Acid Decomposition of p-tert-Butylcumene Hydroperoxide to p-tert-Butylphenol and Acetone

Article abstract of DOI:10.1134/S1070427219110090

p-tert-Butyphenol is a valuable product of basic organic synthesis, widely used in various branches of industry. The relationships of acid decomposition of p-tert-butylcumene hydroperoxide to p-tert-butylphenol and acetone as one of the key steps of the alternative method for p-tert-butylphenol synthesis were studied. The influence exerted by temperature, catalyst concentration, and initial concentration of p-tert-butylcumene hydroperoxide on its acid decomposition was examined. Conditions ensuring preparation of p-tert-butylphenol in 92% yield were found. A kinetic model of the acid decomposition of p-tert-butylcumene hydroperoxide in the presence of concentrated sulfuric acid was constructed; it adequately describes the experimental data and allows substantiation of the reaction mechanism.

Full text of DOI:10.1134/S1070427219110090

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2019, Vol. 92, No. 11, pp. 1524−1530. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Zhurnal Prikladnoi Khimii, 2019, Vol. 92, No. 11, pp. 1427−1434.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Acid Decomposition of p-tert-Butylcumene Hydroperoxide
to p-tert-Butylphenol and Acetone
a
a,
a
a
a
E. M. Yarkina , E. A. Kurganova *, A. S. Frolov , G. N. Koshel’ , and E. M. Denisova
a
Yaroslavl State Technical University, Yaroslavl, 150023 Russia
*
e-mail: kurganovaea@ystu.ru
Received January 22, 2019; revised August 5, 2019; accepted August 20, 2019
Abstract—p-tert-Butyphenol is a valuable product of basic organic synthesis, widely used in various branches
of industry. The relationships of acid decomposition of p-tert-butylcumene hydroperoxide to p-tert-butylphenol
and acetone as one of the key steps of the alternative method for p-tert-butylphenol synthesis were studied. The
influence exerted by temperature, catalyst concentration, and initial concentration of p-tert-butylcumene hydrop-
eroxide on its acid decomposition was examined. Conditions ensuring preparation of p-tert-butylphenol in 92%
yield were found. A kinetic model of the acid decomposition of p-tert-butylcumene hydroperoxide in the presence
of concentrated sulfuric acid was constructed; it adequately describes the experimental data and allows substantia-
tion of the reaction mechanism.
Keywords: p-tert-butylcumene, p-tert-butylcumene hydroperoxide, acid decomposition, p-tert-butylphenol,
kinetic model
DOI: 10.1134/S1070427219110090
p-tert-Butylphenol is one of the main phenol
homologs; it is used as an intermediate in basic organic
synthesis. Its application sphere steadily expands,
covering the production of antioxidants, pesticides,
rubbers, varnishes, paints, and in the recent time also
pharmaceuticals [1]. Promising applications fields of
p-tert-butylphenol include production of phenolic resin
acetone, consisting of three main steps: synthesis of
p-tert-butylcumene by alkylation of cumene with
tert-butyl alcohol, oxidation of p-tert-butylcumene to
hydroperoxide, and subsequent acid decomposition of
the hydroperoxide to p-tert-butylphenol and acetone
(Scheme 1).
The key step of the joint synthesis of p-tert-
2
402 used in glued leather items and of macrocylic
butylphenol and acetone is acid decomposition of p-tert-
butylcumene hydroperoxide. Despite available ample
data on the relationships of the acid decomposition
of sec-alkylarene hydroperoxides, including cumene
hydroperoxide [4], into phenol and carbonyl compounds,
the relevant data concerning p-tert-butylcumene
hydroperoxide are lacking. Therefore, it is topical to
examine the relationships of the acid decomposition of
p-tert-butylcumene hydroperoxide. That was the subject
of this study.
compounds, calixarenes [2].
In industry, p-tert-butylphenol is synthesized by
alkylation of phenol with isobutylene in the presence
of KU-type ion-exchange resins and, in the recent time,
of Amberlyst macroporous sulfonic cation-exchange
resins at 100–110°С [3]. The drawback of this method
of low selectivity (70–75%) of p-tert-butylphenol
formation: ortho and meta isomers of tert-butylphenol
are also formed. The boiling points of these isomers are
close to that of p-tert-butylphenol, which considerably
complicates isolation of sufficiently pure p-tert-
butylphenol from the reaction mixture.
EXPERIMENTAL
The problem can be solved by using an alternative
method for preparing p-tert-butylphenol jointly with
p-tert-Butylcumene hydroperoxide was prepared
by aerobic oxidation of p-tert-butylcumene by the
1524

ACID DECOMPOSITION OF p-tert-BUTYLCUMENE HYDROPEROXIDE
1525
Scheme 1.
1
1
procedure described in [5]. The product precipitated
on cooling the oxidate was filtered off and dried in air
Н NMR spectroscopy. Н NMR spectrum, δ, ppm (J,
1
arom 3
Hz): 9.01 s ( H, ОН), 7.18 d (2H , J = 6.71), 6.68
d (2H , J = 6.71), 1.2 m (9H, СН ). The Н NMR
arom
3
1
at room temperature; purity 98.5%, Т = 72°С. The
m
3
structure of p-tert-butylcumene hydroperoxide was
spectrum was recorded with a Bruker DRX 400 NMR
1
1
confirmed by Н NMR spectroscopy. Н NMR spectrum
spectrometer (400.4 MHz). A DMSO-d –CCl mixture
6
4
t-Bu
(
2
400 MHz), δ, ppm: 1.35 m (9H, 3CH
), 1.63 m (6H,
was used as a solvent, and tetramethysilane, as an
internal reference.
3
CH3i-Pr), 7.28 s (1H, O–O–H), 7.42 m (4H, 4CHarom).
Acid decomposition of p-tert-butylcumene hydrop-
RESULTS AND DISCUSSION
eroxide was performed in acetone in a reactor equipped
with a stirrer and a sampler. The reactor design allowed
the loss of the reactants to be virtually fully excluded. A
mixture of the hydroperoxide and acetone was heated
to the preset temperature maintained with a water bath.
When the required temperature was reached, a calculated
amount of 98% H SO was added to the reaction mixture
Experiments on studying the influence of the main
process parameters on the acid decomposition of p-tert-
FID-2, mV
2
4
with continuous stirring. Samples (0.2–0.3 g each) were
taken at 5-min intervals to determine the residual con-
tent of p-tert-butylcumene hydroperoxide by iodomet-
ric titration. After the reaction completion, the products
were analyzed chromatographically for the content of p-
tert-butylphenol and acetone. Chromatographic analysis
was performed with a Khromatek-Kristall 5000.2 chro-
matograph under the following conditions: flame ioniza-
tion detector; SK-5 capillary column 30 m long and 0.32
mm in diameter, coated with 5% phenyl–95% dimethyl-
3
–1
polysloxane; carrier gas nitrogen, flow rate 2 cm min ;
programmed heating from 80 to 200°С at a rate of 8 deg
2
, 3, 5, 6, 7 are
unidentified
products
–1
min . The quantitative analysis of the acid decomposi-
tion products was performed using an internal reference.
p-tert-Butylphenol and acetone were isolated from the
products by fractional distillation. Figure 1 shows the
chromatogram of the products obtained by acid decom-
position of p-tert-butylcumene hydroperoxide.
Fig. 1. Chromatogram of the products formed by acid
decomposition of p-tert-butylcumene hydroperoxide at 40°С,
catalyst content of 0.6 wt %, and initial p-tert-butylcumene
hydroperoxide concentration of 30 wt %.
The synthesized p-tert-butylphenol was 99.3% pure
and had Т = 97.6°С. Its structure was confirmed by
m
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1526
YARKINA et al.
Table 1. Influence of process parameters on the acid decomposition of p-tert-butylcumene hydroperoxide to p-tert-butylphenol
and acetone
Catalyst
(
concentrated
Initial p-tert-
butylcumene
hydroperoxide
concentration, M
p-tert-
p-tert-
Butylphenol
formation
H SO )
Initial reaction
2
4
Temperature,
°C
Time,
min
Butylcumene
hydroperoxide
conversion, %
2
rate W × 10 ,
0
concentration,
wt % relative
to the loaded
hydroperoxide
–
1
–1
mol L min
selectivity, %
0
.065
.065
30
35
35
15
55
55
20
15
0.28
1.03
2.31
0.53
1.02
1.56
2.64
0.26
84.6
87.1
8
8.3
4
5
0
0
0.6
0.3
99.0
98.7
98.7
100.0
98.7
99.3
97.1
89.5
89.7
89.4
87.9
87.3
89.6
0
40
0
0
1
.6
.9
.5
0.026
0.065
0.132
40
0.6
35
0.96
1.91
99.3
95.0
89.3
91.0
butylcumene hydroperoxide to p-tert-butylphenol and
With an increase in the temperature from 30 to
acetone was performed in the temperature interval 30–
50°С, the initial rate of the acid decomposition of
p-tert-butylcumene hydroperoxide increased by a factor
of approximately 8. The preferable temperature for
performing acid decomposition of p-tert-butylcumene
hydroperoxide is 40°С.
5
0°С in acetone; the initial hydroperoxide concentration
was varied from 0.026 to 0.132 M. Concentrated
sulfuric acid was used as the decomposition catalyst; its
concentration was varied from 0.3 to 1.5 wt % relative
to the loaded p-tert-butylcumene hydroperoxide. The
reaction progress was monitored by determining the
unchanged p-tert-butylcumene hydroperoxide by
iodometric titration.
An increase in the catalyst amount from 0.3 to
1
.5 wt % relative to the loaded hydroperoxide leads to
an increase in the initial reaction rate by a factor of 5,
but does not noticeably influence the p-tert-butylphenol
yield.
The p-tert-butylcumene hydroperoxide conversion
under these conditions reaches virtually 100%,
and the p-tert-butylphenol formation selectivity is
approximately 90% (Table 1).
An important factor influencing the acid decompo-
sition is the initial concentration of p-tert-butylphenol
hydroperoxide. As seen from Table 1, with an increase
in the initial concentration of the hydroperoxide from
The kinetic curves of the acid decomposition of
p-tert-butylcumene hydroperoxide (Fig. 2) have a
complex shape and cannot be described by any of
equations for simple reactions. The kinetics was
0
.026 to 0.132 M the initial rate of the acid decomposi-
tion increases by a factor of approximately 7. The initial
concentration of p-tert-butylcumene hydroperoxide of
evaluated by the initial rates W , because in the initial
0
0
.132 M is preferable. Because the acid decomposition
period the concentration of reaction products is low and
their effect on the decomposition rate is insignificant.
The initial rates were determined from the slope of the
tangent to the kinetic curve at the initial time moment.
of p-tert-bnutylcumene hydroperoxide occurs with large
heat release, further increase in the initial hydroperoxide
concentration is unsafe.
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ACID DECOMPOSITION OF p-tert-BUTYLCUMENE HYDROPEROXIDE
1527
(a)
(b)
Time, min
Time, min
(c)
Time, min
Fig. 2. Kinetic relationships of the acid decomposition of p-tert-butylcumene hydroperoxide under various conditions. (a) Temperature,
C: (1) 30, (2) 40, and (3) 50; catalyst concentration 0.6 wt %. (b) Initial hydroperoxide concentration, M: (1) 0.132, (2) 0.065, and
3) 0.026; temperature 40°С; catalyst concentration 0.6 wt %. (c) Catalyst concentration, wt %: (1) 0.3, (2) 0.6, (3) 0.9, and (4) 1.5;
°
(
temperature 40°С.
Based on the data obtained, the following conditions
for p-tert-butylcumene hydroperoxide decomposition
can be recommended: reaction time of 45 min,
temperature of 40°С, and initial concentration of p-tert-
butylcumene hydroperoxide in acetone of 0.132 M.
Under the chosen conditions, we performed a balance
experiment and constructed the material balance
of the acid decomposition of p-tert-butylcumene
hydroperoxide. It confirmed the formation of p-tert-
butylphenol in 92.8% yield at 100% conversion of
p-tert-butylcumene hydroperoxide (Table 2).
To substantiate the mechanism, we constructed
a kinetic model of the acid decomposition of p-tert-
butylcumene hydroperoxide. It included the steps
of the formation of the hydroperoxide dimer and of
complexes of the hydroperoxide with p-tert-butylphenol
and acetone. The probability of the formation of such
complexes and their higher reactivity compared to the
individual hydroperoxide were proved in numerous
studies [4, 6–9]. The sulfuric acid decomposition of
the hydroperoxide involves parallel occurrence of the
decomposition of the hydroperoxide proper, its dimer,
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 92 No. 11 2019

1528
YARKINA et al.
Table 2. Material balance of the acid decomposition of p-tert-butylcumene hydroperoxide in acetone. Conditions: initial
hydroperoxide concentration 0.132 M, reaction time 45 min, temperature 40°C, catalyst amount 0.6 wt % relative to the loaded
hydroperoxide
Initial mixture
Products
Molar mass,
g mol
Substance
–
1
g
wt %
30.00
g
wt %
0.29
p-tert-Butylcumene hydroperoxide
208
23.70
0.00
Sulfuric acid
Acetone
98
58
150
‒
0.14
55.15
0.00
0.18
69.82
0.00
0.14
60.10
15.80
2.05
0.18
75.86
19.94
2.59
p-tert-Butylphenol
By-products
Loss
0.00
0.00
‒
0.00
0.00
0.90
1.14
Total
‒
78.99
100.00
78.99
100.00
and complexes with decomposition products. The
overall reaction is a complex process characterized both
by autocatalysis and by inhibition with the reaction
product.
concentration of the hydroperoxide; then, the material
balance equation with respect to the hydroperoxide will
have the form
c0HP = сHP + (сОН + с )/2, сОН = с ,
(1)
(2)
(3)
(4)
(5)
(6)
А
А
Thus, the kinetic model of the p-tert-butylcumene
hydroperoxide decomposition can be presented as
follows:
с0К = с + с ,
К
IV
с = K с с
,
I
1 HP ОН
с = K с с ,
II
2 HP A
HP + OHK HP…OH,
1
сIII = K с 2,
3 HP
HP + AK HP…A,
2
сIV = K с с ,
4 К A
HP + HPK HP…HP,
3
H SO + AK H SO …A,
where cC is the running catalyst concentration; c0C,
initial catalyst concentration; c , c , c , c , running
2
4
4
2
4
Ι
ΙΙ
ΙΙΙ
ΙV
+
HPH k OH + A,
1
concentrations of complexes Ι, ΙΙ, ΙΙΙ, and ΙV; c0HP, initial
hydroperoxide concentration; and c , c , c , running
+
IH k OH + A,
2
HP ОН
А
concentrations of hydroperoxide, p-tert-butylphenol,
and acetone.
+
IIH k OH + A,
3
+
IIIH k OH + A,
4
The overall reaction rate is the sum of the decompo-
sition rates of the hydroperoxide and its complexes with
reaction products, which are proportional to the catalyst
concentration raised to nth power and concentrations of
hydroperoxide and the respective complexes:
where K , K , K , and K are the equilibrium constants
1
2
3
4
of the formation of complexes Ι–ΙΙΙ and ΙV; k , k , k ,
and k are the rate constants of the decomposition of
the hydroperoxide and complexes Ι, ΙΙ, and ΙΙΙ; HP is
hydroperoxide; ОН is p-tert-butylphenol; and А is
acetone.
1
2
3
4
HP
C
HP
Because of low equilibrium constants of formation
of complexes I–III [6], it can be assumed that their
concentration is considerably lower than the initial
where n is the reaction order with respect to the catalyst.
Taking into account Eqs. (1)–(6), we finally obtain
HP
C
(7)
HP
HP
HP
HP
HP
HP
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 92 No. 11 2019

ACID DECOMPOSITION OF p-tert-BUTYLCUMENE HYDROPEROXIDE
1529
Table 3. Constants of Eq. (7) describing the acid decomposition of p-tert-butylcumene hydroperoxide at 40°С
k1
k2
k3
k4
K4
а
b
n
L mol–1 s–1
1
0.1
33.4
269.8
11.5
0.1
11.9
14.2
1
CONCLUSIONS
where
.
The results of studying the influence of various
process parameters on sulfuric acid decomposition of
p-tert-butylcumene hydroperoxide to p-tert-butylphenol
and acetone show that the optimum reaction conditions
are as follows: temperature of 40°С, reaction time of
45 min, initial concentration of p-tert-butylcumene
hydroperoxide in acetone of 0.132 M, and sulfuric acid
concentration of 0.6 wt %. Under these conditions,
p-tert-butylphenol can be obtained in a yield exceeding
90%.
The differential equation was solved using numerical
methods, and the сHP = f(τ) dependence was obtained
(Fig. 3). The rate constants of the acid decomposition of
p-tert-butylcumene hydroperoxide are given in Table 3.
The reaction is first-order with respect to the catalyst.
The reaction order was determined graphically from the
slope of the logarithmic plot of the initial reaction rate
vs. catalyst concentration.
As seen from Fig. 3, Eq. (7) adequately describes
the acid decomposition of p-tert-butylcumene
hydroperoxide. The approximation reliability for each
The results of mathematical modeling suggest that
p-tert-butylphenol is mainly formed by decomposition
of the complex of p-tert-butylcumene hydroperoxide
with acetone, as indicated by high rate constant of the
2
kinetic curve was R ≈ 0.99. The error of measuring the
constants did not exceed ±4%.
decomposition of this complex (k ). This conclusion
3
agrees with the conclusions made previously in
[6, 7] when studying the relationships of the acid
decomposition of cyclohexylbenzene hydroperoxide,
and also in [9].
CONFLICT OF INTEREST
The authors declare that they have no conflict of interest.
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