Ozonolysis of 1-methylcyclohexanol

Article abstract of DOI:10.1023/A:1026344514179

The kinetic features and composition of products of 1-methylcyclohexanol ozonolysis were studied.

Full text of DOI:10.1023/A:1026344514179

Russian Journal of Applied Chemistry, Vol. 76, No. 6, 2003, pp. 962 966. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 6, 2003,
pp. 990 994.
Original Russian Text Copyright
2003 by Syroezhko, Begak.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Ozonolysis of 1-Methylcyclohexanol
A. M. Syroezhko and O. Yu. Begak
St. Petersburg Technological Institute, St. Petersburg, Russia
Mendeleev Russian Research Institute of Metrology, Federal State Unitary Enterprise, St. Petersburg, Russia
Received January 30, 2003
Abstract The kinetic features and composition of products of 1-methylcyclohexanol ozonolysis were studied.
In low-temperature selective ozonolysis of methyl-
cyclohexane involving cleavage of the C H bond,
1-methylcyclohexanol (MCHl) is formed by recombi-
nation of R and OH radicals after primary initiation,
radical-chain transformations of 1-methylcyclohexyl
hydroperoxide, and attack of RO radicals at the start-
ing substrate [1].
An examination of the kinetic features (Fig. 1) and
composition of products of MCHl ozonolysis (40
115 C, [O3] = 1 4 vol %) [2 8] showed that oxida-
tion of this alcohol yields hydrogen peroxide, MCHl
-hydroperoxide, mono- and dicarboxylic acids,
-
ketoenanthic acid (Table 1), and esters. The ratio of
monocarboxylic and steam-undistillable acids is with-
in 0.25 0.30, being virtually independent of temper-
ature, ozone content in the oxidizing gas, and reaction
time.
In the developed process, the forming MCHl is
consumed, and the selectivity with respect to MCHl
decreases. In this study, we analyzed the features of
MCHl transformation in ozonolysis. The substrate
was oxidized and the products analyzed by the pro-
cedures described in [2].
The selectivity of MCHl ozonolysis with respect to
acids (Fig. 2) grows with increasing conversion and
temperature.
Fig. 2. Yields of acids RCOOH and esters RCOOR vs. MCHl
conversion at (1 10) various temperatures and (11 14) var-
Fig. 1. Kinetic curves of accumulation of (a, d) acids
RCOOH, (b, e) esters RCOOR , and (c, f) peroxides
ious ozone concentrations. ( c ) Total content of MCHl
ROOH in ozonolysis of MCHl. ( ) Time. (a c) [O ] =
i
3
conversion products. (1 10) [O ] = 4 vol %; (11 14) T =
4 vol %; T, C: (1) 40, (2) 60, (3) 70, (4) 100, and (5) 115.
3
100 C. T, C: (1, 6) 40, (2, 7) 60, (3, 8) 70, (4, 9) 100,
(d f) T = 100 C; [O ], vol %: (1) 1, (2) 2, (3) 3,
3
and (4) 4.
and (5, 10) 115. [O ], vol %: (11, 13) 3 and (12, 14) 4.
3
1070-4272/03/7606-0962 $25.00 2003 MAIK Nauka/Interperiodica

OZONOLYSIS OF 1-METHYLCYCLOHEXANOL
Table 1. Composition of monocarboxylic, dicarboxylic, and keto acids formed in MCHl ozonolysis
Acid content, mol % based on the sum of acids
963
T,
C
, min
propi-
onic
methyl-
succinic
-meth-
yladipic enanthic
-keto-
acetic
butyric valeric caproic
10% conversion
succinic glutaric
10
6.3
7.0
23.5
29.2
35.0
40
70
80
100
115
360
240
210
180
120
75
10.3
9.7
9.5
9.3
8.6
5.2
4.2
3.7
3.0
2.5
6.5
5.5
5.1
4.3
3.7
3.0
2.3
2.0
1.5
1.8
78.3
79.7
81.9
83.2
6.5
5.0
7.2
6.3
11.5
6.1
9.0
6.8
18.2
33.7
30.5
24.5
20.5
10.0
15.3
20.4
44.3
45.2
38.0
42.0
25% conversion
40
70
80
100
115
540
420
300
300
240
75.5
77.0
78.0
80.0
81.5
10.6
10.0
9.8
9.5
9.0
4.7
4.5
4.1
3.5
3.1
6.3
5.7
5.6
5.0
4.5
4.0
2.8
2.5
2.0
1.9
1.5
1.5
2.2
4.6
4.8
9.5
9.0
7.8
9.5
7.3
25.5
20.0
35.0
32.0
30.2
32.0
27.0
12.5
19.0
20.6
31.5
42.5
42.5
35.0
37.1
At low temperatures (40 60 C) the selectivity
with respect to esters weakly decreases with increas-
ing MCHl conversion, apparently, owing to their con-
sumption. At higher temperatures (70 115 C), the
rates of both MCHl esterification by monocarbox-
ylic acids (primarily acetic acid) and ozonolysis of
esters increase [1]. However, the esterification rate
is higher; therefore, with increasing conversion, the
yield of esters weakly grows. The selectivity of per-
oxide formation decreases with increasing MCHl con-
version.
lower carboxylic acids are formed by ozonolysis of
higher dicarboxylic acids and -ketoenanthic acid.
This has been confirmed in experiments with labeled
acids [9].
Thus, the major products of MCHl ozonolysis are
-ketoenanthic and -methyladipic acids. -Ketoen-
anthic acid is formed in isomerization of 2-hydroxy-2-
methyl-1-cyclohexyloxy and 1-methyl-1-cyclohexyloxy
radicals with ring opening, accompanied by oxidation
by oxygen and ozone, and also in ozonolysis of MCHl
-hydroperoxide (at elevated temperatures) or -hy-
drotrioxide (at 10 70 C).
The ozone concentration (Fig. 1) affects only slight-
ly the ratio of acids and esters accumulating in MCHl
oxidation products. Table 1 shows that, with increas-
ing temperature (at the same conversion), the content
of acetic acid grows, and that of propionic, butyric,
valeric, and caproic acids decreases. In the course
of MCHl ozonolysis, the C3 C6 acids undergo de-
carboxylation and oxidation with cleavage of the
C C bond, as judged from experiments with labeled
acids [1].
Table 2. Composition of dicarboxylic and keto acids
formed in MCHl ozonolysis (100 C, 300 min)
Content, mol %, at indicated
ozone concentration, vol %
Acid
1
2
3
4
Methylsuccinic
Succinic
10.5
23.5
13.0
41.5
11.5
6.0
17.0
19.0
38.5
19.5
4.5
12.1
23.2
36.4
24.2
4.6
9.5
Tables 1 and 2 show that, with increasing ozone
content, the yields of -ketoenanthic and glutaric
acids grow and that of -methyladipic acid decreases.
The parallel variation of the content of methylsuc-
cinic and methyladipic, and of glutaric and -keto-
enanthic acids suggests their genetic relationship:
Glutaric
32.0
19.0
35.0
-Methyladipic
-Ketoenanthic
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 6 2003

964
SYROEZHKO, BEGAK
a
.
+ HO + O2
.
O3, k1
H3C
H3C
OH
k2
b
H3C
OH
.
.
OOOH
+ HO2
O
H3C
H3C
OH
OH
.
OO
H3C
OH
CHO
OH
CHO
.
C
C
O2, k4
k3
.
O
H3C
OH
.
CH3
C
CH3
C
OO
H3C
O
O
OH
C
CHO
COOH
CHO
O3, O2, k5
k5
H2O
k6
+ O2
.
.
OO
H3C
OH
H3C
OH
k7
+
+ O2
.
.
.
2
O
OO
OO
H3C
OH
H3C
OH
H3C
OH
_
80 115 C, k8
+
+
.
.
OO
OOH
H3C
OH
H3C
OH
H3C
OH
H3C
OH
.
k9
OH +
.
O
OOH
H3C
OH
H3C
OH
The probability of ozone attack at the O H bond
in MCHl, which is stronger than the C H bond, is
low. However, the alkoxy radical formed by this and
other pathways [10] also contributes to formation of
-ketoenanthic acid by ring opening, followed by re-
action with oxygen and ozone:
k10
.
.
+ O3
HO3(HO + O2) +
H3C
H3C
.
O
H3C
CH3
OH
CH3
C
O
O
O
.
C
C
.
.
.
O3, O2, RH, k13
COOH + OH + O2
CHOO
CH2
O2, k12
k11
.
H3C
O
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 6 2003

OZONOLYSIS OF 1-METHYLCYCLOHEXANOL
It has been shown [10] that the source of the 1-meth-
965
yl-1-cyclohexyloxy radical at high temperatures is the
adduct of hydrogen peroxide with MCHl [10]. 2-Hy-
droxy-2-methyl-1-cyclohexyloxy radical can also form
by decomposition of unstable MCHl hydrotrioxide
and recombination of the 2-hydroxy-2-methyl-1-per-
oxycyclohexyl radical.
-Methyladipic acid is presumably formed in
ozonolysis of MCHl by the following pathway:
CH3
H3C
OH
OH
.
.
O
O
CH3
CH3
O3, O2
Fig. 3. Kinetic curves of MCHl (ROH) consumption.
COOH
COOH
COOH
.
(1 5) [O ] = 4 vol %; (5 , 6 8) T = 100 C. T, C:
3
CH2
(1) 40, (2) 60, (3) 70, (4) 100, and (5) 115. [O ], vol %:
3
(5 ) 1, (6) 2, (7) 4, and (8) 4.
Lower mono- and dicarboxylic acids are partially
formed by further ozonolysis of -ketoenanthic and
-methyladipic acids.
When discussing the mechanism of MCHl ozonol-
ysis, we disregarded the MCHl association [10].
Figure 3 shows the typical kinetic curves of MCHl
consumption in ozonolysis. The tertiary alcohol is
consumed with autoacceleration. The experimental
results were fitted with the equation
CONCLUSIONS
(1) Consumption of 1-methylcyclohexanol in
ozonolysis at 10 115 C and ozone concentrations
in the range 1 4 vol % is described by Eq. (1),
with the constants k1 and k2 calculated from Eqs. (2)
and (3).
d[ROH]/d = k1 [ROH]0[O3]0
+ k2 ([ROH]0
[ROH])[ROH] = kapp [ROH], (1)
where [ROH] and [ROH]0 are the running and initial
MCHl concentrations, respectively (M); kapp is the ap-
1
(2) 1-Methylcyclohexanol is oxidized by ozone
to form hydrogen peroxide, 1-methylcyclohexanol
-hydroperoxide, C2 C6 monocarboxylic acids, dicar-
boxylic acids (succinic, methylsuccinic, glutaric,
-methyladipic), -ketoenanthic acid, and esters of
these acids with the starting alcohol.
parent rate constant (min ).
The first reaction order with respect to MCHl and
ozone was found from the initial reaction rates. Thus,
the first term in Eq. (1) is determined by bimolecular
reaction of MCHl with ozone, and the second implic-
itly takes into account the reactions of the products
with ozone and radicals with MCHl. The constants
k1 and k2 were determined by computer fitting for
each particular dependence at different initial con
centrations of the reactants and were then refined by
numerical integration of the set of differential equa-
tions in the whole range of the initial concentrations
of the alcohol and ozone.
REFERENCES
1. Syroezhko, A.M., Liquid-Phase Oxidation of Alkanes,
Cycloalkanes, and Their Oxygen-Containing Deriv-
atives with Oxygen and Ozone in the Presence of
s- and 3d-Metal Compounds, Doctoral Dissertation,
Leningrad, 1985.
The consumption of MCHl in ozonolysis in the
examined range of temperatures and ozone concentra-
tions is described by Eq. (1) at the following constants
2. Vikhorev, A.A., Syroezhko, A.M., and Proskurya-
kov, V.A., Zh. Prikl. Khim., 1975, vol. 48, no. 9,
pp. 2059 2062.
1
k1 and k2, l mol 1 s :
3. USSR Inventor’s Certificate, no. 555084.
k1 = (1.2 0.1) exp [ (16500 2500)/RT ],
(2)
(3)
4. Dobinson, F., Chem. Ind., 1959, vol. 26, no. 1,
3
k2 = (1.42 0.11) 10 exp [ (16500 2500)/RT ].
pp. 853 854.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 6 2003

966
SYROEZHKO, BEGAK
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