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

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.^1,2The 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).

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their common application in the preparation of compounds used to prepare dyestuffs,

perfumes, flavors, agricultural aids, and pharmaceuticals.³Performing 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.⁴This 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.^4-9Although 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.^10-12Their easy preparation,

unlimited functionalization, and variously sized cavities make them unique macrocyclic

compounds,^13,14which 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.^15-17Despite 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

Fe₃O₄nanoparticles 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.⁵The 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

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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

Fe₃O₄

SO₃H

HO₃S

SO₃H

HO₃S

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

HO

OH

AlCl₃,

n

n=1, 1

n=3, 2

n=5, 3

n=1, 4

n=3, 5

n=5, 6

OHOH

O

OH

n

HO₃S

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

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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).^19,20All compounds were characterized by using FTIR, ¹H-

NMR, ¹³C-NMR spectroscopy and elemental analysis (see Supporting information).

Fe₃O₄nanoparticles and [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-coated

Fe₃O₄nanoparticles (EPPTMS-MN) were prepared according to the literature.²¹C[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^-1for C[4]SO₃H-MNP; 1508 and 1447 cm^-1for C[6]SO₃H-MNP; and, 1466 and

1411 cm^-1for C[8]SO₃H-MNP, all of which are stretching vibrations of the aromatic C=C

bonds of the calix[n]arene derivatives. ^19,20It 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^-1for

C[4]SO₃H-MNP, 867 cm^-1for C[6]SO₃H-MNP, and 855 cm^-1for C[8]SO₃H-MNP.

However, additional peaks of all compounds centered at 1200, 1078, 955, and 796 cm^-1for

C[4]SO₃H-MNP; 1038, 952, and 790 cm^-1for 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

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vibrations of the SO₂bands 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 Fe₃O₄magnetic 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 Fe₃O₄nanoparticles. 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

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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); Fe₃O₄magnetic nanoparticles, (b); C[4]SO₃H-MNP, (c);

C[6]SO₃H-MNP, and (d); C[8]SO₃H-MNP.

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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).

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Table 2. The coupling reaction of 10a-b with 11 in H₂O

Ar

OH

Calix-Cat.

Ar-H

+

O

H₂O, 50 ^oC,150 rpm

O

10a-b

12a-b

11

O

N

O

,

10b

10a

N

O

12a

12b

Entry

Catalyst

Ar-H sec-

Time H₂O

Product Yield (%)^a

loading

5 mol%

-

Alcohol /h

/mL

1

15

30

15

30

15

24

48

0.5

47

50

86

99.9

40

62

40

70

45

97

63

56

63

58

28

12

0

7

10a

10b

10a

10b

11

12a

12b

12a

12b

2

1

7

3

2

7

4

1

7

5

0.5

8

6

1

8

7

2

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

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

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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

H₂O, 50 ^oC,150 rpm

O

10a-b

12a-b

11

O

N

O

,

10b

10a

N

O

12a

12b

Entry

Catalyst

loading

Ar-H sec-

Time H₂O

Product

Yield (%)^a

Alcohol

11

/h

/mL

1

C[4]SO₃H-MNP 5 mg

C[6]SO₃H-MNP 5 mg

C[8]SO₃H-MNP 5 mg

C[4]SO₃H-MNP 5 mg

C[6]SO₃H-MNP 5 mg

C[8]SO₃H-MNP 5 mg

C[4]SO₃H-MNP 5 mg

C[6]SO₃H-MNP 5 mg

C[8]SO₃H-MNP 5 mg

48

6

63

10a

10b

10a

10b

10a

10b

10a

10b

12a

12b

12a

12b

12a

12b

12a

12b

2

85

11

3

1

73

4

2

67

5

1

68

6

48

6

1

82

7

2

86

8

1

98

9

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

62.4^a, 62.3^b, 62.3^c

99.8^a, 99.8^b, 98.9^c

73.2^d, 72.8^e, 72.7^f

96.6^d, 96.4^e, 95.8^f

82.1^g, 82^h, 81.8ⁱ

1

96.2^g, 95.4^h, 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.

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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%

-

Ar-H

10a

10b

10a

10b

sec-Alcohol

Time/h H₂O/mL

Product Yield (%)^a

61

86

61

86

61

86

15

61

15

61

15

61

86

1

53

81

7

13

14a

14b

14a

14b

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

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

0

9

2

9

None

1 or 2

None

-

0

^aReaction conditions: 10a-b (0.18 mmol), 13 (19 mg, 0.09 mmol). Isolated yield.

11

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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

10b

sec-Alcohol

Time/h H₂O/mL

Product Yield (%)^a

C[4]SO₃H-MNP

C[6]SO₃H-MNP

C[8]SO₃H-MNP

C[4]SO₃H-MNP

C[6]SO₃H-MNP

C[8]SO₃H-MNP

6

1

2

1

2

1

2

1

2

1

2

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

14a

14b

2

5 mg

48

6

3

5 mg

4

5 mg

5

5 mg

6

5 mg

7

5 mg

48

61

24

61

24

61

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

20 mg

10 mg

5 mg

20 mg

10 mg

5 mg

^aReaction conditions: 10a-b (0.18 mmol), 13 (19 mg, 0.09 mmol). Isolated yield.

12

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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.^19,20Silica-based magnetic Fe₃O₄-

13

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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).¹⁹White solid. Yield: 95%, m.p. > 350 ^oC. FTIR

(ATR) cm^-1: 3133 (ν_OH), 1682 (ν_H2O), 1597, 1459 ve 1377 (ν_C=C), 1151, 1105 (ν_SO2

asymmetric), 1023 (ν_SO2symmetric) and 784 (ν_S-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).¹⁹White solid. Yield: 40%; M.p.: >350 C. FTIR

(ATR) cm^-1: 3154 (ν_OH), 1685 (ν_H2O), 1591, 1472 and 1340 (ν_C=C), 1273 (ν_C-O-C), 1151, 1108

1

(ν_SO2asymmetric), 1020 (ν_SO2symmetric), and 870 (ν_S-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).¹⁹White solid. Yield: 39%; M.p.: >350 C. FTIR

(ATR) cm^-1: 3435 (ν_OH), 1649 (ν_H2O), 1420 (ν_C=C), 1211 (ν_C-O-C), 1172, 1114 (ν_SO2

1

asymmetric), 1047 (ν_SO2symmetric), and 879 (ν_S-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 (V_OH), 1644 (V_H2O), 1524, 1447, 1418

(V_C=C), 1078 (V_Si-O, V_SO2asymmetric and symmetric), 864 (V_S-O), 796 (V_Si-O), and 560 (V_Fe-O).

4.2.4.2. C[6]SO₃H-MNP.

FTIR (KBr) cm^-1: 3408 (V_OH), 1508, 1453 (V_C=C), 1075 (V_Si-O

,

V_SO2asymmetric and symmetric), 867 (V_S-O), 793 (V_Si-O), and 557 (V_Fe-O).

4.2.4.3. C[8]SO₃H-MNP.

FTIR (KBr) cm^-1: 3421 (V_OH), 1460, 1411 (V_C=C), 1081 (V_Si-O

,

V_SO2asymmetric and symmetric), 855 (V_S-O), 799 (V_Si-O), and 560 (V_Fe-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.^5,22Typically, 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

15

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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 NaHCO₃aq. 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 NaHCO₃aq., 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).²²Purified 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).⁵Purified 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); Fe₃O₄magnetic 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

N

,

O

13a

13b

OH

14

N

O

15b

or

15a

________________________________________________________________________________

23

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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

ACCEPTED MANUSCRIPT

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

2000

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

4000

3500

3000

2500

2000

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

4

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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

Article Doi

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

DOI: 10.1016/j.tet.2014.06.034

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

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