Synthesis of Unsaturated Spiroacetals, Cyclopentanone Derivatives, in the Presence of Natural Aluminosilicate Modified with Zirconium Cations

Article abstract of DOI:10.1134/S0965544119060021

Abstract: Conditions for the condensation of cyclopentanone and n-valeric aldehyde to 2-pentylidenecyclopentanone in the presence of an alcoholic solution of piperidine have been developed. The isomerization of the latter in a continuous-flow system over γ-Al₂O₃ yields 2-pentylcyclopent-2-en-1-one. The condensation of the obtained unsaturated ketones with ethane-1,2-diol in the presence of a heterogeneous catalyst, a natural aluminosilicate (perlite) modified with zirconyl sulfate, has been studied. The optimum conditions for the preparation of the corresponding unsaturated spiroacetals have been found. The synthesized compounds can be used as synthetic fragrances for different purposes.

Full text of DOI:10.1134/S0965544119060021

ISSN 0965-5441, Petroleum Chemistry, 2019, Vol. 59, No. 6, pp. 603–607. © Pleiades Publishing, Ltd., 2019.
Synthesis of Unsaturated Spiroacetals, Cyclopentanone Derivatives,
in the Presence of Natural Aluminosilicate Modified
with Zirconium Cations
M. F. Abbasova, Kh. M. Alimardanova, N. S. Abbaszadea, *, F. A. Guseinovaa, and A. M. Azimlia
aMamedaliev Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan,
Baku, AZ1025 Republic of Azerbaijan
*e-mail: narmin.yunusova87@mail.ru
Received November 7, 2018; revised February 4, 2019; accepted February 12, 2019
Abstract—Conditions for the condensation of cyclopentanone and n-valeric aldehyde to 2-pentylidenecyclo-
pentanone in the presence of an alcoholic solution of piperidine have been developed. The isomerization of
the latter in a continuous-flow system over γ-Al2O3 yields 2-pentylcyclopent-2-en-1-one. The condensation
of the obtained unsaturated ketones with ethane-1,2-diol in the presence of a heterogeneous catalyst, a nat-
ural aluminosilicate (perlite) modified with zirconyl sulfate, has been studied. The optimum conditions for
the preparation of the corresponding unsaturated spiroacetals have been found. The synthesized compounds
can be used as synthetic fragrances for different purposes.
Keywords: cyclopentanone, n-valeric aldehyde, 2-pentylidenecyclopentanone, natural aluminosilicate,
unsaturated spiroacetals
DOI: 10.1134/S0965544119060021
INTRODUCTION
This communication presents the results of study-
ing the condensation of unsaturated ketones, 2-pen-
tylidenecyclopentanone and 2-pentylcyclopent-2-en-
1-one, with ethylene glycol in the presence of a het-
erogeneous catalyst, a zirconyl cation-modified natu-
ral aluminosilicate (perlite), as well as the influence of
various factors at each stage of preparation of unsatu-
rated ketones and acetals.
Cyclic acetals and ketals (1,3-dioxalanes), which
are the products of condensation of carbonyl com-
pounds with vicinal di- and triols, find practical appli-
cation as monomers, intermediates, and auxiliary sub-
stances in the synthesis of general rubber goods and
paint-and-lacquer materials [1–3] or perfumery and
cosmetics [4–6]. Recently, these compounds have
also been attracting special interest in connection with
the possibility for their use in the composition of
motor fuels for improving octane characteristics,
increasing phase stability of alcohol-containing gaso-
lines, and decreasing the toxicity of exhaust gases.
Ketals obtained via the interaction of acetone, buta-
none, or cyclohexanone with ethylene glycol, propyl-
ene glycol, and glycerol have been studied as compo-
nents of fuel blends in most detail [7–10].
EXPERIMENTAL
Cyclopentanone obtained via dry distillation of
adipic acid in the presence of barium oxide hydrate
[14], n-valeric aldehyde, and reagent grade ethylene
glycol were used as the reactants after their appropriate
purification.
Preparation Procedure for Unsaturated Ketones
Both homogeneous (sulfuric and orthophosphoric
acids and toluenesulfonic acid) and heterogeneous
(cation-exchange resins, zeolites, and polyoxometa-
lates supported onto a mesoporous or carbon-based
material) catalysts are used for the preparation of
ketals [10–12].
2-Pentylidenecyclopentanone was obtained via
crotonic condensation of cyclopentanone with
n valeric aldehyde. Cyclopentanone in an amount of
42 g (0.5 mol), 50 mL of propan-2-ol (as a solvent),
and 21.5 g (0.25 mol) of n-valeric aldehyde were
Earlier, we reported the preparation of spiroacetals simultaneously placed into a 250-mL flask equipped
via the condensation of alkyl- and cycloalkylcyclopen- with a mechanical stirrer, a thermometer, and a reflux
tanones and cyclohexanones with dihydric alcohols in condenser. A 15% aqueous sodium hydroxide solution
the presence of various homogeneous and heteroge- or a 5% piperidine solution in alcohol was added to the
neous catalysts [12–14].
mixture dropwise in equal portions at 20°C. The reac-
603

604
ABBASOV et al.
RESULTS AND DISCUSSION
%
100
The main products of the catalytic conversion of
cyclopentanone with n-valeric 2-cyclopentylidenecy-
clopentanone, 2-pentylidenecyclopentanone, 2-pen-
tylcyclopent-2-en-1-one, and 2-(1-hydroxypen-
tyl)cyclopentanone, as well as the aldehyde and
ketone dimerization products 2-propylhept-2-en-1-al
and 2-cyclopentylidenecyclopentanone, respectively.
The ratio of these products depends on the reaction
conditions, namely, the temperature, the reaction
time, the molar ratio of the reactants, and amount of
the catalyst (Table 1).
1
2
80
60
40
20
0
280
300
320
350
T, ꢀC
250
The results of the study show that the yield and
composition of the desired product strongly depend
on both the amount of piperidine (or NaOH) and the
reaction temperature. For example, the main product
of condensation of cyclopentanone and n-valeric
aldehyde at 3°C is ketoalcohol C (50.6%). With an
increase in the temperature, the yield of ketoalcohol
decreases from 54.3 to 32.3 wt %.
By varying other parameters affecting the yield and
composition of the desired product (reaction time
and ketone to aldehyde molar ratio), the optimum
conditions for the condensation of cyclopentanone
with n-valeric aldehyde in the presence of piperidine
were found to be as follows: a ketone : aldehyde molar
ratio of 3 : 1, a temperature of 3–5°C, and a reaction
time of 3 h. Under these conditions, the yield of
ketoalcohol is 54.3% and the yield of unsaturated
ketone is 16.6 wt %. Ketoalcohol C undergoes dehy-
dration during vacuum distillation.
According to the GLC data, the obtained product
of crotonic condensation of cyclopentanone with
n-valeric aldehyde consists of two isomers, 2-pen-
tylidenecyclopentanone D (85.0) and 2-pentylcyclo-
pent-2-en-1-one E (15.0%).
The isomerization of the condensation product in
the flow system over γ-Al2O3 at 300–320°C results in
high yield of 2-pentylcyclopent-2-en-1-one. The
isomerization product consists of compounds E (94.0)
and D (6.0%). The dynamics of the isomerization of
2-pentylidenecyclopentanone to 2-pentylcyclopent-
2-en-1-one is shown in Fig.1.
Fig. 1. Results of the isomerization of (1) 2-pen-
tylidenecyclopentanone to (2) 2-pentylcyclopent-2-en-
1-one over γ-Al O at different temperatures.
2
3
tion mixture was stirred for additional 2 h at 30°C; the
organic phase was separated from the catalyst, washed
to a neutral reaction, and dried over Na2SO4; and the
desired product was isolated by fractional distillation
under vacuum.
The isomerization of 2-pentylidenecyclopenta-
none to 2-pentylcyclopent-2-en-1-one was performed
in a continuous-flow system including a fixed-bed
glass reactor with grade A alumina at 300–320°C and
a feed space velocity of 0.5 h−1.
The catalyst for the condensation of unsaturated
ketones with ethane-1,2-diol was prepared by impreg-
nating samples of natural perlite from the Kemerli
deposit (Azerbaijan) with a size of 2–3 mm by an
aqueous–alcoholic solution of reagent grade
ZrO(NO3)2 or ZrOCl2 followed by their treatment
with 70% H2SO4, drying at 100–120°C, and calcining
at 400–420°C.
The preparation procedure of spiroacetals is pre-
sented in [12].
The purity and isomeric composition of the syn-
thesized compounds were determined by GLC using a
Tsvet-500 chromatograph, equipped with a thermal
conductivity detector, on a column of a 2 m length and
a 2 mm diameter packed with 10 wt % polyethylene
glycol succinate-coated Chromosorb N-AW. The col-
umn temperature was 100–120°C, the evaporator
temperature was 230–250°C, the detector tempera-
ture was 200–210°C, the detector bridge current was
100–110 mA, and the carrier gas (helium) flow rate
was 30–40 mL/min.
To determine the optimum conditions for the con-
densation reaction of 2-pentylidenecyclopentanone
and 2-pentylcyclopent-2-en-1-one with ethylene gly-
col, the influence of temperature, reaction time, reac-
tant molar ratio, catalyst amount, and solvent nature
on the yields of the desired products was examined.
The dependence of the buildup rate of spiroacetals
upon the above factors was monitored using GLC. It
was found that the activity of the untreated
perlite samples in the condensation reaction of the
ketone under study with ethylene glycol was not high
(8–15 wt %) (Fig. 2).
The structure of the synthesized product was con-
firmed by the data of elemental analysis and IR spec-
troscopy (Alpha in the range of 400–4000 cm−1), gas
chromatography–mass spectrometry (GC–MS) , and
1H NMR spectroscopy (Bruker, 300.18 MHz).
However, the successive treatment of perlite
with an aqueous alcohol solution of zirconyl
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SYNTHESIS OF UNSATURATED SPIROACETALS, CYCLOPENTANONE DERIVATIVES
605
Table 1. Conditions and results of experiments on the condensation of (a) cyclopentanone with (b) n-valeric aldehyde
Product composition according
Reaction conditions
to GLC data, wt %*
Residue,
wt %
amount
duration, h of catalyst,
wt %
tempera- molar ratio
A
B
C
D + E
ture, °C
a : b
In the presence of piperidine
5
5
5
5
5
10
5
5
5
5
1 : 1
2 : 1
3 : 1
4 : 1
5 : 1
3 : 1
3 : 1
3 : 1
3 : 1
3 : 1
3 : 1
2
2
2
2
2
2
3
1
2
2
4
6
6
6
6
6
6
6
6
4
8
6
16.8
13.7
12.6
3.8
1.9
6.3
13.2
7.5
11.2
17.4
18.2
3.2
4.3
6.9
26
39
48
50
50.6
30.3
50.3
19.4
47.8
20.1
43.4
–
27
23
3.2
3.8
5.2
7.3
10.7
4.2
1.4
2.3
5.7
4.8
22.5
20.2
18.9
36.3
23.3
11.4
17.6
21.2
24.2
9.8
11.3
11.4
7.2
1.3
4.4
14.5
8.7
5
In the presence of alkali (NaOH)
30
30
30
30
30
30
30
30
30
25
40
2 : 1
3 : 1
4 : 1
5 : 1
3 : 1
3 : 1
3 : 1
3 : 1
3 : 1
3 : 1
3 : 1
2
2
2
2
3
4
1
2
2
2
2
6
6
6
6
6
6
6
4
8
6
6
15.6
6.1
4.6
4.4
8.7
11.8
13.5
9.0
8.4
2.3
6.6
10.7
6.3
4.6
3.0
3.7
2.6
2.0
1.8
1.5
1.9
0.8
2.9
2.7
37
25
58.3
49.7
47.4
58.3
55.5
49.2
42.4
43.3
49.9
36.8
22.0
20.4
18.6
20.1
23.6
12.7
11.8
25.5
12.1
26.5
2.2
10.0
10.3
3.9
5.5
10.8
10.2
20.2
14.4
* A is 2-propylhept-2-en-1-al, B is 2-cyclopentylidenecyclopentanone, C is 2-(1-hydroxypentyl)cyclopentanone, D is 2-pen-
tylidenecyclopentanone, and E is 2-pentylcyclopent-2-en-1-one.
nitrate and sulfuric acid results in the formation of
zirconyl sulfate , which leads to an increase in the
acidity and activity of the system. It is these sites
that exhibit high activity in the condensation reac-
tion of unsaturated ketones with ethylene glycol
(see Scheme 1).
It is supposed that the reaction proceeds through
the protonation of the basic site of the catalyst (O2−) by
glycol and stabilization of the hydroxyethoxo anion on
the Lewis acid site to form a glycolate complex fol-
lowed by the protonation of the carbonyl group in the
reactant ketone:
R1
+δ
−Oδ
O
R1
R2
OH
O
HO
HO
O
O
R1
R2
O=
n+
n+
n+
Me
R2
MeO2−
MeO2−
HO
Me
+
+
−H2O
OH
OH
Scheme 1.
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606
80
ABBASOV et al.
of hemiacetal and 1,4-dioxane as a side product of the
69
reaction.
As the ZrOSO4 loading in perlite is increased (from
65
66
70
60
50
40
30
20
10
0
57
1 to 5%), the activity of the catalyst in the condensa-
tion reaction of 2-pentylidenecyclopentanone or
2-pentylcyclopent-2-en-1-one with ethylene glycol
increases, and the yields of spiroacetals reach 69.8 and
71.5 wt %, respectively. A further increase in the salt
loading leads to an increase in the rate of the side reac-
tions and a decrease in the yield of the desired product.
50
39
15
0
It was experimentally found that of azeotrope-
forming solvents, such as benzene, toluene, and isooc-
tane, toluene is the most appropriate in terms of selec-
tivity for the condensation of alkylidenecyclopenta-
none with ethylene glycol.
1
2
3
4
5
6
wt %
One of the important factors affecting the conden-
sation reaction is the molar ratio of 2-pentylidenecy-
clopentanone and ethylene glycol. It was found that
increasing the 2-pentylidenecyclopentanone : eth-
ylene glycol ratio from 1 : 1 to 1 : 3 promoted an
increase in the yield of unsaturated spiroacetal from 40
to 69.8%.
Fig. 2. Dependence of the yield of spiroacetals on the con-
centration of ZrOSO in the natural aluminosilicate
4
(T =110°C, τ = 5 h). The dark and light columns refer to
5-pentylidene-1,4-dioxaspiro[4.4]nonane and 5-pentyl-
1,4-dioxaspiro[4.4]non-5-ene, respectively.
With varying temperature in the range of 80–110°C
(depending on the dehydrating solvent), the yield of
acetal passes through a maximum. The highest yield of
the desired products in the presence of toluene is
It is known that reactions of this type require the
presence of medium-strength acid–base sites on the
catalyst surface [15]. This ketalization mechanism is
supported by the fact of formation of a certain amount 71.6%. A further increase in temperature leads to a
Table 2. Conditions and results of experiments on the condensation of (a) 2-pentylidenecyclopentanone with (b) ethylene
glycol in the presence of natural perlite modified with 5 wt % zirconyl sulfate
Reaction conditions
duration, h
Conversion, %
Acetal yield, wt %
a
b
molar ratio
a : b
amount
of catalyst, wt %
%
residue, wt %
%
%
In benzene, reaction temperature 80°C
1 : 2
1 : 2
1 : 2
1 : 2
1 : 2
1 : 2
1 : 3
1 : 2
1 : 2
6
6
6
6
6
6
6
5
7
1
2
2
4
5
6
5
5
5
66.5
74.0
79.4
80.4
84.1
85.7
84.4
82.0
84.6
73.6
76.4
80.8
84.1
86.2
87
87.3
85.7
86.5
35.9
47.5
58.6
63.4
69.8
68.7
69.9
66.3
69.4
1.1
1.3
1.5
1.7
1.9
2.2
1.4
1.3
1.5
In toluene, reaction temperature 110°C
1 : 2
1 : 3
1 : 4
1 : 2
1 : 2
1 : 2
1 : 2
6
6
6
6
6
5
7
5
5
5
4
6
5
5
85.5
85.2
85.5
81.5
84.8
82.2
84.4
88.4
88.8
89.5
84.8
87.7
85.5
87.0
71.4
71.6
71.8
64.2
68.9
65.6
67.9
1.8
1.5
1.7
1.8
2.4
1.9
1.8
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SYNTHESIS OF UNSATURATED SPIROACETALS, CYCLOPENTANONE DERIVATIVES
607
decrease in the acetal yield by 12%, a change that is
due to an increase in the rate of further transforma-
tions of the forming acetals to polyoxy compounds and
dehydration of glycol to dioxane.
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Translated by E. Boltukhina
PETROLEUM CHEMISTRY Vol. 59 No. 6 2019