Electrochemical synthesis of pentamethylenediazirine

Article abstract of DOI:10.1007/s11172-006-0544-0

Electrochemical synthesis of pentamethylenediazirine at the Pt/Ti anode was conducted. The reaction is reversible. The rate constants of the direct and reverse processes were estimated. The product and current yields of the target compound approach to 100%.

Full text of DOI:10.1007/s11172-006-0544-0

Russian Chemical Bulletin, International Edition, Vol. 55, No. 11, pp. 2013—2015, November, 2006
2013
Electrochemical synthesis of pentamethylenediazirine*
M. D. Vedenyapina,a V. V. Kuznetsov,a E. A. Nizhnikovskii,b E. D. Strel´tsova,a N. N. Makhova,a
ꢀ
M. I. Struchkova,a and A. A. Vedenyapina
ꢀ
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (495) 135 5332. Eꢀmail: mvedenyapina@yandex.ru
bInterdepartment Scientific Council on Complex Problems of Physics, Chemistry, and Biology
at the Presidium of the Russian Academy of Sciences,
5 ul. Dm. Ul´yanova, 119333 Moscow, Russian Federation.
Fax: +7 (495) 914 8654. Eꢀmail: nizhnikovsky@mail.ru
Electrochemical synthesis of pentamethylenediazirine at the Pt/Ti anode was conducted.
The reaction is reversible. The rate constants of the direct and reverse processes were estimated.
The product and current yields of the target compound approach to 100%.
Key words: pentamethylenediazirine, pentamethylenediaziridine, electrochemical synthesis.
Diazirines are efficient sources of carbenes.1 For inꢀ
stance, photolysis of pentamethylenediazirine 1 under high
pressure affords cyclohexene 2 in high yield (Scheme 1).2
The oxidation products of compound 3 in an undiꢀ
vided cell using the Pt/Ti anode were analyzed by 1H,
13С NMR and UV spectroscopy. The analysis showed
that the oxidation of compound 3 affords up to 50% of
compound 1 without formation of byꢀproducts. The
UV spectra of the electrolyte containing a mixture of comꢀ
pounds 1 and 3 coincided with the published5 spectra of
compound 1. The UV spectra of a solution of compound 3
oxidized in an undivided cell upon passing different
amounts of electricity are shown in Fig. 1. When the
content of compound 1 increases monotonically, the conꢀ
tent of compound 3 decreases, correspondingly, to some
limiting value (Fig. 2) equal approximately to 50%, which
can be due to reversibility of the process in an undivided
cell. This conclusion was completely confirmed by the
electrolysis of the initial compound in a diaphragmꢀdiꢀ
vided cell loaded with a mixture of equal amounts of
compounds 1 and 3. In the presence of a diaphragm, the
initial substrate in this mixture can be oxidized with alꢀ
most 100% conversion, i.e., until the initial substrate disꢀ
appeared completely (Fig. 3).
Scheme 1
Usual methods for the synthesis of diazirines are the
oxidation of the corresponding diaziridines with mercury
oxide, bichromate, silver oxide, and others.
In the present work, compound 1 was synthesized by
the electrochemical oxidation of pentamethylenediꢀ
aziridine 3 (Scheme 2).3,4
Using the data presented in Fig. 3, we estimated the
rate constant of substrate oxidation in the direct pathꢀ
way (k) by the firstꢀorder equation
Scheme 2
Сt/С0 = ехр(–kt),
(1)
where С0 and Сt are the initial concentration of comꢀ
pound 3 and its concentration to the moment t. The
k value was 0.12 h–1. The curve for the consumption of
compound 3 calculated by the firstꢀorder equation with
k = 0.12 h–1 is shown in Fig. 3. Since in the absence of a
diaphragm and in equilibrium the contents of the initial
* Dedicated to Academician O. M. Nefedov on the occasion of
his 75th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1939—1941, November, 2006.
1066ꢀ5285/06/5511ꢀ2013 © 2006 Springer Science+Business Media, Inc.

2014
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 11, November, 2006
Vedenyapina et al.
A (%)
Y (%)
100
4, 5
1
2
80
60
40
20
3
90
80
70
60
50
2
1
0
1
2
3
4
t/h
Fig. 2. Dependence of the content of compound 3 on the elecꢀ
trolysis time for an undivided cell according to the data of
UV spectroscopy (1) and iodometry (2). Solid line is theoretical.
300
350
400
450
λ/nm
Fig. 1. Change in the UV spectra of pentamethylenediaziridine
with the electrolysis time. The amount of electricity passed
through an undivided cell: 0.6 (1), 0.9 (2), 1.2 (3), 1.5 (4), and
1.8 kC (5).
Y (%)
50
substrate and reaction product are equal, the equilibrium
constant should be equal to 1, i.e., the rate constant of the
reverse reaction k´ should be equal to the rate constant of
the direct reaction k.
Using the values of rate constants for the direct and
reverse reactions, we calculated the curve of accumulaꢀ
tion of compound 1 in the absence of a diaphragm. In this
case, the overall process is described by a system of differꢀ
ential equations
40
30
20
10
0
5
10
15
20
t/h
(2)
Fig. 3. Dependence of the content of compound 3 on the elecꢀ
trolysis time according to the iodometry data for a divided cell.
Solid line is the calculation of the content of compound 3 by the
firstꢀorder equation.
where С1 and С2 are the concentrations of the initial subꢀ
strate and reaction products, respectively. The k and
k´ values for an undivided cell were calculated from the
constant values obtained for a divided cell taking into
account that the current density in an undivided cell is by
2.5 times higher than that in a divided cell. Therefore, for
an undivided cell the k and k´ values were accepted to be
2.5k or 0.3 h–1. In this case, the calculated data agree with
the experimental results.
decreases with an increase in the conversion, although it
remains at a rather high level (Fig. 4).
Potentiometric studies of a working solution of comꢀ
pound 1 in the background electrolyte at the platinum
microelectrodes showed that in the whole potential reꢀ
gion (from hydrogen evolution at the cathode to oxygen
evolution at the anode) the I,E curves in the initial soluꢀ
tion virtually coincide with the curves recorded in the
background solution. This implies that the oxidation of
compound 3 occurs in a region of higher anodic potenꢀ
tials (simultaneously with oxygen evolution) or it is a
secondary process, for instance, chemical oxidation inꢀ
volving oxygen evolved at the anode.
The current yields (J ) of compound 1 for the both
types of cells were calculated by the formula
J = 2nyF/100%•It,
where у is the conversion of the initial compound, F is the
amount of passed electricity, n is the number of moles of
the initial substrate, t is the time of achievement of the у
conversion, and I is the total current. The current yield

Synthesis of pentamethylenediazirine
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 11, November, 2006 2015
J (%)
the absorption of the solution at the wavelength 352 nm.
Iodometric analysis of the content of compound 3 was the same
as in Ref. 5.
To determine the composition of the electrolysis products of
compound 3 performed in cells of both types, the reaction
mixture was saturated with К2СО3 and extracted with Et2O
(3×50 mL). The extract was dried over К2СО3, the solvent was
distilled off under atmospheric pressure, and the residue was
distilled collecting the fraction with b.p. 30—35 °C (30 Torr).
The product was obtained in 49.8% yield (0.98 g, 8.9 mmol).
(The boiling point, nd20, and elemental analysis of the obtained
sample coincided with the characteristics published6 for comꢀ
1
2
80
60
40
20
1
pound 1.) Н NMR of compound 1 (CDCl3), δ: 1.14 (m, 4 Н,
2 НС(2), 2 НС(6)); 1.55 (m, 2 Н, 2 НС(4)); 1.68 (m, 4 Н,
2 НС(3), 2 НС(5)). 13С NMR (CDCl3), δ: 24.5 (t, С(3), С(5),
1J = 128.0 Hz); 25.3 (t, С(4), 1J = 127.0 Hz); 28.2 (s, C(1)); 31.7
(t, С(2), С(6), 1J = 129.0 Hz). Diazirine 1 was additionally
characterized by the HSQСꢀqs and HMBCꢀqs methods. Correꢀ
lation through the bond of the 1Н—13С(3), 1Н—13С(4), and
1Н—13С(2) signals was observed in the 2D HSQСꢀqs spectrum.
The 2D HMBCꢀqs spectrum exhibited signal correlation
through the two bonds 1Н—С(2)—13С(3), 1Н—С(3)—13С(4),
1Н—С(3)—13С(2), and 1Н—С(2)—13С(1) and through three
bonds 1Н—С(2)—С(3)—13С(4), 1Н—С(3)—С(2)—13С(1), and
1Н—С(4)—С(3)—13С(2).
To elucidate the nature of electrodic processes leading to the
oxidation of compound 3, potentiometric studies at the Pt elecꢀ
trode with a diameter of 0.5 mm were carried out at a potential
sweep of 20 and 50 mV s–1 using the silver oxide reference elecꢀ
trode.
0
1
2
3
4
t/h
Fig. 4. Change in the current yield (J ) of compound 1 during
electrolysis of compound 3 for an undivided cell according to
the data of iodometry (1) and UV spectroscopy (2).
Thus, the results obtained indicate that the electroꢀ
chemical synthesis of compound 1 from 3 can be carried
out easily and with high current yield using platinated
titanium.
Experimental
1
H NMR spectra were recorded on Bruker WMꢀ250
The authors are grateful to A. M. Skundin for taking
part in discussion of the results.
(250 MHz) and Bruker DRXꢀ500 (500 MHz) spectrometers.
13C NMR spectra were obtained on Bruker AMꢀ300 (75.5 MHz)
and Bruker DRXꢀ500 (125 MHz) spectrometers relative to the
signal of Me4Si,
References
The initial pentamethylenediaziridine 3 was synthesized acꢀ
cording to a previously described procedure6 and additionally
characterized by the 1H and 13C NMR spectra, which coincided
with the published7 spectra. The melting point of compound 3
(103 °C) coincided with that given in Ref. 6. 13C NMR without
proton decoupling (CDCl3), δ: 24.4 (t, С(3), С(5), 1J =
129.4 Hz); 24.6 (t, С(4), 1J = 129.3 Hz); 35.7 (t, С(2), С(6),
1J = 128.0 Hz); 56.9 (s, C(1), 2J = 5.1 Hz).
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75, 723.
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6. E. Schmitz and R. Ohme, Chem. Ber., 1961, 94, 2166.
7. J. Hiroyuki. H. Kiyoto, S. Hiroyasu, J. Yoshio, and
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A 1% solution of compound 3 in a background 0.1 N soluꢀ
tion of К2СО3 in an aqueousꢀethanol (1 : 1) mixture was subꢀ
jected to electrolysis. Electrolysis was carried out in cells
with both divided anodic and cathodic spaces and without a
diaphragm. In the both cases, perforated platinated titanium
with a thickness of the platinum galvanic coating of 5 µm was
used as the anode and the cathode was titanium. Electrolysis
was performed in the galvanostatic regime using a PIꢀ50
potentiostat. The current density based on the surface of
the anodes and electrolyte volume for an undivided cell was
1.25 A dm–2 and 1.0 A dm–3, respectively; that for a divided cell
was 0.5 A dm–2 and 0.35 A dm–3, respectively. The process was
conducted at a constant current. The composition of the prodꢀ
1
ucts was determined by H and 13С NMR. The reaction course
was monitored using two methods: iodometry and UV spectroꢀ
scopy. The content of compound 1 in the electrolyte was deterꢀ
mined by UV spectroscopy using a Specordꢀ40 instrument from
Received October 6, 2006;
in revised form October 20, 2006