Acylation of piperidine and morpholine with phenyl benzoates in the mixtures water-2-propanol and water-dioxane

Article abstract of DOI:10.1134/S1070363215060109

Kinetics of acylation of piperidine and morpholine with 4-nitro- and 2,6-dinitrophenyl benzoates was studied in binary systems water-2-propanol and water-dioxane. Structural and energy characteristics of solvate complexes of morpholine and piperidine with the components of the mixed solvents were calculated. Kinetic regularities of acylation are considered from the viewpoint of specific solvation of amines.

Full text of DOI:10.1134/S1070363215060109

ISSN 1070-3632, Russian Journal of General Chemistry, 2015, Vol. 85, No. 6, pp. 1416–1423. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © L.B. Kochetova, N.V. Kalinina, L.V. Kuritsyn, T.P. Kustova, 2015, published in Zhurnal Obshchei Khimii, 2015, Vol. 85, No. 6,
pp. 949–956.
Acylation of Piperidine and Morpholine with Phenyl Benzoates
in the Mixtures Water–2-Propanol and Water–Dioxane
L. B. Kochetova, N. V. Kalinina, L. V. Kuritsyn, and T. P. Kustova
Ivanovo State University, ul. Ermaka 39, Ivanovo, 153025 Russia
e-mail: kochetova_lb@mail.ru
Received February 2, 2015
Abstract—Kinetics of acylation of piperidine and morpholine with 4-nitro- and 2,6-dinitrophenyl benzoates
was studied in binary systems water–2-propanol and water–dioxane. Structural and energy characteristics of
solvate complexes of morpholine and piperidine with the components of the mixed solvents were calculated.
Kinetic regularities of acylation are considered from the viewpoint of specific solvation of amines.
Keywords: piperidine, morpholine, esters, acylation, specific solvation, solvate complexes
DOI: 10.1134/S1070363215060109
The interest to reactivity of heterocyclic amines in
the reactions of N-acylation is due to their wide
application in the synthesis of practically valuable
morpholine in the reaction with 4-nitrophenyl benzoate
I and 2,6-dinitrophenyl benzoate II in binary mixtures
water–2-propanol and water–dioxane.
compounds, first of all
–
biologically active
The processes occurring in the system are
represented by Eqs. (1) and (2) by the example of the
piperidine reaction with compound I. Along with
aminolysis [Eq. (1)], in water-organic medium the
hydrolysis of the ester [Eq. (2)] can proceed.
compounds, like drugs, inhibitors of enzymes,
pesticides. It is known that piperidine and morpholine
derivatives are low-toxic analgesics and anesthetics,
the piperidine ring is a constituent of a large number of
natural and synthetic alkaloids, morpholine acts as a
building block in the synthesis of antibiotics and
anticancer drugs [1–3].
NH(CH
2
)
5
+ PhCOOC
PhCON(CH + HOC
PhCOOC NO + H
2
PhCOOH + HOC NO .
6
H
4
NO
2
k
→
2
)
5
6
H
4
NO
2
,
(1)
(2)
Kinetic studies on model reactions aiming at
elucidation of the influence of the reagents structure
and effects of medium on the rate of the process are
important for optimization of the synthesis conditions
of the morpholine and piperidine acyl derivatives.
Nowadays, as one of such models, the reaction of
amines of different types with esters in solutions or
microemulsions is considered [4–7]. In the industrial
synthesis of amides, water–organic media are widely
used [8, 9], which allows to substantially vary the rate
of the target reaction and the simultaneously occurring
hydrolysis of the acylation agent [7]. However, no
systematic studies of the influence of the composition
of water-organic media on the reactions of amide
formation with participation of heterocyclic amines
were performed so far.
6
H
4
2
2
O
k
hydr
→
6
H
4
The rate of concentration variation of the acylation
agent under the condition c >> c is determined by
0
eff
Eq. (3).
dceff
– —— = (k + kc )c .
hydr
0
eff
(3)
dτ
Here, ceff denotes the concentration of ester at time
τ, c is the initial concentration of amine, k and khydr
0
denote the rate constants of reactions (1) and (2).
Our previous studies have shown that in water-
organic media at рН = 9–10 the rates of reactions (1)
and (2) are comparable, but at рН < 9 the rate of
hydrolysis of the esters decreases and becomes
negligible with respect to the rate of acylation [7, 10].
The present work consists in the experimental and
theoretical studies of the reactivity of piperidine and
1
416

ACYLATION OF PIPERIDINE AND MORPHOLINE WITH PHENYL BENZOATES
1417
To create the required рН value, a predetermined
amount of HCl was added to the solution of amine.
acylation reagents in the reaction of the acyl group
transfer, according to the available data [7, 10–13],
plays a subordinate role.
The concentration of the nonprotonated amine (c ) was
0
determined as the difference between its initial
concentration in the solution and the concentration of
НСI. The observed rate constant kobs taking into
account khydr is defined by Eq. (4).
Table 3 presents the results of the kinetic study of
the reactions of piperidine and morpholine with
compounds I and II in the system water (40 wt %)–
dioxane. The discrepancies between the rate constants
k determined at various initial concentrations of
amines in aqueous dioxane are small, allowing to
neglect the contribution of the ester hydrolysis to kobs.
For equal amounts of water in the system the values of
k for all studied reactions in the mixture water–dioxane
are considerably larger than the k values for the same
reactions in aqueous 2-propanol (Tables 1–3). The
accelerating effect of aqueous dioxane as compared to
aqueous 2-propanol on the rate constants of N-
acylation was observed also in other reactions, for
example, in the reactions of ammonia, aliphatic amines
and α-amino acids with esters and sulfonyl chlorides
k
obs = khydr + kc
0
.
(4)
In the absence of hydrolysis (khydr ≈ 0) the value of
k can be calculated by Eq. (5).
k = kobs /c
0
.
(5)
If khydr << kc , the rate constant k, calculated by
0
Eq. (5), should be constant within experimental error
with varying c . Substantial deviations in the values of
0
k determined at different c0 are indicative of a
considerable contribution of khydr into the observed rate
constant k . In this case, k can be determined by
obs
Eq. (4) describing the dependence of kobs on c0.
[7, 10–13].
The obtained kinetic data are presented in Tables 1, 2.
They show that at 298 K and at the molar fraction of
In Table 4, the activation parameters of the studied
water in the mixture x < 0.77 the contribution of
reactions are presented as determined from the
temperature dependence of the rate constants. The
energy of activation is substantially decreased with
increase of water content in 2-propanol. Thus, for
1
hydrolysis into the rates of the reactions under con-
sideration is small, so the rate constant for reaction (1)
was calculated as the arithmetic mean of k values
determined from Eq. (5). With the increase of tem-
perature and concentration of water in the solution the
contribution of hydrolysis is increased resulting in
substantial variations of k. In this case, the value of k
was calculated by Eq. (4) using the root-mean-square
method (Tables 1, 2).
variation of x from 0.69 to 0.87 the value of Е for the
1
а
reaction of compound II with morpholine is decreased
by 18 kJ/mol, and for the reaction of compound I with
≠
piperidine, by 24 kJ/mol, and the value of ∆S becomes
more negative. The value of Е
compound II with morpholine in the mixture water
for the reaction of
а
≠
(
40 wt %)–dioxane is lower, and the ∆S value is more
The adequacy of the two methods of calculation of
k values is proved by the data of Table 1, in which k
values for the reaction of piperidine with ester I in
negative than for the same reaction in aqueous 2-
propanol having the same water fraction, which is
consistent with a higher value of k in aqueous dioxane.
aqueous 2-propanol (x = 0.83, 308 K) calculated by
1
Eq. (5) are given. The mean value of k = 1.1±
For the reactions proceeding in aqueous 2-propanol,
the compensation effect is observed, which is
characterized by Eq. (6) (I + piperidine) and Eq. (7)
(II + morpholine):
–
1
–1
0
.1 L mol s . The value of k calculated by Eq. (4)
–
1
–1
using the same kinetic data is 1.12±0.06 L mol
s
with the coefficient of correlation 0.994. A similar
approach was realized for investigation of the kinetics
of the reaction of morpholine with compound II (Table 2).
≠
≠
∆
H = (94220±1770) – (393±11)∆S , n = 6, r = 0.999, (6)
≠
≠
∆
H = (89336±2791) – (372±18)∆S , n = 5, r = 0.997. (7)
The data of Tables 1, 2 show that with the increase
of water content in 2-propanol the rate constants of
acylation k increase, the dependences of k and ln k on
x1 being nonlinear (Tables 1, 2; Fig. 1). The depen-
dence of ln k on the Kirkwood function is also
nonlinear (Fig. 2), which is indicative of an important
role of specific solvation of amines and transition
states of the reaction of acylation. The solvation of the
The isokinetic temperature (Т ) for the two
iso
reactions is close to the solvent boiling temperature or
exceeds it. These values are consistent with the values
of Тiso for the reactions of diethylamine and dibutyl-
amine with compound I in aqueous 2-propanol [7].
The value of Тiso is in the range typical for the
reactions of nucleophilic substitution at the carbonyl
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 6 2015

1
418
KOCHETOVA et al.
a
Table 1. Rate constants kobs and k for the reaction of piperidine with 4-nitrophenyl benzoate I in the system water–2-propanol
2
2
с
0
× 10 ,
с
0
× 10 ,
mol/L
50 wt % Н
2
–1
–1 –1
2
–1
–1 –1
Т, K
k
obs × 10 , s
k, L mol s
Т, K
k
obs × 10 , s
k, L mol s
mol/L
3
0 wt % Н
2
О (х
1
= 0.59)
2
О (х
1
= 0.77)
2
3
3
98
08
13
2.45
2.45
1.22
0.396±0.001
0.647±0.003
0.406±0.002
0.820±0.002
0.406±0.004
0.270±0.003
0.161±0.001
0.264±0.002
0.333±0.002
0.335±0.001
0.332±0.003
0.331±0.003
308
1.22
0.737±0.003
0.787±0.005
1.28±0.06
0.53±0.02
0.64±0.06
1.53
2.45
2
1
.45
.22
313
0.385
0.538
0.611
0.770
1.22
0.094±0.004
0.195±0.003
0.330±0.002
0.360±0.001
0.644±0.001
0
.815
3
2 1
5 wt % Н О (х = 0.64)
2
2
93
98
2.45
2.45
0.405±0.003
0.493±0.004
0.241±0.006
0.654±0.005
0.796±0.004
0.388±0.001
0.165±0.002
0.201±0.002
0.198±0.004
0.267±0.003
0.325±0.002
0.318±0.001
2 1
60 wt % Н О (х = 0.83)
1
.22
298
308
0.441
0.221
0.441
0.662
0.883
1.10
0.431±0.003
0.245±0.009
0.478±0.002
0.685±0.002
0.990±0.005
1.30±0.01
0.977±0.07
1.11±0.04
1.08±0.01
1.03±0.01
1.12±0.01
1.18±0.01
1.07±0.01
1.56±0.06
3
3
03
08
2.45
2.45
1
.22
4
2 1
0 wt % Н О (х = 0.69)
2
2
3
3
93
98
03
08
1.22
1.22
1.22
1.22
0.265±0.001
0.326±0.005
0.386±0.002
0.473±0.003
0.217±0.001
0.267±0.004
0.316±0.002
0.388±0.003
1.32
1.41±0.01
313
298
0.221
0.441
0.662
0.883
0.140±0.002
0.267±0.002
0.769±0.002
1.03±0.03
5
2 1
0 wt % Н О (х = 0.77)
2
3
3
98
03
08
0.294
0.141±0.004
0.170±0.003
0.261±0.002
0.305±0.001
0.489±0.005
0.67±0.01
0.40±0.03
0.46±0.02
0.53±0.02
0
0
0
.306
.588
.611
70 wt % Н
2 1
О (х = 0.89)
0.175
0.262
0.350
0.430
0.524
0.612
0.699
0.787
0.175
0.350
0.437
0.612
0.699
0.305±0.004
0.405±0.004
0.420±0.004
0.598±0.002
0.866±0.002
1.06±0.04
1.87±0.09
1
.22
.53
1
0.294
0.189±0.004
0.400±0.004
0.467±0.004
0.71±0.01
0
0
.588
.611
1.30±0.05
1
.18
.22
.44
1.34±0.05
1
0.719±0.003
1.23±0.01
308
0.062±0.002
0.391±0.002
0.635±0.005
0.933±0.005
1.21±0.01
2.16±0.08
2
0.294
0.130±0.004
0.135±0.005
0.335±0.004
0
0
.306
.588
a
1
Hereinafter, x is the molar fraction of water.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 6 2015

ACYLATION OF PIPERIDINE AND MORPHOLINE WITH PHENYL BENZOATES
1419
Table 2. Rate constants kobs and k for the reaction of morpholine with 2,4-dinitrophenyl benzoate II in the system water–
2
-propanol
2
2
с
0
× 10 ,
0
с × 10 ,
2
–1
–1 –1
2
–1
–1 –1
Т, K
k
obs × 10 , s
k, L mol s
Т, K
k
obs × 10 , s
k, L mol s
mol/L
mol/L
х
1
= 0.69
2
2
98
98
1.95
10.7
2.54±0.01
5.94±0.01
0.128±0.001
0.055±0.001
308
298
1.95
4.70±0.01
2.35±0.01
0.241±0.001
1.54±0.01
a
b
0.153
1
х = 0.77
2
3
2
3
98
0.244
0.344±0.001
0.679±0.001
1.31±0.01
0.135±0.002
308
0.244
0.488
0.976
0.976
0.564±0.001
1.07±0.01
2.51±0.01
3.72±0.01
0.27±0.02
0.363±0.001
0.291±0.009
0
0
.488
.976
18
98
03
0.244
.488
0.843±0.002
1.80±0.01
318
0
х
1
= 0.83
308
0.0975
0.227±0.003
0.489±0.002
0.962±0.003
0.216±0.002
0.615±0.003
1.15±0.004
0.411±0.03
0.192±0.003
0.195
0.244
0.290
0.341
0.390
0.439
0.488
0.729±0.006
0.804±0.003
0.941±0.004
1.07±0.001
1.23±0.001
1.27±0.002
1.56±0.002
0
0
.244
.488
0.0975
0.24±0.01
0
0
.244
.488
3
2
08
98
0.0975
х
1
= 0.89
0.290
1.04±0.01
1.61±0.02
2.27±0.01
3.16±0.04
0.956±0.001
1.68±0.01
2.39±0.01
4.29±0.03
0.72±0.04
303
308
0.680
0.195
0.290
0.390
0.487
0.585
0.680
5.20±0.05
1.00±0.02
1.70±0.01
2.90±0.02
3.60±0.01
5.12±0.04
5.51±0.04
0.89±0.03
0.98±0.05
0
0
0
.390
.488
.585
3
2
03
98
0.195
0.89±0.03
0
0
0
.290
.390
.580
х
1
= 0.93
308
0.420
7.30±0.06
9.38±0.04
15.2±0.6
17.6±0.2
27.2±0.2
2.04±0.07
0.350
0.420
0.840
1.40
8.20±0.06
9.40±0.08
19.2±0.1
34.3±0.4
2.45±0.09
0
0
0
1
.560
.840
.980
.40
a
b
Rate constants for the reaction of morpholine with 4-nitrophenyl benzoate I. Rate constants for the reaction of piperidine with 2,4-
dinitrophenyl benzoate II.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 6 2015

1
420
KOCHETOVA et al.
(
ε – 1)/(2ε + 1)
1
x , ppm
Fig. 1. Dependence of ln k for the reactions of (1) piperidine
with ester I and (2) morpholine with ester II (2) on the
molar fraction of water x in the system water–2-propanol
1
Fig. 2. Dependence of ln k for the reactions of (1) piperidine
with ester I and (2) morpholine with ester II on the
Kirkwood function for the solvent water–2-propanol at
298 K.
at 298 K.
Table 3. Rate constants kobs and k for the reactions of piperidine
and morpholine with 4-nitrophenyl benzoate I and 2,4-
dinitrophenyl benzoate II in the system water–dioxane
Table 4. Energies, enthalpies, and entropies of activation for
the reactions of piperidine and morpholine with esters I and
II at 298 K
a
а
3
–1
–1 –1
Т, K
с
0
, mol/L
k
obs × 10 , s
k, L mol s
≠
≠
–1
–1
х
1
Е
а
, kJ/mol
∆Н , kJ/mol –∆S , J mol K
Morpholine + I
Piperidine + I, water–2-propanol
2
2
98
98
0.0113
.0111
1.06±0.07
1.05±0.07
0.0958±0.0006
0.0955±0.0006
0
0
0
.59
.64
.69
38
35
29
24
18
11
36
33
27
22
15
9
142
150
168
180
193
211
0
Piperidine + I
9.42±0.06
0.00367
2.56±0.02
2.68±0.06
2.61±0.05
0
0
.00507
.00155
13.6±0.3
0.77
3.84±0.01
0
0
.83
.87
Morpholine + II
3.26±0.02
2
98
0.0145
0.225±0.001
0.229±0.001
0.227±0.002
0.285±0.005
0.283±0.003
0.369±0.0007
0.359±0.003
Morpholine + II, water–2-propanol
0
0
.00868
.00483
1.65±0.01
1.99±0.01
4.12±0.08
4.08±0.05
2.67±0.05
2.60±0.02
0
.69
48
43
32
24
14
45
41
30
27
12
109
125
159
175
200
3
3
03
08
0.0145
.0145
0.00724
.00724
0.77
0
0
0
0
.83
.87
.93
0
Piperidine + II
42.3±0.2
Morpholine + II, water–dioxane
36 33
2
98
0.00309
13.7±0.6
12.6±0.1
12.9±0.5
0
.69
144
0
0
.00155
.00184
19.5±0.2
a
≠
23.7±0.1
а
Error in determination of Е and ∆Н does not exceed 4 kJ/mol,
a
≠
–1
–1
x
1
= 0.77, c
0
is the initial concentration of amine.
of ∆S – 10 J mol K .
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 6 2015

ACYLATION OF PIPERIDINE AND MORPHOLINE WITH PHENYL BENZOATES
1421
Scheme 1.
Solv
Solv
Х
N
Х
N
Х
N
H
Solv
H
H Solv
K1
K2
K3
X = CH
2
, O; Solv = H O, i-PrOH, dioxane.
2
group and suggest the similarity of the mechanisms of
the studied reactions [14].
reactions we performed quantum-chemical simulation
of molecular complexes of three types of the studied
amines with one and two molecules of the components
of binary muxtures (Scheme 1).
The increase in the rate constants and decrease in
the energy and entropy of activation with increase in
water content in the mixture can be due to the
rearrangement of the structure of the binary solvent
and the corresponding variations in the structure of the
solvate shells of the amine molecules and transition
states of the reactions. For better understanding of the
role of specific solvation of amines in the studied
In complexes of the type K1: piperidine–H O (Iа),
2
piperidine–dioxane (IIа), piperidine–i-PrOH (IIIа),
morpholine–H O (IVа), morpholine–dioxane (Vа) and
2
morpholine–i-PrOH (VIа) the H-bond is formed by the
proton of the NH group, and the molecule of the
solvent acts as an H-acceptor. In complexes of the type
Table 5. Quantum-chemical parameters of solvate complexes K1–K3
2
z
Comp. no.
–ΔE
c
, kJ/mol
ЕHOMO, eV
Ср
(N)
φр
z
(N)
rN–H, Å
r
N···H, Å
r
O···H, Å
K1
Iа
13.1
13.1
15.7
10.5
7.9
–9.28
–9.39
–9.28
–9.50
–9.58
–9.52
0.863
0.891
0.848
0.817
0.837
0.797
1.683
1.702
1.674
1.694
1.716
1.683
1.001
0.999
1.000
1.001
0.999
1.001
–
–
–
–
–
–
2.258
2.180
2.195
2.233
2.150
2.200
IIа
IIIа
IVа
Vа
VIа
10.5
K2
K3
VIIа
VIIIа
IXа
28.9
31.5
21.0
23.6
–10.37
–10.31
–10.56
–10.50
0.506
0.511
0.331
0.452
1.509
1.503
1.441
1.530
1.002
1.002
1.001
1.001
2.132
2.024
2.124
2.117
–
–
–
–
Xа
XIа
42.0
42.0
39.3
36.7
34.1
36.7
–9.90
–9.90
0.839
0.846
0.545
0.755
0.740
0.498
1.689
1.693
1.490
1.698
1.695
1.505
1.002
1.002
1.001
1.003
1.018
1.002
2.133
2.132
2.067
2.122
1.929
2.088
2.213
2.128
2.093
2.193
2.010
2.074
XIIа
XIIIа
XIVа
XVа
XVIа
–9.93
–10.10
–10.10
–10.12
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1
422
KOCHETOVA et al.
K2: piperidine–H O (VIIа), piperidine–i-PrOH
which include the constants of acylation of the solvate
complexes of different structure. It can be assumed
that in the system water–dioxane the main reacting
species are the solvate complexes Iа, IIа, IVа, and Vа,
while in the system water–2-propanol they are Iа, IIIа,
IVа, and VIа. The results of calculations prove the
suggestion of low reactivity of solvate complexes in
which the bond with the solvent molecule is formed by
the lone electron pair of nitrogen. These complexes are
most stable and do not contribute significantly in the
kinetics of the process since they require large energy
expenditure for breaking the hydrogen bond formed by
the nitrogen atom with the solvent.
2
(
VIIIа), morpholine–H O (IXа), morpholine–i-PrOH
2
(Xа) the H-bond is formed by the lone pair of the
nitrogen atom, and the solvent acts as an H-donor.
Also the formation is possible of mixed complexes of
the type K3: piperidine–2H O (XIа), piperidine–H O–
2
2
i-PrOH (XIIа), piperidine–H O–dioxane (XIIIа),
2
morpholine–2H O (XIVа), morpholine–H O–i-PrOH
2
2
(
XVа), morpholine–H O–dioxane (XVIа), in which,
2
according to calculations, the molecule of water (or
one of water molecules in complexes XIа, XIVа) is
always coordinated to the lone electronic pair, being
the H-donor.
The results of calculations are presented in Table 5.
The comparison of the geometrical and charge
characteristics of the NH group of the solvated amines
with the rate constants of the studied reactions revealed
no correspondence. Previously we have shown that
some reactions of acylation of aliphatic amines and α-
amino acids are orbital controlled, and that the values
It is presumable basing on the results of quantum-
chemical simulation that the variations in the solvate
shells of amines is not the main reason of the increase
in the rate constants of acylation of amines with the
increase in water content in the mixed solvent.
Apparently, the main factor affecting the rates of the
studied reactions is the interaction of the components
of the binary solvent with the transition states of the
reactions. This assumption is based on the results of
previous calculations [11] of the potential energy
surface for the reaction of ammonia with phenyl
benzoate. The simulation has shown that the increase
in the number of water molecules in the transition state
decreases the activation energy and increases the
acylation rate constants when the fraction of water in
the binary solvent is increased.
of population [φр (N)] and squares of contribution of
z
2
z
the 2р –АО of nitrogen in the HOMO [Ср (N)] can
z
serve as descriptors of reactivity of amines and their
molecular complexes with the components of the
solvents in N-acylation [15].
Some conclusions can be made by comparing the
rate constants with the characteristics of 2р –АО of
z
nitrogen in the solvate complexes. The analysis of
Table 5 shows that the least stable are the complexes
of amines with one molecule of the solvent acting as
an Н-acceptor (K1), as follows from small energies of
EXPERIMENTAL
their formation ΔE . These complexes must be most
reactive, since they are characterized by maximum
c
Piperidine and morpholine (pure for analysis) were
distilled in a vacuum. 2-Propanol (“chemically pure”
grade) was dried with anhydrous copper sulfate and
distilled on a column at atmospheric pressure. Dioxane
values of squares of contributions of the 2p –AO of
z
nitrogen to the HOMO and high values of population
of 2p –АО, as well as highest lying HOMO. The
z
(
“pure for analysis” grade) was dried with KOH and
highest reactivity should be observed for the
distilled over sodium metal. For preparation of
solutions saturated solution of NaOH (“chemically
pure” grade) and bidistillated water was used. Esters I,
II were synthesized by acylation of nitrophenols with
benzoyl chloride and identified by melting points [16].
All physicochemical constants of the reagents and
solvents used in this study corresponded to the
literature data [16, 17].
complexes with one molecule of dioxane (see IIа and
2
z
Vа, Table 5), having maximum values of Ср (N) and
φр (N).
z
The results of calculations agree with the kinetic
data showing that the reactions in aqueous dioxane
proceed with higher rates that in aqueous 2-propanol:
for both amines the complexes with dioxane have
2
z
larger values of Ср (N) and φр (N) than the
z
The kinetics of the reactions was studied spectro-
photometrically measuring the variation of concentra-
tion of nitrophenolate ions formed in the course of the
reaction at working wavelength 400 nm. The optical
density was measured on a KFK-2UKhL 4.2 photo-
complexes with 2-propanol (see IIа, IIIа, Vа and VIа
in Table 5).
One should keep in mind that the experimental rate
constants of acylation of amines are effective values,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 6 2015

ACYLATION OF PIPERIDINE AND MORPHOLINE WITH PHENYL BENZOATES
1423
colorimeter, equipped with a digital voltmeter. The
observed rate constants kobs were calculated from the
Guggenheim equation.
Chem., 2005, vol. 75, no. 7, p. 1108. DOI: 10.1007/
s11176-005-0376-x.
6. Um, I.-H., Chun, S.-M., and Akhtar, K., Bull. Korean
Chem. Soc., 2007, vol. 28, no. 2, p. 220.
Quantum-chemical calculations were performed
using Firefly 7.1.G program [18] in the supermolecule
approximation with full geometry optimization of all
7
. Kochetova, L.B., Kalinina, N.V., Kuritsyn, L.V., and
Kustova, T.P., Butlerov Commun., 2014, vol. 38, no. 5,
p. 39.
*
*
solvate complexes by the RHF/6-311+G method.
Correspondence of the found structures of the solvate
complexes to the minima on the potential energy
surface was proved by vibrational calculations at the
same level of theory. The energy of complex formation
was calculated as the difference of the total energies of
the solvate complex and the isolated molecules
constituting it.
8
9
. Mikhalkin, A.P., Russ. Chem. Rev., 1995, vol. 64, no. 3,
p. 259. DOI: 10.1070/RC1995v064n03ABEH000149.
. Sokolov, L.B., Kuritsyn, L.V., Fedotov, Yu.A., and
Bobko, L.A., Vysokomol. Soed. A, 1982, vol. 24, no. 3,
p. 606.
1
1
1
1
0. Khripkova, L.N., Kuritsyn, L.V., Kalinina, N.V., and
Sadovnikov, A.I., Russ. J. Gen. Chem., 2004, vol. 74,
no. 10, p. 1543. DOI: 10.1007/s11176-005-0052-1.
1. Kochetova, L.B., Kalinina, N.V., Kuritsyn, L.V., and
Kustova, T.P., Russ. J. Gen. Chem., 2011, vol. 81,
no. 10, p. 2114. DOI: 10.1134/S1070363211100136.
ACKNOWLEDGMENTS
The authors are grateful to the Ministry of
Education and Science of Russian Federation for
financial support of this study.
2. Kochetova, L.B., Kalinina, N.V., Kuritsyn, L.V., and
Kustova, T.P., Russ. J. Gen. Chem., 2012, vol. 82, no. 5,
p. 885. DOI: 10.1134/S1070363212050143.
3. Ishkulova, N.R., Oparina, L.E., Kochetova, L.B.,
Kustova, T.P., Kalinina, N.V., and Kuritsyn, L.V., Russ.
J. Gen. Chem., 2010, vol. 80, no. 5, p. 964. DOI:
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