Thermal Stability Study of 4-(1-Adamantyl)phenol

Article abstract of DOI:10.1134/S0965544120110171

Abstract: The thermal stability of 4-(1-adamantyl)phenol has been studied in the temperature range of 703–753 K, the components of the thermolysis reaction mixture have been identified, and the rate constants and parameters of the Arrhenius equation for t

Full text of DOI:10.1134/S0965544120110171

ISSN 0965-5441, Petroleum Chemistry, 2020, Vol. 60, No. 11, pp. 1300–1308. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Neftekhimiya, 2020, Vol. 60, No. 6, pp. 844–853.
Thermal Stability Study of 4-(1-Adamantyl)phenol
V. A. Shakuna, *, T. N. Nesterovaa, S. V. Tarazanovb, and V. S. Sarkisovaa
aSamara State Technical University, Samara, 443100 Russia
bAll-Russia Research Institute for Petroleum Processing, Moscow, 111116 Russia
*e-mail: ShakyH@mail.ru
Received June 6, 2020; revised July 3, 2020; accepted July 10, 2020
Abstract—The thermal stability of 4-(1-adamantyl)phenol has been studied in the temperature range of 703–
753 K, the components of the thermolysis reaction mixture have been identified, and the rate constants and
parameters of the Arrhenius equation for the thermal degradation of the compound under study have been
calculated. It has been found that of the thermal stability of 4-(1-adamantyl)phenol significantly surpasses
that of 4-tert-butylphenol.
Keywords:4-(1-adamantyl)phenol, thermal stability, thermal degradation, isomerization, kinetics, rate con-
stant, Arrhenius equation
DOI: 10.1134/S0965544120110171
It is known that the modification of organic com-
The results of the studies devoted to adamantyl-
pounds and polymers with adamantane and its deriv- phenols show the possibility of their effective applica-
atives imparts additional resistance against extreme tion as inhibitors and antioxidants. Sokolenko et al. [9]
mechanical impacts to materials and increases their have shown that 4-(1-adamantyl)phenol and 2,4-di-
thermo-oxidative stability.
(1-adamantyl)phenol exhibit high antioxidant activity
by way of example of the model reaction of cumene
oxidation. The prospects for application of adaman-
tyl-substituted phenols, cresols, catechol, and hydro-
quinone as radical chain polymerization inhibitors in
the processing of liquid pyrolysis products are dis-
cussed in [10, 11].
Overall, taking into account the above informa-
tion, the question about the thermal stability of ada-
mantane derivatives including adamantylarenes plays
a serious role in the development of advanced polymer
materials and lubricants.
Currently, a great deal of attention is being paid to
carboxylic acid esters of the adamantane series as
promising components of thermally stable lubricating
oils. Thus, Bagrii and Maravin [1] evaluated the vis-
cosity–temperature properties and thermo-oxidative
stability of alkyl esters of 5,7-dimethyladamantane-
1,3-dicarboxylic acids and showed their advantages
over conventional lubricating oils. The cited authors
have recommended using such structures as thermally
stable synthetic lubricating oils for gas turbine power
plants and as cable oil in view of strong electrical insu-
lation properties. The results of extensive studies [2–5]
on the physicochemical characteristics and thermo-
oxidative stability of esters of dicarboxylic acids of the
adamantane series also show serious advantages of this
type of compounds in the development of unique
lubricating materials.
Adamantane derivatives are also of great interest in
the creation of advanced polymers. For example, it has
been shown in [6, 7] that epoxy resins based on 1,3-
bis(4-hydroxyphenyl)adamantane are characterized
by increased hardness and thermal stability and have
improved dielectric properties. According to the data
of the patent [8], copolymers of dialkyladamantane
EXPERIMENTAL
Initial Substances
4-(1-Adamantyl)phenol (4-(1-Ad)Ph) was synthe-
sized by alkylating phenol (provided by Novokuiby-
shevsk Petrochemical Company, 99.9 wt % by gas–
liquid chromatography (GLC)) with 1-bromoada-
mantane at 353 K in a jacketed glass reactor equipped
with a stirrer and a reflux condenser. The thermostat-
ing was provided by benzene boiling in the reactor
jacket.
To a phenol melt, Amberlyst 36 Dry sulfonated cat-
and di-tert-butylbenzenes possess a high glass transi- ion-exchange resin preliminarily dried to a constant
tion point (182°C), are resistant to extreme tempera- weight at 105°C in an air bath was added in amount of
tures and thermo-oxidative degradation and find 30 wt % and held for 30 min under constant stirring for
application as protective coatings.
the catalyst to swell. Then, 1-bromoadamantane was
1300

THERMAL STABILITY STUDY OF 4-(1-ADAMANTYL)PHENOL
1301
added and stirring was continued for another 30 min. the value of the calibration factor for 4-(1-Ad)Ph was
The phenol/1-bromoadamantane molar ratio was in 1.1455 0.051.
the range of (4–3)/1.
The qualitative analysis of the components of the
mixtures was performed by GC/MS on an Agilent
6850 gas chromatograph equipped with an Agilent
19091S-433E capillary column (30 m × 250 μm ×
0.25 μm) with an HP-5MS stationary phase and an
Agilent 5975CVL MSD mass selective detector at an
ionizing potential of 70 eV.
The catalyst was separated from the reaction mix-
ture by vacuum filtration and rinsed with hot acetoni-
trile on the filter; the resulting solution was combined
with the reaction products. The solvent was distilled
off under atmospheric pressure, and the excess of phe-
nol, under vacuum. The residue was recrystallized
from acetonitrile; the white needle-like crystals
formed were filtered off and dried at room tempera-
ture. The concentration of 4-(1-Ad)Ph was 99.9 wt %
by GLC after the removal of the solvent.
4-(1-Adamantyl)phenol Thermolysis Reaction Mixture
A typical chromatogram of the 4-(1-Ad)Ph ther-
molysis products is given in Fig. 1:
The products were identified by GC/MS using
the spectral data (EI, 70 eV) from the NIST 2017
library [13].
4-MePh, 4-EtPh, 4-IPPh, and 4-NPPh were addi-
tionally identified by comparing the retention times of
the components of the reaction mixture under study
with the reference standards of the compounds. It was
found as a result that the position isomers of the spec-
ified alkylphenols (APhs) were absent in the 4-(1-
Ad)Ph thermolyzate.
To identify the structure of components 14, 16, 17,
19, and 21–24, we used the data, rules, and
approaches described in [14–19], finding the correla-
tions between the degradation of adamantylarenes in
the mass spectrometer chamber under electron ioniza-
tion and thermal decomposition. The correctness of
this approach is confirmed in the works by Lobodin
and Lebedev [20] and Dougherty [21]. The assump-
tion about the structure of components A1 and A2 (17,
22) was additionally based on the data of the study of
the thermal stability and degradation of 1,3-dimeth-
yladamantane [22], in which similar adamantane cage
opening products due to breaking of one or two bonds
between the bridgehead and bridge carbons were
found. The characteristics of the mass spectra of com-
ponents 12–24 are presented in Table1, and their
structures are shown in Fig. 1.
Procedure for Studying 4-(1-Ad)Ph Thermolysis
The thermal stability of 4-(1-Ad)Ph in the gas
phase was studied in a the temperature range of 703–
753 K (in increments of 5 K) by thermostating in
enclosed reactors—glass capillaries sealed on both
sides. The substances were preliminarily dehydrated,
and the capillary was purged with helium after loading.
The schematic of the oven in which the samples were
thermostated is presented in our paper [12] describing
the investigation of the thermal stability of 4-tert-
butylphenol (4-TBPh). The accuracy of temperature
control in the isothermal zone was provided within
1°C. The time to reach isothermal conditions after
placing the capillary into the oven did not exceed 60 s.
The pyrolysis process was completed by quenching in
a cooled test tube, after which the capillary was slightly
notched by a needle-point file, immersed into a test
tube with a solvent, and broken with a stainless steel
rod. Ethanol was used as the solvent.
The kinetics of 4-(1-Ad)Ph thermolysis was stud-
ied at the conversion value within 30%. In this case,
the number of moles increased by no more than 5% of
the initial value during the process, because of which
an assumption was adopted about the possibility of the
transition from the number of moles of the products to
molar concentration when evaluating the changes in
the thermolyzate composition.
RESULTS AND DISCUSSION
Analysis of Thermal Transformations of 4-(1-Ad)Ph
Product Analysis and Identification
The composition of the main products of thermol-
ysis of 4-(1-Ad)Ph at the process temperature of 733 K
selected from the middle of the range under study of
703–753 K is shown in Table 2. All the features
revealed for this temperature point are characteristic
for the entire temperature range examined.
The information about the character of change in
the concentrations of all the individual products and
groups of components in the reaction mixture is
reflected in Fig. 2.
GLC was used as the main method of analysis of
the reaction mixtures. The analysis was performed on
a Kristall 2000M instrument equipped with a flame
ionization detector, a carrier gas flow splitter, and a
quartz capillary column (60 m × 250 μm × 0.25 μm)
with the bonded stationary phase SE-30. Helium used
as the carrier gas had the column inlet pressure of
3 atm. The evaporator temperature was 250°C, and
the detector temperature was 280°C.
The quantitative analysis of the composition of the
reaction mixture was performed using the internal
standard method with n-C24H50 (99.9 wt % by GLC);
The analysis of the possible interconversion of the
identified components was based on the existing infor-
mation about the pathways and products of degrada-
PETROLEUM CHEMISTRY Vol. 60 No. 11 2020

1302
SHAKUN et al.
Standard
90000
85000
80000
75000
70000
65000
60000
55000
50000
45000
40000
35000
30000
25000
20000
15000
10000
473 К
Solvent
OH
OH
5 К/min
OH
20
333 К
4
OH
17
OH
21
5
HO
OH
OH
19
2
СH
3
23
14
1
OH
24
13
8
9
18
16
22
6
10
12
3
15
11
7
10
15
20
25
30
35
40
45
50
5
Time, min
Fig. 1. Chromatogram of the reaction mixture of 4-(1-Ad)Ph thermolysis (733 K, 17 min): (1) toluene; (2) o-, m-, and p-xylenes;
(3) trimethylbenzene (TMB); (4) phenol; (5) adamantane; (6) 4-MePh; (7) isobutenylbenzene (IBenB); (8) 1-methylindane
(1-MeIn); (9) 4-ethylphenol (4-EtPh); (10) 4-isopropylphenol (4-IPPh); (11) 4-n-propylphenol (4-NPPh); (12) 4-hydroxybi-
phenyl (4-HBPh); (13) (1-adamantyl)benzene (1-(Ad)B); (14) 4-hydroxy-3ꢀ-methyl-biphenyl (4-H-3ꢀ-MeBPh); (15) 1-ben-
zyl(adamantane) (1-BAd); (16) 4-(1-adamantyl)toluene (4-(1-Ad)T); (17) component A ; (18) unidentified (X ); (19) 2-(1-
1
1
adamantyl)phenol (2-(1-Ad)Ph); (20) 4-(1-Ad)Ph; (21) 4-(2-adamantyl)phenol (4-(2-Ad)Ph); (22) component A ; (23) 4-(1-
2
adamantyl)-2-methylphenol (4-(1-Ad)-2-MePh); and (24) 4-(1-adamantyl)-2,6-dimethylphenol (4-(1-Ad)-2,6-di-MePh).
tion of adamantane derivatives by thermolysis and Ad)Ph were 0.42 and 0.18 mol %, respectively, at
electron ionization [14–16, 19, 22]; the character of
the rate curves (Fig. 2) according to the data by
S. Walas [23] for typical complex reactions was also
taken into account.
733 K over the first minute at a 4-(1-Ad)Ph conver-
sion of 0.85 mol % (Table 2). Taking into account only
the positional changes of the substituents in the struc-
ture, these components were defined as isomerization
products. This assumption is based on the substantial
effect of isomerization processes found in our studies
on the thermolysis of 4-tert-butylphenol [12] and
4-tert-butyldiphenyl oxide [24]; thus, the mechanism
of 4-(1-Ad)Ph → 4-(2-Ad)Ph isomerization can be
similar, involving a three-membered intermediate
Thus, 2-(1-Ad)Ph, 4-(2-Ad)Ph, and components
A1 and A2 were attributed to the products of direct
transformation of 4-(1-Ad)Ph (Fig. 2).The initial
stage of thermolysis of 4-(1-Ad)Ph was characterized
by a high rate of 2-(1-Ad)Ph and 4-(2-Ad)Ph buildup
throughout the entire range of the temperatures. For
example, the concentrations of 2-(1-Ad)Ph and 4-(2- cycle:
OH
OH
OH
OH
OH
T, K
−H
+H
C
~
CH
C
CH
4-(1-Аd)Ph
4-(2-Аd)Ph
Apparently, the formation of components A1 and
Cbridge–Cbridgehead bond rupture. Presumably, the pro-
A2 results from 4-(1-Ad)Ph degradation via the cess proceeds by the following mechanism:
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THERMAL STABILITY STUDY OF 4-(1-ADAMANTYL)PHENOL
1303
Table 1. Characteristic of the mass spectra of 4-(1-Ad)Ph and products of its thermolysis
Species
Mass spectrum , 70 eV: m/z, major abundances (rel. %)
+•, 170(100); 165(2), 157(2), 152(4), 141(20), 128(1), 115(12), 107(0.2)
12
13
14
15
16
17
M
M+•, 212(100); 169(13),155(100), 141(5), 128(7), 115(8), 103(2), 94(8), 91(9)
M+•, 184(100); 167(5), 165(12), 157(1), 155(5), 153(6), 141(4), 128(4), 121(0.2) 115(4), 107(0.3),91(2)
M
+•, 226(50); 207(5), 183(10), 169(10), 153(2), 135(100), 128(1), 115(5), 107(11), 93(12), 91(9), 79(8)
M+•, 226(76); 211(2), 194(1), 183(7), 169(100), 154(11), 141(5), 132(15), 128(6), 115(5), 105(7), 94(3), 91(6)
M+•, 228(28); 213(4), 198(3), 185(100), 172(17), 157(7), 152(2), 144(2), 141(2), 131(1), 128(2), 115(2), 107(5),
94(1), 91(2)
+•, 226(100); 211(9), 197(6), 183(46), 170(30), 165(8), 157(6) 153(7), 144(4), 141(6), 128(6), 115(7), 103(1),
18
19
20
21
22
23
24
M
94(1), 91(1)
M+•, 228(100); 213(2), 200(1), 185(20), 171(88), 165(4), 158(6), 153(23), 145(6), 141(3), 134(14), 131(7),
128(7), 121(5), 115(7), 107(14), 94(7), 91(8)
M+•, 228(80); 213(1), 200(1), 199(1), 185(11), 171(100), 165(1), 157(5), 153(21), 145(4), 141(3), 134(23),
131(4), 128(5), 119(3), 115(5), 107(11), 94(2), 91(6)
M
+•, 228(100); 211(6), 200(1), 199(1), 185(3), 171(1), 165(1), 157(1), 152(1), 145(3), 141(1), 133(5), 131(3),
121(6), 115(3), 107(24), 93(6), 91(5)
+•, 228(61); 213(2), 208(7), 195(1), 181(1), 169(3), 157(6), 152(1), 146(14), 135(12), 131(11), 127(10),
120(100), 107(23), 92(22), 91(6)
+•, 242(100); 224(2), 213(1), 209(1), 199(12), 185(98), 171(6) 167(13), 157(3), 152(5), 148(22), 141(3), 131(2),
128(3), 121(7), 115(3), 91(3)
+•, 256(100); 241(3), 213(10), 209(1), 199(75), 183(4), 171(25) 162(21), 157(2), 153(7), 147(5), 141(3), 135(8),
M
M
M
128(4), 121(1), 115(4), 107(1), 91(6)
OH
OH
~
OH
OH
H
HC
CH2
CH2
CH3
C
Component A2
[4-(1-Аd)Ph]
OH
OH
OH
H
CH3
C
CH3
CH3
Component A1
CH3
H3C
C
CH3
The composition of the reaction mixture (Table 2) bond with the formation of phenol and adamantane.
shows that in the process developing within the 4-(1-
Ad)Ph conversion of 10%), the degradation of the
adamantyl substituent form components A1 and A2 is
not inferior to the decomposition by the CAr–CAd
The isomerization of 4-(1-Ad)Ph with the forma-
tion of 2-(1-Ad)Ph and 4-(2-Ad)Ph has a predomi-
nant character within the specified limits of conver-
sions.
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SHAKUN et al.
Table 2. Main products of 4-(1-Ad)Ph thermolysis at 733 K, mol %
Time,
min
4-H-3'-
MeBPh
A1
A2
Phenol Adamantane
4-HBPh
2-(1-Ad)Ph 4-(1-Ad)Ph 4-(2-Ad)Ph
APh
0.0
1.0
1.5
2.0
3.0
5.0
6.0
6.5
7.0
0.00
0.11
0.10
0.23
0.60
0.73
1.02
0.82
0.76
1.16
1.53
1.72
1.28
1.90
2.89
3.01
3.58
4.31
4.67
5.71
5.81
0.00
0.01
0.01
0.03
0.14
0.22
0.37
0.23
0.25
0.44
0.69
0.61
0.54
0.79
1.32
1.65
1.91
2.35
2.72
3.24
3.36
0.00
0.00
0.00
0.02
0.02
0.04
0.10
0.09
0.19
0.11
0.15
0.15
0.31
0.32
0.30
0.43
0.53
0.79
1.22
1.32
1.81
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.02
0.03
0.01
0.04
0.02
0.05
0.06
0.06
0.05
0.09
0.09
0.15
0.16
0.21
0.00
0.00
0.00
0.00
0.00
0.01
0.03
0.02
0.06
0.02
0.09
0.11
0.15
0.19
0.15
0.32
0.42
0.62
0.77
0.72
0.85
0.00
0.04
0.08
0.22
0.58
0.64
0.91
1.14
1.23
1.29
1.67
1.51
2.02
2.25
1.90
2.10
2.41
2.91
3.24
3.33
3.44
0.00
0.42
0.57
0.69
0.94
1.23
1.30
1.46
1.46
1.52
1.37
1.33
1.39
1.39
1.30
1.24
1.01
0.90
0.61
0.56
0.43
100.00
99.15
98.95
98.30
97.23
96.32
94.98
95.11
93.96
93.95
92.60
92.47
91.47
89.91
88.68
87.19
85.13
82.40
79.51
77.01
75.05
0.00
0.18
0.19
0.37
0.21
0.40
0.65
0.58
0.98
0.58
0.89
0.78
1.26
1.36
1.41
1.55
1.96
1.94
2.10
2.09
2.28
0.00
0.04
0.06
0.07
0.13
0.12
0.14
0.15
0.13
0.14
0.16
0.10
0.13
0.11
0.10
0.10
0.09
0.09
0.07
0.08
0.08
8.0
9.0
10.0
11.0
12.0
14.0
15.0
17.0
20.0
23.0
25.0
27.0
4-MePh, 4-EtPh, 4-IPPh,and 4-NPPhare presented as a group of total alkylphenols
The thermolysis products of 4-(1-
(APh .
)
Ad)Ph which reached noticeable concentrations only in the developed process at a 4-(1-Ad)Ph conversion over 10%, such as toluene,
xylenes, TMB, IBenB, 1-MeIn, X , (1-Ad)B, 1-BAd, 4-(1-Ad)T, 4-(1-Ad)-2-MePh, and 4-(1-Ad)-2,6-di-MePh, are not presented in
1
Table 2.
With an increase in the depth of 4-(1-Ad)Ph trans- tert-butyl radical in some cases. Apparently, the ada-
formation, the rate of formation of phenol and ada- mantyl radical formed upon the breaking of the CAr–
mantane increases, which is explained by the growth
in the intensity of the degradation processes in general
and by the degradation of 2-(1-Ad)Ph and 4-(2-
Ad)Ph in particular. This is also confirmed by the data
on the composition of the reaction mixture (Table 2)
and the shape of the rate curves of these components.
As regards the breaking of the CAr–CAd bond
throughout the entire study range, we found that the
concentration of adamantane was substantially lower
than the concentration of phenol in the developing
process. With an increase in the degree of conversion
of 4-(1-Ad)Ph and in the thermolysis temperature, the
C(adamantane)/C(phenol) molar ratio increases but
does not reach 1.0 mol/mol. Thus, it is stabilized at the
levels of 0.35–0.40 at 703 K, 0.55–0.60 at 733 K, and
0.65–0.75 at 753 K (Fig. 3).
CAd bond during the thermolysis of 4-(1-Ad)Ph
undergo degradation with the formation of hydrogen,
light C1–C4 hydrocarbons, and alkylaromatic hydro-
carbons similarly to the degradation of adamantane
and methyl- and dimethyladamantanes [14, 22]. As is
seen from the data presented in Fig. 3, the concentra-
tion of adamantane relative to phenol increases with
an increase in the depth of the process, which appar-
ently results from the appearance of molecular and
atomic hydrogen, which promote the stabilization of
the adamantyl radical and its conversion to adaman-
tane.
To verify this hypothesis, we compared the charac-
ter of the thermolysis of 4-(1-Ad)Ph at 703 K in
helium and hydrogen atmospheres (Fig. 3). The size of
the capillaries and degree of loading of the substance
remained unchanged, but the capillary was filled with
hydrogen instead of helium. As a result, the C(ada-
mantane)/C(phenol) ratio increased at each time
Such a character of the process probably indicates
the destruction of the adamantyl radical formed as a
result of hydrolytic breaking of the CAr–CAd bond in
4-(1-Ad)Ph. According to E.I. Bagrii [14], the stability point and reached a level of 0.7 mol/mol in the limit,
of the adamantyl radical is even lower than that of the with the level of the concentration of phenol remain-
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THERMAL STABILITY STUDY OF 4-(1-ADAMANTYL)PHENOL
1305
6
3
100
80
3
1
4
2
4
2
1
0
2
60
40
10
20
30
0
0
10
20
30
τ, min
τ, min
1.6
4
3
2
1
5
1.2
0.8
0.4
7
6
8
0
10
10
20
30
0
0.5
0.4
0.3
0.2
0.1
10
10
20
30
τ, min
τ, min
1.0
0.8
0.6
0.4
0.2
10
11
9
12
0
20
30
0
20
30
τ, min
τ, min
0.3
0.8
0.6
0.4
0.2
15
13
0.2
0.1
16
14
0
10
10
20
30
30
0
10
10
20
30
τ, min
τ, min
1.0
0.8
0.6
0.4
0.2
4
3
2
1
18
19
17
0
20
30
0
20
τ, min
τ, min
Fig. 2. Concentration curves of the products of thermal transformations of 4-(1-Ad)Ph at 733 K: (1) 4-(1-Ad)Ph, (2) 2-(1-Ad)Ph,
(3) phenol,(4) adamantane, (5) component A , (6) 4-(2-Ad)Ph, (7) 4-(1-Ad)-2-MePh, (8) 4-(1-Ad)-2,6-di-MePh, (9) 4-
1
MePh, (10) 4-EtPh, (11) 4-IPPh, (12) 4-NPPh, (13) (1-Ad)B, (14) Σ(1-BAd, 4-(1-Ad)T), (15) X , (16) component A , (17) 4-
1
2
HBPh, (18) 4-H-3'-MeBPh, and (19) Σ(toluene, xylenes, TMB, IBenB, 1-MeIn).
PETROLEUM CHEMISTRY Vol. 60 No. 11 2020

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SHAKUN et al.
0.8
0.6
0.4
0.2
0.8
0.6
3
4
2
1
1
0.4
0.2
0
10
20
τ, min
30
40
0
10
20
τ, min
30
40
Fig. 3. Change in the C(adamantane)/C(phenol) molar concentration ratio: (1) 703 K (He), the ultimate conversion of 4-(1-
Ad)Ph is 7.95%; (2) 703 K (H ), the ultimate conversion of 4-(1-Ad)Ph is 10.33%; (3) 733 K (He), the ultimate conversion of 4-
2
(1-Ad)Ph s 24.95%; and (4) 753 K (He), the ultimate conversion of 4-(1-Ad)Ph is 26.38%.
1.6
100
90
80
70
60
4
3
2
1
0
6
1
1.2
0.8
0.4
2
8
7
5
4
3
0
10
20
τ, min
30
40
10
20
τ, min
30
40
50
0
Fig. 4. Change in the concentration of the products of 4-(1-Ad)Ph thermolysis in helium and hydrogen atmospheres at 703 K:
(1) 4-(1-Ad)Ph (He), (2) 4-(1-Ad)Ph (H ), (3) 2-(1-Ad)Ph (He), (4) 2-(1-Ad)Ph (H ), (5) adamantane (He), (6) phenol (He),
2
2
(7) adamantane (H ), and (8) phenol (H ).
2
2
ing unchanged and that of adamantane increasing
(Fig. 4).
(3) 4-HBPh and 4-H-3'-MeBPh are the degrada-
tion products of component A1;
(4) 1-AdBis is the product of degradation of 4-(1-
In general, the intensity of the degradation pro-
cesses increased in the hydrogen atmosphere. The rate
constant of the 4-(1-Ad)Ph → products decomposi-
tion increased by a factor of 1.78; thus, k703 = (3.21
Ad)Ph as a result of abstraction of hydroxyl;
(5)
Alkylphenols—4-MePh,
4-EtPh,
and
4-IPPh—are the products of degradation of compo-
nent A2, and 4-NPPh is the product of isomerization
of 4-IPPh;
0.07) × 10−5 s−1 in an inert atmosphere and
=
k703 H
(
)
(5.71 0.36) × 10−5 s−1 in a hydrogen atmosph2ere.
The fact that the character of 2-(1-Ad)Ph buildup
slightly changed also generated interest.
(6) 1-BAd and 4-(1-Ad)T probably result from the
recombination of adamantyl and benzyl radicals.
Transformation routes similar to those presented in
clauses 1–3 were revealed upon the thermolysis of 1,3-
dimethyladamantane [22]. The existence of route 4
was shown in the study of hydroquinone thermolysis
in the range of 623–1123 K [24].
Regarding the formation routes of other products
of 4-(1-Ad)Ph thermolysis in the inert atmosphere in
the range of 703–753 K, we made the following
assumptions:
(1) 4-(1-Ad)-2-MePh and 4-(1-Ad)-2,6-di-MePh
are the products of successive methylation of 4-(1-
Ad)Ph;
Calculation of the Arrhenius Parameters for the Reaction
4-(1-Ad)Ph → Products
(2) Toluene, xylenes, TMB, IBenB, and 1-MeIn
are the products of adamantane degradation;
The kinetic analysis of the experimental data for
the 4-(1-Ad)Ph → products thermal decomposition
PETROLEUM CHEMISTRY
Vol. 60
No. 11
2020

THERMAL STABILITY STUDY OF 4-(1-ADAMANTYL)PHENOL
1307
Table 3. Values for the rate constants of thermal decompo-
erization with the formation of 4-(2-adamantyl)phe-
nol and 2-(1-adamantyl)phenol, dissociation of the
Cbridgehead–Cbridge bonds in the adamantyl substituent,
and degradation via CAr–CAd bond rupture leading to
the formation of phenol and products of decomposi-
tion of the adamantyl substituent. The processes of
isomerization and dissociation of the Cbridgehead–Cbridge
bonds with the cleavage of the adamantane cycle make
a significant contribution to the thermal degradation
of 4-(1-adamantyl)phenol.
sition of 4-(1-Ad)Ph
4-(1-Ad)Ph → products
T, K
ki × 105, s−1
R2
n
ultimate conversion, %
703
708
713
718
723
728
733
738
743
748
753
3.21 0.07 33 0.99
4.12 0.28 24 0.94
6.88 0.33 22 0.97
9.08 0.54 20 0.96
7.95
10.08
15.04
13.70
24.63
21.58
24.95
15.90
14.20
22.46
26.38
The mechanism of 4-(1-Ad)Ph → 4-(2-Ad)Ph
radical isomerization through a three-membered
intermediate cycle has been proposed.
10.9 0.5
13.8 0.5
17.4 0.5
20.1 0.8
25.6 1.5
49.1 2.3
60.8 15.6
21 0.98
18 0.99
21 0.99
18 0.98
18 0.96
15 0.98
17 0.93
The preexponential factor of k0 = 1013.7 0.8 and the
activation energy of Ea = 244.8 11.7 kJ/mol found
for the 4-(1-Ad)Ph → products decomposition reac-
tion in the temperature range of 703–753 K show that
the thermal stability of 4-(1-Ad)Ph significantly sur-
pass that of 4-TBPh.
The information acquired as a result of this study is
aimed at expanding the theoretical and informational
background for the development of thermally stable
composite and lubricating materials, high-tempera-
ture stabilizers and antioxidants, and monomers for
the polymers with improved properties.
reaction was performed at each temperature point in
the range of 703–753K and the entire range of 4-(1-
Ad)Ph conversions using the equation for the of the
first-order rate constant (1):
C0
C
(1)
ln = kτ.
CONFLICT OF INTEREST
The values of the calculated reaction rate constants
are presented in Table 3.
The authors declare that they have no conflict of inter-
est.
The parameters were calculated from the experi-
mental values of the rate constants by linearization of
the Arrhenius equation in the lnki–1000/T coordi-
nates. It has been found as a result that the preexpo-
nential factor is k0 = 1013.7 0.8 and the activation energy
is Ea= 244.8 11.7 kJ/mol for the 4-(1-Ad)Ph → prod-
ucts decomposition reaction in the studied range of
temperatures.
SUPPLEMENTARY MATERIALS
Supplementary materials are available for this article at
doi: 10.1134/S0965544120110171 and are accessible for
authorized users.
ADDITIONAL INFORMATION
For comparison, in the temperature range of 673–
V.A. Shakun, ORCID: https://orcid.org/0000-0003-
2682-3024
T.N. Nesterova, ORCID: https://orcid.org/0000-0002-
3496-1075
V.S. Sarkisova, ORCID: https://orcid.org/0000-0002-
8550-0711
S.V. Tarazanov, ORCID: https://orcid.org/0000-0003-
1344-7613
738 K, the activation energy is lower by 14.9 kJ/mol
(Ea = 229.9
4.1 kJ/mol) at a comparable value
of the preexponential factor (k0 = 1013.2 0.3) for the
4-TBPh → products degradation process [12].
The evaluation of the rate constants presented in
Table 3 as the most sensitive characteristics also shows
that 4-(1-Ad)Ph is more stable and is capable of
retaining its structure at higher temperatures than 4-
TBPh. The comparative analysis of the degradation
rate constants of 4-(1-Ad)Ph and 4-TBPh in the tem-
perature range of 703–738 K showed that the degrada-
tion of 4-(1-Ad)Ph proceeds three- to fourfold slower
on the average.
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2020