Novel application of Fe-Zn double-metal cyanide catalyst in · PDF fileNovel application of...

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Supplementary Information

Novel application of Fe-Zn double-metal cyanide catalyst in the synthesis of biodegradable, hyperbranched polymers

Joby Sebastiana and Darbha Srinivas*a

Catalysis Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411 008, India. E-mail: [email protected]; Fax: +91 20 2590 2633; Tel: +91 20 2590 2018. S1: Catalyst preparation S2: Catalyst characterization S3: Procedures for product analysis S4: FTIR, MALDI-TOF-MS and 2D-NMR spectra of G-SA and G-AA polymers S5: XRD and FTIR of recycled catalyst S6: Tentative mechanism for polyesterification over DMC

Electronic Supplementary Material (ESI) for Chemical CommunicationsThis journal is © The Royal Society of Chemistry 2011

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S1: Method for the preparation of Fe-Zn double-metal cyanide (DMC) catalyst

In a typical preparation of Fe-Zn DMC,11(b) solution 1 was made by dissolving

0.01 mol of K4[Fe(CN)6] (Merck, India) in 40 ml of double-distilled water. Solution 2

was prepared by dissolving 0.1 ZnCl2 (Merck, India) in a mixture of distilled water (100

ml) and tert.-butanol (20 ml). Polyethylene glycol (PEG – 4000) (15 g) was separately

dissolved in 2 ml of distilled water and 40 ml of tert.-butanol to prepare solution 3.

Solution 2 was added slowly to solution 1 at 50 ºC over 1 h with vigorous stirring.

White precipitation occurred during the addition. Then, solution 3 was added to the above

reaction suspension over a period of 5 min and stirring was continued for another 1 h.

The solid cake formed was filtered, washed with 500 ml of distilled water, and dried at 25

ºC for 2-3 days. This material was activated at 180 – 200 ºC for 4 h prior to using in the

reactions or for characterization. Color: white; yield = 98%.

S2: Catalyst characterization

X-ray diffraction (XRD) patterns of the powdered samples were recorded in the

2 range of 5 – 85 with a scan speed of 2/min on a Philips X’Pert Pro diffractometer

using Cu-K radiation ( = 0.15406 nm) and a proportional counter detector. Surface area

of the sample was estimated by BET method from the N2-adsorption-desorption

isotherms, measured at -196 °C (NOVA 1200 Quanta Chrome equipment). Prior to N2-

adsorption, the sample was evacuated at 373 K. Average pore diameter was determined

by the BJH method and micropore surface area was calculated from the t-plot. Infrared

spectrum of the sample, as KBr pellet, was recorded on a Shimadzu 8201 PC FTIR

spectrophotometer in the region of 400 – 4000 cm-1. The morphological characteristics of

the samples were determined using a scanning electron microscope (SEM; Leica 440)


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and high resolution transmission electron microscope (HRTEM; FEI Technai F 30). In

HRTEM studies, the catalyst sample were dispersed in isopropyl alcohol, deposited on a

Cu grid, dried and imaged. The type and density of the acid sites were determined by

diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy of adsorbed pyridine

and temperature-programmed ammonia desorption (NH3-TPD) techniques. Details of the

experimental procedures were reported by us earlier.12(b) In water adsorption studies, the

Fe-Zn catalysts were first activated at 180 °C for 4 h and then exposed to water vapor at

100 °C. Water adsorbed on the catalysts was monitored by gravimetry.

Fig. 1. XRD pattern of Fe-Zn DMC catalyst.

1 0 2 0 3 0 4 0 5 0 6 0

( 2 2 1 )

( 2 1 1 )

( 2 1 0 )

( 2 0 0 )

Inte

nsi

ty

2 ( d e g r e e )

( 1 1 0 )


4

Fig. 2: FTIR spectrum of DMC as KBr pellet.

Fig. 3: N2-physisorption of DMC

4000 3500 3000 2500 2000 1500 1000 5000

20

40

60

80

100

2096 [(CN)]

% T

ran

smit

tan

ce

Wavenumber (cm-1)

0.0 0.2 0.4 0.6 0.8 1.0

12

14

16

18

20

22

Vol

um

e (c

c/g)

Relative Pressure (P/Po)

0 2 4 6 8 10 12 14 16 180.004

0.008

0.012

0.016

0.020

Dv(

log

d)

(cc/

g)

Pore diameter (nm )

0.0 0.2 0.4 0.6 0.8 1.0

12

14

16

18

20

22

Vol

um

e (c

c/g)


0.0 0.2 0.4 0.6 0.8 1.0

12

14

16

18

20

22

Vol

um

e (c

c/g)


0 2 4 6 8 10 12 14 16 180.004

0.008

0.012

0.016

0.020

Dv(

log

d)

(cc/

g)

Pore diameter (nm )

0 2 4 6 8 10 12 14 16 180.004

0.008

0.012

0.016

0.020

Dv(

log

d)

(cc/

g)

Pore diameter (nm )


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Fig. 4: NH3-TPD of DMC.

Fig. 5: DRIFT of adsorbed pyridine

1700 1650 1600 1550 1500 1450

2000C

1500C

1000C

500C

145014881541

1608

Ab

sorb

ance

(a.

u)

Wavenumber (cm-1)


6

Fig. 6: HRTEM images of Fe-Zn DMC at different resolutions.


7

Fig. 7: SEM image of the Fe-Zn DMC catalyst

S3: Procedure for product analysis

Inverse gated 13C nuclear magnetic resonance (NMR) spectroscopy was used to analyze

the degree of branching in the hyperbranched polymer. The measurements were done on

a Bruker AV 500 NMR spectrometer: pulse program: Zgig 30, aquition time = 1.1 s, time

delay = 5 s, number of scans = 4180. The various branching and linear segments of the

polymer were assigned with the help of distortionless enhancement polarization transfer

(DEPT) experiments. In correlation spectroscopy (COSY; program = gpqf) and total

correlation spectroscopy (TOCSY; program = gpphw5) the following parameters were

used: Acquisition time = 0.297 s (F2) and 0.037 s (F1), spectral width = 6.8947 ppm,

receiver gain = 8, O1(Hz) = 1751.3. For heteronuclear single quantum correlation

(HSQC; program = ctgp) acquisition time = 0.045 s (F2) and 0.0057 s (F1), spectral

width = 9.997 ppm, receiver gain = 18400, O1 = 2496 Hz and O2 = 12106 Hz. In

heteronuclear multiple-bond correlation (HMBC, program = gp12ndqf) the spectral


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parameters used are: acquition time = 0.59397 s (F2) and 0.0047 s (F1), spectral width =

6.8947 ppm, receiver gain = 16400, O1 = 1751.3 Hz and O2 = 13619.9 Hz.

Inherent viscosity (ŋ) of the polymer product was measured in tetrahydrofuran at 30oC

using an Ubbelhode viscometer. The viscosity measurements were repeated three times

and the average of the reading is reported.

FTIR spectra of the polymer were recorded on a Shimadzu 8201 PC spectrophotometer

by placing the sample in between the KBr discs.

Mass Spectra from matrix–assisted laser desorption ionization time-of-flight mass

spectrometry (MALDI-TOF-MS) with automated tandem TOF fragmentation of selected

ions were acquired with a Voyager–DE STR (Applied Biosystems Voyager System

4383) in positive reflector mode with a laser intensity of 2324, accelerating voltage of

20000 V and number of laser shots of 50/spectrum. An aliquot (1 µL) of polymer

solution (1 mg/ mL in acetone) was mixed with 24 µL of 2,5-dihydroxybenzoic acid

(DHB) matrix solution (10 mg/ mL, acetonitrile-water 50:50 v/v) and 1 µL of the

resulting solution was spotted on the MALDI plate for analysis.


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S4: FTIR spectra of hyperbranched polymers

Fig. 8: FTIR spectra of G-SA and G-AA polymers obtained over DMC. The

characteristic peaks due ester linkage, terminal OH groups and –CH stretchning

vibrations are marked.

4000 3500 3000 2500 2000 1500 1000 500

GLY+AA

1170

3470 2952

1733

Tra

nsm

itta

nce(

%)

Wave Number (cm-1)4000 3500 3000 2500 2000 1500 1000 500

GLY+SA

1165

34902966

1735

Tra

nsm

itta

nce(

%)

Wave Number (cm-1)


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Fig. 9(a): MALDI-TOF-mass spectrum of G-SA polymer obtained over DMC

Fig. 9(b): MALDI-TOF-mass spectrum of G-AA polymer obtained over DMC

499 .0 799.2 1099 .4 1399 .6 1699 .8 2000.0

M ass (m/z )

0

2921.9

0

10

20

30

40

50

60

70

80

90

100

% I

nte

ns

ity

590.0853

690 .2281

564.4817864.4930

764 .3524

964 .6103706.2165

562.46731138.8654

1038.7367606 .0907

880 .4867664 .2073537.5138 980.6015724.3152 1154.8945

1413.25061313 .1197

824.4604624.1813545.9002 1054 .7744 1587 .5338712 .2298620.3366 1429.29801329.1316525.2162 1212 .9940886.5465

499 .0 899.4 1299.8 1700 .2 2100.6 2501.0

M ass (m/z )

0

2921 .9

0

10

20

30

40

50

60

70

80

90

100

% I

nte

ns

ity

590 .0853

690.2281

564 .4817864.4930

764.3524

964 .6103706 .2165

562.46731138.8654

1038 .7367606.0907

880 .4867664 .2073537.5138 980.6015724.3152 1154.8945

1413 .25061239.0113

824 .4604624.18131054 .7744 1587.5338592 .5429 1429.29801212 .9940746 .3240 886 .5465


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Fig. 9(c): MALDI-TOF-mass spectrum of G-AA polymer obtained over Amberlyst-70


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Fig. 10(a): COSY of G-SA polymer

ppm

23456 ppm

2

3

4

5

6

1H

1H

ppm

23456 ppm

2

3

4

5

6

1H

1H


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Fig. 10(b): TOCSY of G-SA polymer

ppm

23456 ppm

2

3

4

5

6

1H

1H

ppm

23456 ppm

2

3

4

5

6

1H

1H


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Fig. 10(c): HSQC of G-SA polymer

ppm

4.64.85.05.25.45.8 5.6 ppm

70

72

74

76

78

1H

13C

ppm

4.64.85.05.25.45.8 5.6 ppm

70

72

74

76

78

1H

13C

ppm

3.43.63.84.04.24.6 4.4 ppm

58

60

62

64

66

68

70

72

74

1H

13C

ppm

3.43.63.84.04.24.6 4.4 ppm

58

60

62

64

66

68

70

72

74

1H

13C


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Fig. 10(d): HMBC of G-SA polymer

ppm

4.74.84.95.05.15.2 ppm

172

174

176

1H

13C

ppm

4.74.84.95.05.15.2 ppm

172

174

176

1H

13C

ppm

3.83.94.04.14.24.34.4 ppm

172

173

174

175

1H

13C

ppm

3.83.94.04.14.24.34.4 ppm

172

173

174

175

1H

13C


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S5: Characterization data of reused DMC catalyst

Fig. 11: XRD of reused DMC in G-SA reaction showing structural integrity

Fig. 12: FTIR of reused DMC (9th run). Band at 1725 cm-1 is due to adsorbed and

activated succinic acid.

10 20 30 40 50

9th run

7th run

5th run

3rd run

Ist run

Neat

Inte

nsit

y

Degree

4000 3500 3000 2500 2000 1500 1000 500

1725 (adsorbed diacid)

Wavenumber (cm-1)

(CN): 2096

% T

ran

smit

tan

ce


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S6: Tentative mechanism of polyesterification over tetrahedral Zn2+ ions in DMC

ZnO

OH

O

HO

OOH

OHH

+ZnO

+OH2

O

HO

OOH

OH

Zn2+

ZnO

HO

O

OH

+

ZnO

OH

O

HO

+

OHOH

HO

Ester + H2O

O

HOO

OH


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