rebound step to lead to an adamantanol complex. The activation energies for the C-H cleavage step are 6.9 kcal/mol in the 1-adamantanol pathway and 8.4 kcal/mol in the 2-adamantanol pathway, respectively, at the B3LYP/6-311++G** level of theory, whereas those of the second reaction step corresponding to the rebound step are relatively small. Thus, the rate-determining step in the two pathways is the C-H bond dissociation step, which is relevant to the regioselectivity for adamantane hydroxylation. The relative rate constant (3°)/(2°) for the competing H-atom abstraction reactions is calculated to be 9.30 at 75 °C, which is fully consistent with an experimental value of 10.1.
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M3 - Article
AN - SCOPUS:84962419878
VL - 68
SP - 3958
EP - 3965
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 10
ER -