A hydrogen-atom transfer mechanism in the oxidation of alcohols by [FeO4]2- in aqueous solution

Article abstract of DOI:10.1039/c7dt03830e

The ferrate(vi) ion, [FeO₄]^2-, has attracted much interest in recent years because of its potential use as a green oxidant in organic synthesis and water treatment. Although there have been several reports on the use of ferrate(vi) for the oxidation of alcohols to the corresponding carbonyl compounds, the mechanism remains unclear. In this work, the kinetics of the oxidation of a series of alcohols with α-C-H bond dissociation energies ranging from 81 to 95 kcal mol^-1 have been studied by UV/Vis spectrophotometry. The reactions are first-order in both [FeO₄]^2- and [alcohol]. The deuterium isotope effects for the oxidation of methanol/d₄-methanol, ethanol/d₆-ethanol and benzyl alcohol/d₇-benzyl alcohol are 18.0 ± 0.1, 4.1 ± 0.1 and 11.2 ± 0.1, respectively. A linear correlation is found between the second-order rate constants and the α-C-H bond dissociation energies (BDEs) of the alcohols, consistent with a hydrogen atom transfer (HAT) mechanism. The proposed HAT mechanism is supported by DFT calculations.

Full text of DOI:10.1039/c7dt03830e

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DOI: 10.1039/C7DT03830E
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Hydrogen-atom Transfer Mechanism in the Oxidation of Alcohols
2
−
by [FeO ] in Aqueous Solution
4
Received 00th January 20xx,
Accepted 00th January 20xx
a,b
b
b
b
b
Jianhui Xie, Po-Kam Lo, Chow-Sing Lam, Kai-Chung Lau,* and Tai-Chu Lau*
2
−
DOI: 10.1039/x0xx00000x
4
The ferrate(VI) ion, [FeO ] , has attracted much interest in recent years because of its potential use as a green oxidant in
organic synthesis and water treatment. Although there have been several reports on the use of ferrate(VI) for the
oxidation of alcohols to the corresponding carbonyl compounds, the mechanism remains unclear. In this work the kinetics
of the oxidation of a series of alcohols with α-C-H bond dissociation energies ranging from 81 to 95 kcal mol− have been
www.rsc.org/
1
2
]
−
studied by UV/Vis spectrophotometry. The reactions are first-order in both [FeO
effects for the oxidation of methanol/d -methanol, ethanol/d -ethanol and benzyl alcohol/d
.1 ± 0.1 and 11.2 ± 0.1, respectively. A linear correlation is found between the second-order rate constants and the α-C-H
bond dissociation energies (BDEs) of the alcohols, consistent with a hydrogen atom transfer (HAT) mechanism. The
proposed HAT mechanism is supported by DFT calculations.
4
and [alcohol]. The deuterium isotope
4
6
7
-benzyl alcohol are 18.0 ± 0.1,
4
Introduction
The oxidation of alcohols to carbonyl compounds is an
important reaction in organic synthesis and in biological
1
systems. Metal-oxo species are often used as oxidants for this
transformation, since the conversion of hydroxyl to carbonyl
group is a two-electron process and many metal oxo species
2
are facile two-electron oxidants.
Two mechanisms are commonly proposed for alcohol
oxidation by metal-oxo species, namely one-electron hydrogen
atom transfer (HAT) or two-electron hydride transfer
mechanism (Scheme 1). HAT mechanism has been proposed
3
Scheme 1 Hydrogen atom and hydride transfer mechanisms in the oxidation
for oxidation of alcohols by iron(IV) oxo complexes. Hydride
2
transfer mechanism are found for [(bpy) (py)Ru(O)] (bpy =
+
of alcohol by metal oxo species.
2
4
,2'-bipyridine; py = pyridine) and trans-dioxoruthenium(VI)
2
1
2
5
9.7. The oxidation of 2-propanol exhibits a kinetic isotope
effect of 2.8 when the α-hydrogen is replaced by deuterium.
The proposed mechanism involves initial 2 + 2 addition of α-C-
H to an Fe=O, followed by homolytic cleavage of the
organometallic intermediate (Scheme 2a). Norcross and Lee
also studied the oxidation of alcohols in strong alkaline
oxidants. On the other hand, both HAT and hydride transfer
mechanisms are proposed to operate in the oxidation of
6
alcohols by aqueous Fe(IV).
Among the transition metal oxo complexes, the ferrate(VI)
2
ion ([FeO ] ) has attracted much interest during the last few
−
4
decades because of its potential use as a green oxidant for
7
1
3
-9
2
−
solutions (0.5 - 8 M KOH). The rate constant increases with
[ROH] and large deuterium isotope effects of 5.3‒10 are
observed. The reacting species are proposed to be
water treatment and organic synthesis.
0
[FeO4] is a
powerful oxidant in water (E = 2.20 and 0.72 V vs. NHE at pH =
1
and 14, respectively), and it is capable of oxidizing a variety
0
0
of organic compounds, including various organic pollutants, as
1
well as bacteria and viruses in water.
1
Although there have been several reports on the oxidation
of alcohols to the corresponding carbonyl compounds by
ferrate(VI), the mechanism remains unclear. Lee and Gai
studied the kinetics of the oxidation of various alcohols at pH
Scheme 2 Oxidation of alcohols at a) pH 9.7 and b) 0.5 – 8 M KOH via
organometallic intermediate.
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(OH)] − and RO , which combine to form an intermediate alcohols were at least in 10-fold excess of that of [FeO
3
−
] .
2
−
[
FeO
that undergoes concerted proton transfer from α C-H of RO to Stock solutions of [FeO
an oxo ligand and heterolytic Fe-C bond cleavage via a cyclic solution at pH = 10, at this pH ferrate(VI) is stable for >20 h at
transition state (Scheme 2b). 23 °C. Stock solutions of alcohols were prepared in
In this work we have investigated the oxidation of a number NaH PO /Na HPO buffer. The reaction was initiated by mixing
at pH 9.5 in order to obtain more insight the ferrate(VI) solution with the alcohol solution and the pH of
4
4
−
2
−
4
] were prepared in sodium hydroxide
2
4
2
4
2
4
]
−
of alcohols by [FeO
−
8
into the mechanism. Since the pKa of HFeO
4
is 7.3, at pH 9.5 the mixture was determined with a pH meter. The reaction
2
−
2
−
the predominant species is [FeO
is also stable for >4 h at room temperature. We have chosen 510 nm, the
to study a series of alcohols with α-C-H bond dissociation constants, kobs, were obtained by nonlinear least-squares fits
4 4
] . At this pH the [FeO ] ion progress was monitored by observing absorbance changes at
−
2 8
λ
4
max of [FeO ] . Pseudo-first-order rate
energies (BDEs) that differ >13 kcal mol− in order to of A
1
vs t for at least 3 half-lives according to the equation A
+ (A - A ) exp(-kobst), where A and A are the initial and
t
t
understand the relationship between rate of oxidation and =A
∞
0
∞
0
∞
2
−
BDE. We have also investigated the [FeO4] oxidation of final absorbance, respectively. Kinetics carried out in the air
methanol by DFT calculations. Through a combination of and under argon were found to give the same rate constants;
experimental studies and DFT calculations, we provide therefore, most kinetic studies were done in the air. For the
2
−
evidence that the oxidation of alcohols by [FeO4] occurs by a alcohols that are sparingly soluble in water, including
HAT mechanism.
substituted benzyl alcohols, diphenylmethanol and d -benzyl
7
alcohol, tert-butanol was added to enhance the solubility.
Control experiments show that there is no reaction between
2
FeO4] and tert-butanol and the reactions between [FeO4] −
2
−
Experimental section
[
and benzyl alcohol (0.01 M) give similar pseudo-first-order rate
Materials.
constants with or without addition of tert-butanol (Fig. 1 and
Potassium ferrate (K
2
FeO
1
4
) (>98%) was prepared according to Fig. S1
†
).
4
a literature method. Benzyl alcohol (Aldrich, 99.8%) and
cyclohexanol (Aldrich, 99%) were purified by fractional
DFT calculations.
1
5
distillation under argon. Methanol (Aldrich, 99.9%), ethanol The structures and energies of all molecules were performed
1
6
17
(Aldrich, 99.5%), isopropanol (Aldrich, 99.9%), tert-butanol at the B3LYP level with the LanL2TZ(f) basis sets for Fe and
(Aldrich, 99.5%), 4-methoxybenzyl alcohol (Aldrich, 98%), 4- 6-311++G(d,p) basis sets for H and O. The solvation effect of
methylbenzyl alcohol (Aldrich, 98%), 3-chlorobenzyl alcohol molecular species in water medium was treated by hybrid
Aldrich, 98%), 4-chlorobenzyl alcohol (Aldrich, 99%), solvation model, which consists of 15 water molecules
diphenylmethanol (Aldrich, 99%), d -benzyl alcohol (98 atom % surrounding ferrate and methanol and the additional solvent
D, Aldrich), d -methanol (99.8 atom % D, Aldrich) and d
(
7
1
8
4
6
-
effect by polarizable continuum model (PCM). All calculations
1
9
ethanol (99.5 atom % D, Aldrich) were used as received. Water were performed with Gaussian 09 package of program.
for kinetic experiments was distilled twice from alkaline
permanganate. Ionic strength was maintained with sodium
perchlorate.
Results and Discussion
Kinetics.
Kinetics of the oxidation of benzyl alcohol.
Kinetic experiments were performed using an Agilent 8453 The kinetics of the oxidation of benzyl alcohol were studied by
diode array spectrophotometer. The concentrations of monitoring absorbance changes at 510 nm. In the presence at
Fig. 1 Spectral changes at 200 s intervals for the oxidation of benzyl alcohol
Fig. 2 Plot of kobs vs. [benzyl alcohol]. For benzyl alcohol (solid circle): slope =
2
0.01 M) by ferrate (2.00 × 10− M) at pH 9.5, I = 0.1 M and 25 °C. Inset
4
(1.74 ± 0.01) × 10−1, y-intercept = − (2.77 ± 4.45) × 10−2 , r = 0.9998. For d
−5
(
7
-
shows the absorbance-time trace at 510 nm, kobs = (1.74 ± 0.02) × 10−
3
s
−1
.
benzyl alcohol (open circle): slope = (1.55 ± 0.07) × 10 , y-intercept = (6.74 ±
5
2
3
.49) × 10− , r = 0.9998.
2
| J. Name., 2012, 00, 1-3
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Journal Name
ARTICLE
ꢏ
ꢏ
ꢏ
ꢆ ꢅ ꢗꢁH ꢄ⁄ꢐꢘ ꢎ ꢁH ꢄꢑꢚꢆ
′
ꢎ ꢗꢘ ⁄ꢐꢘ ꢎ ꢁH ꢄꢑꢚꢆ"ꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢐ6ꢑ
ꢊ
ꢙ
ꢙ
ꢙ
−
K
a
4
is the acid dissociation constant of HFeO and is taken as
.0 ×10− M at 25.0 °C. k’ and k’’ are the rate constants for the
7
9
2
−
2
−
oxidation by HFeO
4
4
and [FeO ] , respectively. From a
nonlinear least-squares fit of the data to equation (6) (Fig. 3),
−
the rate constants of the oxidation of benzyl alcohol by HFeO
2
4
−
are found to be 2.04 ± 0.04 M s− and (1.68 ±
−
1
1
and [FeO
4
]
0
.21) × 10 M− s , respectively, at I = 0.1 M and 25.0 °C. The
−
1
1
−
1
2
]
−
rate constant for [FeO
4
agrees with that determined at pH
9
.5, as described above, indicating that at pH 9.5, the
2
−
4
predominant reacting species is [FeO ] .
Fig. 3 Plot of k
2
vs. pH for the oxidation of benzyl alcohol by ferrate(VI) at I =
Activation parameters. The effects of temperature were
‡
0
.1 M and 25 °C. The solid line represents the fit of the experimental data studied from 15 °C to 45 °C. The activation parameters ΔH and
‡
according to equation (6).
2
ΔS were obtained from the plot of ln(k /T) vs. 1/T according to
‡
‡
Eyring equation (Fig. S2†). ΔH and ΔS are found to be (9.0 ±
least 10-fold excess of benzyl alcohol, clean pseudo-first-order 0.1) kcal mol− and
1
−
1
−
1
−
(32 ± 1) cal mol K , respectively.
decay was observed for over three half-lives (Fig. 1). The
Kinetic isotope effect. Since d -benzyl alcohol is only
7
pseudo-first-order rate constant depends linearly on [benzyl sparingly soluble in water, tert-butanol (30% by volume) was
alcohol] and the second-order rate constant, k , is found to be added to enhance its solubility. The second-order rate
2
1.74 ± 0.01) × 10− M− s− at pH 9.5, I = 0.1 M and 25.0 °C (Fig. constant for the oxidation of d -benzyl alcohol was found to be
1
1
1
(
7
). The experimentally determined rate law is as shown in (1.55 ± 0.07) × 10− M− s− at pH 9.5, I = 0.1 M and 25.0 °C (Fig.
2
1
1
2
equation (1)
2), this gives a KIE of 11.2 ± 0.1.
ꢂꢃ
ꢂꢃ
ꢂꢃ
Kinetics of the oxidation of various alcohols. The kinetics of
the oxidation of various other alcohols were also studied and
representative second-order rate constants are shown in Table
ꢀ
dꢁFe ꢄ⁄dt ꢅ ꢆ ꢁFe ꢄ ꢅ ꢆ ꢁbenzylꢋalcoholꢄꢁFe ꢄꢋꢋꢋ(1)
ꢇꢈꢉ
ꢊ
Effect of pH. The kinetics were studied over the pH range
1
. The kinetic isotope effects (KIE), k(CH
3 3
OH)/k(CD OH) and
6
.5‒9.5 at 25.0 °C. Due to the formation of the more active
+
−
k(C H OH/C D OH) are found to be 18.0 ± 0.1 and 4.1± 0.1,
2 5
2
5
4
HFeO , the rate constants increase with [H ], which is also
respectively (Fig. S4† and S5†).
observed in the oxidation of other substrates by ferrate(VI),
2
0
21
Substituent effects and Hammett correlation. The kinetics
of the oxidation of a series of para- and meta-substituted
benzyl alcohols were investigated, and representative second-
such as phenols and organosulfur compounds. This pH
dependence can be represented by equations (2)-(4), and the
rate law is shown in equations (5) and (6):
order rate constants are shown in Table S1†. A reasonably
linear correlation was obtained between log(k /k ) and σ
K
a
X
H
HFeOꢍ
ꢌ
FeO ꢊꢌ ꢍ ꢎ H ꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢐ2ꢑ
ꢏ
2
2
with ρ = −0.48 (Fig. 4). Such a small negative ρ value is similar
to those reported for the oxidation of alcohols by cytochrome
ꢒꢓ
ꢍ
HFeO ꢎ alcohol → productꢋꢋꢋꢋꢋꢋꢋꢋꢋꢐ3ꢑ
ꢌ
22
P450 enzymes and iron(IV) oxo complexes, which proceed via
3
HAT mechanism. On the other hand, if a hydride transfer
ꢒꢓꢓ
FeO ꢊꢌ ꢍ ꢎ alcohol ꢔꢕ productꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢐ4ꢑ
mechanism operates, a benzyl alcohol cationic intermediate
would be generated which should be greatly stabilized by
electron-donating substituents and destabilized by electron-
ꢂꢃ
ꢍ
ꢀ
dꢁFe ꢄ⁄dt ꢅ ꢆ′ꢁHFeO ꢄꢁalcoholꢄ ꢎ
ꢌ
ꢖꢖ
ꢊꢍ
ꢂꢃ
ꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢋꢆ ꢁFeOꢌ ꢄꢁalcoholꢄ ꢅ ꢆ ꢁFe ꢄꢁalcoholꢄꢋꢋꢐ5ꢑ
ꢊ
2
3
withdrawing substituents.
(2.96 ± 0.01) × 10−
(1.74 ± 0.01) × 10−
(1.15 ± 0.03) × 10−
(3.27 ± 0.03) × 10−
(4.68 ± 0.09) × 10−
(3.68 ± 0.11) × 10−
1
(2.96 ± 0.01) × 10−1
diphenylmethanol
81.3
1
(8.74 ± 0.01) × 10−2
(1.15 ± 0.03) × 10−2
(3.27 ± 0.03) × 10−3
(2.34 ± 0.05) × 10−3
(1.23 ± 0.04) × 10−3
b
8
9
9
9
9
3.0
1.2
2.4
3.4
4.8
2
3
3
3
a
The 0 K gas-phase BDE of the α-C-H bond in various alcohols are computed using the theoretical method of G3//B3LYP. Values are at 25.0 ˚C and
corrected per active hydrogen of the substrates.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Fig. 2 Plot of k
2
vs pH for the oxidation of benzyl alcohol by ferrate at I
=
0.1 M and 25 °C. The solid line represents the fit of the experimental
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Fig. 4 Hammett plot for the oxidation of benzyl alcohols by ferrate(VI).
Mechanism. In the oxidation of alcohols by ferrate(VI), the
observed large deuterium isotope effects are consistent with a
mechanism which involves α-C-H bond cleavage in the rat-
Scheme 3 Triplet and quintet potential energy surfaces for methanol
2
−
4 2
oxidation by [FeO ∙15H O] at the B3LYP level using LanL2TZ(f) basis set
3
,24
‡
(Fe) and 6-311++G(d,p) basis set (H and O). Not all water molecules are
shown for simplicity. Relative 298 K Gibbs free energies in water are given
in kcal mol− and selected bond lengths are in Å.
limiting step.
The observed large negative ΔS suggests an
ordered transition state.
1
Correlation between rate constants and α-C‒H bond
strengths. Mayer and co-workers have shown that for HAT
reactions the rates should correlate with the X-H bond
9.4 kcal mol− (Scheme 3). In INT1, the Fe bears +1.4 electron
1
3
1
and each oxo ligand has +0.2 electron spin. On the other hand,
the electron spin density on each oxo ligand is not evenly
2
4
strengths of the substrates. In the literature, there are often
several BDE values for an alcohol which usually differ
5
1
2
3
distributed in INT1: O (+1.1), O (+0.2), O (+0.2), O (+0.4)
4
2
5
significantly with one another. Hence in order to make the
data more consistent and comparable, the 0 K gas-phase BDE
of the α-C-H bond in various alcohols were computed using the
1
5
3
5
and Fe (+2.1). The O −H distance in INT1 and INT1 are 2.632
and 2.308 Å, respectively. The INT1 then undergoes HAT
3
3
(
TS1) via a spin intercrossing between the triplet and quintet
5
2
6
theoretical method of G3//B3LYP and the data are collected
in Table 1. In Table 1 the rate constant per active hydrogen,
‡
298
potential energy surfaces to form INT2, with a barrier (ꢀG )
−
1
of 17.7 kcal mol . The spin density on Fe increases to +2.3 and
k
2
’, is obtained by dividing the second-order rate constant k
with the number of α-hydrogens of the alcohol. A reasonably
linear correlation is obtained between log(k ’) and BDE of the
alcohols (Fig. 5), suggesting that a HAT mechanism operates in
2
1
the spin density on O decreases to +0.1 in INT2 and INT2
3
5
.
2
The spin densities are +0.2 on O , O and O in the two spin
3
4
2
3
states. The structures and spin distribution of INT2 and INT2
5
are similar; except that the methylene carbon is of opposite
3
0.9 in INT2 and electron spin of +0.9 in
2
−
the oxidation of alcohols by [FeO
4
] .
spin (electron spin of
3
−
5
5
INT2). Both INT2 and INT2 species have negligibly energy
difference (0.2 kcal/mol). Formaldehyde is generated via
DFT Calculations.
2
]
−
The reaction mechanism of methanol oxidation by [FeO
4
in
6
2
5
another HAT (H ) to the oxo ligand (O ) via TS2 and mediated
aqueous solution has been investigated using density
‡
by two H-bonded water molecules, with
ꢀG298 of 4.7 kcal
3
2
−
functional theory (DFT). The [FeO ] and CH OH first combine
4
3
3
to form an intermediate, [FeO …CH OH∙15H O]
5
which is more stable than [FeO …CH OH∙15H O]
2
−
3
(
INT1),
4
3
2
−
2 5
( INT1) by
4
3
2
Scheme 4 Triplet potential energy surfaces for methanol oxidation by
2
−
[
4 2
FeO ∙15H O] via organometallic intermediate at the B3LYP level using
2
−
LanL2TZ(f) basis set (Fe) and 6-311++G(d,p) basis set (H and O). Not all
water molecules are shown for simplicity.
Fig. 5 Plot of log(k
2
’) vs. BDE for the oxidation of alcohols by [FeO
4
] . [Slope
−
1
1
2
=
−(1.61 ± 0.14) ×10 , intercept = (1.25 ± 0.13) × 10 , r = 0.96]
4
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2
−
4
Scheme 5 Summary of calculated mechanisms of oxidation of methanol by [FeO ] in water.
−
1
mol .
The deuterium kinetic isotope effect (KIE) on HAT is Fe(IV) product is known to oxidize water to give Fe
calculated as the ratio of the rate constants for the oxidation
of CH OH and CD OH. The oxidation of CD OH follows similar
mechanism as the oxidation of CH OH and the calculated
OH) is 18.8 kcal mol . Based on the transition-state
theory, the rate constant can be evaluated using equation (7).
at pH 9.5. At this pH the predominant ferrate(VI)
the preferred mechanism according to our calculations. The
2
8
2 3
O .
3
3
3
Conclusions
3
‡
−
1
ꢀG298 (CD
3
We have experimentally investigated the oxidation of alcohols
2
]
−
by [FeO
4
2
−
species present in solution is [FeO
4
] . The rate constants for
ꢒ
ꢞ
ꢛ
∆ꢤ‡
ꢆꢛꢜꢛ ꢅ ꢝ ꢠ ꢡꢢꢣ ꢝꢀ ꢥꢛ
ꢠ (7)
the oxidation of a series of alcohols under these conditions
show a linear correlation with the α-C-H BDEs of the alcohols,
consistent with a HAT mechanism. Such a mechanism is
supported by DFT calculations, which show that there is an
ꢟ
The predicted KIE value at T = 298.15 K is 6.3, which is much
lower than the experimental value of 18, suggesting that there
2
7
2
−
is significant tunneling effects in HAT.
3
After the formation of INT2, it is also possible for the
3 4
initial rate-limiting HAT from CH OH to [FeO ] , followed by a
second HAT to form the carbonyl product. Pathways involving
formation of organometallic intermediates after the initial HAT
could also be located, but they are energetically much less
favourable.
hydroxymethyl radical to attack the Fe from the front
3
TS1front, ꢀG298 = 15.3 kcal mol ) or back ( TS1back, ꢀG
298
13.8 kcal mol ) to form an organometallic intermediate
‡
−
1
3
‡
(
−
1
=
3
C bond lengths are 2.641 ( INT1front) and
(
Scheme 4). The Fe−
3
.193 Å ( INT1back), respectively. In order to form the Fe
2
−C
bond, Fe and C should be of opposite spin. The spin density on Conflicts of interest
Fe is +2.3 in INT2 and INT2, while that on C should be
3
5
There are no conflicts of interest to declare.
3
3
3
negative ( INT2). Therefore, only TS1front and TS1back are
located. After the formation of Fe C bond, the spin densities
−
3
on Fe/C decrease to +2.1/
−
0.4 ( INT1front) and +1.8/
−
0.1
O remain similar to that
.
Formaldehyde is formed by further hydrogen atom
Acknowledgements
3
1
4
(
INT1back). The spin densities on O −
3
of INT2
The work described in this paper was supported by the Hong
Kong University Grants Committee Areas of Excellence Scheme
transfer from hydroxylmethyl group to an oxo ligand, which is
mediated by 2 H-bonded water molecules.
(
AoE/P-03/08) and the Research Grants Council of Hong Kong
CityU 101713).
(
The calculated mechanisms are summarized in Scheme 5.
2
]
−
The first step is HAT to from α-C-H of CH
3
OH to [FeO
(OH) . This followed by either (a) an
second HAT to generate HCHO and Fe(IV), or (b) formation of
4
to
−
2 3
generate •CH OH and FeO
Notes and references
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−
1
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Table of Content Graphic
2−
Hydrogen-atom Transfer Mechanism in the Oxidation of Alcohols by [FeO4] in
Aqueous Solution
a,b
b
b
b
b
Jianhui Xie, Po-Kam Lo, Chow-Sing Lam, Kai-Chung Lau,* and Tai-Chu Lau*
2
−
The oxidation of alcohols by [FeO4] in aqueous solution is found to proceed via
hydrogen atom transfer (HAT) mechanism based on the deuterium isotope effects,
correlation between rate constants and bond dissociation energies (BDEs) and DFT
calculations.