Thermal Stability Study of 4-tert-Butylphenol

Article abstract of DOI:10.1134/S0965544119010134

Abstract: The thermal stability of 4-tert-butylphenol has been studied in the temperature range of 673–738?K, the components of the thermolysis reaction mixture have been identified, a kinetic model of the process has been proposed, and the rate constants and parameters of the Arrhenius equation have been calculated for all of the reactions considered. The predominant role of 4-tert-butylphenol isomerization transformations has been established. Information on the 4-tert-butylphenol thermal stability facilitates to a more substantiated approach to its use as an additive that increases the oxidative stability of fuels and lubricants, as well as an antioxidant for polymer compositions.

Full text of DOI:10.1134/S0965544119010134

ISSN 0965-5441, Petroleum Chemistry, 2019, Vol. 59, No. 1, pp. 120–127. © Pleiades Publishing, Ltd., 2019.
Russian Text © V.A. Shakun, T.N. Nesterova, P.V. Naumkin, 2019, published in Neftekhimiya, 2019, Vol. 59, No. 1, pp. 113–120.
Thermal Stability Study of 4-tert-Butylphenol
a,
a
b
V. A. Shakun *, T. N. Nesterova , and P. V. Naumkin
a
Samara State Technical University, Samara, 443100 Russia
b
OOO INCORGAZ, St. Petersburg, 192029 Russia
*
e-mail: ShakyH@mail.ru
Received January 14, 2017; Revised April 9, 2018; Accepted July 26, 2018
Abstract—The thermal stability of 4-tert-butylphenol has been studied in the temperature range of 673–
738 K, the components of the thermolysis reaction mixture have been identified, a kinetic model of the pro-
cess has been proposed, and the rate constants and parameters of the Arrhenius equation have been calculated
for all of the reactions considered. The predominant role of 4-tert-butylphenol isomerization transformations
has been established. Information on the 4-tert-butylphenol thermal stability facilitates to a more substanti-
ated approach to its use as an additive that increases the oxidative stability of fuels and lubricants, as well as
an antioxidant for polymer compositions.
Keywords: 4-tert-butylphenol, thermolysis, thermal stability, thermal degradation, isomerization, kinetics,
rate constant, Arrhenius parameters
DOI: 10.1134/S0965544119010134
Alkylphenols (APs) are of great practical impor- n-propylgallate, 2-tert-butylhydroquinone and 2,6-
tance in the development of modern industry. They di-tert-butyl-4-methylphenol in air at 458 K. Possible
are used in the manufacture of plastic foams, polymer mechanisms for the decomposition of 2-tert-butyl-4-
emulsions, surfactants, additives for oils and fuels, and
stabilizers of thermal destruction of polymers. Amino-
alkylphenols are used in the preparation of fuel emul-
sions for engines [1–4]. Phenolic resins are used in the
production of electrolytic cells and refractory materi-
als [5]. Phenolic antioxidants have a wide range of
applications. Nevertheless, the issue of the thermal
stability of phenols and their derivatives has been given
attention in quite a limited amount of research:
methoxyphenol, 2,6-di-tert-butyl-4-methylphenol
and 2-tert-butylhydroquinone were proposed. For
2-tert-butylhydroquinone, it was established that
along with the degradation, the isomerization of the
tert-butyl substituent to the isobutyl one id possible.
However, the results of the cited work are limited to
one temperature and do not consider the kinetic
parameters of the occurring transformations.
•
Kachatryan et al. [6, 7] obtained data on the
• Sato et al. [11] established the fact of isomeriza-
tion of the alkyl substituent during pyrolysis of isopro-
pylphenols in supercritical water at 720–820 K; a
model of the occurring transformations was proposed,
and the reaction rate constants were calculated.
•
kinetics of phenoxyl (C H O ) and cyclopentadienyl
C H ) radicals formation during the gas-phase phe-
5 5
6
5
•
(
nol pyrolysis at 673–1273 K and reduced pressures.
Ledesma et al. [8] investigated pyrocatechol
•
pyrolysis under nitrogen atmosphere (at 773–1273 K
• Repkin [12] investigated the thermal stability of
and contact time of 0.4 s) in order to obtain the kinetic 4-tert-butylphenol (4-TBP) in the temperature range
parameters for the formation of condensed polycyclic of 683–733 K; a model of the decomposition was pro-
aromatic hydrocarbons (HCs), which are solid fuels.
posed. However, our studies have shown that the
information on the composition of the reaction mix-
tures of 4-TBP decomposition given in [12] needs to be
clarified and the kinetic model should be changed and
complemented.
•
Adounkpe et al. [9] investigated thermal stability
of hydroquinone in the gas phase over the temperature
range of 623–1123 K; the presence of p-quinol and
cyclopentadienyl radicals was established, and the
effect of the process temperature on their concentra-
tion was revealed.
In this study, we considered in more detail the issue
of the 4-TBP thermolysis mixture composition and
•
In [10], Hamama and Navar described the ther- calculated the kinetic parameters for all transforma-
mal decomposition of 2-tert-butyl-4-methoxyphenol, tions included in the kinetic model.
120

THERMAL STABILITY STUDY OF 4-TERT-BUTYLPHENOL
Procedure for 4-TBP Thermolysis.
121
The thermolysis was carried out in the gas phase in
quartz capillaries (l = 20–25 mm; d = 1.05–
n
5
1
.56 mm), into which the test substance was placed,
after which the capillary was purged with helium
(
purity 99.999%) and sealed with a hydrogen gas
burner. The degree of filling with the substance was
20–30 vol %, which corresponded to the weight of the
substance of 0.4–0.5 mg. The weighing was carried
out on a Shimadzu AUW 120D analytical balance with
2
9
20 V
А
673–773 К
6
−4
4
an accuracy of 10 g. The thermostating was carried
out on a special setup (Fig. 1) ensuring that the tem-
perature in the isothermal zone is maintained constant
accurate to within ±1 K. The pyrolysis process was
always terminated by quenching, which consisted in
immediate transferring the capillary from the furnace
to a test tube cooled to −15°C. To solve the problem of
building the kinetic model of the 4-TBP thermal
decomposition, a certain temperature range of the
study was chosen: 718 K (interval 673–738 K with a
step of 5 K).
3
2
1
7
8
9
2
8
0
7
Fig. 1. Layout of the experimental setup: (1) oven,
2) reactor filled with quartz sand, (3) one-channel TPM1
temperature monitor-regulator, (4) quartz test tube,
(
Product Analysis and Identification
(
5) quartz guide, (6) laboratory transformer, (7) plati-
num–rhodium/platinum type S thermocouple, (8) a cap-
illary with the test substance, and (9) isothermal zone.
The main method for analyzing reaction mixtures
was GLC. The analysis was performed on a Kristall
2000 M instrument with the Chromatec Analytic soft-
ware and hardware system equipped with a flame ion-
ization detector, a precolumn flow splitter, and a
quartz capillary column (60 m × 250 μm × 0.25 μm)
with an SE-30 bonded stationary phase. Helium was
used as a carrier gas; its pressure at the column inlet
was 3 atm, the stability of the pressure was ensured by
double reduction. The temperature profiles of the col-
umn are shown in the corresponding chromatograms
EXPERIMENTAL
Starting Materials
4
-TBP was synthesized, isolated and purified by us
in accordance with the recommendations of [13].
The concentration of the basic substance was
9
9.9 wt %. 4-TBP was obtained by alkylation of phenol
(with an error of ±0.1°C). The evaporator and detector
with isobutylene at a temperature of 353 K and an
isobutylene : phenol molar ratio of 0.25 in the pres-
ence of macroporous Amberlyst 36 Dry sulfonated
temperatures were 200 and 280°C, respectively.
In quantitative analysis, n-tetradecane was used as
cation-exchange resin, dried to constant weight; the an internal standard (purity 99.9 wt % by GLC).
catalyst charge was 10 wt % relative to the weight of the
reaction mixture; contact time, 30 min. The synthesis
was carried out in a three-necked flask equipped with
a capillary for isobutylene supply, a thermometer, and
a reflux condenser with an internal guide for a glass
stirrer. Isobutylene flow rate (concentration 99.99%)
was adjusted using a calibrated rheometer.
Identification of the components of the mixtures
also included GC–MS analysis performed on an Agi-
lent 6850 gas chromatograph equipped with an Agilent
1
9091S-433E capillary column (30 m × 250 μm ×
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.
The isolation of 4-TBP was carried out using vac-
uum rectification (p = 0.8–1.0 kPa) on laboratory
res
columns with an efficiency of 30 theoretical plates.
The purity of the isolated 4-TBP was 99.9 wt %.
4-tert-Butylphenol Thermolysis Reaction Mixture
A typical chromatogram of the pyrolysis products is
depicted in Fig. 2.
The identification of 4-TBP was performed using
gas chromatography–mass spectrometry (GC–MS)
The main products were identified using the NIST
and a comparison of the spectra and the elution time 2011 database to interpret the mass spectra measured
of the obtained sample with a standard 4-TBP sample for the compounds: phenol (m/z 94), 2-methylphenol
(
purity 99 wt %) produced by Sigma-Aldrich. The (2-MeP) and 4-methylphenol (4-MeP) (m/z 108,
probability of coincidence with the NIST 2011 library m/z 107), 4-ethylphenol (4-EP) (m/z 122, m/z 107),
data was 99%.
2-isopropylphenol (2-IPP) and 4-isopropylphenol
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

1
22
SHAKUN et al.
Abundance
(L)
2
2
1
1
1
1
1
200000
000000
800000
600000
400000
200000
000000
(A)
(K)
473 К
(J)
4 К/min
353 K
(C)
800000
600000
400000
200000
(H)
(
G)
(B)
(D)
(
E) (F)
(I)
Time
2
4
6
8
10 12 14 16 18 20 22 24 26 28
Fig. 2. Chromatogram of the products of 4-TBP thermal transformations (T = 718 K, t
= 20 min): (A) phenol, (B) 2-meth-
contact
ylphenol (2-MeP), (C) 4-methylphenol (4-MeP), (D) 4-ethylphenol (4-EP), (E) 2-isopropylphenol (2-IPP), (F) 2-n-propyl-
phenol (2-NPP), (G) 4-isopropylphenol (4-IPP), (H) 4-n-propylphenol (4-NPP), (I) 2-isobutylphenol (2-IBP), (J) 4-TBP,
(
K) 4-isobutylphenol (4-IBP), (L) 4-n-butylphenol (4-NBP) added to the analyzed mixture in order to establish the structure of
4
-IBP using the GC–MS method.
(
4-IPP) (m/z 136, m/z 121, m/z 91, m/z 77), 2-n-pro-
The products of decomposition and further
pylphenol (2-NPP) and 4-n-propylphenol (4-NPP) sequential transformations of 4-IBP had significantly
(
m/z 136, m/z 107, m/z 77), and 4-TBP (m/z 150, lower concentrations. On the whole, 4-IPP, 4-NPP
m/z 135, m/z 107).
(Fig. 3b), and 4-EP (Fig. 3c) made only 3.96 mol %
for 30 min, whereas 4-MeP made 6.03 mol %
Fig. 3d).
The coincidence of the mass spectra with those in
the NIST 2011 database for all components of the
reaction mixture shown in the chromatogram (Fig. 2)
(
As the process depth increased (15–27 min), the
was 99%. The structure of 4-MeP, 4-EP, 4-IPP, and positional isomerization of substituents on the phenol
4
-NPP was additionally determined by comparing the aromatic rings with the formation of the 2-isomers of
elution times and spectra of the reaction products with IBP, IPP, NPP and MeP was also observed. In this
standard Sigma-Aldrich samples with a purity of 99, case, the concentration of 2-IBP was lower than that
3
4
9
9, 98, and 99%, respectively.
of 4-IBP by 2.05 × 10 –1.36 × 10 times. Concentra-
tions in the other groups of positional isomers were in
the following ratios: 4-IPP/2-IPP = (10–25)/1,
4-Isobutylphenol (m/z 150, m/z 107) was identified
by comparing the elution times and mass spectra of the
component (K) formed upon the thermal transforma-
tions of 4-TBP and 4-n-butylphenol (4-NBP, compo-
nent (L)) (> 98% by GLC), which was added to the
analyzed mixture. Components K and L had different
elution times.
4
(
-NPP/2-NPP = (15–35)/1, and 4-MeP/2-MeP =
20–80)/1. The 2-isomers of TBP and EP were not
detected.
Taking into account the significant predominance
of isomers with a substituent in the 4-position and the
possibility of the formation of 2-isomers due to para–
ortho isomerization, we used the notations 4-IBP,
4-IPP, 4-NPP, 4-MeP for the total 4- and 2-isomers.
RESULTS AND DISCUSSION
To establish possible routes of transformation
involving the components listed above, a number of
assumptions were adopted based on the structural fea-
tures of the molecules and the nature of the changes in
their concentrations. The main routes are 4-TBP
isomerization to 4-IBP, the formation of phenol
from 4-TBP due to isobutylene cleavage, the forma-
tion of 4-IPP from 4-IBP due to a loss of methylene
fragment and rearrangement, 4-MeP formation
from 4-IBP due to propylene cleavage, 4-IPP isomer-
ization to form 4-NPP, and degradation of 4-NPP to
form 4-EP.
Instead of the expected β-C–C bond cleavage or 4-
TBP dealkylation, the thermal treatment primarily
resulted in the structural isomerization of the alkyl
substituent to form 4-IBP (Fig. 3a). For 30 min of the
experiment, its content in the reaction mixture
reached 22.70 mol % (at the 4-TBP conversion of
4
0.80%). In this case, the dealkylation of 4-TBP
resulted in the formation of phenol, the concentration
of which reached 8.13 mol % within 30 min (Fig. 3d).
An analysis of the patterns of the rate curves led to the
conclusion that this is the only kind of transformation
suffered by the reactant 4-TBP. The source for the for-
mation of the other components of the reaction mix-
ture is 4-IBP.
Based on the above assumptions, the following
outcomes were obtained:
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THERMAL STABILITY STUDY OF 4-TERT-BUTYLPHENOL
123
1
00
(а)
2.0
1.6
1.2
0.8
0.4
(b)
8
0
0
0
0
6
4
2
0
5
10
15
20
25
30
0
5
10
15
20
25
30
Time, min
(c)
Time, min
(d)
1
.0
10
0.8
0.6
0.4
0.2
8
6
4
2
0
5
10
15
20
25
30
0
5
10
15
20
25
30
Time, min
Time, min
Fig. 3. Changes in the concentration of 4-TBP conversion products in the reaction mixture at 718 K: (a) (j,—) 4-TBP, (e, —)
4-IBP; (b) (s,–∙–) 4-IPP, (r,—) 4-NPP; (c) (n, – –) 4-EP; (d) (s, —) 4-MeP, (e, —) Phenol.
OH
k
2
OH
OH
OH
OH
OH
k
6
k
5
k
1
k
3
k
4
HO
Fig. 4. Scheme of transformations occurring during 4-TBP thermolysis (718 K).
•
general scheme of transformations in the system
d[4 − IBP]
=
k1[4 − TBP]
(
Fig. 4)
(2)
dt
−
k [4 − IBP] − k [4 − IBP],
•
kinetic model of the process:
3
4
d[4 − TBP]
d[4 − IPP]
=
−k [4 − TBP] − k [4 − TBP], (1)
= k [4 − IBP] − k [4 − IPP], (3)
3 5
1
2
dt
dt
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

1
24
SHAKUN et al.
Table 1. Rate constants of thermal transformations accompanying 4-TBP degradation in the range of 673–738 K
4
-TBP
4-TBP
phenol
4-IBP
4-IPP
4-IBP
4-IPP
4-NPP
4-EP
Reaction
4
-IBP
4-MeP
4-NPP
ki, s–1
T, K
k1
k ,
k3
k4
k5
k6
2
.90 × 10–5
2.43 × 10–6
3.69 × 10–6
5.27 × 10–6
7.49 × 10–6
1.06 × 10–5
1.49 × 10–5
2.08 × 10–5
3.35 × 10–5
4.02 × 10–5
5.73 × 10–5
7.61 × 10–5
1.04 × 10–4
1.35 × 10–4
1.80 × 10–4
3.50 × 10–6
5.86 × 10–6
8.64 × 10–6
1.27 × 10–5
1.85 × 10–5
2.68 × 10–5
3.86 × 10–5
6.52 × 10–5
7.91 × 10–5
1.55 × 10–4
1.59 × 10–4
2.24 × 10–4
2.92 × 10–4
3.65 × 10–4
5.57 × 10–6
9.59 × 10–6
1.42 × 10–5
2.10 × 10–5
3.07 × 10–5
4.48 × 10–5
6.49 × 10–5
1.15 × 10–4
1.34 × 10–4
2.37 × 10–4
2.72 × 10–4
3.85 × 10–4
4.75 × 10–4
6.55 × 10–4
2.11 × 10–4
2.92 × 10–4
3.86 × 10–4
5.08 × 10–4
6.65 × 10–4
8.68 × 10–4
1.13 × 10–3
1.61 × 10–3
1.89 × 10–3
2.44 × 10–3
3.11 × 10–3
3.97 × 10–3
5.05 × 10–3
6.05 × 10–3
3.12 × 10–5
4.70 × 10–5
6.59 × 10–5
9.20 × 10–5
1.28 × 10–4
1.77 × 10–4
2.43 × 10–4
3.82 × 10–4
4.55 × 10–4
6.42 × 10–4
8.36 × 10–4
1.13 × 10–3
1.39 × 10–3
1.98 × 10–3
6
73
1
.91 × 10–5
.28 × 10–5
678
683
688
693
698
703
708
2
3
5
.04 × 10–5
.27 × 10–5
.18 × 10–5
.10 × 10–4
.75 × 10–4
.76 × 10–4
7
8
1
1
7
13
18
23
28
33
38
1
.35 × 10–4
.06 × 10–4
7
2
3
7
.27 × 10–4
.70 × 10–4
.92 × 10–4
7
4
5
6
7
7
*
Error in determining the values of the rate constants was no more than 5%.
The adequacy of the model is illustrated in Fig. 5,
where the experimental concentrations of the compo-
nents are compared with the calculated ones obtained
by the Runge–Kutta method using the rate constants
listed in Table 1. The Pearson goodness of fit value for
comparing the concentrations was 0.99.
d[4 − NPP]
=
k [4 − IPP] − k [4 − NPP]. (4)
5
6
dt
d[4 − EP]
=
k6[4 − NPP].
(5)
(6)
dt
d[4 − MeP]
=
k4[4 − IBP].
The values of the k and k rate constants presented
dt
1
2
in Table 1 indicate that upon thermal action on 4-TBP
the 4-TBP → 4-IBP isomerization proceeds 4 times
faster than destructive transformations.
The values of the rate constants for individual
transformations (Table 1) were determined using a dif-
ferential method by coprocessing all experimental data
with optimization criterion (7) for each temperature:
4
-IBP undergoes degradation yielding 4-IPP and
4
-MeP (reactions 3 and 4). In this case, propylene
2


n
dCi
dt experiment
−  dCi 

cleavage resulting in the formation of 4-MeP as a
product proceeds 1.5 times faster than the process



→ min, (7)





 dt calculation
–4
–4
leading to 4-IPP (k = 1.55 × 10 , k = 2.37 × 10 for
3
4
where n is the number of measurements.
Т = 718 K).
PETROLEUM CHEMISTRY
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THERMAL STABILITY STUDY OF 4-TERT-BUTYLPHENOL
125
1
00
25
4
-ТBP
4-IBP
9
0
0
0
0
0
20
15
10
5
8
7
6
5
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
Contact time, min
Contact time, min
1
.4
.2
.0
2.5
4-IPP
4-NPP
1
2
.0
.5
.0
1
1
0.8
0.6
0.4
0.2
1
0.5
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
Contact time, min
Contact time, min
0
0
0
0
0
0
0
0
.9
7
6
5
4
3
2
1
.8 4-EP
4-MeP
.7
.6
.5
.4
.3
.2
0
.1
0
0
5
10
15
20
25
30
35
0
5
10
15
20 25 30 35
Contact time, min
9
Contact time, min
Phenol
8
7
6
5
4
3
2
1
0
5
10
15
20 25 30 35
Contact time, min
Fig. 5. Comparison of experimental (h) and calculated (—) data on the changes in concentrations of the products of 4-TBP ther-
mal transformations at 718 K.
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

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SHAKUN et al.
Table 2. Rate constants for 4-TBP → products thermal products” decomposition reaction using the equations
transformations occurring during 4-TBP thermolysis
at 673–738 K
for calculating the first-order reaction rate constant:
А → В, where А – 4-ТBP,
ki, s−1
T, K*
1000/Т
ln(ki)
(8)
(9)
( )
В – Σ products ,
2
3
3
5
8
9
.38 × 10–5
.36 × 10–5
.95 × 10–5
.85 × 10–5
.36 × 10–5
.55 × 10–5
6
73
1.4859
1.4749
1.4641
1.4535
1.4430
1.4327
1.4225
1.4124
1.4025
1.3928
1.3831
1.3736
1.3643
1.3550
–10.648
–10.302
–10.140
–9.747
–9.389
–9.257
–8.924
–8.560
–8.436
–8.164
–7.945
–7.541
–7.228
–6.963
r = kСA,
678
683
688
693
698
703
708
CA,0
ln
= kt.
(10)
CA
The activation energy and the pre-exponential fac-
tor were obtained by linearizing the Arrhenius equa-
tion in the lnk –1000/T coordinates:
i
1
.33 × 10–4
.92 × 10–4
.17 × 10–4
−E
k = A exp


a
.
(11)
 RT 
1
7
13
18
23
28
33
38
The values of the constants for the “4-TBP →
2
products” decomposition reaction are given in
.85 × 10–4
.54 × 10–4
7
2
3
Table 2, the ln k –1000/T plot is shown in Fig. 6:
i
7
According to the experimental values of the rate
constants, the parameters of the Arrhenius equation
were calculated: in the temperature range under study,
the pre-exponential factor for the “4-TBP → prod-
13.2 ± 0.3
.31 × 10–4
.26 × 10–4
.46 × 10–4
7
5
7
7
7
9
ucts” decomposition reaction is k = 10
, and
0
*
Error in determining the values of the rate constants was no more the activation energy of 4-TBP degradation is 229.9 ±
than 5%.
4.1 kJ/mol.
The Arrhenius parameters were calculated for all
the reactions, included in the kinetic model of the pro-
cess, in the temperature range of 673–738 K (Table 3).
The rate constant k for 4-IPP → 4-NPP isomeri-
6
zation has the highest value, which confirms the pre-
dominance of isomerization transformations of
branched substituents on the aromatic core during the
thermolysis of 4-TBP.
In order to establish the allowable temperature
range for syntheses, isolation, operation, and storage
of 4-TBP, as well as the duration of its stay under the
given conditions, we made an approximate estimate of
the 4-TBP stability duration. By the duration of stabil-
ity, we mean the time during which 1 mol % of the
substance degrades at a given temperature (Table 4).
The calculation was made on the basis of the obtained
values of the activation energy and the rate constant by
Calculation of the Arrhenius Parameters
A kinetic analysis of the experimental data in the
range of 673–738 K was performed for the “4-TBP → Eq. (12):
Table 3. Parameters of the Arrhenius equation for thermal transformations accompanying 4-TBP degradation in the range
of 673–738 K
k0, s−1
Reaction
4-IBP
ki
Ea, kJ/mol
R
m
4-TBP
4-TBP
4-IBP
4-IBP
4-IPP
4-NPP
k1
k2
k3
k4
k5
k6
12.8 ± 0.4
15.7 ± 0.2
17.9 ± 0.5
18.3 ± 0.5
13.0 ± 0.1
15.8 ± 0.2
224.9 ± 4.7
273.7 ± 2.8
299.7 ± 6.7
303.1 ± 6.1
214.1 ± 1.9
260.8 ± 2.8
0.99
0.99
0.99
0.99
0.99
0.99
14
14
14
14
14
14
Phenol
4-IPP
4-MeP
4-NPP
4-EP
PETROLEUM CHEMISTRY
Vol. 59
No. 1
2019

THERMAL STABILITY STUDY OF 4-TERT-BUTYLPHENOL
127
1
000/T, 1/K
For six reactions constituting the kinetic model, the
rate constants and the values for the Arrhenius param-
eters were obtained., For the “4-TBP → products”
decomposition in the temperature range of 673–
1
.30
1.35
1.40
1.45
1.50
–
–


2
4
6
8
738 K, the rate constants, the activation energy (E =
a
2
29.9 ± 4.1 kJ/mol), and the pre-exponential factor
0
y = –27.6545x + 30.4273
13.2 ± 0.3
(
k = 10
) were determined. On the basis of the
2
R = 0.9962
data, time intervals in which 99% of 4-TBP retains its
stability at a given temperature were approximately
estimated. The kinetic parameters were calculated for
all the transformations included in the kinetic model.

10
12
This information can be used in the development of
promising areas of 4-TBP application as a stabilizer or
antioxidant for lubricants or polymers operating at ele-
vated temperatures. In general, the known informa-
tion on the thermal stability of 4-TBP contributes to a
more reasonable approach to its use as an additive that
increases the oxidative stability of fuels and lubricants,
as well as an antioxidant for polymer formulations.

Fig. 6. Plot of the logarithm of rate constant versus the
inverse temperature for 4-tert-butylphenol decomposition
reactions.
Table 4. The duration of 4-TBP stability in the temperature
range 523–773 K
REFERENCES
. J. E. Goldstein and R. J. Pandrazi, US Patent
No. 20050217788 (2005).
T, K
Time
Measurement unit
s
1
2
7
7
73
23
2
25
428
3
6
2
s
s
. K. Holmberg, B. Jönsson, B. Kronberg, and B. Lind-
673
623
573
523
man, Surfactants and Polymers in Aqueous Solution
(
Wiley, Chichester, 2003), 2nd Ed.
h
days
years
3
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Fuels 23, 2517 (2009).
4. B. Filippini, J. Forsberg, T. Steckel, et al., US Patent
No. 20020020106 (2002).
5
6
7
8
9
. The Chemistry of Phenols, Ed. by Z. Rappoport (Wiley,
Chichester, 2003), Part 1.
0
.01
(12)
τ =
.
E/RT
. L. Khachatryan, J. Adounkpe, and B. Dellinger, J.
Phys. Chem. A 112, 481 (2008).
. L. Khachatryan, A. Burcat, and B. Dellinger, Com-
bust. Flame 132, 406 (2003).
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M. J. Wornat, Energy Fuels 16, 1331 (2002).
. J. Adounkpe, L. Khachatryan, and B. Dellinger,
Energy Fuels 22, 2986 (2008).
−
k e
0
CONCLUSIONS
As a result of the study, it has been found that in
the temperature range of 673–738 K, the thermolysis
of 4-tert-butylphenol proceeds in two directions: deal-
kylation with the formation of phenol and isomeriza-
tion into 4-isobutylphenol. At the same time, the
isomerization rate significantly prevails, and 4-isobu-
tylphenol is the main product of the transformations
studied. The reaction mass was also represented by
1
0. A. A. Hamama and W. W. Nawar, J. Agric. Food Chem.
9, 1063 (1991).
1. T. Sato, T. Adschiri, and K. Arai, J. Anal. Appl. Pyrol.
0, 735 (2003).
2. N. M. Repkin, Candidate’s Dissertation in Chemistry
Samara, 2010).
3. I. O. Voronin, T. N. Nesterova, B. S. Strelchik, and
E. A. Zhuravskii, Kinet. Catal. 55, 705 (2014).
3
1
7
1
4
-methylphenol, 4-isopropylphenol, 4-n-propylphe-
(
nol, and 4-ethylphenol.
1
A kinetic model of 4-TBP thermal transformations
that adequately describes the experimental data in the
entire temperature range of the study was proposed.
Translated by V. Makhaev
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019