Hydrogen peroxide oxidation of 2-cyanoethanol catalyzed by metal complexes

Article abstract of DOI:10.1134/S0965544106030054

Oxidation of 2-cyanoethanol, a relatively inert primary alcohol, with several systems (both homogeneous and heterogenized) based on transition metal complexes was studied. The oxidation was performed under homogeneous conditions with 35% hydrogen peroxide upon catalysis by the chlorides FeCl₃ or OsCl₃. The best result was obtained upon the oxidation catalyzed by OsCl₃ at 70°C for 3 h in the absence of solvent: the total yield of the corresponding aldehyde and cyanoacetic acid reached 90%, and the turnover number was 1500. The systems [LMn^IV(O)₃Mn ^IVL]_n(X)_m-oxalic acid (where L = 1,4,7-trimethyl-1,4,7-triazacyclononane) also catalyze oxidation of 2-cyanoethanol with yields of 50-70% either under homogeneous conditions (X = PF^- ₆, n = 1, and m = 2) or with the use of the catalyst in the heterogenized form (as insoluble heteropoly acid salt), where X = W ₁₂SiO^4- ₄₀, n = 2, and m = 1. Nauka/Interperiodica 2006.

Full text of DOI:10.1134/S0965544106030054

ISSN 0965-5441, Petroleum Chemistry, 2006, Vol. 46, No. 3, pp. 167–170. © Pleiades Publishing, Inc., 2006.
Original Russian Text © D.Veghini, L.S. Shul’pina, T.V. Strelkova, G.B. Shul’pin, 2006, published in Neftekhimiya, 2006, Vol. 46, No. 3, pp. 189–192.
Hydrogen Peroxide Oxidation
of 2-Cyanoethanol Catalyzed by Metal Complexes
D. Veghinia, L. S. Shul’pinab, T. V. Strelkovac, and G. B. Shul’pinc, 1
a Organic Fine Chemicals, LONZA Ltd., Visp CH-3930, Switzerland
b Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
ul. Vavilova 28, Moscow, 119991 Russia
c Semenov Institute of Chemical Physics, Russian Academy of Sciences,
ul. Kosygina 4, Moscow, 119991 Russia
1 e-mail: gbsh@mail.ru
Received September 26, 2005
Abstract—Oxidation of 2-cyanoethanol, a relatively inert primary alcohol, with several systems (both homo-
geneous and heterogenized) based on transition metal complexes was studied. The oxidation was performed
under homogeneous conditions with 35% hydrogen peroxide upon catalysis by the chlorides FeCl3 or OsCl3.
The best result was obtained upon the oxidation catalyzed by OsCl3 at 70°C for 3 h in the absence of solvent:
the total yield of the corresponding aldehyde and cyanoacetic acid reached 90%, and the turnover number was
1500. The systems [LMnIV(O)3MnIVL]n(X)m–oxalic acid (where L = 1,4,7-trimethyl-1,4,7-triazacyclononane)
also catalyze oxidation of 2-cyanoethanol with yields of 50–70% either under homogeneous conditions (X =
PF–6 , n = 1, and m = 2) or with the use of the catalyst in the heterogenized form (as insoluble heteropoly acid
salt), where X = W12SiO440– , n = 2, and m = 1.
DOI: 10.1134/S0965544106030054
INTRODUCTION
organic substrates, in particular, alkanes, olefins, and
alcohols. Iron(III) chloride [10], as well as its com-
pound with bipyridyl or other nitrogen ligands [10–13],
was supposed to be the simplest and least expensive
catalyst. We also used osmium(III) chloride (this metal
is an iron analogue in the periodic table) for the oxida-
tion of alkanes [14, 15]. The attempt to use, for the first
time, organometal iron and osmium derivatives (metal-
locenes, carbonyls) as catalysts in these reactions was
also of interest. We found earlier that alkanes, olefins,
and alcohols were efficiently oxidized with hydrogen
peroxide in acetonitrile in the presence of the binuclear
manganese(IV) complex [LMnIV(O)3MnIVL](PF6)2 (4),
where L = 1,4,7-trimethyl-1,4,7-triazacyclononane, as
a catalyst and a carboxylic acid (in particular, oxalic
acid (5)) as a cocatalyst [1, 5, 7, 8, 16–23]. In the
present work, we attempted to oxidize cyanoethanol in
the presence of this homogeneous catalyst, as well as of
its heterogenized form (6) [24].
Oxidation of alcohols into the corresponding alde-
hydes, ketones, and carboxylic acids is an important
process in petrochemical synthesis. Transition metal
complexes are known to catalyze the conversion of pri-
mary alcohols into the corresponding aldehydes and
carboxylic acids by the action of hydrogen peroxide [1–
9]. Preparation of cyanoacetic acid (compound 3) and
the corresponding aldehyde (compound 2) from 2-cya-
noethanol (compound 1) is of practical importance:
NC–CH2–CH2–OH
(1)
NC–CH2–CH=O + NC–CH2–C(=O)–OH
(2)
(3)
Note, however, that primary alcohols usually exhibit
a much lower reactivity in oxidation reactions; more-
over, compound 1 is even less amenable to oxidation
because of the presence of the electron-withdrawing
cyano group in the molecule. Therefore, it was of inter-
est to study transformations of this compound under the
action of various oxidizing systems based on metal
complex catalysts in order to find the most effective and
selective oxidants. We decided to study first the appli-
cability of the systems that had been developed earlier
and appeared to be efficient in the oxidation of some
EXPERIMENTAL
The synthesis and the structure of complex 4 were
described earlier [25, 26]. Catalyst 6 was prepared
using the procedure described elsewhere [24] as insol-
uble orange powder by mixing a solution of complex 4
in acetonitrile with a solution of H4W12SiO40 in aque-
167

168
VEGHINI et al.
Hydrogen peroxide oxidation of 2-cyanoethanol (1) catalyzed by different metal complexes
Run
no.
Conversion Yield of
Yield of
3, %
Catalyst
Co-catalyst
Solvent
T, °C
Time, h
Notes
of 1, %
2, %
a
1 FeCl3
None
2,2'-Bipyridyl
o-Phenanthroline MeCN
None
2,2'-Bipyridyl
None
2,2'-Bipyridyl
o-Phenanthroline None
None
2,2'-Bipyridyl
2,2'-Bipyridyl
2,2'-Bipyridyl
o-Phenanthroline MeCN
None
MeCN
MeCN
70
70
60
20
20
50
50
20
50
50
70
70
70
70
70
22
22
22
22
50
3
3
3
24
24
3
3
24
2
2
4
4
4
3
3
24
48
29
28
4
72
66
35
31
65
70
65
67
18
35
85
88
99
97
97
43
60
70
53
60
0.2
2
67
55
24
13
28
38
32
36
0
a, b
a, c
d
2 FeCl3
3 FeCl3
4 FeCl3
5 FeCl3
6 FeCl3
7 FeCl3
8 FeCl3
9 OsCl3
10 OsCl3
11 OsCl3
12 OsCl3
13 OsCl3
14 OsCl3
15 OsCl3
16 4
12
20
34
23
25
31
15
30
50
39
1
20
24
10
22
48
40
22
None
None
None
None
b, d
e
b, e
c, d
f
MeCN
MeCN
MeCN
MeCN
f, g
0
h
i
30
44
57
70
63
33
48
22
13
38
j
k
None
None
MeCN
MeCN
MeCN
None
b, k
l
2,2'-Bipyridyl
5
5
5
5
5
m
n
17 4
18 4
19 4
20 4
o
p
None
Notes: In all reactions performed at temperatures higher than room temperature, the reactants were mixed at room temperature, after which
the temperature increased to the required level for some minutes.
a
b
c
d
e
f
–3
–1
Substrate 1 (0.1 ml), FeCl (5 × 10 mol l ), MeCN (0.6 ml), and H O (0.8 ml) were used.
3
2 2
–1
The concentration of 2,2'-bipyridyl was 0.05 mol l .
–1
The concentration of o-phenanthroline was 0.05 mol l .
–3
–1
Substrate 1 (0.1 ml), FeCl (5 × 10 mol l ), and H O (1.5 ml) were used.
3
2 2
–2
–1
Substrate 1 (0.1 ml), FeCl (1 × 10 mol l ), and H O (0.8 ml) were used.
3
2 2
–3
–1
Substrate 1 (0.1 ml), OsCl (1 × 10 mol l ), MeCN (0.1 ml), and H O (0.8 ml) were used.
3
2
2
g
h
i
–3
–1
The concentration of 2,2'-bipyridyl was 4 × 10 mol l .
–3
–1
–2
–1
Substrate 1 (0.1 ml), OsCl (5 × 10 mol l ), 2,2'-dipyridyl (5 × 10 mol l ), MeCN (0.6 ml), and H O (0.8 ml) were used.
3
2 2
–2
–1
–2
–1
Substrate 1 (0.1 ml), OsCl (1 × 10 mol l ), 2,2'-dipyridyl (5 × 10 mol l ), MeCN (0.6 ml), and H O (0.8 ml) were used.
3
2 2
j
–3
–1
–2
–1
Substrate 1 (0.1 ml), OsCl (5 × 10 mol l ), o-phenanthroline (5 × 10 mol l ), MeCN (0.6 ml), and H O (0.8 ml) were used.
3
2 2
k
l
–3
–1
Substrate 1 (0.1 ml), OsCl (1 × 10 mol l ), and H O (0.8 ml) were used.
3
2 2
–4
–1
–1
Substrate 1 (0.1 ml), catalyst 4 (1 × 10 mol l ), 5 (0.006 g, 0.025 mol l ), CH CN (1 ml), and H O (0.5 ml) were used.
Substrate 1 (0.1 ml), catalyst 4 (0.7 × 10 mol l ), 5 (0.006 g, 0.017 mol l ), CH CN (1 ml), and H O (1.5 ml) were used.
The oxidant H O (1.5 ml) was added dropwise to the reaction mixture containing other components for 5 h, after which the solu-
tion obtained was stirred for 24 h. The amounts and concentrations of other components after the addition of H O were the same
3
2 2
m
n
–4
–1
–1
3
2 2
2
2
2
2
as in run 17 (see note m).
o
p
The solution of catalyst 4 (2 mg) in substrate 1 (0.1 ml) was added dropwise to the mixture of 4 (6 mg) with H O (0.5 ml) for 4 h,
after which the solution obtained was stirred for 24 h.
Substrate 1 (0.1 ml), catalyst 4 (2 mg), co-catalyst 5 (0.006 g), and H O (0.5 ml) were used.
2
2
2
2
ous ethanol (in the ratio [4] : [H4W12SiO40] = 2 : 1) with trometer) using D2O and nitromethane as internal stan-
dards.
the yield >85%. Other reagents used were commer-
cially available. Oxidation reactions of alcohol 1 were
performed in a glass cylindrical vessel surrounded by a
jacket with water circulating through a thermostat. The
volume of the solution was 1–2 ml. Since cyanoacetic
acid produced from 2-cyanoethanol was completely
decarboxylated in the chromatograph evaporator, the
oxidation products of this alcohol were determined by
RESULTS AND DISCUSSION
In this work, we thoroughly studied the oxidation of
2-cyanoethanol with three systems containing 35%
hydrogen peroxide that were used earlier for the oxida-
tion of alkanes and some other organic compounds. The
the 1H NMR technique (using a Bruker 400 MHz spec- table presents the results of the experiments.
PETROLEUM CHEMISTRY Vol. 46 No. 3 2006

HYDROGEN PEROXIDE OXIDATION OF 2-CYANOETHANOL
169
First, we found that the simplest system consisting yields of aldehyde 2 and acid 3 were 48 and 22%,
of hydrogen peroxide and iron(III) chloride [10, 13] is respectively.
useful for fairly effective conversion of alcohol 1 into
oxo derivatives 2 and 3 (table, runs 1–8). The conver-
sion of 1 reached 30–70%, and the maximum yield of
acid 3 was 67% (run 1). The maximum turnover num-
ber (TON) (i.e., the number of moles of all products
formed per mole of catalyst) reached 135 (run 1). We
showed earlier that the rate of the cyclohexane oxida-
tion reaction was substantially higher in the presence of
2,2'-bipyridyl in the reaction solution [13]. A compari-
son of runs 5 and 4 shows that the addition of 2,2'-bipy-
ridyl leads to a double increase in the product yield in
the case of oxidation of alcohol 1 at room temperature.
However, the addition of the diamine does not lead to a
noticeable improvement of the oxidation characteristics
at elevated temperatures.
Apart from catalyst 4, which is completely soluble
in acetonitrile and alcohol 1, we used heterogenized
catalyst 6 prepared by mixing a solution of complex 4
with the heteropoly acid H4W12SiO40 [24]. As shown
earlier [24], catalyst
6
has the formula
[Mn2O3(TMTACN)2]2[W12SiO40] · xH2O (where x = 2–
4) and is practically insoluble in most solvents. Catalyst
6 can be filtered off after the oxidation process and can
be used in a few new runs with some loss of the initial
activity. The oxidation of alcohol 1 (0.2 ml) with hydro-
gen peroxide (0.8 ml) in the presence of catalyst 6
(6 mol %, 5 mg) and oxalic acid (6 mg), after stirring
for 24 h at 22°C, led to the formation of 2 and 3 with
yields of 33 and 21%, respectively.
The use of some other iron derivatives instead of
iron(III) chloride did not give good results: the oxida-
tion catalyzed by ferrocene (5 × 10–3 mol l–1) and 2,2'-
bipyridyl (2 × 10–2 mol l–1) (conditions: 0.1 ml 1, 0.5 ml
H2O2, 0.4 ml MeCN, 2 h at 60°C) gave aldehyde 2 (8%)
and acid 3 (25%). Using iron carbonyl Fe3(CO)12 (3 ×
ACKNOWLEDGMENTS
We are grateful to the company LONZA Ltd. (Swit-
zerland) for financial support. This work was also sup-
ported by the RussianAcademy of Sciences (Chemistry
and Material Science Division) Program “Theoretical
and experimental study of the nature of chemical bond-
ing and mechanisms of the most important chemical
reactions and processes.”
10–3 mol l–1) as the catalyst led to even lower yields of
2 (9%) and 3 (14%).
It is interesting that osmium(III) chloride, which
was earlier found to exhibit a markedly higher activity
than FeCl3 in the oxidation of alkanes [14, 15], also
turned out to be a much more effective catalyst in the
oxidation of alcohol 1 (see runs 9–15 in table). The
maximum TON was found to be 1500 (run 14), with the
yield of the products reaching 90%. A comparison of
runs 14 and 15 shows that the addition of 2,2'-bipyridyl
practically does not improve the method. However, the
product yield is increased by the addition of 2,2'-bipy-
ridyl upon the reaction in the presence of a small
amount of acetonitrile (cf. runs 10 and 9). The osmium
chloride-catalyzed oxidation of 1 leads to the formation
of significant amounts of aldehyde 2, and we failed to
obtain acid 3 as a single product unless o-phenanthro-
line was used as a cocatalyst (run 13). The use of
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