Electrosynthesis of glutaric acid and regularities of electrocatalytic oxidation of cycloalkanones at a NiOOH anode in aqueous NaOH

Article abstract of DOI:10.1007/s11172-009-0339-1

Methods of preparation of glutaric acid by oxidation of cyclopentanone or pentane-1,5-diol in an undivided cell at a NiOOH electrode in aqueous alkali are developed. Yields of the products were 51% or 90%, respectively. The mechanism of electrooxidation of cycloalkanones at a NiOOH electrode is discussed on the basis of literature data and the regularities of the oxidative transformations of cyclohexanone investigated earlier and those of cyclopentanone.

Full text of DOI:10.1007/s11172-009-0339-1

Russian Chemical Bulletin, International Edition, Vol. 58, No. 12, pp. 2426—2431, December, 2009
2426
Electrosynthesis of glutaric acid and regularities of electrocatalytic oxidation
of cycloalkanones at a NiOOH anode in aqueous NaOH
B. V. Lyalin and V. A. Petrosyan
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federaion.
Fax: (499) 135 5328. Eꢀmail: petros@ioc.ac.ru
Methods of preparation of glutaric acid by oxidation of cyclopentanone or pentaneꢀ1,5ꢀ
diol in an undivided cell at a NiOOH electrode in aqueous alkali are developed. Yields of the
products were 51% or 90%, respectively. The mechanism of electrooxidation of cycloalkanꢀ
ones at a NiOOH electrode is discussed on the basis of literature data and the regularities of
the oxidative transformations of cyclohexanone investigated earlier and those of cycloꢀ
pentanone.
Key words: electrosynthesis, undivided cell, nickel hydroxide electrode, cyclohexanone,
cyclohexaneꢀ and cyclopentanediones, adipic, glutaric and succinic acids, pentaneꢀ1,5ꢀdiol.
We have been investigating the electrosynthesis in
aqueous alkaline media using a Ni anode and the unꢀ
divided cell for several years.1—3 On the surface of a Ni
anode, NiOOH is formed during electrolysis under these
conditions. This is an efficient oxidant, which is selfꢀ
generated in the electrolysis. In particular, this approach
was used for the development of two methods for the
preparation of adipic acid1: by direct oxidation of cycloꢀ
hexanol (the yield was 47%) and by the oxidation of
cyclohexanol to cyclohexanone (the yield was 75%) folꢀ
lowed by oxidation of the latter to adipic acid (the yield
was 52%). The same approach was used in the present
work for the preparation of glutaric acid, which is used in
the synthesis of herbicides4 and pharmaceuticals.5 It is of
note that cyclopentanol is not promising as the starting
material because it is prepared by hydrogenation of
cyclopentanone, which is more accessible.6,7 Therefore,
it was cyclopentanone that we chose as an initial subject
of investigations. Besides, the oxidation of an available
acyclic 1,5ꢀdiol was studied as an alternative for the synꢀ
thesis of glutaric acid. The results of the investigations
were used for generalization of the existing literature
data on the regularities of the electrooxidation of cycloꢀ
alkanones.
it is similar to the scheme of EO of cyclohexanone under
the same conditions.1
Scheme 1
Cathode:
Anode:
In the studies of EO of CP it was found that a decrease
in the temperature of electrolysis from 25 to 10 °C led
to the increase in the yield of glutaric acid by 13% (cf.
entries 1 and 2, Table 1). With increased concentration
of alkali from 0.8 to 1.0 mol L–1, the yield of the acid
also increased, however it decreased again at higher
(1.2 mol L–1) concentration of the alkali (cf. entries 2, 3,
and 4, Table 1).
The increase in the concentration of CP from 0.1 to
0.2 mol L–1 is favorable for the increase in the yield of
glutaric acid (by 20% based on loaded CP) and the conꢀ
version of CP (by 35%) (cf. entries 2, 5, and 6, Table 1).
The dependence of the yield of glutaric acid on current
density passes through a maximum (cf. entries 2, 7, and 8,
Table 1) reaching 58% (based on consumed cyclopentanꢀ
one) at J = 6 mA cm–2. Thus, the conditions were found
Results and Discussion
The first experiments on the electrooxidation (EO) of
cyclopentanone (CP) at a NiOOH anode in aqueous
NaOH (Table 1, entry 1) resulted in the formation of
glutaric acid in the yield of ~44% (based on the consumed
ketone). The oxidation process is presented in Scheme 1,
(Т = 10 °C, СCP = 0.15—0.2 mol L–1, СNaOH = 1.0 mol L–1
,
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2348—2353, December, 2009.
1066ꢀ5285/09/5812ꢀ2426 © 2009 Springer Science+Business Media, Inc.

Electrosynthesis of glutaric acid
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009 2427
acid1 but also small amounts of two other dicarboxylic
acids formed: glutaric (up to 10%) and succinic (up to
4%), whose molecules contain one and two carbon atoms
less than the molecule of adipic acid, respectively. The
same was observed in EO of CP, where the moderate
Table 1. Dependence of the yield (%) of glutaric (GA) and
succinic (SA) acids in the electrooxidation of cyclopentanone
(CP)а
Entry
СCP
Jа
Q/Qtheor Converꢀ
sion of
Yieldb
/mol L–1 /mA cm–2
amount of succinic acid (8—14%) was present along with
glutaric acid in the electrolysis products.
GA SA,
CP (%)
I
II
I
Let us note that adipic, glutaric, and succinic acids
also are formed in chemical oxidation of cyclohexanone
(with oxygen in the presence of cobalt naphthenate10 or
upon γꢀirradiation,11 with H2O2 and V2O5 as a catalyst,12
with peracetic acid in the presence of Ru/С as a cataꢀ
lyst13). This prompted us to analyse and summarize sepaꢀ
rate data on the oxidation of cyclic ketones.
Thus a mechanism of the oxidation of linear and some
cyclic ketones with Na2S2O8—FeSO4 was discussed.14,15
Presumably, in the first step of the oxidation of cycloꢀ
hexanone as an example, an Oꢀcentered radical cation
is formed, one of its reaction routes involves 1,5ꢀshift
of a hydrogen atom to generate Cꢀcentered radical
cation, which is oxidized to cyclohexaneꢀ1,4ꢀdione (the
yield is ∼2%).
1с
2
0.15
0.15
0.15
0.15
0.20
0.10
0.15
0.15
0.15
0.15
6
6
6
6
6
6
16
3
6
6
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.5
3.0
80
49
34
51
68
33
25
54
66
86
35 44
28 58
20 58
28 54
38 55
17 50
12 47
18 34
41 62
8
4
6
7
7
3
2
4
8
3d
4е
5
6
7
8
9
10
51 59 14
a
Undividedꢀcell electrolysis in 1.0 M aqueous NaOH, Ni
anode, Ti cathode, Т = 10 °C, Qtheor = 6 F (mol CP)–1; Ja is
current density, Q is the amount of electricity.
1
b Calculated from Н NMR data for isolated mixture of elecꢀ
trolysis products: I based on the starting CP; II, based on the
consumed CP.
с Т = 25 °C.
Scheme 2
d СNaOH = 0.8 mol L–1
.
е СNaOH = 1.2 mol L–1
.
J = 6 mA cm–2, Q = Qtheor) providing the moderate yield
(55—58% based on the consumed CP) of glutaric acid.
At the same time, the conversion of CP is relatively
low under these conditions (49—68%) (cf. entries 2 and 5,
Table 1) and the yield of the target product (based on
loaded CP) varies in the range of 28—37%. This shortꢀ
coming was partially eliminated by increasing the amount
of passed electricity (cf. entries 2, 9, and 10, Table 1).
Thus the threefold increase (compared to theoretical) in
electricity passed (entry 10, Table 1) increased the conꢀ
version of the ketone to 86%, the yield of glutaric acid
reaching 51% based on the loaded ketone (or 59% based
on the consumed ketone).
Reactants and conditions: i. Na2S2O8—FeSO4; ii. 1,5ꢀShift.
From the comparison of the results obtained with the
data of the dependence of the yield of adipic acid on
conditions of EO of cyclohexanone1 it is obvious that the
regularities of EO of cyclohexanone and CP to the correꢀ
sponding acids are similar. At the same time, EO of CP to
glutaric acid (the yield of acid is 51% based on the loaded
ketone and its conversion of 86%) is more efficient than
EO of cyclohexanone to adipic acid (the yield of the acid
is 37% based on the loaded ketone and its conversion of
70%). These results can probably be rationalized by the
fact that it is enol forms of ketones that are subject to EO,8
the molar fraction of the enol form being 3 times higher in
CP than in cyclohexanone.9
But if this were the case, the simultaneous 1,3ꢀ and
1,4ꢀmigration of a hydrogen atom would occur. Howꢀ
ever, no products of such transformations (cyclohexaneꢀ
1,2ꢀdione and ꢀ1,3ꢀdione, respectively) were found in
the reaction mixture containing much of resinous subꢀ
stances.14,15 Most likely, this was caused by high reactivity
of cyclohexaneꢀ1,2ꢀdione and ꢀ1,3ꢀdione under these conꢀ
ditions. It was confirmed by the data11 on the γꢀradiationꢀ
induced oxidation of cyclohexanone with oxygen, which
proceeds via cyclohexaneꢀ1,2ꢀdione, ꢀ1,3ꢀdione, and
ꢀ1,4ꢀdione to form adipic, glutaric, and succinic acids,
respectively. It was also noted11 that due to the high reacꢀ
tivity, the mentioned cyclic diketones could only be found
in solutions with рН < 11.5. This, in turn, explains the
In EO of cyclohexanone under the conditions analoꢀ
gous to those used in the present work, not only adipic

2428
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009
Lyalin and Petrosyan
Scheme 3
absence of cyclohexanediones in the resulting reaction
mixture in the EO of cyclohexanone or CP at a NiOOH
electrode in the alkaline medium.
In view of the aforesaid, the mechanism of EO of
cyclohexanone in the alkaline medium at a NiOOH elecꢀ
trode corresponds to Scheme 3, where the starting strucꢀ
ture subjected to EO is the enol form of cyclohexanone
(see above). It has sufficiently low9 рК = 11.3 and exists in
1.0 M NaOH solution in the form of the enolate anion.
In the first step of the process, Oꢀcentered radical 1 is
generated, whose further transformations include 1,3ꢀ,
1,4ꢀ, and 1,5ꢀhydrogen shifts to afford cyclohexaneꢀ
1,2ꢀdione, ꢀ1,3ꢀdione, and ꢀ1,4ꢀdione via hydroxycycloꢀ
hexanones 2а, 2b, 2c. Further oxidation of cyclohexaneꢀ
diones 3а, 3b, and 3c, occuring through several respective
steps (Scheme 3) results in adipic (4а), glutaric (6b), and
succinic (7c) acids. This conclusion is confirmed by the
data on EO of cyclohexanediones.
No sample of cyclohexaneꢀ1,2ꢀdione (3а) labile
under ordinary conditions was at our disposal, but it is
known8 that it is diones that are the primary electroꢀ
oxidation products of the respective cyclic diols. Conseꢀ
quently, the electrosynthesis of adipic acid with a yield of
75% in EO of cisꢀ and transꢀcyclohexaneꢀ1,2ꢀdiols in
aqueous K2CO3 occurs16 via cyclohexaneꢀ1,2ꢀdione,
which in turn causes the appearance of the step 3а → 4а
in Scheme 3. It is of note that in EO opening of the
cyclohexane ring takes place between the carbon atoms
of the C=O groups.8,17
In a special investigation, we showed that EO of
cyclohexaneꢀ1,3ꢀdione in aqueous К2СО3 at a NiOOH
anode results in glutaric acid with the yield of 81%. Beꢀ
sides, it is known17 that EO of cyclohexaneꢀ1,3ꢀdione at a
Pt anode in an acidic medium occurs via cyclohexaneꢀ
1,2,3ꢀtrione (4b), which further oxidizes also to glutaric
acid via αꢀketodicarboxylic acid.
Thus, the mechanism of EO of 1,3ꢀdiketone (3b) reꢀ
presented in Scheme 3 involves 1,3ꢀshift of a hydrogen
atom and results in triketone (4b). The further oxidation
of 4b occurs with ring opening to αꢀketodicarboxylic acid
(5b), which in turn oxidizes to glutaric acid (6b) with
elimination of СО2.
Obviously, EO of cyclohexaneꢀ1,4ꢀdione (3с) occurs
by the mechanism analogous to that of EO of cyclohexaneꢀ
1,3ꢀdione (3b). This allows considering cyclohexaneꢀ
1,2,4ꢀtrione (4с) and βꢀketodicarboxylic acid (5с) as most
likely intermediates of the oxidation process (Scheme 3).
The oxidation of keto acid 5с, apparently also occurs
through 1,3ꢀshift of a hydrogen atom, and compound 6с
that formed oxidizes with cleavage of the C—C bond
between the carbon atoms of the carbonyl groups (see
above) resulting in succinic and oxalic acids. This can
indirectly proved by the data on EO of acetylacetone17 to
carboxylic acid and by the fact10 that the oxidation of
cyclohexaneꢀ1,4ꢀdione with HNO3 results in succinic (7с)
and oxalic acids.
Reactants and conditions: i. [NiOOH]; ii. [NiOOH], H2O.

Electrosynthesis of glutaric acid
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009 2429
The resulting products (Scheme 3) of EO of cycloꢀ
hexanone, i.e., dicarboxylic acids, are present in the reacꢀ
tion mixture as dianions, because the electrolysis was
carried out in the alkaline medium.
succinic acid, is present in the reaction mixture together
with glutaric acid as the major product (cf. with EO of
cyclohexanone).
It was of interest to study the electrosynthesis of dicarꢀ
boxylic acids in the EO (under the conditions analogous
to those described above) of cyclic ketones with much
larger number of carbon atoms in the ring. We chose
cyclododecanone as an example the chemical (HNO3)
oxidation of which results in dodecanedioic acid.10
Cyclododecanone turned out to be poorly soluble in
an aqueous alkaline solution. Therefore, its EO was
carried out in an alkaline aqueousꢀalcoholic (50% ButOH)
solution. However, the yield of dodecanedioic acid in the
electrolysis of cyclododecanone under these conditions
was low (5—10%), and variation of different factors (curꢀ
rent density, concentrations of ketone and alkali, temꢀ
perature of the process, the amount of electricity passed)
had not substantial effect on the yield of the target product.
Thus, the extension of the ring size decreases the effectꢀ
ivity of the EO of cycloalkanones at a nickel hydroxide
electrode.
We have also studied the preparation of glutaric acid
by EO of available acyclic alcohol, pentaneꢀ1,5ꢀdiol, at a
NiOOH anode in aqueous NaOH. It resulted in glutaric
acid as the major product, but the formation of trace
amounts (1—3%) of succinic acid was also observed. It
was established that the yield of glutaric acid slightly (by
~5%) reduced (cf. entries 1 and 2 in Table 2) with the
increase in temperature from 25 to 50 °C (which apparꢀ
ently was caused by the oxidation of glutaric acid itself),
but still remained high (87—91%). The decrease in the
yield of the target product by 4% (cf. entries 1 and 3,
Table 2) was caused by the increase in the alkali conꢀ
centration in the range of 0.5—1.0 mol L–1 and by 13%
(cf. entries 1 and 4, Table 2) by the increase in pentaneꢀ
1,5ꢀdiol concentration (from 0.14 to 0.22 mol L–1). The
dependence of the yield of glutaric acid on the current
The analysis of the mechanism of the process sugꢀ
gested in Scheme 3 explains the ratio of adipic, glutaric,
and succinic acids in the EO products of cyclohexanone.
Thus the probability of hydrogen migration in the cycloꢀ
hexanoneꢀderived Oꢀcentered radical (1а) to the position
3 is much higher than that to the position 4, which is
higher than that to the position 5. Therefore the concenꢀ
tration of intermediate cyclohexaneꢀ1,2ꢀdione is much
higher than those of cyclohexaneꢀ1,3ꢀdione and ꢀ1,4ꢀdione.
As a result, the yield of adipic acid in the EO of cycloꢀ
hexanone is noticeably higher1 than those of glutaric or
succinic acids.
These results allow describing the mechanism of the
EO of CP at a nickel hydroxide electrode affording a
mixture of glutaric and succinic acids by Scheme 4 analoꢀ
gous to Scheme 3 considered above.
If the intermediate cyclopentanoneꢀderived Oꢀcenꢀ
tered radical (8, Scheme 4) undergoes 1,3ꢀhydrogen shift,
then its oxidative transformation product occurring via
diketone (9a) should be glutaric acid (6b). In the case of
1,4ꢀshift, cyclopentaneꢀ1,3ꢀdione (9b) and cyclopentaneꢀ
1,2,3ꢀtrione (10) are transiently formed, which results in
succinic acid (7c). Since the probability of 1,3ꢀhydrogen
shift in the EO of CP is higher than that of 1,4ꢀshift
(see above), the yield of glutaric acid more than fourfold
exceeds that of succinic acid (see Table 1).
The EO mechanism in Scheme 4 is in accord with the
data on the chemical (Na2S2O8—FeSO4) oxidation of
CP to cyclopentaneꢀ1,3ꢀdione14 and on the oxidation
of the latter to succinic acid at a Pt anode in an acidic
medium.17
In the EO of CP, only 1,3ꢀ or 1,4ꢀshifts of a hydrogen
atom are possible, therefore only one byꢀproduct, viz.,
Scheme 4
O
Reactants and conditions: i. [NiOOH]; ii. [NiOOH], H2O.

2430
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009
Lyalin and Petrosyan
Table 2. Effect of the experimental conditions on the yield of
glutaric (GA) and succinic (SA) acids in the electrolysis of penꢀ
taneꢀ1,5ꢀdiol (PD) under the conditions of the undividedꢀcell
electrolysis in aqueous NaOH solution*
polarization. This procedure is necessary for the formation of
multiꢀlayer coating containing NiOOH on the Ni anode surface.
Cyclopentanone, cyclohexaneꢀ1,3ꢀdione, and pentaneꢀ
1,5ꢀdiol (Acros) were used without additional purification. In
order to determine the degree of conversion of cyclopentanone,
it was converted to 2,4ꢀdinitrophenylhydrazone according to
the known procedure.19 The obtained acids, glutaric and
succinic, were identified by 1Н NMR spectroscopy (DMSOꢀd6)
on a Bruker ACꢀ300 spectrometer by the comparison with the
spectra of the authentic samples (Acros).
Electrooxidation of CP to glutaric acid (entry 10, Table 1).
A 1 M NaOH solution (200 mL) and CP (2.6 mL, 0.03 mol)
were placed in the cell. The electrolysis was carried out at 10 °C
and a current of 0.744 A. After passage of 18 F (Q = 52110 C,
threefold amount compared to theoretical) per mol of CP, the
electrolysis was stopped. The reaction mixture was stirred for
0.5 h and neutralized with concentrated HCl to pH 6—7. An
aliquot of this solution was withdrawn and the degree of
conversion of CP was determined (see above). The degree
of conversion was 86%. Concentrated HCl was added to the
remaining reaction mixture (to pH 1—2), then water was distilled
off under reduced pressure. The solid residue was treated with
Ме2СО (4×25 mL) and the extract was concentrated to dryness
to yield 2.88 g of a powder that was shown to be a mixture of
glutaric and succinic acids, (1Н NMR spectroscopy). Their molar
ratio equal to 3.75 : 1.0 was determined by the signal integrated
intensities of glutaric (δ 1.70—1.88 (m, 2 Н, СН2)) and succinic
(δ 2.40 (m, 4 Н, 2 СН2)) acids. The yields of these acids based
on the loaded CP were 51 and 14%, respectively. In order to
determine the melting point of the glutaric acid the powder
(2.88 g, see above) was treated with hot С6Н6 (5×10 mL) and
after cooling of the extract, the precipitate of glutaric acid was
filtered off. M.p. was 97—98 °C (m.p. 99 °C).20
Electrooxidation of cyclohexaneꢀ1,3ꢀdione to glutaric acid.
A 0.1 M K2CO3 solution (200 mL) and cyclohexaneꢀ1,3ꢀdione
(0.56 g, 0.005 mol) were placed in the cell. The electrolysis was
carried out at 25 °C and a current of 0.744 A. After passage of
8 F (Q = 3860 C) per mol of cyclohexaneꢀ1,3ꢀdione, the
electrolysis was stopped. The reaction mixture was stirred for
0.5 h and neutralized with concentrated HCl (to pH 1—2), then
water was distilled off under reduced pressure. After workup of
the reaction mixture as described above, we isolated 0.71 g of a
solid that was shown to be a mixture of glutaric and succinic
acids (1Н NMR spectroscopy).The molar ratio of glutaric and
succinic acids equal to 17.1 : 1.0 was determined by the signal
integrated intensities. The yields of glutaric and succinic acids
based on the loaded CP were 81 and 5%, respectively.
Entry
C/mol L–1
PD NaOH
Т/°C
Ja/mA cm–2
Yield (%)
GA
SA
1
2
3
4
5
6
0.14
0.14
0.14
0.22
0.14
0.14
1.0
1.0
0.5
1.0
1.0
1.0
20
50
20
20
20
20
6
6
91
87
96
78
71
81
2
3
2
2
2
1
6
6
16
3
* Conditions: NiOOH anode, Ti cathode, Qtheor = 8 F (mol PD)–1
.
density passes through a maximum (cf. entries 1, 5, and 6,
Table 2), reaching 91% at Ja = 6 mA cm–2
.
It is known that the primary hydroxyl groups, unlike
the secondary ones, are readily oxidized to the carboxyl
groups,8 easily overpassing the step of transient formation
of an aldehyde. Therefore, the formation of glutaric acid
as the major EO product of pentaneꢀ1,5ꢀdiol seems to be
quite appropriate. The formation of trace amounts of sucꢀ
cinic acid appears to be caused by the partial oxidation of
glutaric acid itself.
This process probably occurs also through 1,3ꢀmigraꢀ
tion of hydrogen to form a C=O group in αꢀposition to
the СООН group. The subsequent cleavage of the C—C
bond with elimination of CO2 results in succinic acid.
The oxidation of aliphatic acids at a NiOOH electrode in
an alkaline medium with the formation of lower homologs
of acids has earlier been described in literature.8
Thus, we suggest two alternative and convenient methꢀ
ods for electrochemical preparation of glutaric acid: the
oxidation of CP (the yield of the acid is 59%) and penꢀ
taneꢀ1,5ꢀdiol (the yield of the acid >90%). We discussed
the regularities of EO of cyclic ketones (cyclohexanone
and CP) that allow explaining the formation of the byꢀ
products, i.e., dicarboxylic acids with one or two carbon
atoms less in the chain, along with the target products
(adipic and glutaric acids).
Electrooxidation of pentaneꢀ1,5ꢀdiol to glutaric acid
(entry 1, Table 2). A 1 M NaOH solution (200 mL) and pentaneꢀ
1,5ꢀdiol (2.9 mL, 0.028 mol) were placed in the cell. The
electrolysis was carried out at 20 °C and a current of 0.744 A.
After passage of 8 F (Q = 21616 C) per mol of the diol, the
electrolysis was stopped. Workup of the reaction mixture (as
described above) afforded 3.36 g of the product, glutaric acid,
with admixture (1.75%) of succinic acid (identified by 1Н NMR
spectroscopy). The yield of glutaric acid was 91% (based on the
loaded pentaneꢀ1,5ꢀdiol). In order to determine the melting
point of glutaric acid, the powder (3.36 g, see above) was
recrystallized from С6Н6. M.p. 98—99 °С (m.p. 99 °C).20
Electrooxidation of cyclododecanone to dodecanedioic acid.
A 0.2 M KOH solution (200 mL) in 50% aqueous ButOH and
cyclododecanone (3.64 g, 0.02 mol) were placed in the cell. The
Experimental
The electrolysis was carried out in a galvanostatic mode
using the direct current source B5ꢀ8 in an undivided jacketed cell
with a Ni anode (S = 124 cm2) and a Ti cathode (S = 40 cm2).
The coulometer designed at the SCB IOC was connected to the
electric circuit. During the electrolysis, the reaction mixture
was stirred with a magnetic stirrer and a thermostat Uꢀ1 was
used to maintain constant temperature. Before the experiment,
the Ni anode was activated according to the procedure described
earlier:18 preliminary electrolysis was carried out in the solution
containing 0.1 M NiSO4, 0.1 M NaOAc, and 0.005 M NaOH, at
Ja = 1 mA cm–2 with periodical reverse of the electrodes

Electrosynthesis of glutaric acid
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009 2431
electrolysis was carried out at 20 °C and a current of 0.298 A
(Ja = 2.4 mA cm–2). After passage of 6 F (Q = 11580 C) per
mole of cyclododecanone, the electrolysis was stopped. The
reaction mixture was stirred for 0.5 h. Then ButOH was salted
out by the addition of solid NaCl. The aqueous and organic
layers were separated. ButOH was distilled off under reduced
pressure. The residue, remained after the distillation (nonꢀ
consumed ketone with the admixture of NaCl) was mixed with
water (5 mL) and treated with Et2O (2×10 mL). The nonꢀ
consumed cyclododecanone was additionally extracted from the
aqueous layer with Et2O (3×60 mL). The organic solutions were
combined and dried with Na2SO4. After evaporation of the
solvent, cyclododecanone (3.46 g) was obtained (identified by
1Н NMR spectroscopy), the degree of conversion of the ketone
was 5%. The aqueous layers (after isolation of the ketone) were
combined, acidified with concentrated HCI (to рН 1—2), then
water was distilled off under reduced pressure. The solid residue
was extracted with Ме2СО (4×50 mL). After evaporation of the
solvent, dodecanedioic acid (0.097 g) was obtained (identified
4. US Pat. 6.323.153; Chem. Abstr., 2001, 135, 368015а.
5. PCT Int. Appl. WO 01.28.340; Chem. Abstr., 2001, 134,
291.528q.
6. C. Adkins, J. Am. Chem. Soc., 1930, 52, 4349.
7. S. Mozingo, J. Am. Chem. Soc., 1944, 66, 1859.
8. H. J. Schäfer, Electrochem. 1, 1987, 142, 101.
9. R. P. Bell, P. W. Smith, J. Chem. Soc. (B), Phys. Org., 1966,
3, 241.
10. N. N. Lebedev, Khimiya i Tekhnologiya Osnovnogo Organiꢀ
cheskogo i Neftekhimicheskogo Sinteza [Chemistry and Techꢀ
nology of Basic Organic and Petrochemical Synthesis], 2nd Izd.,
Khimiya, Moscow, 1975, 736 pp. (in Russian).
11. W. F. Serat, J. F. Mead, Radiation Research, 1955, 11, 370.
12. W. Triebs, Ber., 1939, 72b, 1194.
13. S. Myrahashi, N. Komiya, Y. Oda, J. Org. Chem., 2000, 65,
9186.
14. G. I. Nikishin, E. I. Troyansky, Tetrahedron Lett., 1984, 25,
4987.
15. E. I. Troyanskii, V. V. Mizintsev, G. I. Nikishin, Izv. Akad.
Nauk SSSR, Ser. Khim., 1989, 2044 [Bull. Acad. Sci. USSR,
Div. Chem. Sci. (Engl. Transl.), 1989, 38, 1879].
16. H. Ruholl, H. J. Schäfer, Synthesis, 1988, 1, 54.
17. S. Ye, F. Beck, Electrochim. Acta, 1991, 36, 597.
18. J. Kaulen, H. J. Schaefer, Tetrahedron, 1982, 38, 3299.
19. HoubenꢀWeyl, Metoden der Organischen Chemie, Band II,
Analytische Methoden, Verlag Georg Tieme, Stuttgart, 1953.
20. Svoistva organicheskikh soedinenii (spravochnik) [Properties
of Organic Compounds (directory)], Ed. A. A. Potekhin,
Khimiya, Leningrad, 1984, 520 pp. (in Russian).
1
by Н NMR spectroscopy). The yield of the target product was
2.1% (based on the loaded ketone).
This work was financially supported by the Division of
Chemistry and Materials Science of the Russian Academy
of Sciences (program DCꢀ01).
References
1. B. V. Lyalin, V. A. Petrosyan, Izv. Akad. Nauk, Ser. Khim.,
2004, 657 [Russ. Chem. Bull., Int. Ed., 2004, 53, 688].
2. B. V. Lyalin, V. A. Petrosyan, Elektrokhimiya, 2005, 41,
1275 [Russ. J. Electrochem. (Engl. Transl.), 2005, 41, 1138].
3. B. V. Lyalin, V. A. Petrosyan, Izv. Akad. Nauk, Ser. Khim.,
2007, 481 [Russ. Chem. Bull., Int. Ed., 2007, 56, 499].
Received May 13, 2009;
in revised form July 2, 2009