Synthesis and characterization of 4,4″-bipyridinium sulfonic acid chloride as a new and efficient catalyst for the preparation of amidoalkyl phenols and bis amidoalkyl phenols

Article abstract of DOI:10.1016/j.mcat.2017.09.037

4,4′-bipyridinium sulfonic acid chloride {[SO₃H-4,4′-bipyridine-SO₃H]Cl₂}, as a new solid acid, was synthesized and fully characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), ¹H NMR and ¹³C NMR as well as mass spectra. [SO₃H-4,4′-bipyridine-SO₃H]Cl₂ was successfully applied as a new and efficient catalyst for the preparation of amidoalkyl phenols and bis amidoalkyl phenols as a new category of compounds at 110 °C under solvent-free conditions.

Full text of DOI:10.1016/j.mcat.2017.09.037

Molecular Catalysis 449 (2018) 142–151
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Molecular Catalysis
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Editor’s choice paper
Synthesis and characterization of 4,4ꢀ-bipyridinium sulfonic acid
chloride as a new and efficient catalyst for the preparation of
amidoalkyl phenols and bis amidoalkyl phenols
Ahmad Reza Moosavi-Zarea,∗, Mohammad Ali Zolfigolb, Fateme Derakhshan-Panahb,
Saeed Balalaiec
a Sayyed Jamaleddin Asadabadi University, Asadabad, 6541861841, Iran
b Faculty of Chemistry, Bu-Ali Sina University, Hamedan 6517838683, Iran
c Department of Chemistry, K. N. Toosi University of Technology, P. O. Box 15875 − 4416, Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
4,4ꢀ-bipyridinium sulfonic acid chloride {[SO3H-4,4ꢀ-bipyridine-SO3H]Cl2}, as a new solid acid, was
synthesized and fully characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffrac-
tion analysis (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX),
thermal gravimetric analysis (TGA), 1H NMR and 13C NMR as well as mass spectra. [SO3H-4,4ꢀ-bipyridine-
SO3H]Cl2 was successfully applied as a new and efficient catalyst for the preparation of amidoalkyl
phenols and bis amidoalkyl phenols as a new category of compounds at 110 ◦C under solvent-free
Article history:
Received 28 July 2017
Received in revised form
19 September 2017
Accepted 30 September 2017
Keyword:
conditions.
4,4ꢀ-bipyridinium sulfonic acid chloride
Amidoalkyl phenol
© 2017 Elsevier B.V. All rights reserved.
Bis amidoalkyl phenol
Organocatalyst
1. Introduction
ties [16–20]. Based on these reported research, amidoalkyl phenols
are proposed to have the same properties [21–24].
Nowadays, there is a remarkable attention to develop of various
methods in order to synthesize, and design the efficient cata-
lysts, consisting of organocatalysts and organometallic catalysts.
Organocatalysts, which used in the preparation of pharmaceutical
intermediates, have noticeable points in the comparison with the
transition metal catalysts. Organocatalysts are usually inexpensive,
stable and available, showing low poisonous properties, and are
not sensitive against oxygen or moisture. Additionally, organocat-
alysts have high surface ratio to volume, which make them suitable
catalysts because of their high activities [1–8].
Amidoalkyl naphthols are one of the most important cate-
gories of the organic compounds as a result of their capabilities to
be transformed to the biologically active compounds (aminoalkyl
naphthols), which are applied widely to produce of pharmaceutical
compounds, and to treat of different diseases, such as cardiovascu-
lar, bradycardiac and hypotensive [9–16]. Moreover, 1, 3-oxsazin
derivatives can be prepared from aminoalkyl naphthols, with wide
applications, including antibiotics, antitumor and analgesic activi-
Amidoalkyl phenols have been synthesized by one-pot multi-
component condensations of phenols with aromatic aldehydes and
amides. Previously, different catalysts have been introduced for
the synthesis of these compounds such as trityl chloride as an
organocatalyst [21], [Msim]Cl [22], ethylammonium nitrate [23]
and triflic acid [24], which some of them have noticeable draw-
backs, including low efficiencies, high reaction time, hard workup,
difficult purification steps, using of strong acidic conditions, side
reactions, using large amount of catalyst, which are against the
green chemistry. So, by regarding to the mentioned drawbacks, it
is essential to find an effective, efficient, and safe method for the
synthesis of these compounds.
Herein, in continuation of our previous research, related to
design and development of ionic liquid and solid acid in order
to synthesis of organic compounds [25–38], we have synthesized
and identified 4,4ꢀ-bipyridinium sulfonic acid chloride {[SO3H-4,4ꢀ-
bipyridine-SO3H]Cl2}, by the reaction of 4,4ꢀ-bipyridine (1 mmol)
with chlorosulfonic acid (2 mmol) as a new solid acid and catalyst
(Scheme 1) for the synthesize of different derivatives of amidoalkyl
phenols and bis amidoalkyl phenols as a new category of com-
pounds (Schemes 2 and 3).
∗
Corresponding author.
https://doi.org/10.1016/j.mcat.2017.09.037
2468-8231/© 2017 Elsevier B.V. All rights reserved.

A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
143
Scheme 1. The preparation of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.
Scheme 2. The preparation of amidoalkyl phenols.
Scheme 3. The preparation of bis amidoalkyl phenols.
Fig. 1. IR spectrum of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.
2. Experimental
CH2Cl2 (3 × 20) and dried under vacuum to give [SO3H-4,4ꢀ-
bipyridine-SO3H]Cl2 as white powder with 96% yield.
2.1. General procedure for the synthesis of
[SO3H-4,4ꢀ-bipyridine-SO3H]Cl2
2.2. General procedure for the synthesis of amidoalkyl phenols
4,4ꢀ- bipyridine (5 mmol) was added over a period of 20 min into
a round-bottomed flask (50 mL), containing mixture of chlorosul-
fonic acid (10 mmol) and CH2Cl2 (20 mL). Then, reaction mixture
was stirred for 30 min. After the completion of the reaction,
the obtained precipitate was filtered, washed several times with
A mixture of phenolic compound (1 mmol), aldehyde (1 mmol),
amide (1 mmol) and [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 (10 mol%)
was stirred for 20 min in the absence of solvent at 110 ◦C. After
completion of the reaction as monitored by TLC, the reaction mix-

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A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
Fig. 2. 1H NMR spectra of 4.4ꢀ-bipyridine (a); 1H NMR spectra of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 (b).
ture was washed with hot dried ethanol to separate catalyst. Then,
the pure product was obtained by the recrystallization in ethanol.
mixture was washed with hot dried ethanol to separate catalyst.
Afterwards, the pure product was obtained by the recrystallization
in ethanol.
2.3. General procedure for the synthesis of bis amidoalkyl phenols
A mixture of phenolic compound (1 mmol), aldehyde (2 mmol),
benzamide (2 mmol) and [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 (10
mol%) was stirred for 30 min in the absence of solvent at 110 ◦C.
After completion of the reaction as monitored by TLC, the reaction
2.4. Spectral data of compounds
1,1ꢀ-disulfo-[4,4ꢀ-bipyridine]-1,1ꢀ-diium chloride {[SO3H-4,4ꢀ-
bipyridine-SO3H]Cl2}

A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
145
Fig. 3. 13C NMR spectra of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.
Fig. 4. The XRD diagram of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.
mp: 242–244 ◦C. IR (KBr): 3053, 2786, 1735, 1593 Cm−1; 1HNMR
(400 MHz, DMSO-d6): ␦ = 8.54(d, J = 6 Hz, 4H), 8.84(s, 2H), 9.12(d,
J = 6 Hz, 4H); 13CNMR (100 MHz, DMSO-d6): ␦ = 125.5, 145.1, 149.7.
N-[(5-Benzyl-2-hydroxyphenyl)(phenyl)methyl]-benzamide (1a)
7.15–7.28 (m, 7H), 7.37–7.72 (m, 2H), 8.09 (d, J = 8.0 Hz, 2H), 8.76 (d,
J = 8.0 Hz, 1H), 9.56 (s, 1H); 13C NMR (100 MHz, DMSO-d6): ␦ = 23.1,
40.1, 50.6, 115.9, 121.8, 122.1, 126.3, 127.8, 128.8, 129.3, 130.2,
132.1, 134.4, 142.2, 145.2, 148.2, 153.1, 169.3. MS: m/z = 331 [M+].
N-[(5-Benzyl-2-hydroxyphenyl)(p-tolyl)methyl]-acetamide (3a)
mp 182–184 ◦C. IR (KBr): 3412, 3246, 3025, 1648, 1610 cm−1; 1H
NMR (400 MHz, DMSO-d6): ␦ = 1.90 (s, 3H), 2.25 (s, 3H), 3.81 (s, 2H),
6.31 (d, J = 6.0 Hz, 1H), 6.71 (d, J = 5.5 Hz,1H), 6.87 (dd, J = 4.0, 1.4 Hz,
1H), 7.07–7.28 (m, 10H), 8.47 (d, J = 6.0 Hz, 1H), 9.56 (s, 1H); 13C
NMR (100 MHz, DMSO-d6): ␦ = 21.0, 23.1, 41.0, 50.5, 115.6, 126.2,
127.4, 128.4, 128.5, 128.8, 128.9, 129.0, 129.2, 131.7, 136.0, 140.3,
142.3, 153.0, 168.8. MS: m/z = 345 [M+].
mp 202–204 ◦C. IR (KBr): 3403, 3062, 3028, 1630, 1603 cm−1
;
1HNMR (400 MHz, DMSO-d6): ␦ = 3.78 (s, 2H), 6.46 (d, J = 8.4 Hz, 1H),
6.67–6.92 (m, 11H), 7.13–7.27 (m, 7H), 8.23 (d, J = 8.4 Hz, 1H), 9.25
(s, 1H); 13C NMR (100 MHz, DMSO-d6): ␦ = 41.0, 56.4, 111.9, 112.5,
115.4, 115.5, 126.2, 128.4, 128.6, 128.7, 128.9, 128.9, 131.1, 132.8,
142.4, 151.3, 153.5, 153.6, 168.6. MS: m/z = 393 [M+].
N-[(5-Benzyl-2-hydroxyphenyl)(phenyl)methyl]-acetamide (2a)
mp 174–176 ◦C. IR (KBr): 3410, 3179, 3024, 1644, 1611 cm−1
;
1HNMR (400 MHz, DMSO-d6): ␦ = 1.96 (s, 3H), 3.85 (s, 2H), 6.48
(d, J = 8.4 Hz, 1H), 6.77 (d, J = 8.0 Hz, 1H), 6.99 (d, J = 8.0 Hz, 1H),
N-[(5-Benzyl-2-hydroxyphenyl)(3-nitrophenyl)methyl]-
acetamide (4a)

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Fig. 5. SEM micrograph of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.
Fig. 6. Energy-dispersive X-ray spectroscopy (EDX) of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.
mp 210–212 ◦C. IR (KBr): 3381, 3025, 2733, 1635, 1606 cm−1
;
N-[(5-Bromo-2-hydroxyphenyl)(4-chlorophenyl)-
1H NMR (400 MHz, DMSO-d6): ␦ = 1.88 (s, 3H), 3.79 (s, 2H), 6.44 (d,
J = 7.6 Hz, 1H), 6.74 (d, J = 8.0 Hz, 1H), 6.81 (s, 1H), 6.92 (d, J = 8.0 Hz,
1H), 7.13–7.58 (m, 8H), 7.59 (d, J = 4.8 Hz, 1H), 8.41 (s, 1H), 9.39
(s, 1H); 13C NMR (100 MHz, DMSO-d6): ␦ = 22.9, 41.0, 51.5, 115.6,
124.1, 126.3, 127.4, 127.8, 128.8, 128.8, 128.9, 129.0, 129.2, 129.6,
131.2, 133.1, 141.8, 142.1, 153.7, 168.8. MS: m/z = 376 [M+].
N-[(5-Benzyl-2-hydroxyphenyl)(2-nitrophenyl)methyl]-
methyl]acetamide (6a)
mp 220–225 ◦C. IR (KBr): 3309, 3074, 2980, 2739, 1649,
1631 cm−1 1H NMR (400 MHz, DMSO-d6): ␦ = 1.85 (s, 3H), 5.95 (d,
;
J = 8.4 Hz, 1H), 6.68 (s, 2H), 6.99 (d, J = 8.0 Hz, 2H), 7.23–7.35 (m, 3H),
8.66 (s, 1), 9.35 (s, 1H); 13CNMR (100 MHz, DMSO-d6): ␦ = 24.2, 56.4,
116.7, 129.8, 130.1, 130.5, 132.8, 134.0, 143.9, 158.0, 170.0. MS:
m/z = 354 [M+].
N-[(5-Bromo-2-hydroxyphenyl)(2-bromophenyl)-
methyl]acetamide (7a)
acetamide (5a)
mp 226–228 ◦C. IR (KBr): 3403, 3271, 3027, 1656, 1614 cm−1; 1H
NMR (400 MHz, DMSO-d6): ␦ = 1.79 (s, 3H), 3.68 (s, 2H), 6.60–6.70
(m, 3H), 6.82 (dd, J = 6.2, 2.0 Hz, 1H), 7.01–7.18 (m, 3H), 7.32–7.34
(m, 2H), 7.34–7.41 (m, 1H), 7.75 (s, 1H), 7.77 (s, 1H), 7.78 (d,
J = 7.4 Hz, 1H), 8.43 (d, J = 8.0 Hz, 1H), 9.36 (s, 1H); 13C NMR
(100 MHz, DMSO-d6): ␦ = 22.3, 46.9, 56.0, 115.0, 124.1, 125.7, 126.8,
127.6, 128.1, 128.4, 128.5, 128.6, 129.5, 130.9, 132.6, 136.0, 141.5,
148.8, 153.0, 168.4. MS: m/z = 376 [M+].
mp 197–200 ◦C. IR (KBr): 3300, 3064, 2808, 1634, 1613 cm−1
;
1H NMR (400 MHz, DMSO-d6): ␦ = 1.21 (s, 3H), 6.45 (s, 1H), 6.61
(s, 1H), 6.98 (s, 1H), 7.06–7.32 (m, 5H), 7.55 (d, J = 6.8 Hz, 1H), 8.69
(s, 1H); 13C NMR (100 MHz, DMSO-d6): ␦ = 22.8, 51.7, 126.3, 127.2,
127.9, 128.1, 128.7, 128.9, 129.1, 129.3, 133.2, 141.2, 141.4, 169.7.
MS: m/z = 399 [M+].

A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
147
Table 1
The effect of the different amounts of the catalyst, types of solvents and various temperatures on the reaction of 4-benzylphenol with benzaldehyde and benzamide.
Entry
Catalyst (mol%)
Solvent
Temperature (◦C)
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
10
5
10
15
10
5
10
15
10
–
10
10
10
10
10
10
10
–
–
–
–
–
–
–
–
rt
80
80
80
95
110
110
110
180
60
40
40
30
45
20
20
20
180
90
90
90
90
90
90
90
15
30
64
66
70
54
75
75
61
0
9
–
–
120
110
10
11
12
13
14
15
16
17
H2O
EtOH
MeOH
CH3CN
CH2Cl2
CHCl3
EtOH
reflux
reflux
reflux
reflux
reflux
reflux
reflux
5
10
10
15
10
10
5
Table 2
The synthesis of amidoalkyl phenols using [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2.(10 mol%) at 110 ◦C under solvent-free conditions.
1a
2a
3a
4a
[Time:20 min, Yield:75%]
[Time:20 min, Yield:78%]
[Time:20 min, Yield:71%]
[Time:20 min, Yield: 83%]
Mp.202–204 ◦ C (202–204)21
Mp.174–176 ◦C (174–175)21
Mp.182–184 ◦C (182–185)21
Mp.210–212 ◦C (210–212)21
5a
6a
7a
8a
[Tme:20 min, Yield:84%]
[Time:20 min, Yield:68%]
[Time:30 min, Yield:72%]
[Time:30 min, Yield:67%]
Mp.226–228 ◦C (226–228)21
Mp.220–223 ◦C (222–225)21
Mp.197–199 ◦C (197–199)21
Mp.215–217 ◦C (214–217)21
Table 3
The synthesis of bis amidoalkyl phenols using [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 (10 mol%) at 110 ◦C under solvent-free conditions.
1b
2b
3b
4b
[Time:30 min, Yield:46%]
[Time:30 min, Yield:55%]
[Time:20 min, Yield:77%]
[Time:20 min, Yield:78%]
Mp.221–222 ◦
C
Mp.235–237 ◦C
Mp.232–234 ◦C
Mp.248–249 ◦C
5b
6b
7b
[Time:25 min, Yield:75%]
[Time:20 min, Yield:61%]
[Time:30 min, Yield:65%]
Mp.244–246 ◦C
Mp.243–244 ◦C
Mp.223–225 ◦C

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A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
Fig. 7. Thermogravimetric (TG) analysis of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 at range of 0–600 ◦C, with a temperature increase rate of 10 ◦C.
2.5
N-[(5-Bromo-2-hydroxyphenyl)(2,5-dimethoxyphenyl)-
4H), 7.94(d, J = 6 Hz, 8H), 8.26(d, J = 6 Hz, 2H), 8.99(d, J = 3 Hz, 1H),
9.23(d, J = 6 Hz, 1H); 13CNMR (100 MHz, DMSO-d6): ␦ = 39.0, 58.3,
58.4, 115.0, 123.4, 123.5, 127.6, 128.0, 128.3, 128.4, 128.5, 129.5,
131.7, 133.4, 133.5, 146.7, 147.0, 147.5, 165.8, 165.9; Mass: HR-MS
(ESI) = Calc. for C41H32N4O7 [M + H]+ 693.2360 found 693.2344.
N,N’-((5-benzyl-2-hydroxy-1,3-phenylene)bis((4-
methyl]acetamide (8a)
mp 215–217 ◦C. IR (KBr): 3372, 3267, 2854, 1652 cm−1 1HNMR
;
(400 MHz, DMSO-d6): ␦ = 1.82 (s, 3H), 3.31 (s, 3H), 3.76 (s, 3H),
6.30 (d, J = 6.0 Hz, 1H), 6.69 (d, J = 8.4 Hz, 1H), 6.87 (d, J = 6.4 Hz, 1H),
7.09–7.28 (m, 4H), 8.50 (d, J = 9.2 Hz, 1H), 9.35 (s, 1H); 13C NMR
(100 MHz, DMSO-d6): ␦ = 23.1, 41.0, 50.5, 115.7, 126.3, 127.3, 128.3,
128.5, 128.8, 129.0, 129.0, 131.8, 141.5, 142.3, 153.0, 168.7. MS:
m/z = 380 [M+].
chlorophenyl)methylene))dibenzamide (5b)
mp 244–246 ◦C. IR (KBr): 3264, 3084, 2969, 1650, 1549 cm−1
;
1H NMR (400 MHz, DMSO-d6): ␦ = 3.64(s, 2H), 7.01(t, J = 3 Hz, 2H),
7.44-7.47(m, 6H), 7.49-7.51(m, 8H), 7.57 (t, J = 6 Hz, 3H), 7.92(d,
J = 6 Hz, 8H), 8.28(d, J = 3 Hz, 1H), 8.98 (d, J = 3 Hz, 1H), 9.07(d,
J = 6 Hz, 1H); 13CNMR (100 MHz, DMSO-d6): ␦ = 39.0, 58.1, 58.2,
115.0, 123.4, 127.4, 127.5, 128.2, 128.2, 128.3, 128.5, 131.2, 131.6,
132.3, 133.6, 133.7, 139.2, 142.7, 165.6; Mass: HR-MS (ESI) = Calc.
for C41H32Cl2N2O3 [M + H]+ 671.1869 found 671.1863.
N,N’-((5-benzyl-2-hydroxy-1,3-phenylene)bis(phenylmethylene))
dibenzamide (1b)
mp 221–222 ◦C. IR (KBr): 3284, 3090, 2924, 1652, 1544 cm−1
.
1H NMR (400 MHz, DMSO-d6): ␦ = 3.40(s, 2H), 7.05(t, J = 3 Hz, 2H),
7.33(d, J = 3 Hz, 2H), 7.40(t, J = 6 Hz, 4H), 7.49(t, J = 6 Hz, 12H), 7.57(t,
J = 6 Hz, 3H), 7.92(d, J = 6 Hz, 8H), 8.08(d, J = 3 Hz, 1H), 8.87(d, J = 6 Hz,
1H), 9.02(d, J = 6 Hz, 1H); 13CNMR (100 MHz, DMSO-d6): ␦ = 39.0,
58.4, 126.4, 127.4, 127.7, 128.2, 128.3, 131.2, 131.6, 133.7, 133.8,
140.2, 165.5, 165.6; Mass: HR-MS (ESI) = Calc. for C41H34N2O3
[M+H]+ 603.2643 found 603.2642.
N,N’-((5-benzyl-2-hydroxy-1,3-phenylene)bis(naphthalen-1-
ylmethylene))dibenzamide (6b)
mp 243–244 ◦C. IR (KBr): 3277, 3058, 1649, 1546 cm−1 1H NMR
;
(400 MHz, DMSO-d6): ␦ = 3.59(s, 2H), 7.21(d, J = 3 Hz, 2H), 7.47–7.65
(m, 16H), 7.63(d, 2H), 7.47-7.65(m, 16H), 7.94-8.00(m, 14H), 8.27(d,
j = 6 Hz, 1H), 8.98(d, J = 6 Hz, 1H), 9.16(d, J = 6 Hz, 1H); 13CNMR
(100 MHz, DMSO-d6): ␦ = 39.0, 123.9, 125.4, 125.4, 126.6, 126.8,
127.9, 128.0, 128.4, 128.5, 128.8, 132.1, 133.0, 133.1, 134.2, 134.3,
138.1, 138.2, 147.2, 147.2, 166.0, 166.1; Mass: HR-MS (ESI) = Calc.
for C49H38N2O3 [M + H]+ 703.2975 found 703.2955.
N,N’-((5-benzyl-2-hydroxy-1,3-phenylene)bis(p-
tolylmethylene))dibenzamide (2b)
mp 235–237 ◦C. IR (KBr): 3280, 3057, 1649, 1547,cm−1 1H NMR
;
(400 MHz, DMSO-d6): ␦ = 2.301(s, 6H), 3.64(s, 2H), 7.02(t, J = 6 Hz,
2H), 7.19(d, J = 6 Hz, 3H), 7.37(d, J = 6 Hz, 3H), 7.46-7.58(m, 12H),
7.92 (d, J = 6 Hz, 6H), 8.19 (d, J = 6 Hz, 1H), 8.93 (d, J = 6 Hz, 1H),
9.01(d, J = 6 Hz, 2H); 13CNMR (100 MHz, DMSO-d6): ␦ = 21.2, 39.7,
59.0, 126.9, 127.9, 128.8, 129.3, 132.0, 134.3, 137.3, 137.9, 165.9;
Mass: HR-MS (ESI) = Calc. for C43H38N2O3 [M + H]+ 631.2965 found
631.2955.
N,N’-((5-bromo-2-hydroxy-1,3-phenylene)bis(phenylmethylene))
dibenzamide (7b)
mp 223–225 ◦C. IR (KBr): 3290, 3090, 1652, 1545 cm−1 1H NMR
;
(400 MHz, DMSO-d6): ␦ = 7.07(t, J = 6 Hz, 1H), 7.28-7.40(m, 3H),
7.45-7.57(m, 7H), 7.92(d, J = 6 Hz, 4H), 8.32(d, J = 6 Hz, 1H), 9.01(d,
J = 6 Hz, 1H), 9.05(d, J = 6 Hz, 1H); 13CNMR (100 MHz, DMSO-d6):
␦ = 58.7, 123.8, 126.5, 127.5, 127.7, 128.3, 131.6, 133.8, 140.3, 146.2,
165.6 ppm; Mass: HR-MS (ESI) = Calc. for C34H27BrN2O3 [M + H]+
591.1287 found 591.1278.
N,N’-((5-benzyl-2-hydroxy-1,3-phenylene)bis((3-
nitrophenyl)methylene))dibenzamide (3b)
mp 232–234 ◦C. IR (KBr): 3260, 3088, 1651, 1603, 1534 cm−1
;
1H NMR (400 MHz, DMSO-d6): ␦ = 3.66(s, 2H), 7.09(t, J = 3 Hz, 2H),
7.47-7.60(m, 11H), 7.70 (t, J = 6 Hz, 2H), 7.93 (d, J = 6 Hz, 8H), 8.21 (d,
J = 6 Hz, 2H), 8.34 (s, 1H), 8.99 (d, J = 6 Hz, 1H), 9.28 (d, J = 6 Hz, 1H);
13CNMR (100 MHz, DMSO-d6): ␦ = 39.0, 58.8, 121.9, 123.3, 128.1,
128.8, 130.5, 132.2, 133.9, 134.0, 134.2, 142.8, 148.3, 166.3, 166.4;
Mass: HR-MS (ESI) = Calc. for C41H32N4O7 [M + H]+ 693.2357 found
693.2344.
3. Result and discussion
As expected, by the reaction of 4,4ꢀ-bipyridine (1 mmol) with
chlorosulfonic acid (2 mmol) 4,4ꢀ-bipyridinium sulfonic acid chlo-
ride {[SO3H-4,4ꢀ-bipyridine-SO3H]Cl2} was prepared (Scheme 1).
Characterization of {[SO3H-4,4ꢀ-bipyridine-SO3H]Cl2} was carried
N,N’-((5-benzyl-2-hydroxy-1,3-phenylene)bis((4-
nitrophenyl)methylene))dibenzamide (4b)
mp 248–249 ◦C. IR (KBr): 3263, 3095, 2920, 1650, 1633 cm−1
;
out by various analytical techniques including IR, 1H NMR and 13
C
1H NMR (400 MHz, DMSO-d6): ␦ = 3.64 (s, 2H), 7.11 (t, J = 3 Hz,
2H), 7.50 (t, J = 6 Hz, 8H), 7.58 (t, J = 6 Hz, 3H), 7.76(d, J = 6 Hz,
NMR analysis. The IR spectrum of the catalyst displayed a broad
peak at 2700–3300 cm−1 related to the O H stretching of SO3H.

A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
149
Scheme 4. Proposed reaction mechanism for the synthesis of amidoalkyl phenols.
Fig. 8. Reuses of the catalyst in the reaction of 4-benzylphenol with benzaldehyde and benzamide.

150
A.R. Moosavi-Zare et al. / Molecular Catalysis 449 (2018) 142–151
Also, the two peaks observed at 1057 cm−1 and 1196 cm−1 corre-
spond to vibrational modes of N–SO2 and
reused for four runs without any significant effect in the yield of
product (Fig. 8).
O–SO2 bonds. Another peak at 1019 cm−1 could be correlated
with S O bonds (Fig. 1).
4. Conclusion
1H NMR spectra of 4,4ꢀ-bipyridinium sulfonic acid chloride in
comparison with 4,4ꢀ-bipyridine was also studied. The important
peak found in 1H NMR spectra of the catalyst is related to the acidic
hydrogen of SO3H which was observed at 8.84 ppm (Fig. 2).
In 13C NMR spectrum of the catalyst, three peaks were presented
at 149.7, 145.1 and 125.5 ppm which are supported the symmetric
structure of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 (Fig. 3).
In summary, we have prepared 4,4ꢀ-bipyridinium sulfonic acid
chloride as an acidic salt and new catalyst and fully characterized
by fourier transform infrared spectroscopy (FT-IR),
X-ray diffraction analysis (XRD), scanning electron microscope
(SEM), energy-dispersive X-ray spectroscopy (EDX), thermal gravi-
metric analysis (TGA), 1H and 13C NMR as well as mass spectra.
[SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 was succesfully applied for the
preparation of amidoalkyl phenols and bis amidoalkyl phenols at
110 ◦C under solvent-free conditions.
The XRD pattern of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 as solid
salt and catalyst was also investigated in a domain of 2␪ = 0–90◦.
According that, several diffraction lines were observed at 10–30◦
(Fig. 4).
The scanning electron microscope (SEM) micrographs of [SO3H-
4,4ꢀ-bipyridine-SO3H]Cl2, to show the size and morphology of it,
were studied (Fig. 5). As it is shown in Fig. 5, indicates that, the
catalyst was prepared more than 100 nm in size.
Acknowledgements
We thank Bu-Ali Sina University, Sayyed Jamaleddin Asadabadi
University and Iran National Science Foundation (INSF) (Grant
Number: 940124) for financial support to our research groups.
Energy-dispersive X-ray spectroscopy (EDX) of [SO3H-4,4ꢀ-
bipyridine-SO3H]Cl2, to show the presence of sulphur and oxygen,
was also studied. In this investigation, besides of carbon and
nitrogen in the catalyst, sulphur, oxygen and chlorine were also
observed. This witnessing clearly confirmed the existence of SO3H
group in the catalyst (Fig. 6).
Appendix A. Supplementary data
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.mcat.2017.09.
037.
To show the thermal stability of the catalyst, thermogravimet-
ric analysis (TGA) of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2 are studied
and related diagram displayed in Fig. 7. According to the thermal
gravimetric diagram, the catalyst was decomposed after 325 ◦C.
Upon the various characterization of the catalyst, [SO3H-4,4ꢀ-
bipyridine-SO3H]Cl2 was used as a catalyst for the synthesis
of amidoalkyl phenols. For this purpose, the reaction between
parabenzyl phenol, benzaldehyde and benzamide was chosen as a
model reaction to optimize the following variables including tem-
perature, solvent and the amount of catalyst (Table 1). As it is shown
at Table 1, indicates that the solvent-free reaction with 10 mol% of
catalyst at 110 ◦C was the best reaction condition for the model
reaction.
After the optimization of the reaction conditions, various deriva-
tives of amidoalkyl phenols were synthesized with high yields and
in short reaction time (Table 2). These products were identified by
IR, 1H NMR and 13C NMR analysis. As Table 2 indicates that electron-
withdrawing substituent such as NO2 group increased the yields of
products.
To investigate the ability for the synthesis of some novel bis
amidoalkyl phenols, we have used aldehyde (2 mmol) and amide
(2 mmol) in the reaction with various phenols (1 mmol) (Table 3).
Surprisingly, two sides of phenols participate in the reaction to give
bis amidoalkyl phenols as new category of compounds.
In a plausible mechanism, aldehyde is activated by acidic
group of [SO3H-4,4ꢀ-bipyridine-SO3H]Cl2. Then, phenolic com-
pound attacks to activated aldehyde to afford I. In the next step,
orthoquinone methide (o-QMs) (II) is prepared by removing of one
molecule of H2O from I. Then, II is activated by catalyst to give
III as a Michael acceptor. Finally, desired amido-alkyl-phenol was
prepared by Michael addition of acetamide with intermediate III
(Scheme 4) [21,22].
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