Oxidation of Adamantane with H2O2–CF3COCF3 · 1.5 H2O in the Presence of VO(acac)2

Article abstract of DOI:10.1134/S1070428018070035

The system hydrogen peroxide–hexafluoroacetone sesquihydrate effectively oxidizes adamantane in the presence of VO(acac)₂ to afford 64% of adamantan-1-ol in tert-butyl alcohol or 76% of adamantan-2-one in a mixture of acetic acid with pyridine.

Full text of DOI:10.1134/S1070428018070035

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2018, Vol. 54, No. 7, pp. 992–995. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © K.S. Kislitsina, N.A. Shchadneva, R.I. Khusnutdinov, 2018, published in Zhurnal Organicheskoi Khimii, 2018, Vol. 54, No. 7,
pp. 990–993.
Oxidation of Adamantane with H2O2–CF3COCF3 ·1.5H2O
in the Presence of VO(acac)2
K. S. Kislitsinaa,* N. A. Shchadnevaa, and R. I. Khusnutdinova
a Institute of Petrochemistry and Catalysis, Russian Academy of Sciences,
pr. Oktyabrya 141, Ufa, 450075 Bashkortostan, Russia
*e-mail: inklab4@gmail.com
January 19, 2018
Abstract—The system hydrogen peroxide–hexafluoroacetone sesquihydrate effectively oxidizes adamantane
in the presence of VO(acac)2 to afford 64% of adamantan-1-ol in tert-butyl alcohol or 76% of adamantan-2-one
in a mixture of acetic acid with pyridine.
DOI: 10.1134/S1070428018070035
Adamantane and its homologs are oxidized more
readily than saturated aliphatic and alicyclic hydro-
carbons. Oxidative functionalization of adamantane
has been accomplished using a broad series of oxi-
dants, including oxygen, hydrogen peroxide, hydroper-
oxides, peroxyacids, HOCl, HOBr, NaOCl, iodosoben-
zene, and 2,6-dichloropyridine N-oxide in combination
with metal complex catalysts based on Co, Mn, Mo,
Fe, Zn, Pd, and Pt [1–5]. The oxidation of adamantane
with these reagents was usually characterized by low
conversion and selectivity, and mixtures of adamantan-
1-ol, adamantan-2-ol, and adamantan-2-one were ob-
tained. This is related to the radical mechanism of the
reaction involving the system oxidant–metal complex
[1]. For example, the conversion of adamantane in the
oxidation with the most environmentally benign oxi-
dant, hydrogen peroxide, in the presence of iron com-
pounds did not exceed 13% [5].
There are no published data on the use of H2O2–
(CF3)2CO·1.5H2O for the oxidation of saturated hy-
drocarbons. In this work we tried this oxidizing system
for the oxidative functionalization of adamantane in
the presence of vanadium complexes.
The conversion of adamantane largely depends on
the solvent nature, temperature, catalyst, and rate of
addition of H2O2–(CF3)2CO·1.5H2O. An appreciable
reaction rate was achieved at 40°C, and the maximum
conversion of adamantane (Table 1, run no. 20) was
obtained at 70°C. Blank experiments (without adaman-
tane) showed that the oxidant strongly decomposes at
70°C in the presence of VO(acac)2. According to the
iodometric titration data, after 10 min the concentra-
tion of active oxygen decreases by almost an order of
magnitude. Therefore, the reaction was carried out by
gradually adding H2O2–(CF3)2CO·1.5H2O mixture to
the reaction mixture containing adamantane, catalyst,
and solvent, preliminarily heated to 40–70°C. Among
A mixture of hydrogen peroxide with hexafluoro-
acetone sesquihydrate showed a high activity in epox-
idation of olefins, oxidation of aldehydes to carboxylic
acids, and oxidation of sulfides and amines to the
corresponding sulfoxides and amine oxides [6]. The
high oxidizing power of the system H2O2–(CF3)2CO·
1.5H2O may be rationalized as follows. Highly electro-
philic perfluoroacetone reacts with hydrogen peroxide
to produce hydroperoxide A which oxidizes unsaturat-
ed substrate to give epoxide B and hydrate C. The
reaction of the latter with hydrogen peroxide regen-
erates hydroperoxide A, thus resuming the catalytic
cycle [7] (Scheme 1).
Scheme 1.
F3C
O + H2O2
F3C
F3C
F3C
OH
H2O
OOH
A
C
O
F3C
F3C
OH
OH
H2O2
B
992

OXIDATION OF ADAMANTANE WITH H2O2–CF3COCF3 ·1.5H2O
993
Scheme 2.
OH
OH
VO(acac)2, (CF3)2CO·1.5H2O
t-BuOH, 70°C, 7 h
OH
O
+
H2O2
+
+
+
OH
1
2, 64%
3, 12%
4, 15%
5, 9%
the solvents tested (CH2Cl2, CHCl3, EtOH, BuOH,
t-BuOH), tert-butyl alcohol turned out to be the best
one, since it was not involved in side reactions. More-
over, tert-butyl alcohol is miscible with 35% aqueous
hydrogen peroxide, and it readily dissolves adaman-
tane (1) and VO(acac)2.
tanes 5, which were identified by GC/MS (Scheme 2).
Thus, the oxidation of adamantane was not selective,
and the ratio 2:3:4:5 was ~2:1:1:0.5 (Table 1, run
nos. 18–20). In the absence of a catalyst, the conver-
sion of 1 was 77% (run no. 8), and the ratio 2:3 was
2:1. If no (CF3)2CO·1.5H2O was added, the conver-
sion of adamantane did not exceed 44% (run no. 7).
The reactions were carried out at ratios 1–H2O2–
(CF3)2CO·1.5H2O–VO(acac)2 of 100:(500–1000):
(3–7):(100–250) at 40, 60, and 70°C, the reaction time
ranging from 4 to 7.5 h. Under the optimal conditions
(70°C, 7 h), the major product was adamantan-1-ol (2,
yield 64%), and the conversion of adamantane (1) was
99%. The reaction mixtures also contained ~30% of
by-products represented mainly by adamantan-2-ol (3),
adamantan-2-one (4), and isomeric dihydroxyadaman-
Additional experiments showed that the results of
adamantane oxidation are largely determined by the
solvent nature. In the oxidation of 1 in acetic acid–
pyridine, the major product was adamantan-2-one (4)
which was formed with a selectivity of 76%, and the
conversion of adamantane reached 95% (Table 2, run
no. 4). In the absence of (CF3)2CO·1.5H2O, the con-
version of 1 was as low as 49% (run no. 2), while in
Table 1. Oxidation of adamantane (1) with H2O2–(CF3)2CO·1.5H2O in tert-butyl alcohol
Product composition, %
Run
no.
Ratio 1–H2O2–(CF3)2CO·1.5H2O–
Temperature, Reaction Conversion
VO(acac)2
°C
time, h
of 1, %
2
3
4
5
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
100:500:50:0
40
60
70
70
70
70
70
70
70
70
70
70
60
70
40
70
70
70
70
70
7
00
05
18
32
13
40
44
77
83
58
91
86
47
76
19
74
88
90
91
99
–
–
–
–
–
100:500:50:0
7
56
61
64
64
69
68
63
65
65
66
61
66
62
66
62
60
68
65
64
44
25
25
19
31
13
37
12
14
14
14
13
13
21
18
14
14
14
12
–
100:500:50:0
7
14
11
17
–
–
100:500:100:0
100:500:200:0
100:1000:100:0
100:1000:0:7
7
–
7
–
7
–
7
13
–
06
–
100:1000:250:0
100:1000:250:1
100:1000:100:3
100:1000:250:3
100:1000:250:5
100:500:250:7
100:500:250:7
100:1000:100:7
100:1000:100:7
100:1000:100:7
100:1000:250:7
100:1000:250:7
100:1000:500:7
7
7
14
15
15
17
16
15
13
12
15
14
16
15
09
06
05
08
05
10
–
7
0.7.5
7
7
7
7
3
7
08
11
04
05
09
5
7
0.7.5
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 7 2018

KISLITSINA et al.
994
Table 2. Oxidation of adamantane (1) with H2O2–(CF3)2CO·1.5H2O in a mixture of acetic acid with pyridine
Product composition, %
Run
no.
Ratio 1–H2O2–(CF3)2CO·1.5H2O–
Temperature, Reaction Conversion
AcOH–Py–VO(acac)2
°C
time, h
of 1, %
2
3
4
1
2
3
4
5
100:1000:500:300:0:7
100:1000:2500:0:3500:7
100:1000:50:2500:0:7
100:1000:50:2500:3500:7
100:1000:100:2500:3500:7
70
60
60
60
70
7
7
7
7
8
87
49
56
95
37
73
19
52
24
37
9
–
–
–
–
18
81
48
76
63
the absence of pyridine, the substrate conversion de-
creased to 56% (run no. 3), and the reaction mixture
contained adamantan-1- and -2-yl acetates (25%)
which were identified by GC/MS.
GCMS-QP2010 Ultra instrument (Supelco PTE-5
capillary column, 60 m×0.25 mm, carrier gas helium,
oven temperature programming from 40 to 280°C at
a rate of 8 deg/min, injector temperature 260°C, ion
source temperature 200°C; electron impact, 70 eV).
Chromatographic analysis was performed with a Carlo
Erba GC 6000 Vega Series 2 chromatograph (3-m steel
column packed with 15% PEG-6000 on Chromaton
N-AW-HMDS; oven temperature programming from
50 to 180°C at a rate of 8 deg/min; carrier gas helium,
flow rate 47 mL/min). The elemental compositions
were determined with a Carlo Erba 1108 analyzer.
Gas mixtures were analyzed with a Thermo Finnigan
DSQ II GC/MS system; a 0.5-mL sample was injected
with a split ratio of 1:100; isothermal mode, 50°C; the
mass spectra were recorded in the range from 15 to
200 a.m.u.
Study of the kinetics of blank experiments (without
adamantane) showed that the rate of generation of
active oxygen depends on the temperature and catalyst:
the higher the temperature, the higher the rate of
oxygen liberation. In the absence of a catalyst, the rate
of decomposition of H2O2 and (CF3)2C(OH)(OOH) (A)
was 3–5 times lower even at elevated temperature.
Despite intense generation of active oxygen in the
presence of VO(acac)2, the conversion of adamantane
(1) attained 99%; therefore, the rate of oxidation of
adamantane is higher than the rate of decomposition of
the oxidants [H2O2 and (CF3)2C(OH)(OOH)].
Gaseous reaction products contained oxygen and
traces of hydrogen fluoride, indicating partial hydrol-
ysis of hexafluoroacetone. No other gaseous hexa-
fluoroacetone decomposition products were detected.
The use of such metal complexes as Cr(acac)3,
Mn(acac)3, Ni(acac)2, Fe(acac)3, Mo(CO)6, and
W(CO)6 gave no satisfactory results.
Adamantan-1-ol (2). A reaction flask was charged
with 1 mmol of adamantane (1), 0.14 mmol of
VO(acac)2, and 43 mmol of tert-butyl alcohol. The
solution was heated to 70°C, and a mixture of 10 mmol
of 32% hydrogen peroxide and 2.5 mmol of hexa-
fluoroacetone sesquihydrate was added dropwise from
a dropping funnel over a period of 5 h. The mixture
was cooled to 20°C, washed with water, and extracted
with ethyl acetate (3×5 mL). The extract was evap-
orated under reduced pressure, and the residue was
subjected to chromatography on silica gel using
hexane–ethyl acetate (first 9:1 and then 7:3) as eluent.
Yield 66%, mp 246–247°C. IR spectrum, ν, cm–1: 3600
Thus, the system hydrogen peroxide–hexafluoro-
acetone sesquihydrate in the presence of VO(acac)2 is
efficient for the oxidation of adamantane. The reaction
direction depends on the solvent. The oxidation in tert-
butyl alcohol gives mainly adamantan-1-ol (2, 64%),
whereas adamantan-2-one (4, 76%) is formed as the
major product in acetic acid–pyridine.
1
(O–H), 1150 (C–O). H NMR spectrum, δ, ppm:
1.65 m (12H, 2-H, 4-H, 6-H, 8-H, 9-H, 10-H), 2.10 m
(3H, 3-H, 5-H, 7-H), 2.45 s (1H, OH). 13C NMR spec-
trum, δC, ppm: 67.90 (C1), 45.32 (C2, C8, C9), 36.15
(C4, C6, C10), 30.85 (C3, C5, C7). Mass spectrum, m/z
(Irel, %): 152 (24) [M]+, 29 (7), 39 (10), 41 (12),
43 (15), 53 (5), 55 (7), 67 (5), 77 (7), 79 (5), 94
(14), 95 (100), 96 (7), 109 (5). Found, %: C 78.67;
H 10.17. C10H16O. Calculated, %: C 78.89; H 10.59.
M 152.2364.
EXPERIMENTAL
The IR spectra were recorded in KBr or mineral oil
1
13
on a Bruker Vertex 79V spectrometer. The H and C
NMR spectra were measured on a Bruker Avance-400
spectrometer at 400.13 and 100.62 MHz, respectively,
using CDCl3 as solvent and tetramethylsilane as refer-
ence. The mass spectra were recorded on a Shimadzu
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 7 2018

OXIDATION OF ADAMANTANE WITH H2O2–CF3COCF3 ·1.5H2O
Adamantan-2-one (4). A reaction flask was
REFERENCES
995
charged with 1 mmol of adamantane (1), 0.14 mmol of
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0.5 mmol of hexafluoroacetone sesquihydrate was
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of 5 h. The mixture was cooled to 20°C, washed with
brine, and extracted with ethyl acetate (3×5 mL). The
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C10), 46.92 (C1, C3), 216.59 (C2). Found, %: C 79.78;
H 9.12. C10H14O. Calculated, %: C 79.95; H 9.39.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 7 2018