Mesoporous Aluminosilicates in the Synthesis of N-Heterocyclic Compounds

Article abstract of DOI:10.1134/S0023158419020022

Abstract: The catalytic properties of samples of amorphous mesoporous aluminosilicate ASM with different Si/Al molar ratios (40, 80, 160) were studied in the synthesis of practically important pyridines (by the interaction of С₂–С₅ alcohols with formaldehyde and ammonia, cyclocondensation of acetaldehyde and propionic aldehyde with ammonia), dialkylquinolines and alkyltetrahydroquinolines (by reaction of aniline with C₃, C₄ aldehydes) and alkyldihydroquinolines (by interaction of aniline with ketones, acetone and acetophenone). It is found that mesoporous aluminosilicate ASM sample with a molar ratio of Si/Al = 40, which has the highest acidity among the studied samples, exhibits the highest activity and selectivity in these reactions.

Full text of DOI:10.1134/S0023158419020022

ISSN 0023-1584, Kinetics and Catalysis, 2019, Vol. 60, No. 6, pp. 733–743. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Kinetika i Kataliz, 2019, Vol. 60, No. 1, pp. 81–92.
Mesoporous Aluminosilicates in the Synthesis
of N-Heterocyclic Compounds
N. G. Grigor’evaa, b, *, M. R. Agliullina, b, S. A. Kostylevaa, S. V. Bubennova, V. R. Bikbaevab,
A. R. Gataulina, N. A. Filippovaa, B. I. Kutepova, b, and Nama Narenderc
aInstitute of Petrochemistry and Catalysis, Ufa Federal Scientific Research Center, Russian Academy of Sciences,
Ufa, 450075 Russia
bUfa State Petroleuml Technological University, Ufa, 450062 Russia
cCSIR-Indian Institute of Chemical Technology Uppal Road, Telangana State, Tarnaka, Hyderabad, 500 007 India
*e-mail: ngg-ink@mail.ru
Received August 9, 2018; revised October 15, 2018; accepted December 19, 2018
Abstract—The catalytic properties of samples of amorphous mesoporous aluminosilicate ASM with different
Si/Al molar ratios (40, 80, 160) were studied in the synthesis of practically important pyridines (by the inter-
action of С2–С5 alcohols with formaldehyde and ammonia, cyclocondensation of acetaldehyde and propi-
onic aldehyde with ammonia), dialkylquinolines and alkyltetrahydroquinolines (by reaction of aniline with
C3, C4 aldehydes) and alkyldihydroquinolines (by interaction of aniline with ketones, acetone and acetophe-
none). It is found that mesoporous aluminosilicate ASM sample with a molar ratio of Si/Al = 40, which has
the highest acidity among the studied samples, exhibits the highest activity and selectivity in these reactions.
Keywords: mesoporous aluminosilicate ASM, cyclocondensation with ammonia/amines, pyridines, quino-
lines, hydroquinolines, tetrahydroquinolines
DOI: 10.1134/S0023158419020022
INTRODUCTION
anticancer drugs [17] prepared on the basis of quino-
lines are known. The quinoline fragment is found in
some widely used antibiotics [18].
Nitrogen-containing heterocyclic compounds are
a broad class of organic substances, many of which are
of practical importance. Pyridines and quinolines are
among the demanded. Polymer, chemical, pharma-
ceutical and other industries are consumers of pyri-
dines. Over 150 years after the discovery of pyridine,
hundreds of effective medicines have been found and
synthesized [1], and the search for new forms of the
pyridine compounds continues [2–4]. Alkylpyridines,
specifically, α-picoline (2-methylpyridine), γ-pico-
line (4-methylpyridine), and 5-ethyl-2-methylpyri-
dine, are used as a raw material for the production of
2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vin-
ylpyridine, on the basis of which latexes for tire cord
impregnation, ion exchange resins, and photographic
materials are made [5–7]. Alkylpyridines are also raw
materials for the production of chemical plant protec-
tion products against weeds, pests, and various dis-
eases [8, 9]. Extractants, inhibitors of metal corrosion,
solvents, surfactants, rubber vulcanization accelera-
tors, and other products were synthesized on the basis
of substituted pyridines [9–12].
Many methods have been developed for the syn-
thesis of both pyridines and quinolines. Industrially
important methods for producing N-heterocyclic
compounds consist mainly in the condensation of var-
ious carbonyl compounds with ammonia or amines
under the action of acids or bases [19]. These processes
are characterized by the formation of a significant
amount of by-products. The target products are
formed unselectively, therefore the creation of highly
selective heterogeneous catalytic methods for the pro-
duction of N-heterocyclic compounds is an important
and topical task.
In recent years, zeolite catalysts have been actively
used for the synthesis of N-heterocyclic compounds
[20], which provide many advantages in the conver-
sion of harmful environmentally hazardous cyclocon-
densation processes of carbonyl compounds with
ammonia into green chemical production. However, it
should be noted that the significant disadvantages of
zeolites is their rapid deactivation due to the blocking
Quinoline derivatives are important intermediates
in the synthesis of biologically active compounds and of the micropores of the crystal lattice by the reaction
herbicides [13]. A number of antimalarial [14, 15], products and coke. In addition, the microporous
antibacterial, antiseptic, antituberculous drugs [16], structure of the zeolite limits or hinders the synthesis
733

734
GRIGOR’EVA et al.
of bulk molecules with a diameter of about 1 nm or porous aluminosilicates ASM samples with Si/Al
greater.
A new approach to the heterogeneous catalytic syn-
molar ratios of 40, 80, and 160, designated as ASM-40,
ASM-80, and ASM-160, respectively, were obtained.
The prepared aluminosilicate ASM samples were
ground to powders, fraction <100 μm.
thesis of N-heterocyclic compounds is the use of mes-
oporous materials as catalysts, which, as we assumed,
will reduce transport difficulties for the movement of
bulk molecules of reactants and reaction products.
Moreover, in the mesopores, the concentration of the
reacting molecules may be higher, which will lead to
an increase in the number of chemical interaction acts
of the reactants and an increase in the degree of their
conversion. For such bulky molecules as
alkyl(aryl)quinolines, the conditions for their synthe-
sis are created only in the mesopores.
Physicochemical Study of the Catalysts
The chemical composition of the obtained alumi-
nosilicates was investigated by X-ray fluorescence
spectrometry using an EDX-720/900hs instrument
(Shimadzu, Japan).
The phase composition of the samples was ana-
lyzed on a D8 Advance diffractometer (Bruker, Ger-
many) with monochromatic CuKα radiation in the range
of 2θ angles from 5° to 40° with a step of 0.5°/min and a
signal accumulation time at each point of 20 s.
The state of aluminum in the calcined samples was
assessed by 27Al NMR spectra. The spectra were
recorded on an Avance-400 NMR spectrometer
(Bruker, Germany) with a multi-core SD4 sensor in a
simple single-pulse experiment with sample rotation
at a magic angle (~104 Hz) in zirconia rotors. The
external standard was an aqueous solution of AlCl3
with a concentration of 1 mol/L.
The characteristics of the porous structure were
determined using low-temperature adsorption–
desorption of nitrogen (77 K) on an ASAP-2020
instrument (Micromeritics, USA). Before analysis,
the samples were evacuated for 6 h at 350°C.
For the synthesis of basic N-heterocyclic com-
pounds, pyridines and quinolines, we used amor-
phous mesoporous aluminosilicates (ASM), the
preparation of which by the sol–gel method was
described by us earlier [21, 22]. These mesoporous
materials are characterized by a narrow distribution of
mesopores with a size of 2–5 nm and are acidic.
The purpose of this work was to study the catalytic
properties of samples of amorphous mesoporous alu-
minosilicate ASM with different Si/Al molar ratios
(40, 80, 160) in the synthesis of pyridine and its alkyl
derivatives in various ways: by reacting C2–C5 alcohols
with formaldehyde and ammonia, cyclic condensa-
tion of carbonyl compounds (acetic acid) aldehyde,
propionic aldehyde) with ammonia, as well as a study of
the activity and selectivity of the mesoporous aluminos-
ilicate ASM in the synthesis of alkylquinolines, alkyltet-
rahydroquinolines and alkyl dihydroquinolines by the
reaction of aniline with aldehydes and ketones.
The acidic properties of aluminosilicates were
studied by infrared (IR) spectroscopy using low-tem-
perature adsorption of the CO probe molecule. Infrared
spectra were recorded on an FTIR-8400 spectrometer
(Shimadzu, Japan) in the range 700–6000 cm–1.
EXPERIMENTAL
Materials and Reagents
For the synthesis of pyridines, alcohols (ethanol
96%, n-propanol 99%, n-butanol 99%, n-pentanol
99%, Acros), aqueous solutions of formaldehyde
(37%, Acros) and ammonia (28%, analytical purity
grade, Sigma Tech), acetaldehyde (99.5%, Acros),
propionic aldehyde (99%, Acros) were used.
Alkylquinolines, alkyltetrahydroquinolines, and
alkyldihydroquinolines were obtained from aniline
(99.8%, Acros) and carbonyl compounds (Acros):
propionic aldehyde (99%), butyric aldehyde (99%),
and acetophenone (98%). The reagents were used
without further purification.
Synthesis of Pyridines and Quinolines
Synthesis of Pyridines was carried out by interac-
tion of alcohols (ethanol, n-propanol, n-butanol,
n-pentanol) with formaldehyde and ammonia in a
flow-type reactor with a fixed catalyst bed (1 g) at
300–400°C, atmospheric pressure, a space velocity
(w) of 7 h–1, and a molar ROH : CH2O : NH3 ratio of
1.0 : 0.8 : 1.5. After the reaction, the reactor was purged
with nitrogen. The reaction products collected in an
ice-cooled trap were extracted with diethyl ether and
analyzed by gas–liquid chromatography (GLC).
5-Ethyl-2-methylpyridine was obtained by the reac-
Catalysts
tion of acetaldehyde with ammonia in an autoclave at
Mesoporous aluminosilicates were synthesized 150°C and a molar CH3СOH : NH3 ratio of 1 : 3. The
using the procedure developed by us based on the sol–
gel method [21, 22]. The source of silicon was tetra-
ethyl orthosilicate (TEOS) (98%, Acros Organics),
the source of aluminum was Al(NO3)3 ∙ 9H2O (99%,
catalyst concentration was 10 wt %. The reaction time
was 5 h. The reaction products were extracted with
methylene chloride and analyzed using GLC. The
reaction mass was filtered from the catalyst and iso-
Merck), ethanol (98%) served as a solvent. Meso- lated by chromatography using a 200-mm column
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MESOPOROUS ALUMINOSILICATES IN THE SYNTHESIS
735
with 30 g SiO2 (eluent, a mixture of hexane and ethyl temperature 40–300°C, an ion source temperature of
200°C, and an ionization energy of 70 eV).
acetate (20 : 80)).
13
1Н and С NMR and homo- and heteronuclear
2-Ethyl-3,5-dimethylpyridine was obtained by the
reaction of propionic aldehyde with ammonia in a
flow-type reactor at 300°C, atmospheric pressure, w =
5.2 h–1, and propionic aldehyde : NH3 molar ratio of
1 : 3. The reaction products were extracted with
diethyl ether and analyzed by the GLC method.
GLC analysis of pyridines was carried out on a
Vega Series 2 GC-6000 chromatograph (Carlo Erba
Strumentazione, Italy) with a flame ionization detec-
tor (packed column, 3 m, phase 15% PEG-6000 on
Khromaton); the temperature of analysis was 50–
200°С with programmed heating at a rate of 8°C/min;
the temperature of the detector was 200°C; the tem-
perature of the evaporator was 200°C; the carrier gas
was helium (30 mL/min).
COSY, HSQC, HMBC spectra were recorded using an
Avance-400 instrument (Bruker, Germany; the working
frequency for 1Н was 400.13 MHz and that for 13С, 100.62
MHz) and an Avance III 500 HD Ascend instrument
1
(Bruker, Germany; the working frequency for Н was
500.17 MHz; for 13С, 125.78 MHz), CDCl3 solvent.
RESULTS AND DISCUSSION
Physicochemical Properties of Catalysts
The physicochemical properties of the mesoporous
aluminosilicate were studied in detail in [21, 22].
Information on the characteristics of the porous struc-
ture and acidic properties are presented in Table 1.
Dialkylquinolines and dialkyltetrahydroquinolines
were synthesized by the reaction of aniline with alde-
hydes (С3, С4) in an autoclave at 160°C and atmo-
spheric pressure; 6 h; the catalyst content was 20 wt %,
the aniline : aldehyde molar ratio was 1 : 2. After the
reaction cessation, the autoclave was cooled to room
temperature and the ampoule was opened. The reac-
tion mass was filtered from the catalyst and isolated by
chromatography on a SiO2 column (eluent, hexane →
hexane–ethyl acetate mixture).
Alkyldihydroquinoline was obtained by the reaction
of aniline with acetophenone in an autoclave at 130°C
and an atmospheric pressure of 5 h; the catalyst con-
tent was 30 wt %; the aniline: acetophenone molar ratio
was 1 : 2. After the reaction cessation, the autoclave was
cooled to room temperature and the ampoule was
opened. The reaction mass was filtered from the catalyst
and isolated by chromatography on a SiO2 column (elu-
ent, hexane → hexane–ethyl acetate mixture).
ASM samples were characterized by a narrow size
distribution of mesopores from 2 to 5 nm; the meso-
pore volume was in the range 0.50–0.80 cm3/g; the
BET specific surface area was 520–670 m2/g.
Brønsted (BAS) and Lewis (LAS) groups were
found on the surface of the ASM samples. Figure 1
shows the IR spectra of the ASM-80 sample in the
region of stretching vibrations of OH groups before
and after CO adsorption. In the IR spectrum (Figs. 1a,
1b) absorption bands of hydroxyl groups of several
types are observed: strong BAS of type I (the value of
shift is ΔνOH = 300 cm–1), which refer to bridging Si–
O(H)–Al groups, and strong BAS of type II (the value
of shift is ΔνOH = 270–320 cm–1), which belong to the
Si–O(H)…Al3+ or Al–O(H)–Al groups. On the sam-
ple surface, there are also weak acidic silanol groups
(absorption bands at 3742 and 3747 cm–1 in the IR
spectrum before CO adsorption; the value of shift is
ΔνOH = 90–150 cm–1).
According to IR spectroscopic data of adsorbed
CO on the sample surface, there are three types of
Lewis acid sites. In the IR spectrum (Fig. 1c), there
are absorption bands at 2223 and 2231 cm–1, which are
characteristic of CO complexes with Al3+ ions in the
pentahedral coordination and are typical structural
defects of aluminosilicates and zeolites, absorption
The reaction products (dialkylquinolines, dialk-
yltetrahydroquinolines, alkyl dihydroquinolines) were
analyzed using GLC on a GC-9A chromatograph
(Shimadzu, Japan) with flame ionization detector,
packed column (3 m), phase SE-30, programmed
heating 50–250°С, and helium carrier gas.
Mass spectra were obtained on a GCMS-
QP2010Plus chromatograph/mass spectrometer (Shi-
madzu, Japan) with a SPB-5 phase, capillary column bands at 2210–2212 cm–1, which refer to medium-
30 m × 0.25 mm, helium carrier gas, programmed strength LASs, and absorption bands at 2202–2200
Table 1. Physicochemical characteristics of mesoporous aluminosilicates
Concentration of acid centers,
Specific surface
area
SBET, m2/g
Pore volume, cm3/g
Average pore size
μmol/g
Sample
Si/Al
D, nm
Vmicro
Vmeso
LAS
BAS
ASM-40
ASM-80
ASM-160
40
80
120
0.05
0.05
0.05
0.50
0.71
0.80
670
640
520
4
4
4
162
119
74
50
27
15
KINETICS AND CATALYSIS Vol. 60 No. 6 2019

736
GRIGOR’EVA et al.
(а)
(b)
(c)
10
3
0
2
1
2160 2200 2240
3600
3700
3800
3200
3400
3600
3800 2100
2150
2200
2250
Wavenumber, cm–1
Wavenumber, cm–1
Wavenumber, cm–1
Fig. 1. (a) IR spectrum of the ASM-80 sample in the region of oscillations of surface hydroxyl groups; (b) IR difference spectra
in the region of stretching vibrations of surface hydroxyl groups for the ASM-80 sample at a CO pressure of (1) 0.2, (2) 0.3, and
(3) 5 (3) Torr; (c) IR spectra of CO adsorbed on the ASM-80 sample in the region of stretching vibrations of carbonyl groups with
an increase in CO pressure in a range from 0.1 to 10 Torr.
and 2190 cm–1, which refer to the СО complex with
Al3+ ions, and apparently alumina clusters. Types of
acid sites are close to those observed for amorphous
aluminosilicates. [23]. The ASM-40 sample has the
maximum concentration of both BASs and LASs. On
the ASM-80 and ASM-160 samples, the concentra-
tion of acid sites is lower (Table 1).
of pyridine and its methyl derivatives was carried out
by the reaction of ethanol with formaldehyde and
ammonia, which was first carried out under the action
of ZSM-5 zeolites [24]. Both on zeolite catalysts and
on amorphous mesoporous aluminosilicate ASM
samples, the main products of this reaction are pyri-
dine (I), picolines (2-, 3-, and 4-methylpyridines)
(II), and lutidines (dimethylpyridines) (III) (Scheme 1).
In the composition of picolines, 3-methylpyridine
accounts for 80%. In the composition of lutidines,
3,5-isomer prevails. Also, compounds that are heavier
than dimethylpyridines are formed.
Catalytic Properties of Mesoporous Aluminosilicate ASM
in the Synthesis of N-Heterocyclic Compounds
Synthesis of pyridines by the reaction of alcohols
С2–С4 with formaldehyde and ammonia. The synthesis
H
+
+
NH3
+
+
O
OH
N
I
N
II
N
III
H
Scheme 1.
The results of the study of the catalytic properties of
In the reaction products formed under the action of
mesoporous aluminosilicates ASM (with molar ratios the studied catalysts, picolines (mainly 3-methylpyri-
of Si/Al = 40, 80, and 160), differing in acid character- dine) have the highest content: 49–57%. Picolines are
istics in the reaction of ethanol, formaldehyde, and formed most selectively on the samples of mesoporous
ammonia, are given in Table 2.
aluminosilicates with Si/Al molar ratios of 40 and 80.
An increase in the ratio of framework atoms of Si/Al
aluminosilicate samples from 40 to 160 leads to an
increase in the selectivity to pyridine and lutidines,
and the selectivity to picolines and heavy compounds
decreases.
It was found that the ASM-40 sample is the most
active in the reaction. The conversion of ethanol on
mesoporous aluminosilicate samples decreases in the
series ASM-40 > ASM-80 > ASM-160, which is asso-
ciated with a decrease in the concentration of acid sites
due to a decrease in the fraction of aluminum atoms in
We compared the activity and selectivity of meso-
the aluminosilicate framework. The data obtained porous aluminosilicates ASM with the properties of
show that the catalytic systems ASM are active in the microporous catalysts: H-ZSM-5 and Pb-ZSM-5
studied reaction only if they contain a certain number zeolites [24]. It can be seen from the data presented in
of strong acid sites. A decrease in the BAS concentra- Table 2 that the conversion of ethanol at similar tem-
tion below a certain level leads to the loss of catalyst peratures (400 and 420°C) on ASM-40 sample is
activity, which cannot be compensated by the accessi- slightly higher than on the most active zeolite H-
bility of sites.
ZSM-5. Taking into account that experiments on the
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MESOPOROUS ALUMINOSILICATES IN THE SYNTHESIS
737
Table 2. Synthesis of pyridines on mesoporous aluminosilicates ASM by the reaction of ethanol, formaldehyde, and
ammonia*
Selectivity, %
Alcohol
Catalyst
Т, °С
Reference
pyridine
picolines
lutidines
conversion, %
heavy products
(I)
(II)
(III)
ASМ-40
ASМ-80
ASМ-160
ASМ-40
H-ZSM-5** (Si/Al = 150)
Pb-ZSM-5**
300
300
300
400
420
400
50
30
10
80
72.5
44.9
19
20
24
18
53
53
57
56
49
47
32
32
18
22
25
24
15
15
6
2
2
11
This work
This work
This work
This work
24
Not determined
Not determined
24
–1
–1
* Reaction conditions: molar ratio C H OH : CH O : NH = 1.0 : 0.8 : 1.5, w = 7 h . **w = 0.5 h
.
2
5
2
3
ASМ-40 samples were carried out at a higher feed ence of H-ZSM-5 and Pb-ZSM-5 zeolites is 1 : 0.6 :
space velocity of (7 h–1) than on Н-ZSM-5 and Pb-
ZSM-5 zeolites (0.5 h–1) and that alcohol conversion
increases with a decrease in w, we can speak quite con-
fidently about the high activity of mesoporous alumi-
nosilicates ASM in the synthesis of pyridines by the
reaction of ethanol, formaldehyde, and ammonia.
0.3, while for the ASM-40 sample, this ratio is 1 : 3 : 1.
The presented data convincingly show the applica-
bility of amorphous mesoporous aluminosilicates with
acidic properties in the synthesis of pyridines by the
reaction of ethanol, formaldehyde and ammonia. The
activity of ASM-40 mesoporous aluminosilicate sam-
ple is not inferior to the H-ZSM-5 and Pb-ZSM-5
zeolite catalysts, and the total selectivity of the forma-
tion of picolines and lutidines on it reaches 75–78%.
When comparing the composition of products
formed on zeolite catalysts and amorphous aluminos-
ilicates, it is clear that the reaction mass obtained on
mesoporous aluminosilicate is rich in methylpyri-
dines: picolines and lutidines. The pyridine : picolines :
The reaction of other alcohols (n-propanol and
n-butanol) with formaldehyde and ammonia occurs in
the presence of mesoporous aluminosilicates ASM to
lutidines ratio in the products synthesized in the pres- form mainly 3,5-dialkylpyridines (Scheme 2).
CH3
H3C
CH3
+
CH3 H3C
+
CH3
CH3
O
O
OH
NH3
+
+
+
H3C
H
H
H
H
N
IV
N
V
N
VI
H3C
CH3 H3C
+
CH3
CH3
H3C
OH
NH3
+
N
N
VII
VIII
Scheme 2.
In the case of n-propanol, 3,5-lutidine (IV) is the reaction with n-butanol, the main by-product is 2-pro-
main product of the reaction. In the case of n-butanol, pyl-3,5-diethylpyridine (VIII). Data presented in
3,5-diethylpyridine (VII) is the main product. In Table 3 show that the ASM-40 sample has a high
addition to dialkylpyridines (IV) and (VII), light com- selectivity in the synthesis of 3,5-dialkylpyridines. In
pounds are also present in the reaction products, the reaction of n-propanol with formaldehyde and
among which both linear condensation products of ammonia at 300°C, the selectivity to 3,5-lutidine is
alcohol, formaldehyde, and ammonia (imines, pro- 97% with an alcohol conversion of 25%. As the tem-
pyl, and butylamines, acetal) and 3-methylpyridine perature increases to 400°C, alcohol conversion
are identified. In the reaction with n-propanol, 3,4- increases to 70%, but the amount of by-products in
lutidine (V) and a mixture of trialkylpyridines with a the reaction mass increases, as a result of which the
predominant content of 2-ethyl-3,5-dimethylpyridine selectivity to dialkylpyridine decreases. Similar depen-
(VI) are formed along with 3,5-lutidine (IV). In the dences were observed in the interaction of n-butanol
KINETICS AND CATALYSIS Vol. 60 No. 6 2019

738
GRIGOR’EVA et al.
Table 3. Synthesis of 3,5-dialkylpyridines on ASM-40 mesoporous aluminosilicate and zeolite catalysts*
Selectivity, %
Alcohol
other di-
Catalyst
Alcohol
Т, °С conversion,
Reference
light
3,5-di-
and trialkyl- heavy products
pyridines
%
products alkylpyridines
ASM-40
n-propanol 300
n-propanol 350
n-propanol 400
25
3
5
97
84
79
86
63
40
63
41
–
11
15
11
26
25
23
28
–
this work
this work
this work
this work
this work
this work
this work
this work
25
ASM-40
ASM-40
ASM-40
ASM-40
ASM-40
HY
45
–
70
6
–
n-butanol
n-butanol
n-pentanol
300
400
400
22
3
–
62
11
25
11
30
25.1
12
–
20
10
n-propanol 400
n-butanol 400
16
3
1
HY
14
La-ZSM-5** n-propanol 400
Н-ZSM-5*** n-butanol 400
88.6
91.2
72.2
69
2.7
19
not determined
not determined
26
Dashes mean that the corresponding products are not formed. * Reaction conditions: molar ratio ROH : CH O : NH = 1.0 : 0.8 : 3.0;
2
3
–1
–1
400°C, w = 7 h . ** C H OH : CH O : СН ОН : NH = 1.0 : 0.4 : 0.9 : 6, 400°C, w = 0.5 h . *** C H OH : CH O : NH = 1 : 1 : 6,
3
7
2
3
3
4
9
2
3
–1
400°C, w = 0.5 h
.
with formaldehyde and ammonia: with increasing most important industrial reactions is the interaction
temperature from 300 to 400°C, the conversion of of acetaldehyde with ammonia to form 2-methyl-5-
alcohol increases from 22 to 62%, and the selectivity to ethylpyridine (X), which is the main raw material in
3,5-diethylpyridine drops from 86 to 63%.
the production of nicotinic acid and 2-methyl-5-vin-
ylpyridine (Scheme 3).
Further elongation of the hydrocarbon chain of the
alcohol (n-pentanol) worsens the reaction perfor-
mance: even at 400°C, the conversion of alcohol does
not exceed 20%, and a complex mixture of products is
formed, in which the content of 3,5-dipropylpyridine
is 40%.
O
+
NH3
+
H
H
N
N
IX
X
Comparison of the catalytic properties of the
ASM-40 sample and microporous HY zeolite with a
SiO2/Al2O3 molar ratio of 5.0 (our data) in the interac-
tion of n-propanol/n-butanol with formaldehyde and
ammonia showed that the selectivity to dialkylpyri-
dines and the alcohol conversion are higher on the
ASM-40 sample (Table 3). The appearance of a large
number of by-products on the HY zeolite can be asso-
ciated with a significant concentration of nonuniform
active sites in it, including strong Brønsted acid sites.
When comparing the results obtained in this work
with the literature data, it can be seen (Table 3) that
mesoporous aluminosilicate ASM is close to the La-
ZSM-5 zeolite (the reaction of n-propanol with form-
aldehyde, methanol, and ammonia [25]) and the H-
ZSM-5 zeolite (the interaction of n-butanol with
formaldehyde and ammonia [26]) on the selectivity to
dialkylpyridins (IV) and (VII), but its activity is lower.
Scheme 3.
It is known that in industry, methyl ethyl pyridine
(X) is produced by the reaction of paraldehyde (acet-
aldehyde trimer) with ammonia in the liquid phase at
200–250°C and 5–10 MPa in the presence of ammo-
nium salts (e.g., ammonium acetate) or acetic acid.
The yield of methyl ethyl pyridine in this reaction
reaches 60% [19].
The reaction of acetaldehyde with ammonia on the
ASM-40 sample occurs with the formation of pre-
dominantly methyl ethyl pyridine (X), the selectivity
to which under these conditions is 88% with an acetal-
dehyde conversion of 60%. 2-Methylpyridine (IX) is
found in a small amount. On the microporous HY
zeolite, with which we compared the ASM-40 sample,
the conversion of acetaldehyde is higher: 69%. This is
due to the higher acidity of the HY catalyst (Table 4).
Apparently, for the same reasons the selectivity of HY
The reactions of aldehydes with ammonia lead to zeolite is 1.8 times lower than that on the ASM-40
the formation of di- and trialkylpyridines. One of the sample and a significant amount of heavy compounds
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MESOPOROUS ALUMINOSILICATES IN THE SYNTHESIS
739
Table 4. The interaction of acetaldehyde with ammonia on ASM-40 aluminosilicate
Selectivity, %
Catalyst Acetaldehyde conversion, %
2-methylpyridine (IX)
methylethylpyridine (X)
heavy products
ASM-40
HY
60
69
3
5
88
55
9
40
Reaction conditions: acetaldehyde : NH = 1 : 3, 150°С, 10% of catalyst.
3
appear, which are different di- and trialkylpyridines. A
The reaction of propionic aldehyde with ammonia
comparison of our results with literature data shows leads to the formation of a mixture of mono-, di- and
that the yield of methyl ethyl pyridine (X) (53%) is trialkylpyridines, among which 2-ethyl-3,5-dimeth-
close to that observed in industrial units.
ylpyridine (VI) (Scheme 4) is the main product.
CH3
O
H3C
CH3
CH3
H3C
CH3
H3C
+
NH3
+
H
N
N
VI
XI
Scheme 4.
In addition to 2-ethyl-3,5-dimethylpyridine (VI), pounds, which is apparently associated with the
the following products were identified: imines (desig- increased acidity of HY zeolite.
nated as light products), pyridine (I), 3- and 4-meth-
ylpyridines, dimethylpyridines, 3,5-dimethyl-4-eth-
ylpyridine, and compounds heavier than 4-ethyl-3,5-
dimethylpyridine (XI). The conversion of propionic
aldehyde and the composition of products formed on
various samples of zeolite catalysts are given in Table 5.
It was of interests to compare the results obtained
with those already known. It turned out that the reac-
tion of propionic aldehyde with ammonia under the
action of Pb-ZSM-5 zeolite mentioned in [27] takes
place at 400°C and 0.5 h–1 with an aldehyde conver-
sion of 69.5%. The authors of [27] describe the prod-
Under conditions studied (150–300°С, 7 h–1), the uct composition as a mixture of 2,6-lutidine (10%),
conversion of propionic aldehyde on the ASM-40 3,5-lutidine (15%), pyridine, and collidines (75%).
sample reaches 70–91%, the selectivity to 2-ethyl-3,5- Information on the selective formation of 2-ethyl-3,5-
dimethylpyridine (VI) is 40–41%, and the amount of dimethylpyridine (VI) is missing.
heavy compounds does not exceed 10%. The highest
selectivity to 2- and 4-ethyl-3,5-dimethylpyridines
(VI) and (XI) was observed at 300°C (their overall
selectivity was 57%).
On microporous HY zeolite at 300°C, aldehyde acid or base catalysts. Most of the proposed methods are
conversion is lower (85%) and the reaction occurs characterized by several stages, severe reaction condi-
with the formation of a larger amount of heavy com- tions, and low yields of the target products.
Synthesis of quinolines and dihydroquinolines. Syn-
thesis of quinolines and dihydroquinolines. Most often,
for the synthesis of quinolines, the Skraup, Döbner–Von
Miller, Friedländer, and Combes methods are used with
Table 5. Synthesis of 2-ethyl-3,5-dimethylpyridine (VI) in the presence of zeolite catalysts
Selectivity to product, %
Propionic
aldehyde
conversion,
%
pyridine
(I),
picolines
2-ethyl-3,5-
2,6-lutidine dimethylpyridine
(VI)
4-ethyl-3,5-
dimethylpyridine
(XI)
Catalyst Т, °С
light
products
heavy
products
HY
300
85
70
91
26
23
24
8
15
4
–
10
5
43
40
41
8
9
16
15
3
10
ASM-40 150
ASM-40 300
–1
Reaction conditions: molar ratio propionic aldehyde : ammonia = 1 : 3, w = 7 h . A dash means that the corresponding product is not
formed.
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740
GRIGOR’EVA et al.
100
80
60
40
20
0
Aniline conversion, %
2,3-dialkylquinolines
XIIIa, XIIIb
2,3-dialkyl-N-phenyl-
1,2,3,4-tetrahydroquinolin-
4-amines XIVa, XIVb
Selectivity, %:
N-alkylanilines XIIa, XIIb
Other products
ASM-40−propionic
ASM-40−butyric [Rh(norbornadiene)
aldehyde
aldehyde
Cl]2−propionic
aldehyde
Fig. 2. The interaction of aniline with aldehydes C , C in the presence of mesoporous aluminosilicate ASM-40 sample. The ani-
3
4
line : aldehyde molar ratio is 1 : 2; 160°C; 20% catalyst; the solvent is chlorobenzene.
We attempted to synthesize dialkylquinolines in tetrahydroquinolin-4-amines
(XIVa,
XIVb)
the presence of the ASM-40 sample by the reaction (Scheme 5). In addition to compounds (XII)–
of aniline with aldehydes (propionic and butyric). It (XIV), aldehyde condensation products, dialkyl
was found that the products of this reaction are dihydroquinolines, and heavy compounds are pres-
N-alkylanilines (XIIa, XIIb), 2,3-dialkylquinolines ent in the reaction mass. They are indicated in
(XIIIa, XIIIb), and 2,3-dialkyl-N-phenyl-1,2,3,4- Fig. 2, like “others.”
Ar
HN
R'
R'
O
+
NH2
+
+
R'
R'
R
H
N
H
R
N
N
H
XIIа, XIIb
XIIIа, XIIIb
XIVа, XIVb
R = Et, R' = Me (а);
R = Pr, R' = Et (b)
Scheme 5.
Under the conditions studied, the conversion of showed that Rh catalytic systems are more effective in
aniline upon interaction with propionic and butyric the reaction of aniline with propionic aldehyde.
aldehydes is rather high: 71 and 75%, respectively
(Fig. 2). In the composition of the reaction products
with propionic aldehyde, the main compound is dial-
kylquinoline (XIIIa), the selectivity to which reaches
50%. Two main products, dialkylquinoline (XIIIb)
and tetrahydroquinoline (XIVb), were found in a ratio
of about 2 : 1 in the reaction of aniline with butyric
aldehyde. The selectivity to N-alkylanilines (XIIa,
XIIb) in both reactions was 15%.
One of the simplest and most convenient methods
for producing dihydroquinolines is acid-catalyzed
interaction of aniline with ketones [29, 30]. Earlier
[31], we demonstrated that the ASM-40 sample allows
the synthesis of 2,2,4-trimethyl-1,2-dihydroquinoline
from aniline and acetone.
The reaction of aniline with acetophenone on
amorphous aluminosilicates occurs with the forma-
tion of three main products: (Е)-N-(1-phenyle-
thylidene)aniline (XV), (1Е,2Е)-N-(1,3-diphenylbut-
2-en-1-ylidene) aniline (XVI) and 2-methyl-2,4-
diphenyl-1,2-dihydroquinoline (XVII) (Scheme 6).
A comparison of the yield of dialkylquinoline
(XIIIa) obtained in the presence of the ASM-40 sam-
ple (39%) and [Rh(norbornadiene)Cl]2 (59%) [28]
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MESOPOROUS ALUMINOSILICATES IN THE SYNTHESIS
741
H
+
+
+
O
N
N
H
NH2
N
XV
XVI
XVII
Scheme 6.
Also, acetophenone aldol condensation can occur drances for the diffusion and interaction of reagents,
with the formation of 2(Z,E)-1,3-diphenylbut-2-ene- but also the blocking large cavities with dihydroquino-
1-one and the trimerization of acetophenone in the line molecules (XVII) formed, which is due to the fact
presence of aniline with the formation of 1,3,5-triaryl- that the diameter of the entrance windows to the large
benzene, indicated in Table 6 as “others.”
cavity is smaller than the diameter of the cavity (0.75
and 1.2 nm, respectively) [32].
In the reaction of aniline with acetophenone, the
ASM-40 sample is less active than in the reaction with
acetone, as evidenced by a lower conversion of aniline
(57 and 85%, respectively). The selectivity to dihydro-
quinoline (XVII) is 45%. The imines (XV) and (XVI)
formed are the products of the interaction of aniline
with both the initial acetophenone and acetophenone
dimer, which are formed in parallel in the reaction
mass under the conditions studied.
It should be noted that, on microporous alumino-
silicates (zeolite HY), the formation of imine (XVI), as
well as dihydroquinoline (XVII) does not occur. The
only product in this case is the Schiff base (XV), which
is formed as a result of the condensation of aniline
with acetophenone.
The results obtained indicate a significant depen-
dence of the activity and selectivity of the studied cat-
alysts on their textural characteristics. Since most of
the active centers in zeolites (strongly acidic structural
OH groups) are known to be located inside channels
or cavities, their accessibility to reacting molecules is
the main factor determining catalytic properties. The
low activity of zeolite HY and the predominant forma-
In the mesopores of the ASM-40 sample, steric
hindrances to the formation of more bulky molecules
than imine (XV) are absent. Therefore, not only linear
condensation of aniline with acetophenone, but also
other reactions take place: condensation of aniline
with acetophenone dimer and the subsequent hetero-
cyclization of compound (XVI) leading to the forma-
tion of dihydroquinoline (XVII).
CONCLUSIONS
As a result of studying the catalytic properties of
amorphous mesoporous aluminosilicates ASM with
different Si/Al molar ratios (40, 80, and 160) in the
synthesis of basic N-heterocyclic compounds (pyri-
dines and quinolines) it was found that the ASM-40
sample (Si/Al = 40) it is most effective in the studied
cyclocondensation reactions of alcohols/carbonyl
compounds with ammonia/amines. This sample has
the maximum concentration of acid sites.
The interaction of ethanol with formaldehyde and
tion of linear condensation product (XV) on it, rather ammonia in the presence of aluminosilicate ASM-40
than the bulk dihydroquinoline molecule (XVII), are sample takes place with an alcohol conversion of 50–
due to the molecular sieve effect of the microporous 80% at 300–400°C. The reaction mass obtained on
zeolite crystal lattice. Furthermore, the reason for the samples of mesoporous aluminosilicates is character-
low activity of zeolite HY can be not only spatial hin- ized by a high content of methylpyridines (up to 57%
Table 6. The interaction of aniline with acetophenone in the presence of mesoporous ASM-40 aluminosilicate
Selectivity to product, %
(1E,2E)-N-(1,3-
diphenylbut-2-en-
1-ylidene)aniline dihydroquinoline
2-methyl-2,4-
diphenyl-1,2-
Aniline
conversion, %
(E)-N-(1-
phenylethylidene)aniline
(XV)
Catalyst
Ketone
others
(XVI)
(XVII)
ASM-40 Acetophenone
HY Acetophenone
57
79
18
100
23
0
45
0
14
–
–1
Reaction conditions: molar ratio aniline : acetophenone = 1 : 2; 30% of the catalyst; 130°С; w = 5 h . A dash means that the corre-
sponding products are not formed.
KINETICS AND CATALYSIS Vol. 60 No. 6 2019

742
GRIGOR’EVA et al.
picolin and 24% lutidines) and a low content of heavy
compounds.
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Translated by Andrey Zeigarnik
KINETICS AND CATALYSIS Vol. 60 No. 6 2019