Effect of electrolysis conditions on the process of anodic oxidation of tertiary phosphines in the presence of camphene

Article abstract of DOI:10.1134/S1070363212080075

Anodic oxidation of tertiary phosphines (Et₃P, Pr₃P, Bu₃P, i-Bu₃P and Am₃P) in the presence of camphene and heterogenic base (trisodium phosphate) on platinum anode in acetonitrile solution of sodium

Full text of DOI:10.1134/S1070363212080075

ISSN 1070-3632, Russian Journal of General Chemistry, 2012, Vol. 82, No. 8, pp. 1368–1373. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.A. Zagumennov, N.A. Sizova, 2012, published in Zhurnal Obshchei Khimii, 2012, Vol. 82, No. 8, pp. 1288–1293.
Effect of Electrolysis Conditions on the Process of Anodic
Oxidation of Tertiary Phosphines in the Presence of Camphene
V. A. Zagumennov and N. A. Sizova
Kazan (Volga Region) Federal University, ul. Kremlevskaya 18, Kazan, Tatarstan, 420008 Russia
e-mail: zagum@ksu.ru
Received May 23, 2011
Abstract—Anodic oxidation of tertiary phosphines (Et3P, Pr3P, Bu3P, i-Bu3P and Am3P) in the presence of
camphene and heterogenic base (trisodium phosphate) on platinum anode in acetonitrile solution of sodium
perchlorate was studied. It is established that trialkylphosphine radical cations react with camphene to give two
types of products: Camphenylphosphonium salts formed by elimination of proton, and phosphinimino-
terpenylphosphonium salts which are obtained due to the rearrangement of terpenyl skeleton. Conditions of
electrosynthesis are found where the summary yield of terpenylphosphonium products increases. The effect of
length and degree of branching of alkyl substituents in trialkylphosphines on the rate of the reaction of
phosphine radical cations with camphene and starting phosphine is found.
DOI: 10.1134/S1070363212080075
It was shown previously [1] that in the course of
anodic oxidation of tertiary phosphines in the presence
of camphene their addition to the terpene molecule
resulting in the formation of camphenylphosphonium
salts I [scheme (1)] takes place. It was found also that
the process was complicated by the parallel reaction
giving the protonated phosphines and phosphine
oxides II [scheme (2)]. The protonation of starting
phosphine by the protons eliminated from the
carbocation A increases the yields of R3PH+.
_
_e
R3P+
R3P
(1)
_
_e
R3P+
+
_H+
+
+
PR3
+ PR3
I
А
_
__e
+R3P, _e
+ +
R3PPR3
R3P+
R3P
(2)
+ +
+
R3PH + R3PO + H+
R3PPR3 + H2O
II
Note that in the course of electrosynthesis together
with the compounds I (δP 23–24 ppm), the protonated
phosphines (δP 10–15 ppm), the phosphine oxides II
(δP 52–56 ppm), and the other products are also
formed. They include quasiphosphonium salts R3P+OR
III (δP 60–62 ppm) and the compounds with δP at 30–
40 ppm, IV. The complete identification of the latter
was not carried out due to the complications while
isolation.
The aim of the present work was, firstly, to extend
the series of phosphines involved with the purpose of
1368

EFFECT OF ELECTROLYSIS CONDITIONS ON THE PROCESS OF ANODIC OXIDATION
1369
Results of preparative electrochemical oxidation of tertiary phosphines in the presence of camphene (platinum anode,
trisodium phosphate as a base)a
Parameters of electrolysis
Camphene
Run
no.
Content of products in the reaction mixture (δP, ppm)
R3P (М)
concentration,
by 31P NMR data
i,
F,
φ, V
mA cm–2
F mol–1
М
1
2
3
4
Et (0.025)
Et (0.0172)
Pr (0.035)
Pr (0.044)
0.030
0.029
0.037
0.040
0.036
0.032
0.037
0.037
0.037
0.030
0.2–3
0.4–5
0.6–1.0 0.95 I (29.4); 41%, II (54.5); 31%, III (60.5); 9%, IV (40.1 + 37.2); 19%
0.6–1.0 0.93 I (29.7); 19%, II (56.4); 53%, III (62.2); 9%, IV (40.4 + 37.9); 19%
0.4–3.5 0.6–1.0 1.12 I (22.5); 32%, II (55.0); 34%, III (60.8); 6%, IV (34.2 + 31.6); 28%
0.04–0.6 0.8–1.4 0.4 I (22.6); 12%, II (53.9); 64%, III (59.1); 8%, IV (33.4 + 31.0); 16%
5b Pr (0.034)
Bu (0.0326)
7b Bu (0.0345)
0.2–2
0.4–2
0.1–2
0.7–1.0 0.61 I (22.2); 15%, II (56.3); 18%, III (60.1); 4%, IV (31.1 + 34.0); 11%
0.6–1.0 0.96 I (23.7); 28%, II (52.1); 47%, III (59.3); 8%, IV (35.0 + 32.2); 17%
0.7–0.9 0.63 I (23.8); 21%, II (56.0); 19%, III (60.7); 6%, IV (32.6 + 35.1); 11%
6
8
9
i-Bu (0.032)
0.2–2.8 0.7–1.0 1.1
I (19.6); 39%, II (47.5); 38%, III (56.0); 9%, IV (34.9 + 29.1); 14%
Am (0.035)
0.2–1.6 0.7–1.2 0.56 I (23.7); 12%, II (53.2); 65%, III (60.0); 10%, IV (34.9 + 32.1); 13%
0.1–0.2 0.8–1.6 0.63 I (18.9); 3%, II (42.8); 95%, IV (30.7 + 27.6); 2%
10 Bu2PPh (0.025)
a Amount of electricity consumed for oxidation of phosphine, F mol–1. b Data of [1].
establishing the effect of structure of substituents
at phosphorus on the ratio of products of electrolysis.
The second goal was to develop optimal conditions
of performing electrolysis and isolation of the pro-
mol because some part of phosphine was previously
excluded from the anode process due to protonation [1].
For the evaluation of the effect of electrochemical
parameters of electrolysis on the yield of the target
products I and IV we carried out additional elec-
trolyses. Hence, two experiments with triethyl-
phosphine (see the table, exp. nos. 1 and 2) differed
only in the value of the anode current density. As seen
from the table it is necessary to maintain definite i
values for obtaining camphenylphosphonium salts in
high yield. It is found that it must not exceed
3 mA cm–2. The increase in the current density value to
5 mA cm–2 leads to the twofold decrease in the content
of the product I in the reaction mixture. At the same
time amount of phosphine oxide II increases 1,5-fold.
Yields of the other products do not change.
ducts
for
establishing
their
structure
by
physicochemical methods, for example, by NMR
spectroscopy. Changes in the conditions of performing
the electrolysis first of all included the addition of
trisodium phosphate for neutralization of evolving
protons. It should lead to an increase in the yield of the
target products due to the prevention of protonation of
phosphines.
The experiments were carried out on a platinum
anode in a galvanostatic regime in a definite range of
current density with the simultaneous control of the
anode potential. As it was expected, the change in the
conditions of electrolysis lead practically to complete
absence of protonated phosphines in the reaction
mixture. Besides, a complete absence of the products
with chemical shifts about 40 ppm was observed. The
upfield shift of signals of phosphine oxides was
observed as well. The obtained results are generalized
in the table.
The value of the maintained anode potential is also
important for the electrochemical processes under
study. It is clearly seen that while performing
electrolysis at the potentials above 1 V (see exp. nos. 4
and 9) the yields of camphenylphosphonium salts
(about 30–40% in the reaction mixture under optimal
conditions) decrease to 12% while the part of
phosphine oxides increases from 30–45% to 64–64%.
It is surprising that performing electrolysis at the anode
potentials above 1.0 V proceeds at lower values of
current density. For example, while at the electrolysis
of tripropylphosphine (see exp. no. 3) under optimal
conditions the current density value was maintained up
As seen from the table, the addition of the base
leads to an increase in the yield of all the products of
electrosysis (save compound III). It is due to involving
in further electrolysis of the additional amount of
phosphine which is confirmed by the increase in the
amount of consumed electricity from 0.6 to 1 F per
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 8 2012

1370
ZAGUMENNOV, SIZOVA
to 3.5 mA cm–2, during the oxidation at higher
potentials (exp. no. 4) the initially set current density
of 5 mA cm–2 could be maintained only for a small
period of time, about several minutes, but then we
were compelled to decrease i sharply to the value
approximately 8 times lower due to the shift of the
anode potential to more positive range up to the area of
oxidation of camphene (1.4–1.5 V). Probably at higher
anode potentials the adsorption of the solution
components on electrode takes place causing the
passivation of the latter and hence the current density
decreases at the controlled anode potential. As seen
from the results, the adsorption of the solution
components favors the increase in the rate of
electrooxidation of phosphines to phosphine oxides.
Probably under these conditions the adsorbed
trialkylphosphines are oxidized.
phosphorus. Triisobutylphosphine with the branched
substituent showed the result the most close to tri-
propylphosphine which is evidently connected with
definite sterical hindrances in the formation of di-
phosphonium salt.
It follows from the obtained results that the change
in the conditions of the experiment (addition of
trisodium phosphate, choice of the optimal electro-
chemical parameters) besides the increase in the yield
of the target products leads to the decrease in the
number of the products formed in the course of the
electrolysis. Therefore it became possible to isolate
each product in the pure state that had been previously
impossible [1]. The strategy of separation of com-
pounds was as follows. In the first stage phosphorus-
containing compounds I and IV potentially having
terpene substituents were separated from phosphine
oxides II and quasiphosphonium salts III by column
chromatography. It was found that such chromato-
graphic separation was possible in many polar organic
solvents like acetone, acetonitrile, ethanol, chloroform
or dichloromethane. In the next step attempts were
made of separation of camphenylphosphonium salts I
from the other products of electrolysis using different
methods like extraction, column chromatography or
precipitation of one of the components of the mixture
with suitable solvent. The optimal conditions of
separation are described in Experimental.
Hence, the analysis of the effect of electrochemical
conditions of the experiment showed that for the
increase in the yield of camphenylphosphonium salt it
was desirable to carry out the process at current
densities about 2–3 mA cm–2 and the anode potential
excluding the adsorption of phosphines on electrode
(up to 1.0 V). The importance of adsorption is
confirmed by the experiments on the carbon-glass
anode when the yields of phosphine oxides increased
because of the passivation of anode [1]. Electrolyses
with triphenylphosphine and dibutylphenylphosphine
(see the table, no. 10) showed that these compounds
passivate anode even at lower voltage of electrolysis
which practically results in a quantitative electro-
synthesis only of oxides of these compounds (90–95%
in the reaction mixture).
In [2] it was established that in the case of
triethylphosphine the fraction with the increased
content of product I could be obtained by column
chromatography. We managed to isolate a fraction
with 92% content of this compound (see Experi-
mental). The crystallization of this fraction from
methanol gave white needle-like precipitate. Accord-
ing to XRD analysis it was triethylcamphenyl-
phosphonium perchlorate [3]. It is interesting to note
that this compound crystallizes in the conglomerate
form when each optical isomer forms its own crystals.
It takes place despite the fact that racemic camphene
was exposed to electrochemical phosphorylation (see
the figure).
The obtained data permit the evaluation of the
effect of alkyl substituents in phosphines on the ratio
of two main reactions [schemes (1) and (2)]. As seen
from the table (exp. nos. 1, 3, 6, 8, 9) in the
experiments performed under optimal conditions the
increase in the amount of product IV in the reaction
mixture is observed with the elongation of chain in the
substituents of normal structure. It shows that at the
increase in the length of the chain the ratio of the rates
of the reactions of radical cations of trialkylphosphines
with camphene and the starting phosphine [schemes (1)
and (2)] changes to the side of the increase in the
relative rate of diphosphonium salts formation. It may
be ascribed to a higher stabilization of intermediates
formed in the course of the synthesis of diphos-
phonium salts due to the increase in the electron-
donating properties of hydrocarbon substituents on
1
In the H NMR spectrum of triethylcamphenyl-
phosphonium salt alongside the intense signals of
protons of triethylphosphino group (δ 1.09 and
2.36 ppm) a doublet signal of proton at the double
bond with the geminal coupling constant with
2
phosphorus (δ 5.12 ppm, JPH 18.6 Hz) is observed.
Downfield shift of the signal as compared to the values
in starting camphene (4.17 and 4.50 ppm) [4] is due to
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 8 2012

EFFECT OF ELECTROLYSIS CONDITIONS ON THE PROCESS OF ANODIC OXIDATION
1371
the effect of closely located phosphine group.
Phosphine substituent which according to X-ray data
[3] is trans-located in relation to the gem-dimethyl
group also strongly affects tertiary protons on C1 and
C4 carbon atoms (numbering of atoms corresponds to
that shown in the figure). These protons give signals at
3.01 and 2.02 ppm instead of 2.65 and 1.89 ppm in
camphene respectively. Probably due to the influence
of phosphorus the signals of protons on C5 carbon
atom are observed at 1.13 and 1.91 ppm instead of
1.21–1.25 and 1.62–1.64 ppm as in the starting
camphene [4].
New procedure of separation of the products of
electrosynthesis with the initial separation of
phosphine oxides and quasiphosphonium salts permits
not only to obtain the fractions with the increased
content of camphenylphosphonium salts I but also the
fractions containing the compounds with chemical
shifts δP in the range 30–40 ppm. NMR spectra of
these fractions show that their main components are
Crystalline structure of triethylcamphenylphosphonium
perchlorate [3].
probably the individual compounds containing two
different phosphonium substituents. The compound
with tripropylphosphine substituents (δP 34.2 and
31.6 ppm) we managed to isolate in a pure state. In the
1H NMR spectrum of this product increased integral
intensity of the methyl proton signals in phosphino
groups is observed as compared to the intensity of
gem-dimethyl protons (3:1 while in compound I it is
equal to 3:2), the absence of signals of the double bond
protons, the appearance of signal at d 3.82 ppm, and a
quartet at δ ~2.63 ppm are observed. The signals at δ
~2.63 ppm most probably belong to PCH2 protons (δ
imino) group which could be formed only from
acetonitrile used as a solvent. The absence of N–H
bond vibrations in the IR spectrum supports the imine
structure of this substituent. It is presumable that the
synthesis of this product proceeds as the rearrangement
of the terpene skeleton including the intermediate
cycle opening in the carbocation A and the subsequent
addition of acetonitrile molecule to the new cationic
center. Further stabilization of this intermediate
includes the reaction of iminocation with the second
molecule of phosphine resulting in the formation of
phosphiniminoterpenylphosphonium salt [scheme (3)].
The exact pathway of rearrangement of the carbocation
A (cycle opening with the formation of monocyclic
product as it was suggested in [1] or the Wagner
rearrangement) is not clear nowadays. Though the
nonequivalence of protons on C10 atom (numbering of
atoms is shown in the figure) in the molecule IV (δ
2.61 and 2.64 ppm) may be explained by the presence
of the adjacent asymmetric carbon atom (which
indirectly confirms the hypothesis about the bornane
structure of this compound and the occurrence of the
camphene-bornane rearrangement) the refining of the
structure of this compound requires further studies.
2
2
2.61 ppm, JPH 16 Hz; d 2.64 ppm, JPH 13 Hz). The
absence of signals of the double bond protons together
with the simultaneous appearance of the PCH2 group
proves that compound IV is saturated. Unexpected
appearance of a singlet at 3.8 ppm characteristic of the
protons bound with nitrogen or the protons of NCH
fragment permits a suggestion that the product
contains the imine or acetamide group. It is quite
possible because the electrosyntheses were carried out
in acetonitrile. The reactions of electrochemical
acetamidation by anodic generation of various carbo-
cations in the presence of acetonitrile were reported
[5]. The presence of the signal of the methyl group
bound to acetamide or imino group confirms this
hypothesis (a doublet at 2.35 ppm, 3JPH 9 Hz).
Hence, the analysis of 1H NMR spectrum of
compound IV permits a conclusion that it is a saturated
salt with two phosphonium and one acetamide (or
Hence, the obtained results show that in the course
of the anodic addition of trialkylphosphine radical
cations to the terpene molecule the initially formed
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 8 2012

1372
ZAGUMENNOV, SIZOVA
_
_e
R3P+
R3P
_
_e
+
+
R3P+
+
R3P(S)
(3)
+
+
PR3
А
+R3P
+
+
+
+
+
+
N
CCH3
R3P(S) +
R P(S)
N
C(CH3)
R3P(S)N C(CH3)PR3
3
S = terpene hydrocarbon skeleton.
carbocation A may be stabilized by two pathways.
First one includes elimination of proton from the
adjacent exocyclic carbon atom with the formation of
camphenylphosphonium salts [scheme (1)]. Another
one includes rearrangement of the terpene skeleton
leading to new cationic center which adds an
acetonitrile molecule. After that the addition of tertiary
phosphine to the imino group takes place [scheme (3)].
For the evaluation of structural peculiarities of the
products of electrosynthesis investigation of these
compounds by NMR on different nuclei and two-
dimensional spectroscopy is planned.
trialkylphosphine were added to this electrolyte in
small portions. Amounts of camphene and trialkyl-
phosphite taken in each experiment and also the
parameters of electrolysis such as operating values of
current density, anode potentials, and the amount of
consumed electricity are shown in the table. After the
completion of electrolysis trisodium phosphate was
filtered off, solvent was evaporated in a vacuum, and
the residue was treated with 100 ml of dichloro-
methane to remove sodium perchlorate from the pro-
ducts of electrosynthesis. Dichloromethane solution
was evaporated. Compositions of reaction mixtures ac-
31
cording to P NMR data are listed in the table. Reac-
EXPERIMENTAL
tion mixtures were chromatographed on a 50×15 cm
column filled with silica gel (Acros Organics, 0.035–
0.070 mm, pore diameter 6 nm).
NMR spectra were taken on a Varian Unity 300
1
spectrometer (300 MHz H; 121 MHz 31P against
external 85% H3PO4). IR spectra were recorded on a
UR-20 spectrometer.
Procedure for isolation of the products of
electrosynthesis. a. Experiments with triethyl-
phosphine. The composition of fractions obtained by
chromatographic isolation (elution with chloroform)
according to the 31P NMR data was the following.
Fraction 1: compound I, 92%; compound IV, 8%; 1.0 g
of this fraction was dissolved in 10 ml of dry
methanol. Under slow cooling 0.2 g of white
crystalline precipitate identified as (2,2-dimethyl-3-
methylidenenorbornane)triethylphosphonium perchlo-
rate was isolated, mp 107–110°C. XRD analysis data
Conditions of electrosynthesis. Preparative elec-
trochemical oxidation was carried out in a glass cell
with 100 ml anode and cathode volumes separated
from one another with a porous diaphragm. It was
performed in the galvanostatic regime with the
constantly controlled anode potential. P-5827M
potentiostate was used as a current source. Platinum
cylinder with the working surface 50 cm2 was used as
anode. Nickel spiral with the surface area 20 cm2 was
used as an auxiliary electrode (cathode). Anode
potential in the course of electrosynthesis was
measured against Ag/Ag+ (0.01M AgNO3 in aceto-
nitrile) reference electrode. The process was carried
out under argon, and the electrolyte was constantly
stirred.
13
for this substance are presented in [3], and its C and
1
31P NMR spectral data are reported in [2]. H NMR
2
spectrum (CDCl3), δ, ppm: 5.18 d (1H, H10, JPH
18.2 Hz), 3.01 s (1H, H1), 2.28 d.q (6H, PCH2CH3,
3
2JPH 12.3Hz, JHH 7.7 Hz), 2.02 s (1H, H4), 1.19 t (9H,
PCH2CH3, 3JHH 7.7 Hz), 1.09 s [3H, (CH3)2C], 1.10 s [3H,
(CH3)2C], protons of camphene ring: 1.11–1.15 m
(1H), 1.38–1.52 m (2H), 1.68–1.80 m (1H), 1.85–1.93
m (1H). Fraction 2: compound I, 61%; IV, 27%;
Sodium perchlorate, 5–6 g, and trisodium phos-
phate, 5–7 g, were dissolved in a mixture of 60 ml of
acetonitrile and 10 ml of THF. Camphene and
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 8 2012

EFFECT OF ELECTROLYSIS CONDITIONS ON THE PROCESS OF ANODIC OXIDATION
1373
unknown compound (δP 41.3 ppm), 12%. Fraction 3:
compound I, 3%; III, 2%; IV, 82%; unknown
compound (δP 41.3 ppm), 13%. H NMR spectrum
compound I, 26%; II, 36%; III, 13%; IV, 21%; un-
known compound (δP 34.8 ppm), 4%. Fraction 3: com-
pound I, 12%; compound II, 54%; III, 15%; IV, 19%.
1
(CDCl3), δ, ppm (signals only of compound IV): 3.86
d. Experiments with triisobutylphosphine. Com-
position of fractions obtained by chromatography
(elution with 4:1 acetonitrile-diethyl ether) on the basis
of 31P NMR data: Fraction 1: compound I, 83%; IV –
d.d (NCH), 2.60–2.66 d.d (PCH2, 2JPH 13.0 Hz), 2.26 d
3
[CH3C(PEt3)=N, JPH 9.0 Hz]. Fraction 4: compound
I, 1%; II, 59%; III, 36%; IV, 4%.
1
10%, unknown compound (δP 36.2 ppm), 7%. H
b. Experiments with tripropylphosphine. Com-
position of fractions obtained by chromatography
(elution with acetonitrile) on the basis of 31P NMR
data is as follows: Fraction 1: compound I, 56%; IV,
NMR spectrum of the fraction (CDCl3), δ, ppm: 5.10 d
2
(H10, JPH 18.4 Hz), 2.99 s (H1), 2.28 m [PCH2CH·
(CH3)2], 2.01 s (H4), 1.88 m [PCH2CH(CH3)2], 1.01 d
3
1
[PCH2CH(CH3)2, JHH 7.8 Hz]. Fraction 2: compound
32%; unknown compound (δP 35.5 ppm), 12%. H
I, 68%; II, 26%; unknown compound (δP 36.2 ppm),
6%. Fraction 3: compound II, 92%; III, 8%. While
dissolution of fraction 2 in 4:1 methanol-diethyl ether
and cooling the crystals of pure compound I are
formed. 1H NMR spectrum was identical to the above-
presented data.
NMR spectrum (CDCl3), δ, ppm (signals only of
2
compound I): 5.12 d (1H, H10, JPH 18.0 Hz), 3.11 s
(1H, H1), 1.10 s [3H, (CH3)2C], 1.08 s [3H, (CH3)2C].
Fraction 2: compound I, 43%; II, 27%; IV, 18%;
unknown compound (δP 35.5 ppm), 12%. Fraction 3:
compound I, 27%; II, 45%; III, 9%; IV, 19%.
Fraction 4: compound I, 1%; compound II, 63%; III,
33%; IV, 3%. Fractions 1 and 2 were joined and
dissolved in a mixture of methanol with diethyl ether
(4:1 vol/vol). Cooling of the solution obtained yielded
a precipitate containing 12% of compound II and 88%
of compound IV. Repeated crystallization from me-
thanol gave pure compound IV (δP 34.7 and 32.1 ppm).
IR spectrum, (mull in mineral oil), ν, cm–1: 1073 br
(ClO4), 1606 w (C=N). 1H NMR spectrum (CDCl3), δ,
ppm: 3.82 s (1H, H1), 2.64 d [1H, PCH2(A), 2JPH 13.0 Hz],
e. Experiments with tripentylphosphine. Com-
position of fractions obtained by chromatography
(elution with 4:1 acetonitrile-diethyl ether) on the basis
of 31P NMR data: Fraction 1: compound I, 54%; II,
5%; III, 10%; IV, 26%. Fraction 2: compound I,
15%; II, 65%; III, 15%; IV, 5%. Fraction 3:
compound II, 76%; III, 11%; IV, 3%; unknown
compound (δP 40.5 ppm), 10%.
f. Experiments with dibutylphenylphosphine. By
column chromatography (elution with acetone) the
following fraction was isolated: compound I, 35%, II,
2
2.61 d [1H, PCH2(A1), JPH 13.0 Hz], 2.30–2.42 m
3
[6H, PCH2CH2CH3(C=N), JHH 7.8 Hz], 2.28 d [3H,
1
59%, IV, 6%. H NMR spectrum (CDCl3), δ, ppm:
3
CH3C(PPr3)=N, JPH 9.0 Hz], 2.22–2.28 m (6H,
7.0–8.0 (phenyl ring protons), 1.90–2.22
m
1
PCH2CH2CH3, JHH 7.8 Hz), 1.50–1.64 m (12H,
(PCH2CH2CH2CH3), 1.62–1.68 m (PCH2CH2CH2CH3),
1.40–1.46 m (PCH2CH2CH2CH3), 0.88–0.92 t (PCH2·
CH2CH2CH3), clearly seen minor signal 5.51 d (2JPH
20.4 Hz).
PCH2CH2CH3), 1.05–1.12 m (18H, PCH2CH2CH3),
0.99 s [3H, (CH3)2C], 0.96 s [3H, (CH3)2C], protons of
the hydrocarbon skeleton: 1.30–1.38 m (1H), 1.40–
1.48 m (1H), 1.68–1.72 m (2H), 1.74–1.88 m (2H),
2.22 s (1H). 31P NMR spectrum, δP, ppm: 34.7, 32.1.
REFERENCES
c. Experiments with tributylphosphine. Com-
position of fractions obtained by chromatography
(elution with dichloromethane) on the basis of 31P
NMR data: Fraction 1: compound I, 84%; IV, 12%;
unknown compound (δP 34.8 ppm), 4%. H NMR
spectrum (CDCl3), δ, ppm: phosphine group protons
2.28 m (PCH2CH2CH2CH3), 1.42–1.45 m (PCH2·
1. Zagumennov, V.A., Sizova, N.A., and Nikitin, E.V., Zh.
Obshch. Khim., 2009, vol. 79, no. 7, p. 1116.
2. Zagumennov, V.A., Saifutdinov, A.M., Nikitin, E.V.,
Khairutdinov, B.I., and Klochkov, V.V., Zh. Obshch.
Khim., 2005, vol. 75, no. 10, p. 1746.
3. Zagumennov, V.A., Sizova, N.A., Lodochnikova, O.A.,
and Litvinov, I.A., Zh. Strukt. Khim., 2012, vol. 53,
no. 1, p. 209.
4. Silva, M.I., Gonsalves, J.A., Alves, R.B., Howarth, O.W.,
and Gusevskaya, E.N., J. Organomet. Chem., 2004,
vol. 689, no. 2, p. 302.
5. Baizer, M.M. and Lund, Kh., Organicheskaya elektro-
khimiya (Organic Electrochemistry), Moscow: Khimiya,
1988.
1
CH2CH2CH3), 0.90–0.96
m
(PCH2CH2CH2CH3);
clearly seen signals of compound I: 5.12 d (1H, H10,
2JPH 18.2 Hz), 3.00 s (1H, H1), 2.02 s (1H, H4), 1.12 s
[3H, (CH3)2C], 1.10 s [3H, (CH3)2C]; clearly seen
signals of compound IV: 3.82 d (1H, CHN), 2.56–2.60
d.d (2H, PCH2), 0.82 s [3H, (CH3)2C]. Fraction 2:
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 8 2012