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Electronic Supplementary Material (ESI) for Green Chemistry This journal is © The Royal Society of Chemistry 2013

Electronic Supporting Information Synthesis of Soluble Core Cross-Linked Polystyrene Star Polymer by Application of Acrylate-Nitrile Oxide ‘Click Chemistry’ Using Metal-Free Reagents Rakesh Banerjee, Saikat Maiti and Dibakar Dhara*

Department of Chemistry, Indian Institute of Technology Kharagpur West Bengal 721302, India

Table of Contents Contents

Page no.

1.0. (a) Model reaction with poly (4-vinyl benzylchloride) and Anisaldehyde oxime  Preparation of anisaldehyde oxime S2 

Preparation of acryloyl-functionalized homopolymer modified from S2 poly (4-vinyl benzylchloride)



Synthesis of isoxazoline ring in polymeric system

(b) 1H NMR & 13C NMR spectra of acryloyl-functionalized homopolymer 1

13

(c) H NMR & C NMR spectra of polymer containing isoxazoline ring

S3 S4 & S5 S6 & S7

2.0. The NMR spectra of the various compounds (a) 1H NMR spectrum of poly(4-vinylbenzyl chloride) macro-CTA (Fig S1)

S8

(b) 1H NMR spectrum of polystyrene-block-poly(4-vinylbenzyl chloride) (Fig S9 S2) (c) 1H & 13C NMR spectra of pentaerythrityl tetrabromide (Fig S3)

S10 & S11

(d) 1H & 13C NMR spectra of tetra-arm aldehyde (Fig S4)

S12 & S13

(e) 1H & 13C NMR spectra of tetra-arm oxime (Fig S5)

S14 & S15

(f) Molecular weight (Mn) vs. percentage conversion for the synthesis of P2 S16 using XBDTB as chain transfer agent (Fig S6)

S1


1.0. (a) Model reaction with Poly (4-vinyl benzylchloride) and Anisaldehyde oxime: To confirm the formation of isoxazoline ring in the polymeric system via nitrile oxide-alkene ‘click chemistry’, a model reaction was carried out with acryloyl-functionalized homopolymer modified from poly(4-vinyl benzylchloride) (MA) and anisaldehyde oxime (MO). Preparation of anisaldehyde oxime: In a 25 mL single necked round-bottomed (r. b.) flask anisaldehyde (1 g, 7.4 mmol) was mixed with 5 mL of ethanol. On the other hand NH2OH.HCl (0.767 g, 11.2 mmol) and sodium acetate (1.21 g, 14.7 mmol) were dissolved in minimum volume of water. Then these two solutions were mixed and the reaction mixture was stirred overnight at room temperature. After completion of the reaction, EtOH was removed under vacuum and the remaining reaction mixture was extracted with diethyl ether. The diethyl ether extracts were combined and was washed thoroughly with water. The organic part was concentrated in a rotary evaporator under reduced pressure. It was then dried and anisaldehyde oxime obtained as a pale yellow liquid (0.97 g, 87 %). 1H NMR (CDCl3): δ 3.774 (s, 3H), 6.884 (d, 2H, J= 8.0 Hz), 7.471 (d, 2H, J= 8.0 Hz), 8.073 (s, 1H), 8.5 (br s, 1H).

13

C NMR (CDCl3): δ 55.22,

114.22, 124.3, 128.47, 149.5, 161.04.

Preparation of acryloyl-functionalized homopolymer from poly (4-vinyl benzylchloride) (MA): Acrylic acid (0.384 g, 5.33 mmol) was taken in a 25 mL two-necked r. b. flask. in dry DMF (6 mL) under nitrogen atmosphere and heated to 60 C. Potassium carbonate (K2CO3) (1.03 g, 7.46 mmol) was added slowly followed by addition of KI (0.04 g, 0.28 mmol) and the mixture was stirred for another 30 min at that temperature. Then a solution of poly (4-vinyl benzylchloride) (Mn ~ 5800) (0.4 g, 2.63 mmol) in dry DMF (2 mL) was added dropwise for about 30 minutes and the reaction was left to stir at 100 C for 36 h. Then the reaction was quenched and the product was then precipitated out from cold methanol, washed and dried under high vacuum. 1H NMR (CDCl3): δ 1.10 (br, CHCH2 polymer backbone), 1.68 (br, CHCH2 polymer backbone), S2


5.14 (br, -CH2O-(acrylate), polymer), 5.8 (br, alkene, polymer), 6.2 (br, alkene, polymer), 6.5 (br, Ar, polymer), 7.07 (br, Ar, polymer).

13

C NMR (CDCl3): 40.7, 66.3, 126.3, 128.5, 130.6,

131.4, 133.5, 135.2, 166.2. Synthesis of isoxazoline ring in polymeric scaffold: In a 25 mL two-necked r. b. flask anisaldehyde oxime (0.16 g, 1.07 mmol) in dry DCM (5 mL) was taken under nitrogen atmosphere with continuous stirring. Then iodosobenzenediacetate (0.72 g, 2.24 mmol) and MgSO4 (0.4 g, 3.33 mmol) were added into the solution at 0 °C for 10 min with vigorous stirring. MA (0.08 g, 0.425 mmol) in 2 ml of dry DCM was added slowly for 15 min at 0 C and the post reaction mixture was stirred for overnight at room temperature. Unreacted MgSO4 was then removed by filtration and the solvent was evaporated under reduced pressure. The residue was dissolved in 3 ml of THF and the product was precipitated out from cold hexane and dried under high vacuum. Formation of isoxazoline was confirmed by 1H NMR and 13C NMR analysis. 1H NMR (DMSOd6): δ 1.00 (br, CHCH2 polymer backbone), 1.62 (br, CHCH2 polymer backbone), 3.80 (br, CCH2CH-isoxazoline), 5.10 (br,-CHO-(isooxazoline), 5.20 (br, -CH2O-(isoxazoline), polymer) 6.94 (br, Ar, polymer), 7.11 (br, Ar, polymer).

13

C NMR (DMSO- d6): 29.7, 55.8, 56.1, 68.8,

114.5, 123.7, 129.1, 129.9, 131.9, 132.4, 133.5, 161.5, 170.6.

S3


NMR spectra: (b) 1H NMR spectra of acryloyl-functionalized homopolymer from poly(4-vinyl benzylchloride) *

*

O O

S4


13

C NMR spectra of acryloyl-functionalized homopolymer from poly(4-vinyl benzylchloride)

S5


(c) 1H NMR spectra of polymer containing isoxazoline ring *

*

O O

O N O

S6


13

C NMR spectra of polymer containing isoxazoline ring

S7


2.0. NMR spectra of the various compounds are given below: Figure S1: 1H NMR of poly(4-vinylbenzyl chloride) macro-CTA Cl

S S S S

Cl

S8


Figure S2: 1H NMR of polystyrene-block-poly(4-vinylbenzyl chloride) Cl

S S S S

Cl

S9


Figure S3: 1H NMR of Pentaerythrityl tetrabromide Br

Br

Br

Br

S10


13

C NMR of pentaerythrityl tetrabromide

S11


Figure S4: 1H NMR of Tetra-arm aldehyde O

O

O

O

O

O O

O

S12


13

C NMR of Tetra-arm aldehyde

S13


Figure S5: 1H NMR of tetra-arm oxime OH N

HO

N

O

N

O

O O

N OH

S14

OH


13

C NMR of tetra-arm oxime

S15


Figure S6. Molecular weight (Mn) vs. percentage conversion for the synthesis of P2 using XBDTB as chain transfer agent.

15000

1.89

1.68

13000 12000

1.47 11000 10000

1.26

9000 1.05 8000 20

30

40

50

% conversion

S16

60

70

80

PDI (Mw/Mn)

Molecular weight (Mn)

14000