Study of all stages of the Diels–Alder reaction of cyclopentadiene with 2,3-dicyano-1,4-benzoquinone and monoadducts: Kinetics, thermochemistry, and high pressure effect

Article abstract of DOI:10.1002/kin.21350

The kinetic parameters and enthalpies of the Diels–Alder reactions between cyclopentadiene and 2,3-dicyano-1,4-benzoquinone leading to the formation of two different monoadducts and bisadduct were determined. The stability of adducts is compared. Monoadduct appears to be thermodynamically more stable than the bisadduct. Comparison with the other Diels–Alder reactions studied previously allows us to conclude that the heat effects upon formation of the considered Diels–Alder adducts are the lowest in comparison with all the studied dienophiles.

Full text of DOI:10.1002/kin.21350

Received: 7 November 2019
DOI: 10.1002/kin.21350
Revised: 28 January 2020
Accepted: 30 January 2020
A R T I C L E
Study of all stages of the Diels–Alder reaction of cyclopentadiene
with 2,3-dicyano-1,4-benzoquinone and monoadducts: Kinetics,
thermochemistry, and high pressure effect
Anastasia O. Kolesnikova1
Vladimir D. Kiselev1
Dmitry A. Kornilov1
Aidar T. Gubaidullin2
1The A. M. Butlerov Chemical Institute,
Kazan Federal University, Kazan 420008,
Russian Federation
Abstract
The kinetic parameters and enthalpies of the Diels–Alder reactions between cyclopen-
tadiene and 2,3-dicyano-1,4-benzoquinone leading to the formation of two different
monoadducts and bisadduct were determined. The stability of adducts is compared.
Monoadduct appears to be thermodynamically more stable than the bisadduct. Com-
parison with the other Diels–Alder reactions studied previously allows us to conclude
that the heat effects upon formation of the considered Diels–Alder adducts are the
lowest in comparison with all the studied dienophiles.
2The A. E. Arbuzov Institute of Organic and
Physical Chemistry, FRC Kazan Scientific
Center, Russian Academy of Sciences, Kazan
420088, Russian Federation
Correspondence
VladimirD. Kiselev, TheA. M. Butlerov
Chemical Institute, KazanFederalUniversity,
Kremlevskayastr., 18, Kazan 420008 Kazan,
Russian Federation.
K E Y W O R D S
Email:vkiselev.ksu@gmail.com
2,3-dicyano-1,4-benzoquinone, cyclopentadiene, Diels-Alder reaction, high pressure effect, kinetics, ther-
mochemistry
(247.6 kJ mol−1). During the process of cycloaddition, quadri-
1
INTRODUCTION
cyclane loses most of the strain energy, which leads to the
−1
high reaction rate (k = 120 L mol
s
−1) and very high
Quinone derivatives are widespread in nature and attract
increased attention due to the peculiarity of their chemi-
cal behavior and their prospects of pharmacological use.
Chemical compounds with 1,4-benzoquinone moiety exhibit
prominent anticancer,1–4 anti-inflammatory,5 and antimicro-
bial activity.6 2,3-Substituted benzoquinones have two dif-
ferent reaction centers, therefore, we should expect the dif-
ferences in the regio- and stereoselectivity of the Diels–
Alder reaction.7,8 Monoadducts of various dienes with 1,4-
benzoquinone are usually formed much easier than the subse-
quent bisadducts. It was noted that the reaction rates of 1,4-
benzoquinone with dienes are low, and the reaction products
are thermally unstable.9–12 However, quantitative kinetic data
for such reactions are very limited, and the enthalpies of reac-
tion are also unknown. A significant increase in activity was
observed for 2,3-dicyano-1,4-benzoquinone (2) in the reac-
tion of [2ꢀ+2ꢁ+2ꢁ]-cycloaddition with quadricyclane (6).13
Enthalpy of formation of very stressed quadricyclane (339.1)
is significantly higher than that of its precursor, norbornadiene
25
exothermic values of the enthalpy (−236.1 kJ mol−1) of
its reaction with tetracyanoethylene in toluene. The high-
est known exothermic heat effect for Diels–Alder reac-
tions is achieved in reaction of quadricyclane (6) with 4-
−1 −1
phenyl-1,2,4-triazoline-3,5-dione (k = 0.282 L mol
s ,
25
ΔH = −255.1 kJ mol−1).13 These parameters were also very
r-n
=
high for the addition of quadricyclane (6) to C2 C3 bond of
−1
2,3-dicyanobenzoquinone 2+6→7: ΔH = −182.2 kJ mol
r-n
and k = 36.9 L mol−1 s
.
−1 14 The exothermicity of the reac-
25
tion 2+6→7 is noticeably smaller in magnitude compared
with the reactions of the quadricyclane with tetracyanoethy-
lene and 4-phenyl-1,2,4-triazoline-3,5-dione, but it is still
quite high, which makes the reaction 2+6→7 almost irre-
versible under normal conditions.
Similarly, the difference in the reaction enthalpy of differ-
ent dienes with a particular dienophile is also determined by
the difference in the energy of breaking of the ꢀ-bonds in
these dienes.15 This corresponds to the fact that the energy
Int J Chem Kinet. 2020;1–9.
wileyonlinelibrary.com/journal/kin
© 2020 Wiley Periodicals, Inc.
1

2
KOLESNIKOVA ET AL.
S C H E M E 1 Reactions of cyclopentadiene and quadricyclane with 2,3-dicyano-1,4-benzoquinone
−1
◦
=
of C2 C3 bond in dienophile 2 is 54 kJ mol , which is
higher than that of tetracyanoethylene. It should be noted that
the quadricyclane exhibits an increased rate of [2ꢀ+2ꢁ+2ꢁ]-
cycloaddition only with strong electron acceptor dienophiles.
So, the rate of reaction 6+7→8 is 6 orders of magnitude
lower than that of reaction 2+6→7.14 This virtually elimi-
nates the possibility of separately determining the kinetic and
ampoule at 80 C for 4 h. Yellow crystals of 4 were recrystal-
lized from benzene, m.p. 123–125 C (lit.8 123–124 C). H
and 13C NMR spectra of monoadducts (3) and (4) were the
same as previously described.8 White crystals of bisadduct
(5), 3,10-dioxopentacyclo[10.2.11,12.15,8.02,11.04,9]hexadeca-
6,13-diene-2,11-dicarbonitrile, were obtained from solution
◦ ◦
1
◦
of 2 with the large excess of diene (1), m.p. 290–292 C, dec.
1H NMR (400 MHz, DMSO-d6), ꢂ: 1.32 (m, 2H, CH2), 1.92
=
thermochemical parameters of the reactions by C2 C3 and
=
C5 C6 bonds. It was found that cyclopentadiene (1) does not
(s, 2H, CH2), 3.31 (s, 2H, CH), 3.33 (s, 2H, CH), 3.87 (s,
2H, CH), 6.17 (s, 2H, CH), 6.61 (s, 2H, CH). 13C NMR
(101 MHz, DMSO-d6), ꢂ: 46.81, 50.37, 51.89, 56.49, 58.32,
60.65, 117.63, 136.64, 137.68, 199.99.
=
=
show such high rate discrimination with respect to these reac-
tion centers. In the present work, kinetic and thermochemical
data for the reactions 1+2→3, 1+3→5, 1+4→5, and 3→1+2
(Scheme 1) are obtained for the first time.
The crystals for X-ray experiments were grown from the
mixture of dichloromethane and acetonitrile in the ratio of
3:1 (v:v). The X-ray diffraction data of bisadduct (5) were
collected on a Bruker Kappa Apex II CCD diffractome-
ter in the ꢃ and ꢄ-scan modes using graphite monochro-
2
EXPERIMENTAL
˚
mated Mo Kꢅ (ꢆ = 0.71073 A) radiation at 296(2) K. The
2.1 Reagents and products
obtained data were corrected for the absorption effect using
SADABS program.17 The structure was solved by direct
method and refined by the full matrix least-squares using
SHELXTL18 and WinGX19 programs. All non-hydrogen
atoms were refined anisotropically. The hydrogen atoms were
inserted at calculated positions and refined using a “rid-
ing” models. Data collections: images were indexed, inte-
grated, and scaled using the APEX220 data reduction pack-
age. Analysis of the intermolecular interactions was per-
formed using the program PLATON.21 Mercury program22
package was used for figures preparation. Crystallographic
data for compound: C18H14N2O2, colorless prism, size
0.18 × 0.39 × 0.51 mm3, M = 290.31, orthorhombic,
2,3-Dicyano-1,4-benzoquinone (2) was obtained by oxida-
tion of 2,3-dicyanohydroquinone (Sigma–Aldrich, Germany;
98%) with nitrogen oxide at 0 C.16 Quinone (2), m.p. 181–
◦
183 C (lit.16 178–180 C) was sublimed (110 C, 10 Pa) before
the measurements. Cyclopentadiene was obtained by thermal
cracking of the dimer, followed by distillation before measure-
ments. Monoadduct (3), 3,6-dioxotricyclo[6.2.1.02,7]undeca-
4,9-diene-2,7-dicarbonitrile, was obtained as pale yellow
◦
◦
◦
crystals from benzene, m.p. 135–137 C, dec. (lit.7 135–
◦
136 C, dec.). Monoadduct (4), 3,6-dioxotricyclo[6.2.1.02,7
]
◦
undeca-4,9-diene-4,5-dicarbonitrile, was obtained after heat-
ing of 2 g adduct (3) in 50 mL of benzene in a sealed

KOLESNIKOVA ET AL.
3
−1
−1
TA B L E 1 Rate constants (k /L mol
s
−1), enthalpy (∆H≠/kJ mol−1), entropy (∆S≠/J mol
K
−1), and Gibbs activation energies
2
(∆G≠/kJ mol−1, 25 C) of 1+2→3, 1+3→5, 1+4→5, and 3→1+2 reactions in 1,2-dichloroethane
◦
k2
Entry
Reaction
1+2→3
1+3→5
1+4→5
3→1+2
2+6→7a
6+7→8a
2+9c
15◦С
25◦С
35◦С
45◦С
∆H≠
−∆S≠
∆G≠
1.
–
4.57 × 102
5.07 × 102
5.54 × 102
5.1 0.2
177
1
57.9 0.5
−2
−1
−2
−2
2.
1.03 × 10
1.85 × 10
8.87 × 10
1.79 × 10
2.80 × 10
–
–
34.5 2.9
18.3 2.5
163 10
83
73
6
5
7
−1
−4
3.
6.95 × 10
1.24
183
49 10
189
8
−4
−3
4.
–
–
–
–
–
–
–
–
–
6.09⋅10
1.44 × 10
80.0
10.5
63.0
7.9
4
95
5.
3.69 × 101
–
–
–
–
–
–
–
–
5.08 × 101b
66.8
101
59.4
61.2
55.4
44.6
84.3
–
−5
−5
6.
1.35 × 10
2.35 × 102
7.11 × 10
127
173
145
138
179
155
–
7.
3.04 × 102
◦
8.
6+10d
1.04 × 102/20 С
–
–
–
18.0
11.9
−8.7
38.1
–
9.
9+10e
2.81 × 103
10.
11.
12.
13.
aRef. 14.
9+10f
9.27 × 104
1+11→12g
1+12→13h
6+11a
1.19 × 10
−2
−5
6.36 × 10
–
−6
3.41 × 10
◦
b44.4 C.
cRef. 24.
dRef. 13.
eIn toluene.25
fIn 1,2-dichloroethane.25
gRef. 26.
hRef. 10 Numbering of compounds: 1–8 as in Scheme 1; 9, 9,10-dimethylanthracene; 10, tetracyanoethylene; 11, 1,4-benzoquinone; 12, mono-adduct of reaction 1+11;
13, bisadduct of reaction 1+12.
◦
in 1,2-dichloroethane at 15.0, 25.0, 35.0, and 45.0 C
(spectrophotometer Hitachi U-2900, Japan). The course of
the reaction was monitored by the change of monoadduct
(3) absorption at 365 nm, and 4 at 393 nm. The compounds
˚
˚
˚
a = 13.7285(11) A, b = 10.8805(10) A, c = 9.0259(8) A,
3
˚
V = 1348.2(2) A , T = 296(2) K, space group Pnma, Z = 4,
Z’ = 0.5, 휇(Mo Kꢅ) = 0.095 mm−1, 휌
= 1.430 g⋅cm–3,
calc
◦
F(000) = 608, theta range for data collection 3.51–29.25 ,
(1) and (5) do not absorb at this wavelength. 4-Phenyl-1,2,4-
14 335 reflections measured, 1 915 independent reflections
−1 −1
triazoline-3,5-dione quickly (k = 1.6 × 105 L mol
s )
(R = 0.0537), 135 parameters, 0 restraints. Final indices:
25
int
−1 23
and irreversibly (∆H = −134 kJ mol
)
binds cyclopen-
R = 0.0399, wR = 0.1021 (1 473 reflections with I > 2ꢁ ),
r-n
1
2
2
I
tadiene during the decomposition of adduct (3) (entry 4,
Table 1). The decay reaction rate was monitored by a decrease
in 4-phenyl-1,2,4-triazoline-3,5-dione absorption (540 nm).
The relative standard errors of the rate constants did not
exceed 3%.
R = 0.0587, wR = 0.1129 (all data), GoF = 1.010, largest
1
difference in peak and hole (0.416 and −0.249 eA−3).
Crystallographic data for this structure have been deposited
in the Cambridge Crystallographic Data Centre as supple-
mentary publication number CCDC 1919985. Copies of the
data can be obtained free of charge upon application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (fax: +44(0)1223
336033 or e-mail: deposit@ccdc.cam.ac.uk).
˚
2.3 Calorimetric measurements
◦
The heats of reactions were determined at 25 C using a
differential calorimeter as described earlier.27 Diene (1) (in
excess) was dissolved in calorimeter Dewar vessel with 1,2-
dichloroethane (150 mL) and solid dienophile (2), (3), or
(4) (30–50 mg) was placed in small stainless steel cylin-
der, the polished base and top of which were closed with
the thin (0.1 mm) round Teflon gaskets and tightly screwed
onto the lid. After achieving thermal equilibrium, the Teflon
films were cut out with a razor blade. Three measure-
ments of dissolution heat (ΔHdissol) of solid reagents (2),
(3), and (4) were made in 1,2-dichloroethane. The enthalpy
2.2 Kinetic measurements
The rates of the fast reaction 1+2→3 were measured
by the stopped flow method (Cary 50 Bio spectropho-
tometer with RX-2000 accessory, United Kingdom) in
◦
1,2-dichloroethane at 25.0, 35.0, and 45.0 C. The reac-
tion was monitored by the change in absorption of 2,3-
dicyano-1,4-benzoquinone (2) at 440 nm. The compounds
(1) and (3) do not absorb at this wavelength. The rates
of slow reactions 1+3→5 and 1+4→5 were measured

4
KOLESNIKOVA ET AL.
of slow reaction 1+2→5 was determined by adding of
the known weight of solid 2 to 0.5 M solution of 1 in
1,2-dichloroethane. The enthalpy of the reaction in solution
was determined taking into account the dissolution heat of
2: ΔH
= ΔH
− ΔHdissol. The enthalpies of slow
r-n, sol
r-n, exp
reactions 1+3→5 and 1+4→5 were determined at the diene
excess 0.5 and 0.1 M, respectively. The enthalpy of fast reac-
tion 1+2→3 was determined in solution with the only small
excess of 1. The additional heat effect of the reaction 1+2→3
due to the subsequent slow reaction 1+3→5 does not exceed
−1
0.3 kJ mol
.
F I G U R E 1 The dependence of the specific volume (1/d ) during
the reaction 1+3 → 5 on the bisadduct 5 concentration (c5, t) (itn)
2.4 Kinetic measurements under pressure
◦
1,2-dichloroethane at 25 C. 1, d−1 = −(0.0223289 0.000096)∙C
+
The pressure effect on the rate of the reaction 1+3→5
add
(0.8031562 0.0000005); R2 = 0.9994 ∆V = −27.8 cm3 mol
;
−1
◦
r-n
was studied in 1,2-dichloroethane at 25 C using the pres-
C (1) = 15.05 × 10 mol L−1, C (3) = 13.15 × 10 mol L−1. 2,
−3
−3
0
0
sure multiplier (HP-500; Syn Corporation Ltd., Japan),
a quartz cell with the variable volume (PCI-500; Syn
Corporation Ltd., Japan) and UV spectrophotometer
(SCINCO S-3100; SCINCO CO., Ltd., Korea). The
observed activation volume (∆V≠exp) of this reaction
(С01 = С03 = 0.0217 M) was calculated on the basis of the
rate constants measured at ambient pressure and 1 000 bar,
applying the previously proposed relationship (1).28
d−1 = −(0.0229045 0.000109)∙C + (0.8032017 0.0000011);
add
R2 = 0.9995 ∆V = −28.5 cm3 mol−1; C (1) = 22.54 × 10 mol L
,
−3
−1
r-n
0
C (3) = 21.65 × 10 mol L Δ푉푟−푛 = −28.1 0.4 cm3 mol [Color
−3
−1
−1
̄
0
figure can be viewed at wileyonlinelibrary.com]
Equation (6), derived from equation (5), is more convenient
for the measurement of the density of the reaction mixture.
Here, V
and V are the solution volumes at the begin-
(
)
(t = 0)
(t)
(
)
푘푃 =1000
푘푃 =1
휕 ln 푘
휕푃
= (1.15 0.03) × 10−3 × ln
(1)
ning and during the reaction; V is the solvent volume; V1,
V3, and V5 are the partial molarsvolumes of compounds (1),
(3), and (5); c0,1, c0,3, and c5,t are the initial molar concen-
trations of reagents (1) and (3), and the current concentration
of bisadduct (5); ΔVr-n is the volume of reaction 1+3→5. The
current concentrations of adduct (5) were calculated from the
푇 ,푃 =1
(
)
휕 ln 푘
휕푃
Δ푉 ≠ = −푅푇
(2)
exp
푇
Corrected value of the activation volume (∆V≠corr) of the
reaction 1+3→5 was determined by equations (2) and (3)
taking into account isothermal compressibility coefficients of
kinetic data for prepared solutions. Linear dependences 1/d
(t)
−5
−1 29
versus c5 were observed for the measurements up to 95% con-
version (Figure 1). The vibration densitometer, model DSA
5000 M, was employed to measure the solution density at
1,2-dichloroethane, 훽 8.0⋅10 bar
:
T
Δ푉 ≠
= Δ푉 ≠exp + 훽T푅푇
(3)
corr
◦
25 0.002 C.
From the obtained ratio kP = 1000/kP = 1 = 3.38 it follows
that the value ∆V≠
= −34.7 1.0 cm3 mol−1, 훽 RT is
exp
T
−1
2.0 cm3 mol and the value ∆V≠
for reaction 1+3→5 is
corr
−32.7 1.0 cm3 mol
.
−1
3
RESULTS AND DISSCUSION
3.1 Structures of the adducts 3–5
2.5 Reaction volume
The structures of monoadducts (3) and (4) were deter-
mined previously.7,8 The structure of 3,10-dioxopentacyclo-
[10.2.1.15,8.02,11.04,9]hexadeca-6,13-diene-2,11-dicarbonit-
rile (5, Scheme 1) was confirmed by the single-crystal X-Ray
experiments. The molecule 5 is symmetric (Cs) and has a
plane of symmetry passing perpendicular to the directions
to the carbonyl groups through the middle of the central
six-membered cycle (projection c, Figure 2). According to the
data obtained, the molecule 5 realizes its own symmetry in
the crystal and is in the special position of the orthorhombic
unit cell—on the mirror plane perpendicular to the 0b axis
(Figure 2), so that in the independent part of the unit cell one
For reaction 1+3→5, the total volume of solution with
reagents 1, 3, and adduct 5 can be expressed by equations
(4–6):
(
)
(
)
푉(푡) = 푉푠 + 푐0,1 − 푐5 × 푉1 + 푐0,3 − 푐5,푡 × 푉3
, t
+ 푐5,푡 × 푉5
(4)
[
(
)]
(
)
푉(푡) = 푉푠 + 푐0,1 × 푉1 + 푐0,3 × 푉3 + 푐5,푡 × 푉5 − 푉1 − 푉3
= 푉(푡=0) + 푐5,푡 × Δ푉푟−푛
(5)
1∕푑(푡) = 1∕푑(푡=0) + 푐5,푡 × Δ푉푟−푛∕1 000푑(푡=0)
(6)

KOLESNIKOVA ET AL.
5
F I G U R E 2 Three projections of molecule 5 in the crystal with a partial atomic numbering scheme. Non-hydrogen atoms are represented by
thermal vibration ellipsoids (p = 50%), hydrogen atoms are spheres of arbitrary radius: arbitrary view (A), view along 0b (B), and 0a axis (C). Some
–
–
–
–
–
–
–
of bond lengths in the molecule: C1 C9 1.514(1), C1 C8 1.533(2), C1 C2 1.593(2), C2 C10 1.468(1), C2 C3 1.542(1), C2 C2* 1.581(2), C3 O3
–
–
–
–
–
–
–
–
1.212(1), C3 C4 1.499(1), C4 C4* 1.551(2), C4 C5 1.579(1), C5 C7 1.514(2), C5 C6 1.535(2), C7 C7* 1.331(3), C9 C9* 1.331(3), C10 N10
˚
1.144(1) A (*, symmetry operation x,3/2−y,z) [Color figure can be viewed at wileyonlinelibrary.com]
half of molecule 5 are located. Bonds lengths in the molecule
5 (atom numeration as in Figure 1) are in the range of
standard values of bond lengths and no significant deviations
from them are observed, with the exception, perhaps, of four
˚
˚
–
3.473(2) A, d(H9..N10’) 2.59(1) A, angle (C9 H9..N10’)
◦
153(1) (’ – symmetry operation −1/2+x,y,1/2−z). The
combined effect of two pairs of identical intermolecular
–
C H…O hydrogen bonds leads to the formation of three-
–
–
–
–
C C bonds: C1 C2 1.593(1), C2 C2* 1.581(2), C4 C4*
dimensional supramolecular structures (Figure 3B). Param-
˚
–
1.551(2), and C4 C5 1.579(1) A, the values of which are
˚
–
eters of C4 H4..O3’’ interaction are: d(C4..O3’’) 3.473(2) A,
3
◦
–
noticeably higher than the standard C C single bond for sp
˚
–
d(H4..O3’’) 2.59(1) A, angle (C4 H4..O3’’) 137(1) (’’ –
symmetry operation 1−x,1−y,−z). With such mutual packing
of the molecules in the crystal there are practically no voids
potentially accessible for the solvent, and calculated packing
index of the molecules, equal to 0.73, approaches to the upper
limit of the range characteristic of crystals of organic com-
pounds (0.65–0.75).30
hybridized atoms. This bonds elongation can be attributed to
the stressed state of atoms in the rigid carbon frame formed.
This molecule formally possesses eight chiral centers, the
analysis of their relative configuration was performed by
the PLATON program. Taking into account that the center
of the molecule 5 lies on a mirror plane in the unit cell,
only configuration of four chiral centers is independent:
C1—R, C2—S, C4—S, C5—R. Additionally, compound
5 crystallizes in the centrosymmetric space group Pnma,
that is the crystal also contains the molecules with reverse
configuration of the chiral centers.
3.2 Kinetic data
The obtained kinetic parameters are collected in Table 1.
It was previously shown14 that among ꢀ-acceptor
dienophiles, tetracyanoethylene exhibits the highest selectiv-
ity (100%) in the interaction energy with ꢀ-donor solvents,
significantly exceeding 2,3-dicyano-1,4-benzoquinone (2)
(64%), 4-phenyl-1,2,4-triazolin-3,5-dione (19%), maleic
anhydride (15%), and 1,4-benzoquinone (6%). The tremen-
In the absence of classical hydrogen bonds, the main
types of the structure-forming interactions in the crys-
–
tal 5 are presented by the intermolecular C H…O and
–
–
C H…N hydrogen bonds. Pair of C H…N hydrogen bonds
–
form the H chain of molecules along 0a axis (Figure 3A).
–
Parameters of C9 H9..N10’ interaction are: d(C9..N10’)
=
dous cycloaddition rate of the C2 C3 bond of dienophile

6
KOLESNIKOVA ET AL.
–
–
F I G U R E 3 Two projections of the crystal packing in 5: (A) H-chain, view along 0b; (B) crystal packing view along 0c axis. C H…O, C H…N
interactions are shown by the red lines [Color figure can be viewed at wileyonlinelibrary.com]
TA B L E 2 Heats of dissolution of solid reagent (ΔHdissol), observed reaction enthalpies (ΔHr-n, exp), and reaction enthalpies in solution
(ΔHr-n, sol/kJ mol−1) of cyclopentadiene (1) with 2,3-dicyanobenzoquinone (2) with formation of monoadducts (3) and (4) and bisadduct (5) in
◦
1,2-dichloroethane at 25 C
Reaction
1+2→3
1+2→5
1+3→5
1+4→5
Conditions
횫Hdissol
−
−횫Hr-n, exp
79.4 1.0
124.8 1.5
46.6 1.2
51.6 1.0
−횫Hr-n, sol
79.4 1.0
143.5 1.5
64.8 1.2
62.7 1.0
−1
−1
C1 = 0.004 mol L and C2 = 0.002 mol L
−1
C1 = 0.5 mol L and solid 2
18.7 (2)
18.2 (3)
11.0 (4)
−1
C1 = 0.5 mol L and solid 3
−1
C1 = 0.1 mol L and solid 4
2 is observed in reactions with quadricyclane (36.9),
9,10-dimethylanthracene (235), and cyclopentadiene
(457 L mol−1 s−1; Table 1).
Hammond,31 on the basis of the ideas of Bell,32 Evans
and Polanyi,33 predicted an increase in kinetic activity of
the reactants as the exothermicity of the process increases.
However, the difference in the enthalpy of reaction does not
always determine the difference in the Diels–Alder reaction
rate.34 The change in the reaction rate constant with the
It is important to note that the reaction 6+7→8 with
=
the remaining C5 C6 bond in the mono-adduct 7 proceeds
◦
by 2.7 × 106 times slower at 25 C than that of the reac-
=
tion 6+2→7. This is caused both by the significantly lower
active C2 C3 bond of dienophile 2 with cyclopentadiene
electrophilicity of C5 C6 bond in 7 and by the high steric
(457, Table 1), 9,10-dimethylanthracene (235)8 and quadri-
=
−1 −1 14
hindrances upon reaching the transition state on the way
cyclane (36.9 L mol
s
)
does not follow the change
to bisadduct (8). We have noticed that the rate of reaction
in enthalpy of these reactions: −79.4 (Table 2), −50,13 and
◦
−1 14
1+3→5 at 25 C is convenient for the thermochemical mea-
−182.2 kJ mol
,
respectively. The enthalpies of the reac-
=
surements. Due to the huge difference in activity of C2 C3
tion of tetracyanoethylene with these dienes vary in the fol-
and C5 C6 reaction sites of dienophile 2, the direct determi-
lowing way: −113, −88, and −236 kJ mol−1. From these data,
=
=
nation of the rate reaction constant 1+2→4 is impossible.
it can be concluded that the breaking energy of the C2 C3 ꢀ-
=
It can be noted that the rate and activation parameters of
bond in dienophile 2 is greater than the C C ꢀ-bond in tetra-
=
reaction 1+3→5 for C4 C5 bond of monoadduct 3 (entry 2)
cyanoethylene.
are nearly the same as for reaction of cyclopentadiene with
1,4-benzoquinone (entry 11, Table 1). It was found that the
rate of adduct 3 decomposition (3→1+2) in the presence
of 4-phenyl-1,2,4-triazoline-3,5-dione, as a trap of cyclopen-
tadiene, is conveniently observed by reducing absorption
(540 nm) of this trap. The decomposition of monoadduct 4
in such conditions is not observed.
Enthalpy of reaction 1+2→5 in solution is equal to
−143.5 1.5 kJ mol−1. With a small excess of cyclopen-
tadiene (Table 2), only very fast reaction 1+2→3 proceeds
−1
−1
in a calorimeter with the enthalpy −79.4
1.0 kJ mol
.
.
Enthalpy of reaction 1+3→5 is equal to −64.8 1.0 kJ mol
Complete thermal isomerization of adduct (3) to (4)
allowed to obtain monoadduct (4) and carry out the kinetic
−1
(0.887 L mol
s
−1; Table 1) and the heat measurements
(−62.7 1.0 kJ mol−1; Table 2) for the reaction 1+4→5. The
obtained kinetic and thermochemical data allow to describe
the details of all stages of these reactions (Figure 4). The
consistency of the results of independent enthalpy determi-
3.3 Thermochemical data
The high activity of cyclopentadiene (1) with initial
dienophile (2) and monoadducts (3) and (4) allowed to carry
out the heat measurements of all stages of these reactions
(Table 2).
nations of the reactions 1+2→3 (−79.4
1.0), 1+3→5
(−64.8 1.0), and 1+2→5 (−143.5 1.5 kJ mol−1) confirms

KOLESNIKOVA ET AL.
7
◦
F I G U R E 4 Diagram of enthalpy changes (kJ mol−1) in reactions of 1+2→3, 1+3→5, 1+4→5, and 3→1+2 at 25 C in 1,2-dichloroethane.a
The value of enthalpy activation for reaction cyclopentadiene with 1,4-benzoquinone from ref. 10
their reliability. In addition, the difference between the acti-
3.4 Activation and reaction volumes
vation enthalpies of the forward (1+2→3) and the back-
The pressure effect on the rate of reaction 1+3→5 has been
−1
ward (3→1+2) reactions (5.1–80.0 = −74.9 4.0 kJ mol
)
studied. The obtained value of activation volume (∆V≠
is -32.7, and reaction volume (∆Vr-n) is −28.1 cm3 mol
)
corr
closely corresponds to the thermochemical data for the reac-
−1
tion 1+2→3 (−79.4
1.0 kJ mol−1). The enthalpy of
giving the ratio ∆V≠corr/∆V = 1.16. It means a looser (on
r-n
subsequent reactions 1+3→5 (−64.8
1.0) and 1+4→5
4.6 cm3 mol−1) packaging of the adduct (5) in solution com-
pared to the transition state in the reaction 1+3→5. These data
are consistent with the conclusion obtained from the kinetic
and thermochemical data on the increase of steric tension on
the way from mono- (3) to bisadduct (5).
(−62.7 1.0 kJ mol−1) is much smaller than the initial reac-
tions of the monoadduct formation. From the values of the
enthalpies of reactions 1+2→5 and 1+4→5 the value of the
enthalpy of inaccessible reaction 1+2→4 has been calculated
(−80.8 1.0 kJ mol−1).
The endo structure of adducts (3) and (4) has been
proven previously.7,8 A huge difference in the rates of reac-
tion 1+2→3 and 1+4→5 with the participation of activated
4
CONCLUSION
=
C2 C3 bonds (k /k = 515; issues 1 and 3, Table 1), as well
1
2
as with the participation of non-activated bonds (k /k = 187;
The data obtained show a huge difference in the activity of
1
2
issues 11 and 12, Table 1) indicates great steric difficulties in
the formation of a transition state with a parallel arrangement
of diene (1) and monoadducts. The data obtained (Tables 1
and 2) make it possible to calculate activation enthalpies
for the decomposition reactions of the bisadduct 5→1+3
(99 kJ mol−1) and 5→1+4 (81 kJ mol−1). This means that
breaking bonds in the bisadduct, followed by the formation
=
=
C2 C3 and C5 C6 bonds in dienophile (2) in the reaction
with cyclopentadiene. It was shown that the transition from
monoadducts (3) and (4) to bisadduct (5) is accompanied
by increased difficulties, compared with the formation of
these monoadducts. These obstacles are manifested both in
the reaction rate and in the values of the reaction enthalpies.
The increased tension of bisadduct (5) is confirmed by X-ray
=
of conjugated C(CN) C(CN) bonds, is much easier. A sim-
–
diffraction data, where the length of the new C C bonds
ilar conclusion follows from a comparison of the activation
enthalpy of decomposition reactions 3→1+2 and 4→1+2
(Figure 3).
is noticeably longer than usual. The obtained data on the
volumes of activation and reaction also can be considered
as a confirmation of this conclusion. The consistency of

8
KOLESNIKOVA ET AL.
independent measurements of the reactions enthalpies
1+2→3, 1+3→5, and 1+2→5, as well as the difference
between the activation enthalpies of reactions 1+2→3 and
3→2 + 1 indicate the reliability of the data obtained. This
allows us to generalize the conclusion that the first reaction
1+2→3 is accompanied by the formation of a less strained
and therefore more stable monoadduct in comparison with
the next 1+3→5 reaction. The obtained data allow us to
conclude that the exothermicity and stability of the Diels–
Alder reaction adducts with dienophile 2 is the lowest in
comparison with all the studied dienophiles.23,34
9. Rubin W, Wassermann A. Kinetics of the cyclopentadiene-chloranil
reaction. A note on the configuration of transition states in diene
synthesis. J Chem Soc. 1950:2205-2207.
10. Wassermann A. Kinetics of bimolecular associations in solution and
in the gaseous state. The mechanism of additions to double bonds.
Part IV. J Chem Soc. 1936:1028-1034.
11. Ungnade HE, McBee ET. The chemistry of perchlorocyclopentenes
and cyclopentadienes. Chem Rev. 1958;58:249-320.
12. Onishenko AS. Diene Synthesis. London: Oldbourne Press; 1964.
13. Kiselev VD, Kornilov DA, Anikin OV, Sedov IA, Konovalov
AI. Kinetics and thermochemistry of an unusual [2ꢀ+2ꢁ+2ꢁ]-
cycloaddition of quadricyclane with some dienophiles. J Phys Org
Chem. 2017:e3737.
14. Kornilov DA, Anikin OV, Kolesnikova AO, Bermeshev MV,
Gubaidullin AT, Kiselev VD. Kinetics and thermochemistry of the
[2ꢀ+2ꢁ+2ꢁ]-cycloaddition of quadricyclane with 2,3-dicyano-1,4-
benzoquinone. Int J Chem Kinet. 2019;51:405-411.
ACKNOWLEDGEMENT
This work was supported by the Ministry of Education and
Science of Russian Federation (Project No 4.6223.2017/9.10).
15. Kiselev VD, Kashaeva EA, Potapova LN, Kornilov DA, Kono-
valov AI. Enthalpies of the Diels-Alder reactions of a series of
dienes with tetracyanoethylene and 4-phenyl-1,2,4-triazoline-3,5-
dione. Russ Chem Bull. 2015;64:2514-2516.
CONFLICT OF INTEREST
16. Brook AG. The preparation of substituted quinones by a new oxi-
dizing agent. J Chem Soc. 1952:5000-5007.
The authors hereby confirm they have no conflict of interest.
17. Sheldrick G. SADABS, Program for Empirical X-Ray Absorption
Correction. Bruker-Nonius: Gӧttingen; 2004.
ORCID
18. Sheldrick G. SHELXTL v.6.12, Structure Determination Software
Suite. Madison: Bruker AXS; 2000.
Vladimir D. Kiselev
https://orcid.org/0000-0002-2039-3265
19. Farrugia LJ. WinGX suite for small-molecule single-crystal crys-
tallography. J Appl Crystallogr. 1999;32:837-838.
20. APEX2 (Version 2.1), SAINTPlus, Data Reduction and Correction
Program (Version 7.31A). Madison, WI: Bruker AXS; 2006.
21. Spek AL. Single-crystal structure validation with the program PLA-
TON. J Appl Crystallogr. 2003;36:7-13.
REFERENCES
1. Lindsey RH, Jr Bromberg KD, Felix CA, Osheroff N. 1,4-
Benzoquinone is
a topoisomerase II poison. Biochemistry.
22. Bruno IJ, Cole JC, Edgington PR, et al. New software for searching
the Cambridge Structural Database and visualizing crystal struc-
tures. Acta Crystallogr Sect B. 2002;58:389-397.
2004;43:7563-7574.
2. Lee CS. Excision repair of 2,5-diaziridinyl-1,4-benzoquinone
(DZQ)-DNA adduct by bacterial and mammalian 3-methyladenine-
DNA glycosylases. Mol Cell. 2000;10:723-727.
23. Kiselev VD, Kornilov DA, Lekomtseva II, Konovalov AI. Reactiv-
ity of 4-phenyl-1,2,4-triazoline-3,5-dione and diethylazocarboxy-
late in [4+2]-cycloaddition and ene reactions: solvent, temperature,
and high pressure influence on the reaction rate. Int J Chem Kinet.
2015;47:289-301.
3. Beall HD, Murphy AM, Siegel D, Hargreaves RH, Butler J, Ross
D. Nicotinamide adenine dinucleotide (phosphate): quinone oxi-
doreductase (DT-diaphorase) as a target for bioreductive antitumor
quinones: quinone cytotoxicity and selectivity in human lung and
breast cancer cell lines. Mol Pharmacol. 1995;48:499-504.
4. Winski SL, Hargreaves RH, Butler J, Ross DA. A new screen-
ing system for NAD(P)H:quinone oxidoreductase (NQO1)-directed
antitumor quinones: identification of a new aziridinylbenzoquinone,
RH1, as a NQO1-directed antitumor agent. Clin Cancer Res.
1998;4:3083-3088.
24. Kiselev VD, Kornilov DA, Anikin OV, et al. Kinetics and thermo-
chemistry of [2ꢀ+2ꢁ+2ꢁ]-cycloaddition of quadricyclane to tetra-
cyanoethylene. Russ J Org Chem. 2016;52: 777-780, 793-795
25. Kiselev VD, Miller JG. Experimental proof that the Diels-Alder
reaction of tetracyanoethylene with 9,10-dimethylanthracene passes
through formation of a complex between the reactants. J Am Chem
Soc. 1975;97:4036-4039.
5. Filosa R, Peduto A, Aparoy P, et al. Discovery and biological eval-
uation of novel 1,4-benzoquinone and related resorcinol derivatives
that inhibit 5-lipoxygenase. Eur J Med Chem. 2013;67:269-279.
6. Kim MH, Jo SH, Ha KS, Song JH, Jang HD, Kwon YI. Antimi-
crobial activities of 1,4-benzoquinones and wheat germ extract. J
Microbiol Biotechnol. 2010;20:1204-1209.
26. Sauer J, Wiest H, Mielert A. Eine studie der diels-alder-reaktion, I.
die reaktivität von dienophilen gegenüber cyclopentadien und 9.10-
dimethyl-anthracen. Chem Ber. 1964;97:3183-3207.
27. Kiselev VD, Kashaeva EA, Luzanova NA, Konovalov AI.
Enthalpies of solution of lithium perchlorate and Reichardt dye in
some organic solvents. Thermochim Acta. 1997;303:225-228.
28. Kornilov DA, Kiselev VD. New approach to determine the activa-
tion and reaction volumes of low polar molecular processes. Int J
Chem Kinet. 2015;47:389-394.
7. Bott SG, Marchand AP, Kumar KA. Thermodynamic vs. kinetic
control in the Diels-Alder cycloaddition of cyclopentadiene to 2,3-
dicyano-p-benzoquinone. J Chem Crystallogr. 1996;26:281-286.
8. Marchand AP, Ganguly B, Watson WH, Bodige SG. Thermo-
dynamic vs. kinetic control in the Diels-Alder cycloaddition of
cyclopentadiene to 2,3-dicyano-p-benzoquinone: kinetic control
revisited. Tetrahedron. 1998;54:10967-10972.
29. Kiselev VD, Bolotov AV, Satonin AP, Shakirova II, Kashaeva HA,
Konovalov AI. Compressibility of liquids. rule of noncrossing V–P
curvatures. J Phys Chem B. 2008;112:6674-6682.

KOLESNIKOVA ET AL.
9
30. Kitaigorodskij AI. Molecular Crystals and Molecules. London:
Academic Press; 1973.
How to cite this article: Kolesnikova AO, Kornilov
DA, Gubaidullin AT, Kiselev VD. Study of All Stages
of the Diels-Alder Reaction of Cyclopentadiene with
2,3-Dicyano-1,4-Benzoquinone and Monoadducts.
Kinetics, Thermochemistry, and High Pressure Effect.
Int J Chem Kinet. 2020;1-9. https://doi.org/10.1002/
kin.21350
31. Hammond GS. A correlation of reaction rates. J Am Chem Soc.
1955;77:334-338.
32. Bell RP. Acid-Base Catalysis. Oxford: Clarendon Press; 1941.
33. Evans MG, Polanyi M. Further considerations on the thermodynam-
ics of chemical equilibria and reaction rates. Trans Faraday Soc.
1936;32:1333-1360.
34. Kiselev VD, Konovalov AI. Internal and external factors influenc-
ing the Diels-Alder reaction. J Phys Org Chem. 2009;22:466-483.