Theory and Practice of the Preparation of Adamantylarenes

Article abstract of DOI:10.1134/S0965544118100171

Abstract: The adamantylation of diphenyl oxide and phenol with 1-chloro(bromo)adamantanes in a liquid phase has been studied. The reaction has been performed under kinetic control and under the conditions of reaching chemical equilibrium using the following catalysts: Amberlyst 36 Dry, in situ HBr, and AlCl₃. The kinetics of isomerization of (1-adamantyl)- and (2-adamantyl)diphenyl oxides has been studied at 333 and 417 K in the presence of AlCl₃ and Amberlyst 36 Dry, respectively. The equilibrium of the positional and structural “bridge–bridgehead” isomerization has been studied in the range of 333–523 K. It has been found that high selectivity of the adamantylation of diphenyl oxide or phenol can be achieved in the case of the use of sulfonated cation-exchange resins as a catalyst. In the presence of aluminum halides or HBr, the reaction mixture has been represented by all the possible isomers and adamantane.

Full text of DOI:10.1134/S0965544118100171

ISSN 0965-5441, Petroleum Chemistry, 2018, Vol. 58, No. 10, pp. 895–904. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © S.V. Tarazanov, V.A. Shakun, T.N. Nesterova, V.S. Sarkisova, P.V. Naumkin, I.A. Nesterov, O.V. Repina, 2018, published in Neftekhimiya, 2018,
Vol. 58, No. 5, pp. 608–617.
Theory and Practice of the Preparation of Adamantylarenes
S. V. Tarazanova, b, *, V. A. Shakuna, T. N. Nesterovaa, V. S. Sarkisovaa, P. V. Naumkina,
I. A. Nesterova, and O. V. Repinaa
aSamara State Technical University, Samara, 443100 Russia
bAll-Russia Research Institute for Petroleum Processing, Moscow, 111116 Russia
*e-mail: tarazanovsv@rambler.ru
Received July 25, 2017
Abstract—The adamantylation of diphenyl oxide and phenol with 1-chloro(bromo)adamantanes in a liquid
phase has been studied. The reaction has been performed under kinetic control and under the conditions of
reaching chemical equilibrium using the following catalysts: Amberlyst 36 Dry, in situ HBr, and AlCl3. The
kinetics of isomerization of (1-adamantyl)- and (2-adamantyl)diphenyl oxides has been studied at 333 and
417 K in the presence of AlCl3 and Amberlyst 36 Dry, respectively. The equilibrium of the positional and
structural “bridge–bridgehead” isomerization has been studied in the range of 333–523 K. It has been found
that high selectivity of the adamantylation of diphenyl oxide or phenol can be achieved in the case of the use
of sulfonated cation-exchange resins as a catalyst. In the presence of aluminum halides or HBr, the reaction
mixture has been represented by all the possible isomers and adamantane.
Keywords: isomerization, kinetics, chemical equilibrium, adamantane, sulfonated cation-exchange resins,
acids
DOI: 10.1134/S0965544118100171
Starting from 1957 and to the present day, a lot of
The result of adamantylation will probably be fun-
methods for the preparation of adamantylarenes have damentally different in the case of running the process
been developed. Most of them have no fundamental under the conditions of kinetic or thermodynamic
differences from the alkylation of arenes. Compounds control by analogy with the alkylation of arenes with
with 1- and 2-adamantyl substituents are prepared via branched pentenes or halopentanes [9]. Systematic
the adamantylation of the corresponding aromatic studies on these problems are extremely scarce. More
substrate with 1- and 2-haloadamantanes [1, 2] or 1- or less general studies include the following works.
and 2-adamantanols [3–5] in the presence of various Olah et al. [1] investigated the adamantylation of ben-
acidic catalysts including Lewis superacids [1] and zene and toluene with 1- and 2-halo(fluoro, chloro,
solid superacids of the Nafion-H type [2]. To date, a and bromo)adamantanes or 1-adamantanoyl chloride
wealth of sulfonated cation-exchange resins and zeo- and the isomerization of monoaryladamantanes in the
lites with different catalytic activity have been tested as presence of superacids in a medium of various sol-
catalysts. A retrospective (up to 2009) analysis of the vents. The adamantylation of benzene and toluene
potential fields of application of sulfonated cation- with 2-halo(chloro and bromo)adamantanes in a
exchange resins was performed by Alexandratos [6].
dichloromethane medium is accompanied by inten-
sive isomerization (“bridge–bridgehead” and in the
aromatic ring), and the concentration of the initially
formed 2-Ad derivatives decreases at room tempera-
ture within 60 min to 6% for a mixture of Ad-benzenes
and to 10–20%, for Ad-toluenes. The change of the
type of superacids selected in [10] had no influence on
the result of the adamantylation of toluene.
Together with the conventional methods for the
adamantylation of arenes, other approaches are con-
sidered. Butov et al. [7, 8] believe that 1,3-dihydroad-
amantane (1,3-DHA) is a very promising adamantyl-
ating agent. In the presence of catalytic amounts of
sulfuric acid, selective preparation (the yield is 83–
96 wt %) of p-(1-adamantyl)benzenes [7] and p-(1-
adamantyl)phenols is possible with the use of 1,3-
The study with superacids was continued by Laali
DHA as an adamantylating agent [8]. In the absence et al. [11], who showed that the process is character-
of an acidic catalyst, diatomic phenols react with 1,3- ized by high p-(1-Ad)toluene selectivity, which
DHA to form 1-adamantyl phenyl ethers (the yield is reaches 90–100% of total products. The yield of ada-
80–88%) and the products of C-adamantylation are mantane and m-(1-Ad)toluene did not exceed 5% in
byproducts (with a yield of 8–10%) [8].
each of the experiments.
895

896
TARAZANOV et al.
The use of sulfonated cation-exchange resins tions of adamantylarenes, first of all, their isomeriza-
(Amberlyst XN 1010 and Dowex X2-100) instead of tion.
superacids [12] allowed Olah to increase the selectivity
Despite the fact that there is already a considerable
number of works on the adamantylation of arenes,
there is almost no information on the kinetics of the
processes. The only papers on the issue by Pimerzin
and Sarkisova [19, 20] are devoted to the systematic
study of the equilibrium of the transformations of ada-
mantylarenes. They studied the equilibrium of the
bridge–bridgehead isomerization in the liquid- phase
for adamantylarenes (benzenes, toluenes, and ortho-
and meta-xylenes). There is no information of this
kind for compounds of other classes.
for the p-Ad derivatives to 100% in the adamantylation
of monosubstituted benzenes.
The adamantylation of phenols was studied in the
presence of the sulfonated cation-exchange resins
Amberlite 200 and Amberlite IR120 [13] and trifluo-
roacetic acid [14] or without catalysts whatsoever [15,
16], with unsubstituted phenols giving a mixture of
ortho- and para-derivatives with the isomer ratio that
depends on the process conditions [17].
Irrespective of the field of application of ada-
This research is aimed at the reduction of the afore-
mantylarenes, 1-adamantyl derivatives are preferable, mentioned gaps in information on the kinetics and
and only such structures can be used in some cases thermodynamics of the adamantylation of arenes and
[18]. The selective preparation of these structures the interconversion of adamantylation products. The
requires the possession of reliable data on the kinetics compounds under consideration in this work are pre-
of adamantylation and equilibrium of the transforma- sented below:
O
O
O
o-(1-Adamantyl)DPO
p-(1-Adamantyl)DPO
m-(1-Adamantyl)DPO
O
O
O
p-(2-Adamantyl)DPO
m-(2-Adamantyl)DPO
DPO
HO
OH
p-(1-Adamantyl)phenol
o-(1-Adamantyl)phenol
Adamantane
EXPERIMENTAL
(purchased from the Novokuibyshevsk Petrochemical
Company NNK, Russia) was used for the preparation
of adamantylphenols (AdP) without additional purifi-
Diphenyl oxide (DPO) (Vekton, Russia) with the
purity of more than 99 wt % according to GLC data was
used for the synthesis of AdDPO. Phenol 99.9 wt % cation.
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THEORY AND PRACTICE OF THE PREPARATION OF ADAMANTYLARENES
897
1-Chloro- and 1-bromoadamantanes (1-ClAd and capillary column (60 m × 0.25 mm) with the bonded
1-BrAd) containing trace amounts of adamantane SE-30 stationary phase. Helium was used as the car-
were used as an alkylating agent. The alkylation of rier gas. The carrier gas pressure at the inlet to the col-
DPO and phenol was performed using Amberlyst umn was 3 atm, the stability of the pressure was pro-
36 Dry sulfonated cation-exchange resin (Dow vided via double reduction. The column temperature
Chemical) as the catalyst (provided by NNK, Russia). modes were individually selected for each system and
Prior to the experiments, the catalysts were dried in a were maintained accurate to within 0.1°C. The evap-
thermostat at 105°C to constant weight. The alkylation orator temperature of was 543 K, and the detector
was performed in a glass jacketed reactor, equipped temperature was 573 K.
with a stirrer and a reflux condenser, in the tempera-
ture range of 80–150°C. The reactor was thermostated
at an appropriate temperature with a heat-transfer
fluid (benzene, toluene, o-xylene, or n-nonane) boil-
ing in the jacket.
The reactor was charged with diphenyl oxide or
phenol and the catalyst in an amount of 30 wt %, the
mixture was stirred at the temperature of the experi-
ment for 30 min, then 1-ClAd was introduced, and
sampling started. To preclude the formation of diada-
mantyl derivatives, the alkylation was performed with
an excess of the substrate. The 1-ClAd/substrate
molar ratio was varied in the range of 0.01–0.7.
The identification of all the components of the
mixtures included both a chemical experiment and a
chromatographic–mass spectrometric analysis, which
was performed on an Agilent 6850 gas chromatograph
equipped with an Agilent 19091S-433E capillary col-
umn (30 m × 0.25 mm × 0.25 μm) with an HP-5MS
stationary phase (5% diphenylpolysiloxane + 95%
dimethylpolysiloxane) and an Agilent 5975C VL MSD
mass selective detector at an ionizing energy of 70 eV.
RESULTS AND DISCUSSION
The adamantylation of DPO with 1-chlo-
ro(bromo)adamantanes in the presence of A-36
(30 wt %) and at a haloadamantane/DPO molar ratio
not exceeding 0.25 is quite a rapid process; it is com-
pleted within 60–90 min over the operating tempera-
ture range of the sulfonated cation exchanger. The
selectivity of the process for p-(1-Ad)DPO is high,
being at the level of 96–94%.
In the low-temperature region (353–383 K) of the
use of the cation-exchange resins, o-(1-Ad)DPO is
the only impurity to p-(1-Ad)DPO. Note this fact is
characteristic not only for the alkylation step, but also
for the subsequent isomerization up to 270 min, with
the o-(1-Ad)DPO concentration changing by no more
than 2%.
The high-temperature region (≥417 K) of the use of
the cation-exchange resins is characterized by the
noticeable progress of the isomerization of two types:
• in the aromatic ring, resulting in a change in
the o-(1-Ad)DPO concentration and the formation of
m-(1-Ad)DPO and
The isomerization equilibrium of adamantyl
diphenyl oxides (AdDPO) was studied in the liquid
phase using the static method and catalysis with AlCl3
or AlBr3.
The reaction mixture obtained via alkylation over
the sulfonated resin was freed from the catalyst, placed
into an airtight glass reactor, and heated to the reaction
temperature; then, 1–5 wt % AlCl3 was introduced
and the reactor was thermostated with an accuracy of
1°C in a SNOL-58/350 air bath oven. The time of
the experiment was counted from this moment on.
Samples were collected with a microsyringe from the
liquid phase by piercing the seal in the lid of the reac-
tor. The sample taken was immediately quenched with
water, extracted with toluene, dried over calcium chlo-
ride, and chromatographically analyzed.
The experiment consisted of series of measure-
ments. The temperature, the initial composition, and
the type and amount of the catalyst remained constant
within each series, only the duration of the experiment
varied. The series differed between each other only in
the composition of the initial mixture and the amount
of the catalyst.
• in the adamantyl substituents, resulting in the
appearance of p-(2-Ad)DPO and a further growth in
its concentration.
In this region, the rate of formation of p-(2-
Ad)DPO keeps the fivefold higher value relative to the
rate of formation of m-(1-Ad)DPO over the entire
time span of the study.
The values of the rate constants obtained for the
isomerization of a p-(1-Ad)DPO + DPO mixture over
A-36 (30 wt %) at 417 K are presented in Table 1. The
kinetic information was processed by the Runge–
Kutta method using recommendations set out in [23].
The isomerization equilibrium of adamantylphe-
nols was studied in the presence of 20–30 wt % A-36
sulfonated cation-exchange resin. The experimental
procedure was similar to that used for the isomeriza-
tion of AdDPO except that the samples taken were not
subjected to any special treatment; they were just
diluted with toluene and analyzed.
The main method for the analysis of the reaction
mixtures was gas–liquid chromatography. The chro-
matographic analysis was performed on a Kristall
Therefore, the high selectivity of the adamantyla-
2000 M chromatograph with a Chromatec-Analitik tion of DPO over sulfonated cation-exchange resins
software–hardware complex equipped with a flame becomes explainable—forming o-(1-Ad)DPO rapidly
ionization detector, a carrier gas splitter, and a quartz transforms into target p-(1-Ad)DPO. It was experi-
PETROLEUM CHEMISTRY Vol. 58 No. 10 2018

898
TARAZANOV et al.
Table 1. Rate constants for the isomerization of AdDPO over A-36 at 417 K
ki, min−1
ki/k−1 ki/ k−i
Reaction
Reaction symbol
k1
1.Ad
–1.Ad
2.Ad
5.05E-04
1.68E-05
2.70E-05
2.35E-04
5.04E-03
30
1
30
o- 1-Ad DPO ⎯⎯⎯→ p- 1-Ad DPO
(
)
(
)
k−1
p- 1-Ad DPO ⎯⎯⎯→o- 1-Ad DPO
(
)
(
)
k2
1.6
p- 1-Ad DPO ⎯⎯⎯→ m- 1-Ad DPO
(
)
(
)
k3
3.Ad
14
p- 1-Ad DPO ⎯⎯⎯→ p- 2-Ad DPO
(
)
(
)
k−3
–3.Ad
300
21
p- 2-Ad DPO ⎯⎯⎯→ p- 1-Ad DPO
(
)
(
)
mentally found that adamantane was not formed as a 16 h at 523 K) (Fig. 1a) and the concentration of the
byproduct during the adamantylation of DPO over the
A-36 resin and the subsequent isomerization of the
products over the same catalyst in the range of 333–
424 K for 6 h.
meta-isomer increases (Fig. 1b). It is noteworthy that
the p-(1-Ad)DPO/p-(2-Ad)DPO and m-(1-
Ad)DPO/p-(1-Ad)DPO concentration ratios almost
simultaneously reach their equilibrium levels, which
remain unchanged in the case of a tenfold increase in
the residence time under the conditions of the experi-
Practice shows that like phenol and anisole [15,
16], DPO possesses sufficient reactivity to react with
halo(chloro and bromo)adamantanes even in the ment at 523 K. At the same time, the m-(1-
absence of an added catalyst. Higher temperatures are
required for the reaction.
Ad)DPO/m-(2-Ad)DPO
concentration
ratio
decreases, slowly approaching the equilibrium value.
In the range of 523–623 K, the reaction of DPO
with bromoadamantane proceeds almost instanta-
neously. The p-(1-Ad)DPO selectivity of the process
is at the level of 90–92% for several minutes. Then fol-
lows intensive development of the isomerization with
the predominant formation of all mono(1-Ad)DPO
and establishment of equilibrium between them
(Figs. 1a and 1b) with the prevalence of m-(1-
Ad)DPO in the equilibrium mixture.
Thus, the high-temperature adamantylation of
DPO with 1-bromoadamantane can be considered as
an alternative method for the preparation of m-(1-
Ad)DPO.
The total concentration of the ortho-isomers in the
monoAdDPO group did not exceed 7% regardless of
the conditions of adamantylation. The possibility for
the formation of diAdDPO in this work was limited for
practical reasons; it was eliminated by running the
processes in excess DPO.
The adamantylation of DPO over Lewis acids is
accompanied by the fast formation of all the possible
isomers of AdDPO and accumulation of adamantane
in the reaction mixture (Fig. 2).
The values of the rate constants found by studying
the kinetics of the transformations of AdDPO in a
DPO medium (80–5 mol %) over AlCl3 (4.9 wt %) at
The analysis of the results obtained in this study
shows that in the group of 2-AdDPO, the concentra-
tion of the para-isomer stabilizes quite rapidly (within 333 K are presented in Table 2.
(а)
(b)
wt %
90
wt %
4.5
80
70
60
50
40
30
20
10
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5000
10000
15000
0
5000
10000
15000
Duration of experiment, min
Duration of experiment, min
Fig. 1. Isomerization of p-(1-Ad)DPO at 523 K, catalysis with in situ HBr: (◊) p-(1-Ad)DPO, (○) m-(1-Ad)DPO, (r) o-(1-
Ad)DPO, (h) m-(2-Ad)DPO, (n) p-(2-Ad)DPO, and (d) degree of conversion of DPO.
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THEORY AND PRACTICE OF THE PREPARATION OF ADAMANTYLARENES
899
The values of the rate constants of reactions
(1.Ad)–(3.Ad) over AlCl3 exceed ki values for the same
processes over A-36 by more than an order of magni-
tude, despite the fact that the process temperature in
the experiment with AlCl3 is lower by 84 K as com-
pared to A-36. The analysis of the ratios of the rate
constants (Table 2) shows that it is hardly possible to
expect the selective preparation of any AdDPO over
AlCl3.
Concentrations of components, wt %
14
12
10
8
6
4
The following findings also deserve attention:
2
• the rate of p-(1-Ad)DPO decomposition to form
adamantane (Table 2, reaction (6.Ad)) is higher by a
factor of 1.8 than the rate of the coupled isomerization
reaction of p-(1-Ad)DPO to p-(2-Ad)DPO (reaction
(3.Ad)) and sixfold higher than the rate of formation of
m-(1-Ad)DPO (reaction (2.Ad));
• the rate of decomposition of m-(1-Ad)DPO
is sevenfold higher than the rate of decomposition of
p-(1-Ad)DPO; and
0
50
100
150
200
250
300
Duration of experiment, min
Fig. 2. Transformations of AdDPO over AlCl at 333 K:
(d) adamantane, (h) o-1-AdDPO, (n) m-1-AdDPO,
(×) m-2-AdDPO, (r) p-1-AdDPO, and (○) p-2-AdDPO.
3
wise equal conditions. By selecting the type of the cat-
alyst and conditions of the process, the transformation
o-(1-Ad)DPO ↔ p-(1-Ad)DPO (1.Ad) can be singled
out from the set of all the reactions not only in the case
of the kinetic control of the process, but also up to the
point of reaching the equilibrium. In the high-tem-
perature operating region of the cation-exchange res-
ins, the equilibrium of reaction (1.Ad) is reached
within several minutes (5–7 min over 30 wt % A-36 at
417–424 K) and is selectively maintained up to
150 min. At equilibrium, the concentration of p-(1-
Ad)DPO is 30 times that of o-(1-Ad)DPO. Reaction
• the decomposition reactions of AdDPO are
reversible (Fig. 2, Table 2).
Apparently, a similar situation should be expected
for other Lewis acids and, possibly, for strong acids of
other types.
Thus, it was experimentally found that the AdDPO
transformations of the types of ortho–para in the aro-
matic ring, para–meta in the aromatic ring, and
bridge–bridgehead in the adamantane cage are sig-
nificantly different in terms of kinetics.
The ortho–para transformations in the aromatic
ring are characterized by the highest rate under other- (1.Ad) over the cation-exchangers can reach the equi-
Table 2. Rate constants of the isomerization of AdDPO over AlCl3 at 333 K
ki, min−1
ki/ k−1 ki(AlCl3)/ ki(A-36)
Reaction
Reaction symbol
k1
k−1
1.Ad
–1.Ad
2.Ad
5.79E-03
71
1
11
92
34
o- 1-Ad DPO ⎯⎯⎯→ p- 1-Ad DPO
(
)
(
)
8.16E-05
2.49E-03
9.10E-04
8.02E-03
1.29E-01
1.08E-02
1.74E-01
1.04E-02
5.19E-03
1.43E-02
2.03E-04
9.81E-02
p- 1-Ad DPO ⎯⎯⎯→o- 1-Ad DPO
(
)
(
)
k2
30
p- 1-Ad DPO ⎯⎯⎯→ m- 1-Ad DPO
(
)
(
)
k−2
–2.Ad
3.Ad
11
m- 1-Ad DPO ⎯⎯⎯→ p- 1-Ad DPO
(
)
(
)
k3
98
p- 1-Ad DPO ⎯⎯⎯→ p- 2-Ad DPO
(
)
(
)
k−3
–3.Ad
4.Ad
1582
133
2127
127
64
p- 2-Ad DPO ⎯⎯⎯→ p- 1-Ad DPO
(
)
(
)
k4
m- 1-Ad DPO ⎯⎯⎯→ m- 2-Ad DPO
(
)
(
)
k−4
–4.Ad
5.Ad
m- 2-Ad DPO ⎯⎯⎯→ m- 1-Ad DPO
(
)
(
)
k5
p- 2-Ad DPO ⎯⎯⎯→ m- 2-Ad DPO
(
)
(
)
k−5
–5.Ad
6.Ad
m- 2-Ad DPO ⎯⎯⎯→ p- 2-Ad DPO
(
)
(
)
k6
175
2.5
1202
p- 1-Ad DPO ⎯⎯⎯→ Adamantane + DPO
(
)
k−6
–6.Ad
7.Ad
Adamantane + DPO ⎯⎯⎯→ p- 1-Ad DPO
(
)
k7
m- 1-Ad DPO ⎯⎯⎯→ Adamantane + DPO
(
)
PETROLEUM CHEMISTRY Vol. 58 No. 10 2018

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TARAZANOV et al.
Table 3. Results of studying the AdDPO isomerization equilibrium
na
mb
Kxσ
T, K
Catalyst, wt %
Time, min
o-(1-Ad)DPO ↔ p-(1-Ad)DPO (1.Ad)
Composition of reaction mixture
t0.05s
Kx
353
393
417
417
424
424
523
6
7
1
1
1
1
1
1
1
AlCl3, 6%
AlCl3, 3%
A-36, 30%
AlCl3, 5%
A-36, 30%
A-36, 30%
HBr, in situ
15–210
20–180
5–300
52.1 5.6
37.8 5.2
28.2 0.9
29.2 2.6
33.1 0.8
30.1 1.8
14.0 1.0
104
75.6
56.4
58.4
66.2
60.2
28.0
All AdDPO isomers
All AdDPO isomers
No m-AdDPO
All AdDPO isomers
o- and p-(1-Ad)DPO
Other AdDPO < 5%
2-AdDPO < 5%
9
8
1–260
9
3
11
7–150
90–270
960–13800
p-(1-Ad)DPO ↔ m-(1-Ad)DPO (2.Ad)
333
353
353
353
383
393
417
523
4
3
1
1
1
1
1
1
1
1
AlCl3, 3%
AlBr3, 5%
AlCl3, 3%
AlCl3, 6%
AlBr3, 5%
AlCl3, 3%
AlCl3, 5%
HBr, in situ
188–3270
290–530
125–600
15–210
2.57 0.18
2.79 0.04
2.64 0.26
2.82 0.09
2.75 0.03
2.93 0.31
2.67 0.03
2.62 0.02
1.29
1.40
1.34
1.41
1.38
1.47
1.37
1.31
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
2-AdDPO < 5%
10
6
3
140–270
20–180
7
4
90–260
4
8040–13800
p-(2-Ad)DPO ↔ p-(1-Ad)DPO (3.Ad)
353
383
393
417
3
3
6
9
1
1
1
1
AlCl3, 6%
AlBr3, 5%
AlCl3, 3%
90–210
140–270
30–180
1–260
13.3 0.1
12.1 0.5
10.4 0.8
8.9 1.7
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
All AdDPO isomers
AlCl3, 5%
a
b
The number of determinations; the number of sets of experiments;
t
s are respectively the equilibrium constant and the con-
0.05
Kx
fidence interval at the significance level of 0.95.
librium at lower temperatures as well. In that case, the
The value of the enthalpy effect of reaction (1.Ad)
residence time increases (≥30 min at 383 K).
gives evidence for a significant ortho-interaction of the
(PhO) and (1-Ad) substituents on the aromatic ring,
which destabilizes the (1-Ad)-DPO molecule. On the
assumption of the absence of interaction between the
(PhO) and (1-Ad) substituents in the p-(1-Ad)DPO
molecule, the value of the enthalpy term of the ortho-
effect for the same substituents is 11.8 1.4 kJ/mol
(for the liquid state). It is interesting that, this term
obtained similarly for the ortho-effect of the interac-
tion of the (OH) and (1-Ad) substituents in ada-
mantylphenols has a high value of 15.0 1.0 kJ/mol.
Under otherwise equal conditions, the reaction
p-(2-Ad)DPO ↔ p-(1-Ad)DPO (2.Ad) has a lower
rate in comparison with reaction (1.Ad) and cannot be
singled out from the set of AdDPO transformations.
However, these two reactions can be accomplished up
to reaching equilibrium by them providing that all the
other isomeric transformations are almost completely
ruled out. The equilibrium concentration of p-(1-
Ad)DPO 9–13 times that of p-(2-Ad)DPO in the tem-
perature range examined. Reaction (3.Ad) proceeds at
an even lower rate; its equilibrium is reached only in
the case of a significant residence time and the estab-
lished equilibrium of reactions (1.Ad) and (2.Ad).
Reaction (2.Ad) characterizes the bridge–bridge-
head transition in the adamantyl moiety of the
p-AdDPO molecule. The enthalpy of this reaction is
7.7 1.7 kJ/mol.
The values of the equilibrium constants presented
in Table 3 are approximated by a linear equation, the
coefficients of which and the enthalpies and entropies
calculated on their basis for reactions (1.Ad)–(3.Ad)
are presented in Table 4. The errors of all the quantities
are presented by confidence intervals for the signifi-
cance level of 0.05.
Sarkisova [22] obtained the following values of
enthalpy for identical transformations in studying liq-
uid-phase isomerization equilibria:
−9.6 0.6 kJ/mol for (2-Ad)benzene ↔
(1-Ad)benzene,
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THEORY AND PRACTICE OF THE PREPARATION OF ADAMANTYLARENES
901
Table 4. Thermodynamic characteristics of the liquid-phase transformations studied
Coefficients of equation
ln(Kx) = a + 1000b/T
ΔrSm0
Δr Hm0
l
,
Reaction
symbol
,
l
( )
( )
Tin–Tfin, K
Tm, K
J mol−1 K−1
kJ/mol
a
b
1.Ad
2.Ad
3.Ad
353–523
333–523
353–417
405
389
387
–0.0101
0.9722
–0.0107
1.4232
0.0111
0.9292
–11.8 1.4
–0.1 0.4
–7.7 1.7
0.0 3.5
8.1 1.1
–0.1 4.5
0
r Hm0
l
ΔrSm
l
and
are respectively the enthalpy and the entropy of the reaction in the liquid phase.
Δ
( )
( )
−10.5 0.8 kJ/mol for m-(2-Ad)toluene ↔ m-(1- hydrocarbons with new structures and is in good
Ad)toluene, and
agreement with the information accumulated to date.
−11.2 1.1 kJ/mol for p-(2-Ad)toluene ↔ p-(1-
It was experimentally found that both ortho–para
and meta–para transformations can be selectively
accomplished for 1-AdDPO under equilibrium condi-
tions. The results of this study (Table 4) made it possi-
ble to find the temperature dependence of the compo-
sition of equilibrium mixtures in the groups of these
isomers (Fig. 3).
Thus, under the equilibrium between ortho–para
transformations is established (Fig. 3), the concentra-
tion of p-(1-Ad)DPO decreases with an increase in
temperature, remaining at a high level, which reaches
99% at 300 K.
Ad)toluene.
These values are somewhat lower than the value
obtained in the present study. Moreover, there is a cer-
tain trend in the dependence of the enthalpy on the
structure of the molecule is emerging. However, it was
noted [21, 22] that the Allinger molecular mechanics
method with a force field (MM2-1991) gives a single
0
value
= −7.28 kJ/mol for all the reactions in
Δr H298.g
question. It is believed [21, 22] that this value cannot
be used for the determination of the enthalpies of reac-
tions involving aryladamantanes; to eliminate the dis-
crepancy, it is proposed to correct the constants of the
Allinger method. Nonetheless, the coincidence of the
value obtained in the study with the one predicted by
the Allinger method suggests that this issue is still an
open question.
In the system represented by p-(1-Ad)DPO, m-(1-
Ad)DPO, and p-(2-Ad)DPO, the dominating isomer
is m-(1-Ad)DPO. Its concentration slightly depends
on temperature to be at the level of 71 1%, the con-
centration of p-(1-Ad)DPO is 26
Ad)DPO makes no more than 5%.
1%, and p-(2-
The data (Table 4) obtained for reaction (3.Ad)
supplement the quite vast database on the thermody-
namics of the meta–para transformation of aromatic tively reached in both the systems: over the entire
We found (Table 4) that the equilibrium is selec-
(а)
(b)
mol %
100
mol %
100
80
60
40
20
80
60
40
20
0
0
300
400
Temperature, K
500
300
400
Temperature, K
500
Fig. 3. Temperature dependence of the composition of the equilibrium mixture (a) in o- and p-(1-Ad)DPO; the curves and sym-
bols refer to the calculated and experimental values of concentrations, respectively: (▲) p-(1-Ad)DPO, and (■) o-(1-Ad)DPO.
(b) Temperature dependence of the composition of the equilibrium mixture in m- and p-(1-Ad)DPO and p-(2-Ad)DPO. The
curves and symbols refer to the calculated and experimental values of concentrations, respectively: (▲) p-(1-Ad)DPO, (●) m-(1-
Ad)DPO, and (♦) p-(2-Ad)DPO.
PETROLEUM CHEMISTRY Vol. 58 No. 10 2018

902
TARAZANOV et al.
Table 5. Results of studying the isomerization equilibrium of adamantylphenols
ΔrSm0 l ,
Δr Hm0 l ,
( )
( )
na
mb
Kx t0.05
s
T, K
Catalyst, wt %
Time, min
J mol−1 K−1
kJ/mol
o-(1-Ad)phenol
H2SO4, 5–10
A-36, 30
H2SO4, 5–10
A-36, 30
p-(1-Ad)phenol (1.AdP)
ꢀ
373
403
403
413
453
523
573
27
10
36
8
52
44
34
3
1
3
1
5
5
3
2–36
8–32
110.1 0.1
−15.0 1.0
−1.1 2.3
75.2 2.5
77.4 0.1
69.8 3.4
50.4 0.1
26.4 0.04
20.7 0.04
0.5–20
5–22
H2SO4, 1.0–1.5
H2SO4, 1.0
0.5–18
0.08–8
0.08–8
H2SO4, 0.5–1.0
a
b
The number of determinations; the number of sets of experiments;
t
s are respectively the equilibrium constant and the con-
Kx
0.05
0
0
fidence interval at the significance level of 0.95;
the liquid phase.
and
are respectively the enthalpy and the entropy of the reaction in
l
( )
Δr Hm
l
ΔrSm
( )
operating range on the sulfonated resins in the or at Ad-phenols. The p-(1-Ad)phenol/o-(1-Ad)phenol
523 on HBr K for ortho–para transformations and at ratio substantially depends not only on the tempera-
343–447 K on aluminum halides and at 523 K on HBr ture of the process, but also on the residence time. In
for meta–para transformations.
the low-temperature region of the operating range of
the sulfonated cation-exchangers (333–363 K), the
concentration of the o-isomer at the onset of ada-
mantylation exceeds 30 wt % in the mixture of o- and
p-(1-Ad)P; however, the system starts approaching the
equilibrium quite rapidly (within 2–4 h). Increasing
the temperature shortens this period. In addition, the
concentration of p-(2-Ad)P changes slightly even
under the conditions of stable equilibrium for reaction
(1.AdP). The results obtained by Karlina [25] and in
this study of the AdP isomerization equilibrium of are
presented in Table 5’ from the data in the table, it fol-
lows that the p-(1-Ad)P selectivity can reach 99%
when the phenol adamantylation process is performed
under the conditions of established equilibrium.
The adamantylation
of
phenol
with
(1-chloro/bromo)adamantanes or 1-adamantanol
over protic catalysts is also a quite selective process
with respect to p-(1-Ad)phenol. The concentration of
p-(2-Ad)phenol did not exceed 0.3% (of total isomers)
in all the experiments (over A-36 or H2SO4). Adaman-
tane almost did not form in this case, and adamantane
initially introduced into the system transformed into
(1-adamantyl)arene
(2-adamantyl)arene
27
Regarding adamantylbenzenes, there are published
results of a targeted study by Pimerzin and Sarkisova
[19, 20] on the equilibrium of bridge–bridgehead type
isomerization. In the context of this work, it would be
interesting to compare the results of their study and
the data that we obtained for AdDPO. These data
arrays are collated in Fig. 4, showing that the values of
the liquid-phase equilibrium constants of the bridge–
bridgehead isomerization do not differ fundamentally
for the systems of benzenes and diphenyl oxides and
depend on temperature, decreasing almost threefold
with its increase from 303 to 423 K.
22
17
12
7
300
350
400
450
Temperature, K
Since benzenes and DPO exhibit fundamentally
different reactivities in electrophilic substitution reac-
tions, this result can be extended to a significant series
of adamantylation substrates. This means that under
equilibrium conditions, the selectivity of processes for
preparing sterically unstrained (1-adamantyl)arenes
significantly increases with a decrease in the synthesis
temperature.
Fig. 4. Temperature dependence for the equilibrium con-
stants of the bridge–bridgehead isomerization in the liquid
phase of adamantylbenzenes and diphenyl oxides: (s) p-2-
AdDPO
p-1-AdDPO, (h) (2-Ad)benzene
ꢀ
ꢀ
(1-Ad)benzene, (n) m-(2-Ad)toluene
m-(1-Ad)tolu-
ꢀ
ene, (×) p-(2-Ad)toluene
p-(1-Ad)toluene, (r) 4-(2-
ꢀ
Ad)-o-xylene
4-(1-Ad)-o-xylene, and (d) 5-(2-Ad)-
ꢀ
m-xylene
5-(1-Ad)-m-xylene.
ꢀ
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THEORY AND PRACTICE OF THE PREPARATION OF ADAMANTYLARENES
903
Despite the fact that , the data of targeted kinetic or after establishment of chemical equilibrium has
and thermodynamic studies on the adamantylation of shown that the selectivity of the adamantylation of
benzenes are limited, important experimental infor- arenes significantly depends on the choice of the cata-
mation has been obtained so far for answering at least lyst. Thus, it has been found that:
two questions considered below.
(1) the high selectivity of the adamantylation of
DPO at the para-position is provided by using sulfon-
ated cation-exchange resins as a catalyst. Carrying out
the reaction in the low-temperature range of operation
of the cation-exchange resin (353–383 K) leads to
inhibition of the positional and structural “1-adaman-
tyl–2-adamantyl” isomerization. The selectivity for 1-
AdDPO reaches 94–96% even within 6 h of isomeri-
zation;
(2) the replacement of the catalyst by aluminum
halides or HBr not only increases the rate of isomeri-
zation, but also yields a reaction mixture with all the
possible isomers. When these catalysts are used, the
formation of adamantane is also observed. This means
that it is challenging to obtain any of the AdDPO iso-
mers as an individual product in the case of ada-
mantylation over aluminum halides;
(3) chemical equilibrium can be selective estab-
lished in the following reactions: ortho–para isomeri-
zation in the presence of A-36 in the range of its oper-
ability (353–417 K) or HBr at 523 K and para–meta
isomerization on aluminum halides at 343–447 K or
HBr at 523 K. Under equilibrium conditions, 1-ada-
mantylated products predominate over 2-adamantyl
derivatives in concentration; and
(4) the adamantylation of phenol can be selectively
performed with 1-haloadamantane in the presence of
protic catalysts (A-36, H2SO4) to yield p-(1-adaman-
tyl)phenol. The p-1-adamantylphenol selectivity can
be as high as 99%.
One of them concerns the ratio of the concentra-
tions of the isomers in the aromatic ring in the case of
adamantylation of substituted arenes under the condi-
tions of thermodynamic control. The results obtained
by Olah [1] for the adamantylation of toluene and
isomerization of adamantyltoluenes on boron tris(tri-
flate) lead to the conclusion that the isomeric compo-
sition of (1-adamantyl)arenes can be assessed on the
basis of the same approaches which are applied to ter-
tiary alkylarenes [25]. Similar parallels between alkyl-
benzenes and (2-adamantyl)arenes are still impossible
to draw because of the absence of necessary informa-
tion. However, the values of the rate constants pre-
sented in Table 2, which yield the equilibrium constant
of 2.00 for the para–meta isomerization of (2-
Ad)DPO (reaction (3.Ad)), give grounds to expect
that there is analogy in the behavior of (2-adaman-
tyl)arenes and secondary alkylbenzenes [25] as well.
Unlike positional isomers of aromatic compounds,
structural isomers in the classes of adamantyl- and
alkylarenes fundamentally differ with in their relative
thermodynamic stability. Indeed, at follows from the
data in Fig. 4, (1-Ad)arene has more than 20-fold
higher stability than (2-Ad)arene at 300 K. At the
same time, the tertiary isomer in the case of branched
pentylbenzenes is fivefold less stable than secondary
(1,2-dimethylpropyl)arene [9]. This fact should be
reckoned with.
The second question concerns adamantane that is
formed during the adamantylation of arenes and isom-
erization of Ad-arenes in an amount comparable to
that of the main product or even exceeding it [1, 11,
12]. The essence of the question is evident. The selec-
tivity of such processes cannot be considered satisfac-
tory. Nonetheless, adamantane barely formed as a
byproduct during the adamantylation of phenol or
DPO over the sulfonated cation-exchange resins or in
the absence of a catalyst. This fact has been established
in the present study and reported in [15, 16]. However,
passing to AlCl3 in the study of AdDPO isomerization
dramatically changes the situation (Table 2), namely,
the adamantane formation and AdDPO isomerization
rates turn to be comparable even at a relatively low
temperature (333 K). Therefore, the cornerstone of
success in the adamantylation of arenes centers is the
selection of an appropriate catalyst.
ACKNOWLEDGMENTS
This work was supported by the Russian Science
Foundation, project no. 17-73-20386.
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Translated by E. Boltukhina
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2018