Kinetics of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione with β-pinene and 2-carene: Temperature, high pressure, and solvent effects

Article abstract of DOI:10.1002/kin.21189

The data on temperature, solvent, and high hydrostatic pressure influence on the rate of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione (1) with 2-carene (2), and β-pinene (4) have been obtained. Ene reactions 1+2 and 1+4 have high heat effects:

Full text of DOI:10.1002/kin.21189

Received: 26 January 2018
DOI: 10.1002/kin.21189
Revised: 14 May 2018
A R T I C L E
Kinetics of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione
with ꢀ-pinene and 2-carene: Temperature, high pressure, and
solvent effects
Vladimir D. Kiselev1
Dmitry A. Kornilov1
Oleg V. Anikin1
Alexey A. Shulyatiev1
Anastasia O. Kolesnikova1
Alexander I. Konovalov2
1Butlerov Institute of Chemistry, Kazan
Federal University, Kazan, Russian
Federation
Abstract
The data on temperature, solvent, and high hydrostatic pressure influence on the rate
of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione (1) with 2-carene (2), and
ꢀ-pinene (4) have been obtained. Ene reactions 1+2 and 1+4 have high heat effects:
2Arbuzov Institute of Organic and
Physical Chemistry, Kazan Scientific Cen-
ter of Russian Academy of Sciences, Kazan,
Russian Federation
∆Hr-n (1+2) −158.4, ∆Hr-n(1+4) −159.2 kJ mol−1, 25 C, 1,2-dichloroethane.
◦
The comparison of the activation volume (∆V≠(1+2) −29.9 cm3 mol−1, toluene;
∆V≠(1+4) −36.0 cm3 mol−1, ethyl acetate) and reaction volume values (∆Vr-n(1+2)
−24.0 cm3 mol−1, toluene; ∆Vr-n(1+4) −30.4 cm3 mol−1, ethyl acetate) reveals more
compact cyclic transition states in comparison with the acyclic reaction products 3
and 5. In the series of nine solvents, the reaction rate of 1+2 increases 260-fold and
1+4 increases 200-fold, respectively, but not due to the solvent polarity.
Correspondence
Vladimir D. Kiselev, ButlerovInstituteof
Chemistry, KazanFederal University, Kazan,
420008, RussianFederation.
Email:vkiselev.ksu@gmail.com
K E Y W O R D S
activation volume, high pressure, kinetics, reaction heat, reaction volume
ied the pressure influence on these reactions rates, calculated
the values of activation and reaction volumes, and compared
1
INTRODUCTION
the data obtained with the parameters of a number of other
4-Phenyl-1,2,4-triazoline-3,5-dione (1) contains a very active
N=N bond and easily enters ene reactions with substrates
containing an allylic hydrogen atom.1–5 These reactions are
of both synthetic 1,4 and mechanistic interest.2,4–7 An exten-
sive use of 1 in organic synthesis caused by its ability to
be involved in a large number of easily running quantita-
tive and selective reactions with a wide variety of active and
low-active substrates.1,4,8–16 Reagent 1 shows increased activ-
ity in [4+2]-, [2+2]-cycloaddition and ene reactions com-
pared to other dienophiles, including the strongest ꢁ-acceptor
dienophile, tetracyanoethylene.2,16–21
reactions involving 1.
It has been proven that 2-carene (2) and ꢀ-pinene (4) enter
ene reactions with 1 to form adducts 3 and 5, respectively.22
However, there were no quantitative data dealing with the
kinetics of these reactions.
2
EXPERIMENTAL
2.1 Materials
In this work, we determined the rate constants of the reac-
tions 1+2 → 3 and 1+4 → 5 in nine solvents at 20, 30, and
2-Carene ((1S,6R)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene)
о
40 С as well as the enthalpies of these reactions. We also stud-
(2) (Sigma-Aldrich, 97%, Switzerland) and ꢀ-pinene (6,6-
Int J Chem Kinet. 2018;1–8.
wileyonlinelibrary.com/journal/kin
© 2018 Wiley Periodicals, Inc.
1

2
KISELEV ET AL.
dimethyl-2-methylenebicyclo[3.1.1]heptane) (4) (Sigma-
Aldrich, 99%, USA, MO) were used without further
purification. 4-phenyl-1,2,4-triazoline-3,5-dione (Sigma-
2.4 Reaction volumes
The reaction volume of the reaction 1+2 → 3 was determined
by the kinetic method.26 This method uses the dependence of
the reaction mixture density on the concentration of the adduct
(Equation 4):
◦
Aldrich, 97%, USA, MO) was sublimated at 100 C and
◦
100 Pa before the measurements. The m.p. of 1 is 165-170 C,
decomp.18 The purity of 1 was tested according to the known
1
absorption coefficients.16 The H and 13C NMR spectra of
퐶
add(푡) ⋅ Δ푉푟−푛
1000 ⋅ 푑(푡=0)
1
푑(푡)
1
=
+
(4)
the obtained adducts 3 and 5 completely coincide with the
spectra given earlier.22 All solvents were purified by known
methods.23
푑(푡=0)
Here d(t = 0) and d(t) are the densities of solution at the begin-
ning and during reaction; Сadd,(t) is the current concentration
of adduct, calculated from kinetic data. The density of reac-
tion mixtures was determined using a precision ( 2 × 10−6 g
cm−3) densitometer (DSA 5000 M, Anton Paar, Austria) at 25
2.2 Kinetic measurements at ambient
pressure
◦
The reaction rate was monitored with the UV spectropho-
tometer (Hitachi U-2900, Japan) according to a change in the
absorption of 1 (530-550 nm). The temperature of the work-
ing solution in a quartz cuvette with a ground glass stopper
0.002 C.
The volume of the reaction 1+4 → 5 was determined in two
ways: by the kinetic method 26 and from the difference of the
partial molar volumes (Equation 5):
◦
was maintained with an accuracy of 0.1 C. The stability of
Δ푉푟−푛 = 푉ꢀ − 푉ꢁ − 푉ꢂ
(5)
reagent 1 in all the studied solvents was checked by stability
of its absorption during the reaction time. The inaccuracies of
Here V1, V4, and V5 are the partial molar volumes of
the rate constants were 3%, the enthalpy of activation 2 kJ
compounds 1, 4, and 5, respectively.
−1
mol−1, and activation entropy 6 J mol−1 K
.
2.5 Calorimetric measurements
2.3 Kinetic measurements at elevated
hydrostatic pressure
The enthalpies of the reactions 1+2 → 3 and 1+4 → 5 were
◦
determined in 1,2-dichloroethane at 25 C with the employ-
The pressure effect on the rate of the reactions 1+2 → 3
ment of the differential calorimeter. The protocol of measure-
ment was described earlier.16,17 A sample of the crystals 1
was introduced into each of the solutions of bicyclic monoter-
penes, 2 or 4 taken in excess. Three consecutive measurements
were made for each reaction, 1+2 → 3 and 1+4 → 5. The val-
ues of reaction enthalpy were calculated taking into account
◦
(toluene) and 1+4 → 5 (ethyl acetate) was studied at 25 C
with the usage of a pressure multiplier (HP-500, Japan), a
quartz cell with the variable volume (PCI-500, Japan) and UV
spectrophotometer (SCINCO S-3100, Korea). The observed
activation volume (∆V≠exp; Equation 2) of the reactions
1+2 → 3 and 1+4 → 5 was calculated on the basis of the rate
constants measured at 1 and 1000 bar, applying the previously
proposed24 relationship 1. Kinetics of the reactions 1+2 → 3
and 1+4 → 5 was studied in various solvents to optimize mon-
itoring conditions:
the heat of solution of crystals 1 in 1,2-dichloroethane, 21.9 kJ
−1
mol
.
3
RESULTS AND DISCUSSION
(
)
(
)
푘푃 =1000
푘푃 =1
휕 ln 푘
휕푃
= (1.15 0.03) × 10−3 ⋅ ln
(1)
The kinetic data and the activation parameters obtained of the
reactions 1+2 → 3 and 1+4 → 5 in nine solvents are collected
in Table 1.
푇 ,푃 =1
(
)
It should be noted that the rates of the reactions 1+2 → 3
and 1+4 → 5 in such polar solvents as dimethylformamide
and acetonitrile is noticeably less than in low polar solvents.
The activation entropy of the reactions 1+2 → 3 and 1+4 → 5
closely corresponds to the activation entropy of other reac-
tions of ene synthesis as well as the [4+2]-, [2ꢁ+2휎+2휎]-,
[2ꢁ+2ꢁ+2ꢁ]-cycloaddition, but is significantly less in mag-
nitude than that of the [2ꢁ+2ꢁ]-cycloaddition reaction
(Table 2).
휕 ln 푘
휕푃
Δ푉 ≠ = −푅푇
(2)
exp
푇
Corrected values of activation volumes (∆V≠corr) of the
reactions 1+2 → 3 and 1+4 → 5 were determined by Equa-
tion 3, taking into account isothermal compressibility coeffi-
cients of toluene, ꢀ 9.19 × 10−5 bar−1, and ethyl acetate, ꢀ
T
T
−4
1.20 × 10 bar−1, respectively:25
In the reaction 1+9 the C=C bond shifting to the nodal
atom of bicycle 9 is forbidden by the Bredt rule. However, the
Δ푉 ≠
= Δ푉 ≠exp + ꢀT푅푇
(3)
corr

KISELEV ET AL.
3
−1
◦
TA B L E 1 The rate constants (k /L mol
s
−1) of the reactions 1+2 → 3 and 1+4 → 5 in the temperature range 20–40 C in a series of solvents
2
with different permittivity (휀), enthalpy (∆H≠/kJ mol−1), entropy (∆S≠/J mol
K
−1), and Gibbs free energy (∆G≠/kJ mol−1) of activation
1+4 → 5
−1
1+2 → 3
k2
k2
k2
∆G≠
k2
k2
k2
∆G≠
о
о
о
о
о
о
о
о
Solvent
ꢁ (25 C) a (20◦C) (30 C) (40 C) ∆H≠ –∆S≠ (20 C) (20 C) (30 C) (40 C) ∆H≠ –∆S≠ (20 C)
N,N-Dimethylformamide 36.7
0.0172 0.0337 0.0623 46.7 119 81.6
0.0247 0.0477 0.0827 43.3 128 80.8
0.0215 0.0407 0.0690 42.1 133 81.1
0.0347 0.0667 0.1226 45.7 117 80.0
2-Propanone
Ethyl acetate
1,4-Dioxane
Acetonitrile
Toluene
20.6
6.0
0.0506 0.0912 0.153
0.0518 0.0941 0.156
39.8 134 79.1
39.6 134 78.9
35.3 144 77.5
32.4 146 75.2
32.9 141 74.2
31.3 143 73.2
22.2 161 69.4
20.7 157 66.7
2.2
0.0438 0.0744 0.121
38.8 139 79.5
32.6 148 76.0
32.4 149 76.1
31.2 151 75.5
21.5 170 71.3
0.0990 0.177
0.266
0.637
0.945
1.36
4.64
–
35.9
2.4
0.172
0.162
0.238
1.39
0.296
0.276
0.388
1.93
–
0.432
0.405
0.574
2.58
–
0.256
0.374
0.563
2.44
0.423
0.606
0.917
3.38
Benzene
2.3
1,2-Dichloroethane
Chloroform
10.4
4.6
4.45
–
–
68.0
7.55
10.0
aThe values of permittivity are taken from Ref. 23.
reaction of the [2ꢁ+2ꢁ]-cycloaddition has turned out to be
less advantageous in comparison with the Wagner-Meerwein
rearrangement.14,20 The increased activity of 1, even with
regard to tetracyanoethylene, as well as the increased stabil-
ity of adducts in all reactions with 1 (Table 2) allowed us
to carry out the [4+2]-cycloaddition reaction of 1 with 9,10-
diphenylanthracene (13), where the active 9,10-reaction cen-
ters of 13 are sterically inaccessible. Nevertheless, the reac-
tion 1+13 easily proceeds on the available 1,4-diene atoms of
13.30,31
reaction rate at atmospheric (1 bar) and elevated (1000 bar)
pressure (Equations 1–3). From the obtained ratio kP = 1000/kP
equal to 3.10, the observed value ∆V≠
= −32.2
exp
= 1
−1
1.0 cm3 mol has been calculated. Taking into account
the change in the reagents concentration due to the solvent
compressibility, the corrected activation volume (∆V≠
)
corr
−1
is −29.9 1.0 cm3 mol (ꢀ RT = 2.3 cm3 mol−1). The
T
activation volume (∆V≠corr) for the reaction 1+4 → 5 in
ethyl acetate is equaled −36.0 1.5 cm3 mol (kP = 1000
/
−1
kP = 1 = 3.92, ∆V≠
= −39.0 1.0 cm3 mol−1, ꢀ RT = 3.0
exp.
T
The energy balance between breaking and formation of the
bonds reflected in the reaction enthalpy is minimal in the reac-
tions 1+10 and 1+13 and is maximal for the reaction with
nonconjugated norbornadiene, 1+8, and also for the reac-
tion involving two cyclopropane rings of quadricyclane, 1+7.
However, according to the data presented (Table 2), it follows
that the high exothermicity of the reaction rarely determines
the reaction rate.
cm3 mol−1). The difference in the values of the activation
volume of these reactions (ΔΔV = 6.1 cm3 mol−1) can
be explained by the solvent influence: For the reaction of
≠
bisadamantylidene 10 with 1, the activation volume ∆V
corr
−1
is −50.8
1.4 cm3 mol in toluene, and −55.8
1.5
cm3 mol in ethyl acetate, that is the difference in activa-
−1
tion volumes is equal to 5.0 cm3 mol
.
It can be noted
−1 29
that the activation volumes of the reactions of 1+2 → 3
The enthalpies of the reactions 1+2 → 3 and 1+4 → 5 were
(∆V≠
= −29.9 1.0 cm3 mol−1, toluene) and of 1 with
corr
◦
determined in 1,2-dichloroethane at 25 C from the data of
cyclohexene (∆V≠
= −29.1
0.5 cm3 mol−1, toluene,
corr
◦
three consistent dissolutions of crystals 1 in the solutions of
2 and 4, respectively. Taking into account the heat of dissolu-
tion of 1 in 1,2-dichloroethane (21.9 kJ mol−1) for the reac-
25 C [Ref. 13]) coincide within the limits of measurement
inaccuracies. To determine the reaction volume (∆Vr-n) of
1+2 → 3, two cycles of measurements (Equations 6 and 7)
were carried out. The volume of reaction 1+4 → 5 was deter-
mined by the kinetic method (Equations 8 and 9) and by the
difference of the partial molar volumes of the adduct and
reagents in ethyl acetate (Equation 10):
−1
̄
tion 1+2 → 3, the value of Δ퐻푟−푛 is −158.4 0.9 kJ mol
(−157.3, −159.7, and −158.2 kJ mol−1), and for the reaction
−1
of 1+4 → 5 this value is −159.1 1.1 kJ mol (−157.5,
−160.5, and −159.4 kJ mol−1). High exothermicity of these
1+2 → 3 and 1+4 → 5 reactions allows us to consider them
practically irreversible. It can be noted that these values of
enthalpies of the 1+2 → 3 and 1+4 → 5 reactions are very
close to that of the reaction of 1 with cyclohexene (∆Hr-n
푑−1 = − (0.0278995 0.000126) ⋅ 푐ꢃ
+ (1.1594608 0.0000004); 푅2 = 0.9996
−155.9 0.4 kJ mol−1, toluene, 25 C [Ref. 13]).
◦
Δ푉ꢂ
= −24.1 cm3mol−1; 푐0ꢂ = 5.06 × 10−3mol 퐿−1
,
+ꢄ→ꢃ
The activation volume for the reaction 1+2 → 3 has been
◦
푐0ꢄ = 5.50 × 10−3mol 퐿−1
(6)
determined in toluene at 25 C according to the data on the

4
KISELEV ET AL.

KISELEV ET AL.
5

6
KISELEV ET AL.
tions 1+2 → 3 and 1+4 → 5 with regard to the [2ꢁ+2휎+2휎]-
cycloaddition reaction of 1 with quadricyclane (7),27 ene reac-
tion with 2-methylbutene-2 (14),35 [2ꢁ+2ꢁ]-cycloaddition
푑−1 = − (0.0277264 0.000180) ⋅ 푐ꢃ
+ (1.1593645 0.0000006); 푅2 = 0.9992
reaction of 1 with 2-chloroethylvinyl ether (15),36 ene reaction
14,20
between 1 and norbornene (9)
with Wagner-Meerwein
Δ푉ꢂ
Δ푉ꢂ
= −23.9 cm3 mol−1; 푐0ꢂ = 5.06 × 10−3mol L−1
,
+ꢄ→ꢃ
rearrangement, ene reaction of 1 with trans-hexene-3 (16),21
[4ꢁ+2ꢁ]-cycloaddition reaction of 1 with anthracene (17),17
and [2ꢁ+2ꢁ]-cycloaddition reaction of 1 with bisadamantyli-
dene (10)29 (Equations 11–18):
푐01 = 5.50 × 10−3mol L−1
= −24.0 0.1 cm3 mol−1
.
(7)
+ꢄ→ꢃ
푑−1 = − (0.0346118 0.00039) ⋅ 푐ꢀ
+ (1.1178038 0.00000087) ; 푅2 = 0.9979
= −30.9 0.5cm3 mol−1
ln푘 (ꢂ + ꢄ) = (1.04 0.03) ⋅ ln푘 (ꢂ + ꢁ) − (0.65 0.07) ;
푅2 = 0.9939, 푁 = 9
(11)
Δ푉ꢂ
;
+ꢁ→ꢀ
ln푘 (ꢂ + ꢅ) = (0.82 0.14) ⋅ ln푘 (ꢂ + ꢁ) + (0.13 0.29) ;
푐0ꢂ = 푐0ꢁ = 5.00 × 10−3mol L−1
(8)
푅2 = 0.8515, 푁 = 8
(12)
푑−1 = − (0.0331679 0.000279) ⋅ 푐5
+ (1.1177995 0.00000066) ; 푅2 = 0.9985
= −29.8 0.3 cm3 mol−1
ln푘 (ꢂ + ꢂꢀ) = (0.52 0.03) ⋅ ln푘 (ꢂ + ꢁ) + (2.65 0.08) ;
푅2 = 0.9869, 푁 = 5
(13)
Δ푉1
Δ푉1
;
+4→5
푐01 = 푐02 = 5.00 × 10−3mol L−1
= −30.4 0.5 cm3 mol−1
.
ln푘 (ꢂ + ꢆ) = (0.46 0.01) ⋅ ln푘 (ꢂ + ꢁ) − (6.73 0.01) ;
(9)
+4→5
푅2 = 0.9995, 푁 = 4
(14)
Δ푉ꢂ
= 푉ꢀ − 푉ꢂ − 푉ꢁ = 257.2 − 129.0 − 158.8
= −30.6 1.0 cm3 mol−1
+ꢁ→ꢀ
ln푘 (ꢂ + ꢂꢇ) = (0.88 0.18) ⋅ ln푘 (ꢂ + ꢁ) − (2.55 0.35) ;
(10)
푅2 = 0.9588, 푁 = 3
(15)
Both methods give identical values of the reaction volume
of 1+4 → 5. The ratio of activation and reaction volumes
(∆V≠corr/∆Vr-n) for the reaction of 1+2 → 3 is 1.25, and for
1+4 → 5 is 1.18. Note that for all ene reactions under the study
the ratio ∆V≠corr/∆Vr-n is always more than one.13–17 Sol-
vent electrostriction for the activated complex can be excluded
from consideration due to small and irregular solvent effect on
the reaction rates. These ratios can be explained by the cyclic
and, therefore, more compact form of the activated complex as
compared with the acyclic form of the reaction adduct. This
conclusion agrees with the results of the study of ene reac-
tions of alkenes with enophiles containing C=O and C≡ C
reaction centers,32–34 where the value of ∆V≠corr/∆Vr-n was
in the range 1.1-1.3.
ln푘 ꢂ + ꢂꢅ = 0.88 0.04 ⋅ ln푘 ꢂ + ꢁ − 0.20 0.06 ;
(
)
(
)
(
)
(
)
푅2 = 0.9919, 푁 = 7
(16)
ln푘 (ꢂ + ꢂꢈ) = (1.0730 0.2603) ⋅ ln푘 (ꢂ + ꢁ)
− (2.2136 0.5648) ; 푅2 = 0.7081, 푁 = 9
(17)
ln푘 (ꢂ + ꢂꢁ) = (0.99 0.03) ⋅ ln푘 (ꢂ + ꢁ) + (0.67 0.06) ;
푅2 = 0.9912, 푁 = 9
(18)
In the series of solvents (Table 1), the reaction rates of the
1+2 → 3 and 1+4 → 5 differ by two orders of magnitude;
however, these changes take place not due to the solvent polar-
ity. Similar activation of dienophiles in H-donor solvents is
well known for other types of reactions. Previously, the sol-
vent effect on the rate of the number of reactions involving
dienophile 1 has been considered, which makes it possible to
compare the solvent effect on the rate of the studied ene reac-
For the ene reactions (1+2), (1+4), and (1+14), as well as
the Diels-Alder reaction (1+17), a high proportionality of the
solvent effect on the reaction rate with the angular coefficient
close to one has been observed. The close solvent effect on
the rate of different reactions presupposes a slight difference
in the solvent effect on the energy level of the transition state.

KISELEV ET AL.
7
6. Elemes Y, Foote CS. Stepwise mechanisms in the ene reaction
of .alpha.,.beta.-unsaturated esters with N-phenyl-1,2,4-triazoline-
3,5-dione and singlet oxygen. Intermolecular primary and sec-
ondary hydrogen isotope effects. J Am Chem Soc. 1992;114:6044−
6050.
4
CONCLUSIONS
Ene reactions of structurally similar bicyclic 2 and 4 monoter-
penes with 1 go with nearly the same energy and volume
parameters: enthalpy, entropy, Gibbs free energy of activa-
tion, reaction enthalpy, activation volume, and reaction vol-
ume. A high proportionality in the solvent effect on the reac-
tion rate of the reactions 1+2 → 3 and 1+4 → 5 is observed.
In a series of nine solvents, the rate of these reactions changes
by two orders of magnitude but not due to the solvent polar-
ity, which is similar to other reactions of ene synthesis as well
as cycloaddition reactions. The ratio of activation volume to
reaction volume (∆V≠corr/∆Vr-n) for the reaction 1+2 → 3 is
1.25, and for the 1+4 → 5 ∆V≠corr/∆Vr-n is 1.18. Low solvent
polarity effect on the reaction rates suggests that there is no
solvent electrostriction. Such ratio of volume parameters can
be explained by the cyclic and, therefore, more compact form
of the transition state in comparison with the acyclic form of
the reaction adduct.
7. Chen JS, Houk KN, Foote CS. The nature of the transition
structures of triazolinedione ene reactions. J Am Chem Soc.
1997;119:9852−9855.
8. Christoforou A, Nicolaou G, Elemes Y. N-phenyltriazolinedione as
an efficient, selective, and reusable reagent for the oxidation of thiols
to disulfides. Tetrahedron Lett. 2006;47:9211−9213.
9. Ajaj KA, Hennig L, Findeisen M, Giesa S, Muller D, Welzel
P. Synthesis of a complex disaccharide precursor of phospho-
nate analogues of the antibiotic moenomycin A12. Tetrahedron.
2002;58:8439−8451.
10. Wilson RM, Hengge A. Nucleophilic additions to triazolinedione
ylides, extremely reactive carbonyl equivalents: a new class of con-
densation reactions. J Org Chem. 1987;52:2699−2707.
11. Breslow R, Corcoran RJ, Snider BB, Doll RJ, Khanna PL, Kaleya
R. Selective halogenation of steroids using attached aryl iodide tem-
plates. J Am Chem Soc. 1977;99:905−915.
12. Nicolaou G, Elemes Y. N-phenyltriazolinedione as an initiator in
the radical addition of thiophenol to alkenes. Tetrahedron Lett.
2008;49:6324−6326.
DECLARATION OF INTEREST STATEMENT
The authors hereby confirm they have no conflicts of
interest.
13. Kiselev VD, Kornilov DA, Kashaeva HA, Potapova LN, Konovalov
AI. 4-phenyl-1,2,4-triazoline-3,5-dione in the ene reactions with
cyclohexene, 1-hexene and 2,3-dimethyl-2-butene. The heat of reac-
tion and the influence of temperature and pressure on the reaction
rate. J Phys Org Chem. 2014;27:401−406.
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation for
Basic Research (Projects No. 16-03-00071 and 18-33-00063),
the Ministry of Education and Science of Russian Federa-
tion (Project No 4.6223.2017/9.10), and the research grant of
Kazan Federal University.
14. (a) Kiselev VD, Kornilov DA, Kashaeva EA, Potapova LN, Sedov
IA, Konovalov AI. Atmospheric and high pressure ene reaction of
norbornene with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione. Russ J
Org Chem. 2015;51:401–405;
(b) Russ J Org Chem, Engl Transl. 2015;51:387–391.
15. (a) Kiselev VD, Kornilov DA, Lekomtseva II, Reshetnikova OY,
KonovalovAI. Ene reaction of 4-phenyl-3H-1,2,4-triazole-3,5(4H)-
dione with dicyclopentadiene. Russ J Org Chem. 2015;51:397–
400;
ORCID
Vladimir D. Kiselev
http://orcid.org/0000-0002-2039-3265
(b) Russ J Org Chem, Engl Transl 2015;51:382–386.
16. Kiselev VD, Kornilov DA, Konovalov AI. Cyclic and acyclic N═N
bonds in reactions with some alkenes and dienes. Int J Chem Kinet.
2017;49:562–575.
REFERENCES
1. Corey EJ, Snider BB. A new synthetic route to prostaglandins.
Tetrahedron Lett. 1973;14:3091−3094.
17. 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.
2. Cheng CC, Seymour CA, Petti MA, Greene FD, Blount JFJ. Reac-
tion of electrophiles with unsaturated systems: triazolinedione-
olefin reactions. J Org Chem. 1984;49:2910−2916.
3. Cheng CC, Greene FD, Blount JF. Reaction of triazoline-
diones with acetylenes. Electrophilic addition. J Org Chem.
1984;49:2917−2922.
18. Burrage ME, Cookson RC, Gupte SS, Stevens IDR. Substituent and
solvent effects on the Diels–Alder reactions of triazolinediones. J
Chem Soc, Perkin Trans II. 1975:1325–1334.
4. Gau A-H, Lin G-L, Uang B-J, Liao F-L, Wang S-L. Regio-
and diastereoselective ene reaction of 4-phenyl-1,2,4-triazoline-3,5-
dione with chiral allylic alcohols and their derivatives. J Org Chem.
1999;64:2194−2201.
19. Seymour CA, Greene FD. Mechanism of triazolinedione-olefin
reactions. Ene and cycloaddition. J Am Chem Soc. 1980;102:6384–
6385.
20. Adam W, Carballeira N. On the mechanism of the cycloaddition
of 1,2,4-triazoline-3,5-diones with bicycloalkenes leading to rear-
ranged urazoles. J Am Chem Soc. 1984;106:2874–2882.
5. Syrgiannis Z, Koutsianopoulos F, Muir KW, Elemes Y. Reaction of
a triazolinedione with simple alkenes. Isolation and characterization
of hydration products. Tetrahedron Lett. 2009;50:277−280.

8
KISELEV ET AL.
21. Ohashi S, Butler GB. Ene reaction of triazolinediones with alkenes.
30. Kiselev VD, Shakirova II, Kashaeva HA, et al. Why can the
Diels–Alder reaction of 9,10-diphenylanthracene with 4-phenyl-
1,2,4-triazoline-3.5-dione pass by an abnormal way? Mendeleev
Commun. 2013;23:235–236.
2. Kinetics and substituent effects. J Org Chem. 1980;45:3472–
3476.
22. Adam W, De Lucchi O, Hill K. Reaction of 4-phenyl-1,2,4-
triazoline-3,5-dione (PTAD) with bicyclic monoterpenes. Chem
Ber. 1982;115:1982–1989.
31. (a) Kiselev VD, Kornilov DA, Kashaeva EA, et al. Fea-
tures of the Diels-Alder reaction between 9,10-diphenylanthracene
and 4-phenyl-1,2,4-triazoline-3,5-dione. Russ J Phys Chem A.
2014;88:1914–1921;
23. Riddick JA, Bunger WB, Sakano TK. Organic solvents: physical
properties and methods of purification. 4th ed. New York, NY:
Wiley; 1986.
(b) Russ J Phys Chem A, Engl Transl. 2014;88:2073–2080.
32. Jenner G, Ben Salem R, El'yanov BS, Gonikberg EM. Piezochem-
ical interpretation of (C ⋯ H ⋯ X) hydrogen transfer in ene reac-
tions. J Chem Soc,Perkin Trans II. 1989:1671–1675.
24. 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.
33. El'yanov BS, Gonigberg EM, Jenner G. Linear free energy relation-
ship for the pressure dependence of rate constants in ene reactions.
J Chem Soc, Perkin Trans II. 1992:137–142.
25. 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.
34. (a) Houk KN, Li Y, Evanseck JD. Transition structures of hydro-
carbon pericyclic reactions. Angew Chem. 1992;104:711–739;
(b) Angew Chem, Int Ed 1992;31:682–708.
26. Kiselev VD. High-pressure influence on the rate of Diels–Alder
cycloaddition reactions of maleic anhydride with some dienes. Int
J Chem Kinet. 2013;45:613–622.
35. Desimoni G, Faita G, Righetti PP, Sfulcini A, Tsyganov D. Sol-
vent effect in pericyclic reactions. IX. The ene reaction. Tetrahe-
dron. 1994;50:1821–1832.
27. Kiselev VD, Kornilov DA, Anikin OV, Sedov IA, Konovalov AI.
Kinetics and thermochemistry of the unusual [2ꢁ + 2휎 + 2휎]-
cycloaddition of quadricyclane with some dienophiles. J Phys Org
Chem. 2017. https://doi.org/10.1002/poc.3737.
36. Hall JH, Jones ML. Reactions of azodiones with electron-rich
alkenes. 1,2,4-triazoline-3,5-diones and vinyl ethers. J Org Chem.
1983;48:822–826.
28. Kiselev VD, Shakirova II, Kornilov DA, Kashaeva HA, Potapova
LN, Konovalov AI. Homo-Diels–Alder reaction of a very inac-
tive diene, bicyclo[2,2,1]hepta-2,5-diene, with the most active
dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione. Solvent, tempera-
ture, and high pressure influence on the reaction rate. J Phys Org
Chem. 2013;26:47–53.
How to cite this article: Kiselev VD, Kornilov
DA, Anikin OV, Shulyatiev AA, Kolesnikova
AO, Konovalov AI. Kinetics of the ene reac-
tions of 4-phenyl-1,2,4-triazoline-3,5-dione with
ꢀ-pinene and 2-carene: temperature, high pressure,
and solvent effects. Int J Chem Kinet. 2018;1–8.
https://doi.org/10.1002/kin.21189
29. (a) Kiselev VD, Kornilov DA, Anikin OV, Sedov IA, Kono-
valov AI. [2ꢁ + 2ꢁ]-cycloaddition of biadamantylidene to 4-
phenyl-3H-1,2,4-triazole-3,5(4H)-dione. Effects of temperature,
high pressure, and solvent. Russ J Org Chem. 2017;53:1864–
1869;
(b) Russ J Org Chem, Engl Transl. 2017;53:1864–1869.