Br?nsted acidic magnetic nano-Fe3O4-adorned calix[n]arene sulfonic acids: Synthesis and application in the nucleophilic substitution of alcohols

Article abstract of DOI:10.1016/j.tet.2014.06.034

Three magnetically recoverable Br?nsted acidic calix[n]arene derivatives were successfully constructed by immobilizing calix[n]arene sulfonic acids onto silica-coated magnetic nanoparticles, a process, which allows calix[n]arene derivatives to acquire magnetic properties. All of the magnetically recoverable Br?nsted acidic calix[n]arenes efficiently catalyze the coupling of electron-rich arenes with some alcohols in water. After separation and recovery from the reaction mixture by a simple magnet, these Br?nsted acidic calix[n]arenes can be recycled many times without losing their catalytic activity.

Full text of DOI:10.1016/j.tet.2014.06.034

Accepted Manuscript
Brønsted acidic magnetic nano-Fe O -adorned calix[n]arene sulfonic acids:
3 4
Synthesis and application in the nucleophilic substitution of alcohols
Serkan Sayin, Mustafa Yilmaz
PII:
S0040-4020(14)00894-1
10.1016/j.tet.2014.06.034
TET 25700
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 20 March 2014
Revised Date: 24 May 2014
Accepted Date: 10 June 2014
Please cite this article as: Sayin S, Yilmaz M, Brønsted acidic magnetic nano-Fe O -adorned
3 4
calix[n]arene sulfonic acids: Synthesis and application in the nucleophilic substitution of alcohols,
Tetrahedron (2014), doi: 10.1016/j.tet.2014.06.034.
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ACCEPTED MANUSCRIPT
Brønsted acidic magnetic nano-Fe3O4-adorned calix[n]arene sulfonic acids:
Synthesis and application in the nucleophilic substitution of alcohols
Serkan Sayin* and Mustafa Yilmaz*
Department of Chemistry, Selcuk University, Konya-42075, Turkey
ABSTRACT
Three magnetically recoverable Brønsted acidic calix[n]arene derivatives were successfully
constructed by immobilizing calix[n]arene sulfonic acids onto silica-coated magnetic
nanoparticles, a process which allows calix[n]arene derivatives to acquire magnetic
properties. All of the magnetically recoverable Brønsted acidic calix[n]arenes efficiently
catalyze the coupling of electron-rich arenes with some alcohols in water. After separation
and recovery from the reaction mixture by a simple magnet, these Brønsted acidic
calix[n]arenes can be recycled many times without losing their catalytic activity.
Keywords: Calix[n]arene sulfonic acids, magnetic nanoparticles, Brønsted acid catalysis,
alkylation of aromatic compounds, green chemistry.
1. Introduction
Recently, the formation of C-C bonds derived from reactions between nucleophiles,
such as arenes and heteroarenes, and halide/alcohols or related derivatives has attracted the
attention of researchers.1,2 The popularity of examining these reactions derives largely from
____________________________________________________________________
To whom correspondence should be addressed. Tel: +90 332 2232774 ; fax: +90 332 2410106
E-mail: myilmaz42@yahoo.com (M.Yilmaz), and saynserkan@gmail.com (S. Sayin).
1

ACCEPTED MANUSCRIPT
their common application in the preparation of compounds used to prepare dyestuffs,
perfumes, flavors, agricultural aids, and pharmaceuticals.3 Performing the reaction between an
alcohol as an electrophile and reactive nucleophiles in particularly attractive because
preparing the reactive materials is not required, plus, only H2O is depends how the alcohol is
activated generated as a byproduct. Indeed, this process can provide significant and
environmentally friendly ways to save energy.4 This kind of reaction requires a catalyst to
activate either the alcohol or nucleophile to allow the process to proceed not just in water.
Several catalysts suitable for this kind of reaction have been developed, including Lewis
acids, Brønsted acids, and transition metal reagents, among others.4-9 Although some of these
catalysts seem promising for this reaction, designing a new efficient catalyst is necessary.
Calixarenes, derived from the condensation reaction of phenol and formaldehyde,
represent very useful building blocks in supramolecular chemistry.10-12 Their easy preparation,
unlimited functionalization, and variously sized cavities make them unique macrocyclic
compounds,13,14 which have been widely used in sensors, enzyme-mimics, ion carriers, solid-
phase support materials, ion selective electrodes, drug-delivery agents, and in catalysis
studies, among others.15-17 Despite their wide employment, the separating the calixarenes
from the reaction product can be difficult and time consuming. To address these
disadvantages, efforts have recently focused on immobilizing the calixarenes onto magnetic
Fe3O4 nanoparticles to facilitate their separation & recovery. 18
More recently, calix[6]arenes, which act similarly to surfactant-type Brønsted acids
were used to catalyse nucleophilic substitutions in water. This study found that some of these
Brønsted acidic-calix[6]arene derivatives were effective catalysts for the alkylation of
aromatic compounds with allyl alcohols in water.5 The results from this study encouraged us
to develop a new catalyst for the alkylation of aromatic compounds with alcohols in water. To
the best of our knowledge, there are no examples of Brønsted acidic magnetic Fe3O4-grafted
calix[n]arene sulfonic acids being employed as catalysts. In this study, we report the synthesis
2

ACCEPTED MANUSCRIPT
of magnetic Fe3O4-grafted calix[n]arene sulfonic acids (C[4]SO3H-MNP, C[6]SO3H-MNP,
and C[8]SO3H-MNP) and an evaluation of their ability to catalyse catalytic affinities toward
the coupling of electron-rich arenes with alcohols in aqueous media, along with facile
recovery.
O
O
O
Fe3O4
SO3H
HO3S
SO3H
HO3S
O
O
EPPTMS-MN
N(C2H5OH)3
HO
OH
OH HO
n=1, 7
n=3, 8
n=5, 9
OH
HCHO,
H2SO4
Fe3O4
HO
OH
OH
OH
OH
OH
HO
OH
AlCl3,
n
n
n=1, 1
n=3, 2
n=5, 3
n=1, 4
n=3, 5
n=5, 6
OHOH
O
OH
n
HO3S
HO3S
SO3H
SO3H
n=1, C[4]SO3H-MNP
n=3, C[6]SO3H-MNP
n=5, C[8]SO3H-MNP
Scheme 1. Preparation of C[4]SO3H-MN, C[6]SO3H-MN and C[8]SO3H-MN
2. Results and discussion
2.1. Synthesis and characterizations of Brønsted acidic calix[n]arene derivatives
3

ACCEPTED MANUSCRIPT
The aim of this study was the synthesis of Brønsted acidic calix[n]arene derivatives (7,
8, 9) and their magnetic nanoparticles (C[4]SO3H-MN, C[6]SO3H-MN, C[8]SO3H-MN) and
evaluation of their catalytic abilities for coupling electron-rich arenes with some alcohols in
water without co-solvents. For this purpose, we synthesized calix[4]arene-p-tetrasulfonic acid
(7), calix[6]arene-p-hexasulfonic acid (8) and calix[8]arene-p-octasulfonic acid (9) starting
from p-tert- butylcalix[4]arene (1),
p-tert-butylcalix[6]arene (2), and p-tert-
butylcalix[8]arene (3) (Scheme 1).19,20 All compounds were characterized by using FTIR, 1H-
NMR, 13C-NMR spectroscopy and elemental analysis (see Supporting information).
Fe3O4 nanoparticles and [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-coated
Fe3O4 nanoparticles (EPPTMS-MN) were prepared according to the literature.21 C[n]SO3H-
MNPs (n= 4, 6 and/or 8) were prepared by the immobilization of the calix[n]arene sulfonic
acids (7, 8 and/ or 9) onto [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-coated Fe3O4
nanoparticles (EPPTMS-MN) (Scheme 1, 2, and 3). The structures of these calix[n]arene-
grafted magnetic nanoparticles (C[4]SO3H-MN, C[6]SO3H-MN, C[8]SO3H-MN) were
determined by a combination of FTIR spectroscopy, TEM and elemental analysis.
FT-IR spectroscopy was used to elaborate the structure of C[4]SO3H-MNP,
C[6]SO3H-MNP, and C[8]SO3H-MNP. Characteristic peaks appeared at 1518, 1447, and
1414 cm-1 for C[4]SO3H-MNP; 1508 and 1447 cm-1 for C[6]SO3H-MNP; and, 1466 and
1411 cm-1 for C[8]SO3H-MNP, all of which are stretching vibrations of the aromatic C=C
bonds of the calix[n]arene derivatives. 19,20 It is then possible to distinguish the vibration bend
of S-O, which derives from the calix[n]arene sulfonic acids by appearing at 867 cm-1 for
C[4]SO3H-MNP, 867 cm-1 for C[6]SO3H-MNP, and 855 cm-1 for C[8]SO3H-MNP.
However, additional peaks of all compounds centered at 1200, 1078, 955, and 796 cm-1 for
C[4]SO3H-MNP; 1038, 952, and 790 cm-1 for C[6]SO3H-MNP; and 1088, 958, and 800 cm-1
for C[8]SO3H-MNP. These additional peaks were due to the symmetric and asymmetric
4

ACCEPTED MANUSCRIPT
vibrations of the SO2 bands of the calix[n]arene sulfonic acids and the Si-O groups of the
silica part of EPPTMS-MN (Fig. 1).
72
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
4000
3500
3000
2500
2000
1500
1000
500450
cm-1
Name
Description
C[4]SO3H-MNP
C[6]SO3H-MNP
C[8]SO3H-MNP
Figure 1. FTIR (KBr) spectra of C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-MNP.
Transmission electron microscopy (TEM) of the Fe3O4 magnetic nanoparticles (Fig. 2a),
C[4]SO3H-MNP (Fig. 2b), C[6]SO3H-MNP (Fig. 2c), and C[8]SO3H-MNP (Fig. 2d),
respectively, was used to obtain more direct information regarding particle size and
morphology (Fig. 2). TEM images of the calixarene-adorned magnetic nanoparticles show
that the morphologies of the magnetic core has a uniform-size with a typical size range of 8±3
nm surrounded by calixarene units that are approximately 8-10 nm thick. After the
C[n]SO3H-MNP immobilization, the particle dispersion was improved due to the
electrostatic repulsion force and steric hindrance between the C[n]SO3H-MNP on the surface
of Fe3O4 nanoparticles. In addition TG and dTG curves can indicate that the anchoring of
C[n]SO3H on EPPTMS-MN (Fig. 3). Upon heating, the weight loss of EPPTMS-MN was
o
observed about 5 % within a broad temperature range of 250 and 650 C. Thermal
5

ACCEPTED MANUSCRIPT
degradation between 300-900 oC temperature ranges, the decompositions of C[6]SO3H-MNP
and C[8]SO3H-MNP were found as 20% and 21.1%, respectively (see Fig. 3.).
Figure 2. TEM images of (a); Fe3O4 magnetic nanoparticles, (b); C[4]SO3H-MNP, (c);
C[6]SO3H-MNP, and (d); C[8]SO3H-MNP.
6

ACCEPTED MANUSCRIPT
Figure 3. TGA curves of C[6]SO3H-MNP and C[8]SO3H-MNP
Table 1. Elemental analysis results of C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-
MNP
C(%)
8.29
H(%)
1.84
S(%)
0.35
Bounded amount of calixarene (mmol/g)a
0.44
C[4]SO3H-MNP
13.1
14.0
2.94
3.03
0.47
0.82
0.88
2.06
C[6]SO3H-MNP
C[8]SO3H-MNP
13.20
2.61
-
-
EPPTMS-MN
aCalculated according to the S content.
Elemental analysis was performed to characterize the amount of grafted calixarene on
the nanoparticles (EPPTMS-MN) by measuring the amount of sulfur the calix[n]arene
sulfonic acids provided sulfur with 035, 0.47, and 0.82% sulfur corresponding to 0.44, 0.88,
and 2.06 mmol of C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-MNP/g of support,
respectively to iron oxide nanoparticle (Table 1).
7

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Table 2. The coupling reaction of 10a-b with 11 in H2O
Ar
OH
Calix-Cat.
Ar-H
+
O
O
H2O, 50 oC,150 rpm
O
O
10a-b
12a-b
11
O
O
N
O
O
,
10b
10a
N
O
O
12a
12b
Entry
Catalyst
Catalyst
Ar-H sec-
Time H2O
Product Yield (%)a
loading
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
-
Alcohol /h
/mL
1
15
15
15
30
15
15
15
30
15
15
15
24
24
24
24
24
24
48
48
0.5
47
50
86
99.9
40
62
40
70
45
97
63
63
56
63
58
28
12
0
7
10a
10a
10a
10a
10a
10a
10a
10a
10a
10a
10a
10b
10b
10b
10b
10b
10b
10a
10b
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
12a
12a
12a
12a
12a
12a
12a
12a
12a
12a
12a
12b
12b
12b
12b
12b
12b
12a
12b
2
1
7
3
2
7
4
1
7
5
0.5
8
6
1
8
7
2
8
8
1
8
9
0.5
9
10
11
12
13
14
15
16
17
18
19
1
9
2
9
1
7
2
7
1
8
2
8
1
9
2
9
none
none
1 or 2
1 or 2
-
0
aReaction conditions: 10a-b (0.18 mmol), 11 (22 mg, 0.09 mmol); isolated yield
.
2.2. Catalysis efficiencies of Brønsted acid type calix[n]arene derivatives
8

ACCEPTED MANUSCRIPT
Table 3. The coupling reaction of 10a-b with 11 in H2O in the presence of C[n]SO3H-MNP
catalysts
Ar
OH
Calix-Cat.
Ar-H
+
O
O
H2O, 50 oC,150 rpm
O
O
10a-b
12a-b
11
O
O
N
O
O
,
10b
10a
N
O
O
12a
12b
Entry
Catalyst
Catalyst
loading
Ar-H sec-
Time H2O
Product
Yield (%)a
Alcohol
11
/h
/mL
1
1
C[4]SO3H-MNP 5 mg
C[4]SO3H-MNP 5 mg
C[6]SO3H-MNP 5 mg
C[6]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
C[4]SO3H-MNP 5 mg
C[4]SO3H-MNP 5 mg
C[4]SO3H-MNP 5 mg
C[6]SO3H-MNP 5 mg
C[6]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
C[4]SO3H-MNP 5 mg
C[4]SO3H-MNP 5 mg
C[6]SO3H-MNP 5 mg
C[6]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
C[8]SO3H-MNP 5 mg
48
48
48
48
6
63
10a
10a
10a
10a
10a
10a
10a
10b
10b
10b
10b
10b
10b
10b
10a
10b
10a
10b
10a
10b
12a
12a
12a
12a
12a
12a
12a
12b
12b
12b
12b
12b
12b
12b
12a
12b
12a
12b
12a
12b
2
2
85
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
3
1
73
4
2
67
5
1
68
6
48
48
6
1
82
7
2
86
8
1
98
9
24
24
24
24
24
24
48
24
48
24
48
24
1
99.9
99.8
96.6
95
10
11
12
13
14
15
16
17
18
19
20
2
1
2
1
96
2
84
1
62.4a, 62.3b, 62.3c
99.8a, 99.8b, 98.9c
73.2d, 72.8e, 72.7f
96.6d, 96.4e, 95.8f
82.1g, 82h, 81.8i
1
1
1
1
1
96.2g, 95.4h, 95.5i
b
aReaction conditions: 10a-b (0.18 mmol), 11 (22 mg, 0.09 mmol); isolated yield. Second reuse of
c
d
e
C[4]SO3H-MNP. Third reuse of C[4]SO3H-MNP. Fourth reuse of C[4]SO3H-MNP. Second reuse of
f
g
C[6]SO3H-MNP. Third reuse of C[6]SO3H-MNP. Fourth reuse of C[6]SO3H-MNP. hSecond reuse of
C[8]SO3H-MNP. iThird reuse of C[8]SO3H-MNP. jFourth reuse of C[8]SO3H-MNP.
9

ACCEPTED MANUSCRIPT
As shown in Tables 2, 3, 4 and 5, the catalytic abilities of calix[n]arene sulfonic acids
and their magnetic nanoparticles for coupling of various hetero-aromatic compounds (10a-b)
o
with two activated sec-alcohols (11 and 13) at 50 C in water were investigated. The
corresponding products (12a-b and 14a-b) were isolated in good to excellent yields (up to
99%) (Supporting information). It is clear that the yields are affected dramatically when the
water amount used is changed (see Fig. 2). The reason may depend upon on the formation of
micelle capability of Brønsted-type calix[n]arene sulfonic acids and their magnetic
nanoparticles.
Easy and rapid separation of the preferred product from organic reaction mixture by
magnetism promise a very attractive method for the C-C bond-forming reaction. It was,
nevertheless, a very time-consuming task to complete the separation of desired products 12a-
b and/or 14a-b from micelle mixture when calix[n]arene sulfonic acids (7-9) were employed
as catalysts for the coupling reaction of 4,4'-dimethoxybenzhydrol and/or (E)-trans-1,3-
diphenyl-2-propen-1-ol with 2-methyl furan and/or 1-methylindole. Therefore, providing
magnetic properties for calix[n]arene sulfonic acids (7-9) would allow them to receive
increased attention due to their easy separation. In order to see any changes on yield of 12a-b
and/or 14a-b, various amounts of magnetic calix[n]arene sulfonic acid nanoparticles
(C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-MNP) were employed as catalysts
(Tables 3 and 5). All three, magnetic calix[n]arene sulfonic acid nanoparticles (C[4]SO3H-
MNP, C[6]SO3H-MNP, and C[8]SO3H-MNP) exhibited excellent catalytic ability with
yields up to 99% for all products 12a-b and/or 14a-b. In the absence of the catalyst, no
product was obtained.
10

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Table 4. The coupling reaction of 10a-b with 13 in H2O
OH
Ar
Calix-Cat.
Ar-H
+
H2O, 50 oC,150 rpm
10a-b
14a-b
13
N
O
,
O
10b
10a
N
14a
14b
Entry
1
Catalyst
Catalyst loading
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
5 mol%
-
Ar-H
10a
10a
10a
10a
10a
10a
10a
10a
10a
10b
10b
10b
10b
10b
10b
10b
10b
10b
10a
10b
sec-Alcohol
Time/h H2O/mL
Product Yield (%)a
61
61
86
61
61
86
61
61
86
15
61
61
15
61
61
15
61
61
86
86
1
53
81
7
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
14a
14a
14a
14a
14a
14a
14a
14a
14a
14b
14b
14b
14b
14b
14b
14b
14b
14b
14a
14b
2
2
7
3
1
81
7
4
1
89
8
5
2
86
8
6
1
69
8
7
1
42
9
8
2
61
9
9
1
57
9
10
11
12
13
14
15
16
17
18
19
20
1
96
7
1
99.9
99.8
23
7
2
7
1
8
1
99
8
2
98
8
1
74
9
1
99.8
99.8
0
9
2
9
None
1 or 2
1 or 2
None
-
0
aReaction conditions: 10a-b (0.18 mmol), 13 (19 mg, 0.09 mmol). Isolated yield.
11

ACCEPTED MANUSCRIPT
Table 5. The coupling reaction of 10a-b with 13 in H2O in the presence of C[n]SO3H-MNP
catalysts
OH
Ar
Calix-Cat.
Ar-H
+
H2O, 50 oC,150 rpm
10a-b
N
14a-b
O
13
,
O
10b
10a
N
14a
14b
Entry
1
Catalyst
Catalyst loading
5 mg
Ar-H
10a
10a
10a
10a
10a
10a
10a
10a
10b
10b
10b
10b
10b
10b
10b
10b
10b
10b
10b
10b
10b
10b
10b
sec-Alcohol
Time/h H2O/mL
Product Yield (%)a
C[4]SO3H-MNP
C[4]SO3H-MNP
C[4]SO3H-MNP
C[6]SO3H-MNP
C[6]SO3H-MNP
C[8]SO3H-MNP
C[8]SO3H-MNP
C[8]SO3H-MNP
C[4]SO3H-MNP
C[4]SO3H-MNP
C[4]SO3H-MNP
C[4]SO3H-MNP
C[4]SO3H-MNP
C[6]SO3H-MNP
C[6]SO3H-MNP
C[6]SO3H-MNP
C[6]SO3H-MNP
C[6]SO3H-MNP
C[8]SO3H-MNP
C[8]SO3H-MNP
C[8]SO3H-MNP
C[8]SO3H-MNP
C[8]SO3H-MNP
6
1
1
2
1
2
1
1
2
1
1
1
1
2
1
1
1
1
2
1
1
1
1
2
73
88
86
63
89
77
92
98
92
98
98.9
80
93
83
98.9
84
93
99.9
89
87
81
83
72
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
14a
14a
14a
14a
14a
14a
14a
14a
14b
14b
14b
14b
14b
14b
14b
14b
14b
14b
14b
14b
14b
14b
14b
2
5 mg
48
48
48
48
6
3
5 mg
4
5 mg
5
5 mg
6
5 mg
7
5 mg
48
48
61
61
61
24
24
61
61
61
24
24
61
61
61
24
24
8
5 mg
9
20 mg
10 mg
5 mg
10
11
12
13
14
15
16
17
18
19
20
21
22
23
5 mg
5 mg
20 mg
10 mg
5 mg
5 mg
5 mg
20 mg
10 mg
5 mg
5 mg
5 mg
aReaction conditions: 10a-b (0.18 mmol), 13 (19 mg, 0.09 mmol). Isolated yield.
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3. Conclusion
In summary, three Brønsted acidic calix[n]arene derivatives were synthesized and
immobilized onto the silica-based magnetic nanoparticles surface (EPPTMS-MN) to impact
both rigid structural properties and to provide easy separation capability from reaction
mixture by using an external magnet. Additionally, the catalytic properties of these new
calix[n]arene sulfonic acid-grafted magnetic nanoparticles for coupling of various hetero-
aromatic compounds with two activated sec-alcohols in water were investigated. Results
reflect that not only calix[n]arene sulfonic acid but also these calix[n]arene sulfonic acid-
grafted magnetic nanoparticles were effective catalysts for the substitution reactions. In
addition, allowing calixarene compounds to acquire magnetic properties would attract new
insight into the catalytic C-C bond-formation reactions due to their easy separation from the
reaction system by using an external magnet, as well as the sustained catalytic activity in
recyclable processes.
4. Experimental
4.1. General Remarks
A Ez-Melt apparatus in a sealed capillary was used to determine all melting points of the
synthesized compounds. NMR spectra were recorded on a Varian 400 MHz spectrometer,
indicating chemical shifts as ppm that are relative to an internal standard tetramethylsilane (δ=
0.0). FT-IR spectra were recorded with a Perkin-Elmer 100 spectrometer. Elemental analyses
were performed on a Leco CHNS-932 analyzer.
4.2. Synthesis
p-tert-Butylcalix[4]arene (1), p-tert-butylcalix[6]arene (2), p-tert-butylcalix[8]arene
(3), calix[4]arene (4), calix[6]arene (5), calix[8]arene (6), and calix[n]arene-p-sulfonates (7, 8,
9) were synthesized according to the literature procedure.19,20 Silica-based magnetic Fe3O4-
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nanoparticles (EPPTMS-MN) were prepared as described in our previously study.21
Calixarene-adorned magnetic nanoparticles (C[4]SO3H-MNP, C[6]SO3H-MNP and
C[8]SO3H-MNP) are reported for the first time.
4.2.1. Calix[4]arene-p-tetrasulfonic acid (7).19 White solid. Yield: 95%, m.p. > 350 oC. FTIR
(ATR) cm-1: 3133 (νOH), 1682 (νH2O), 1597, 1459 ve 1377 (νC=C), 1151, 1105 (νSO2
asymmetric), 1023 (νSO2 symmetric) and 784 (νS-O). 1H-NMR (400 MHz, D2O): δ 3.86 (s, 8H,
Ar-CH2-Ar), 7.43 (s, 8H, ArH). 13C-NMR (100 MHz, D2O): δ 31.96 (Ar-CH2-Ar), 125.97 (C-
Ar), 126.10 (C-Ar), 130.71 (C-Ar), 133.36 (C-Ar), 156.21 (ArC-O). Anal. Calcd. For
C28H24O16S4·6H2O (%): C, 39.43; H, 4.25; S, 15.04. Found (%); C, 39.38; H, 4.32; S, 15.00.
o
4.2.2. Calix[6]arene-p-hexasulfonate (8).19 White solid. Yield: 40%; M.p.: >350 C. FTIR
(ATR) cm-1: 3154 (νOH), 1685 (νH2O), 1591, 1472 and 1340 (νC=C), 1273 (νC-O-C), 1151, 1108
1
(νSO2 asymmetric), 1020 (νSO2 symmetric), and 870 (νS-O). H-NMR (400 MHz, D2O): δ 3.82
13
(s, 12H, Ar-CH2-Ar), 7.35 (s, 12H, ArH). C-NMR (100 MHz, D2O): δ 32.63 (Ar-CH2-Ar),
125.71 (C-Ar), 125.80 (C-Ar), 129.05 (C-Ar), 132.01 (C-Ar), 157.95 (ArC-O). Anal. Calcd.
For C42H28O24S6Na8·9H2O (%): C, 34.67; H, 3.19; S, 13.22. Found (%); C, 34.55; H, 3.09; S,
13.31.
o
4.2.3. Calix[8]arene-p-octasulfonate (9).19 White solid. Yield: 39%; M.p.: >350 C. FTIR
(ATR) cm-1: 3435 (νOH), 1649 (νH2O), 1420 (νC=C), 1211 (νC-O-C), 1172, 1114 (νSO2
1
asymmetric), 1047 (νSO2 symmetric), and 879 (νS-O). H-NMR (400 MHz, D2O): δ 3.78 (s,
16H, Ar-CH2-Ar), 7.21 (s, 16H, ArH). 13C-NMR (100 MHz, D2O): δ 32.35 (Ar-CH2-Ar),
125.34 (C-Ar), 129.30 (C-Ar), 130.61 (C-Ar), 159.66 (ArC-O). Anal. Calcd. For
C56H35O32S8Na13·18H2O (%): C, 32.04; H, 3.41; S, 12.22. Found (%); C, 32.08; H, 3.38; S,
12.16.
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4.2.4. General procedure for the preparation of Brønsted acidic magnetic calix[4]arene
derivatives C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-MNP.
A mixture of the
calix[n]arene-p-sulfonate derivative (7, 8 or 9) (0.3 g) and N(C2H5OH)3 (10 M, 25 mL) in
o
DMSO (10 mL) was stirred at 30 C for 17 h then EPPTMS-MN (0.3 g) was added, and the
o
solution heated at 50 C for 4 days. After magnetic separation, the residue was washed with
water three times to remove excess of calix[n]arene-p-sulfonate derivative, and then treated
with 0.1 M HCl and dried under vacuum.
4.2.4.1. C[4]SO3H-MNP.
FTIR (KBr) cm-1: 3424 (VOH), 1644 (VH2O), 1524, 1447, 1418
(VC=C), 1078 (VSi-O, VSO2 asymmetric and symmetric), 864 (VS-O), 796 (VSi-O), and 560 (VFe-O).
4.2.4.2. C[6]SO3H-MNP.
FTIR (KBr) cm-1: 3408 (VOH), 1508, 1453 (VC=C), 1075 (VSi-O
,
VSO2 asymmetric and symmetric), 867 (VS-O), 793 (VSi-O), and 557 (VFe-O).
4.2.4.3. C[8]SO3H-MNP.
FTIR (KBr) cm-1: 3421 (VOH), 1460, 1411 (VC=C), 1081 (VSi-O
,
VSO2 asymmetric and symmetric), 855 (VS-O), 799 (VSi-O), and 560 (VFe-O).
4.3. General procedure for Brønsted acidic calix[n]arene derivatives catalyzed
nucleophilic substitutions of two sec-alcohols in water
Method 1.
The reaction was carried out according to the literature procedure.5,22 Typically, the
alcohol (11 or 13) and a hetero-aromatic compound (10a-b) were added to a solution of the
catalysis in water (as listed in the tables of main text). The mixture was stirred at 50 oC for the
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period of time given in the tables (see main text), after that the mixture was centrifuged to
separate water-soluble calixarene-based catalysts. Et2O and NaHCO3 aq. were added to the
organic layer, and the ether phase was separated and washed with H2O to adjust pH 7, and
dried over MgSO4. The solvent was evaporated under reduced pressure, the crude product was
purified by column chromatography to obtain the desired substitution product (12a, 12b, 14a
or 14b).
Method 2.
To a mixture of calixarene-grafted magnetic nanoparticles (C[4]SO3H-MNP,
C[6]SO3H-MNP, and/or C[8]SO3H-MNP) in H2O was added a sec-alcohol (11 or 13) and a
o
hetero-aromatic compound (10a-b). The mixture was stirred at 50 C for a period of time
given in the tables of the main text. Then, catalyst was easily separated from the mixture by
using a simple magnet. The remaining residue was treated with Et2O and NaHCO3 aq., and
the ether phase was separated and washed with water to neutral pH, and dried over MgSO4.
The solvent was removed under reduced pressure, the crude was purified by column
chromatography to obtain desired product (12a, 12b, 14a or 14b).
4.3.1. 2-[Bis(4-methoxyphenyl)methyl]-5-methylfuran (12a).22
Purified
by
column
chromatography (SiO2, hexane/ethyl acetate= 3/1 (v/v)). FTIR (ATR) cm-1: 2928, 1645, 1602,
1
1511, 1251, 1031, 833, 769. H-NMR (400 MHz, CDCl3): δ 2.24 (s, 3H, Ar-CH3), 3.78 (s,
6H, O-CH3), 5.29 (s, 1H, -CH), 5.71 (d, 1H, J= 3.2 Hz, ArH (furan)), 5.86 (dd, 1H, J1= 0.8
Hz, J2= 2.0 Hz, ArH (furan)), 6.83 (d, 4H, J= 8.8 Hz, ArH), 7.08 (d, 4H, J= 8.8 Hz, ArH).
13C-NMR (100 MHz, CDCl3): δ 13.69 (-CH3, furan), 49.25 (-CH), 55.23 (O-CH3), 105.84
(ArC, furan), 108.74 (ArC, furan), 113.69 (ArC), 129.61 (ArC), 132.25 (ArC), 151.35 (ArC,
furan), 155.50 (ArC, furan), 158.16 (ArC-O) (see Supporting information). Anal. Calcd. For
C20H20O3 (%): C, 77.90; H, 6.54. Found (%); C, 77.84; H, 6.62.
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4.3.2. 1-Methyl-3-(di(4-methoxyphenyl)methyl)-1H-indole (12b).22 Purified with column
chromatography (SiO2, petroleum ether/ethyl acetate= 98/2 (v/v)). FTIR (ATR) cm-1: 3019,
2928, 1605, 1505, 1239, 1028, 744. 1H-NMR (400 MHz, CDCl3): δ 3.70 (s, 3H, N-CH3), 3.79
(s, 6H, O-CH3), 5.57 (s, 1H, -CH), 6.40 (s, 1H, C=CH), 6.82 (d, 4H, J= 8.8 Hz, ArH), 6.98 (t,
1H, J= 8.0, ArH), 7.14 (d, 4H, J= 8.4 Hz, ArH), 7.17-7.24 (m, 2H, ArH), 7.29 (d t, 1H, J1=
8.0 Hz, J2= 1.2 Hz, ArH). 13C-NMR (100 MHz, CDCl3): δ 32.73 (N-CH3), 47.07 (-CH),
55.26 (O-CH3), 109.10 (ArC), 113.57 (ArC), 118.74 (ArC), 120.10 (ArC), 121.56 (ArC),
127.30 (ArC), 128.65 (ArC), 129.82 (ArC), 132.27 (ArC), 136.66 (ArC), 137.44 (ArC),
157.84 (ArC-O) (see Supporting information). Anal. Calcd. For C24H23NO2 (%): C, 80.64; H,
6.49; N, 3.92. Found (%); C, 80.49; H, 6.34; N, 4.02.
4.3.3. (E)-2-(1,3-Diphenyl allyl)-5-methylfuran (14a).5
Purified
with
column
chromatography (SiO2, petroleum ether/ethyl acetate= 12/1 (v/v)). FTIR (ATR) cm-1: 3029,
1
2922, 1709, 1599, 1453, 1218, 964, 747, 695. H-NMR (400 MHz, CDCl3): δ 2.26 (s, 3H, -
CH3), 4.84 (d, 1H, J= 7.6 Hz, -CH), 5.89-5.90 (m, 1H, ArH (furan)), 5.96 (d, 1H, J= 3.2 Hz,
ArH (furan)), 6.39 (d, 1H, J= 16 Hz, ArCH=C), 6.56 (dd, 1H, J1= 7.2 Hz, J2= 15.8 Hz,
C=CH), 7.19-7.38 (m, 10H, ArH). 13C-NMR (100 MHz, CDCl3): δ 13.64 (-CH3), 48.42 (-
CH), 105.98 (ArC), 107.45 (ArC), 126.37, 126.63, 127.07, 127.67, 128.26, 128.53, 130.13,
131.56, 137.15, 141.42, 151.43, 154.22 (see Supporting information). Anal. Calcd. For
C20H18O (%): C, 87.56; H, 6.61. Found (%); C, 87.47; H, 6.74.
4.3.4. (E)-3-(1,3-Diphenyl allyl)-1-methyl-1H-indole (14b).5 Purified with column
chromatography (SiO2, petroleum ether/ethyl acetate= 12/1 (v/v)). FTIR (ATR) cm-1: 3053,
1
2925, 1709, 1465, 1239, 1013, 735, 699. H-NMR (400 MHz, CDCl3): δ 3.75 (s, 3H, -CH3),
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5.12 (d, 1H, J= 7.2 Hz, -CH), 6.45 (d, 1H, J= 15.6 Hz, Ar-CH=C-), 6.70-6.76 (m, 2H, -
CH=C- ve N-CH=C-), 7.18-7.44 (m, 14H, ArH). 13C-NMR (100 MHz, CDCl3): δ 32.75 (-
CH3), 48.20 (-CH), 109.23, 118.90, 119.97, 121.65, 126.34, 127.17, 127.42, 128.51, 130.42,
132.71, 137.51, 143.55 (see Supporting information). Anal. Calcd. For C24H21N (%): C,
89.12; H, 6.54; N, 4.33. Found (%); C, 88.99; H, 6.58; N, 4.45.
Acknowledgements
The authors thank the Research Foundation of Selcuk University, Konya, Turkey for financial
support of this work produced from Serkan Sayin's PhD Thesis.
Supplementary data
TEM images, TGA thermograms, FTIR spectra, 1H-NMR and 13C-NMR data.
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Figure captions:
Figure 1. FTIR (KBr) spectrums of C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-
MNP.
Figure 2. TEM images of (a); Fe3O4 magnetic nanoparticles, (b); C[4]SO3H-MNP, (c);
C[6]SO3H-MNP, and (d); C[8]SO3H-MNP.
Figure 3. TGA curves of C[6]SO3H-MNP and C[8]SO3H-MNP
Scheme 1. Preparation of C[4]SO3H-MN
Scheme 2. Preparation of C[6]SO3H-MNP
Scheme 3. Preparation of C[8]SO3H-MNP
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Graphical Abstract
___________________________________________________________________________
Brønsted acidic magnetic nano-Fe3O4-adorned calix[n]arene sulfonic acids: Synthesis and
application in the nucleophilic substitution of alcohols
Serkan Sayin, Mustafa Yilmaz
or
Fe3O4
O
OH
16
17a
N
17b
Ar-H
13a-b
C[n]SO3H-MNP
or
, 50 oC
pm
H O
150 r
,
O
2
O
O
N
,
O
O
13a
13b
OH
14
N
O
O
O
15b
or
15a
________________________________________________________________________________
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Supporting information
Brønsted Acidic Magnetic Nano-Fe3O4-Adorned Calix[n]arene Sulfonic Acids: Synthesis
and Application in the Nucleophilic Substitution of Alcohols
Serkan Sayin* and Mustafa Yilmaz*
Department of Chemistry, Selcuk University, Konya-42075, Turkey. E-mail:
1. FTIR spectrums.................................................................................................................2
2. 1H-NMR and 13C-NMR spectrums...................................................................................5
1

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1. FTIR spectrums:
Figure 1S. FTIR (KBr) spectrums of C[4]SO3H-MNP, C[6]SO3H-MNP, and C[8]SO3H-
MNP
72
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
4000
3500
3000
2500
2000
1500
1000
500450
cm-1
Name
Description
C[4]SO3H-MNP
C[6]SO3H-MNP
C[8]SO3H-MNP
2

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Figure 2S. FTIR (ATR) spectrums of 12a and 12b:
101
100
98
96
94
2928,1
92
90
88
86
84
82
80
78
76
74
72
1645,5
769,1
833,23
1602,8
1031,7
1511,2
1251,6
70
69
4000
3500
3000
2500
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1500
1000
650
cm-1
Name Description
12a
97
90
3019,7
80
70
60
50
40
30
2928,1
1605,8
1028,7
1505
1239,4
744,67
650
20
17
4000
3500
3000
2500
2000
1500
1000
cm-1
Name Description
12b
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Figure 3S. FTIR (ATR) spectrums of 14a and 14b:
102
100
2922
90
80
70
60
50
40
30
3028,9
1599,7
1453,1
1709,7
964,54
1218
695,8
747,72
20
15
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1500
1000
650
cm-1
Name Description
14a
99
95
90
85
80
75
70
65
60
55
50
45
40
35
3053,3
1709,7
2925
1013,4
1239,4
1465,4
698,86
735,5
29
4000
3500
3000
2500
2000
1500
1000
650
cm-1
Name Description
14b
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2. 1H-NMR and 13C-NMR data:
Figure 4S. 1H-NMR spectrum of 12a:
5

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Figure 5S. 13C-NMR spectrums of 12a:
6