Palladium NPs-Decorated Graphene Nanosheets as Highly Regioselective Catalyst for Cyclotrimerization Reaction
Cheng et al.
Table S1. Catalytic performances comparisons for commercial 5% Pd/C, Pd NPs/GR and Pd NPs/CSGR catalysts.a
Entry
Catalyst
5%Pd/Ce
Acetylene
Conversionb
Yieldc (%)
Regioselectivityd
1
2
3
4
5
6
7
8
1a
1a
1a
1a
1a
1b
1c
1d
35.1
79.2
97.6
100
100
100
100
100
18.7
72.4
89.3
96.5
96.9
99.1
98.5
97.8
76.16:23.84f
90.56:9.44
99.50:0.35g
100:0
Pd NPs/GR
Pd NPs/CSGR-OH
Pd NPs/CSGR-NH2
Pd NPs/ECSGR-NH2
Pd NPs/CSGR-NH2
Pd NPs/CSGR-NH2
Pd NPs/CSGR-NH2
100:0
100:0
100:0h
100:0i
aThe reaction conditions were as follows: acetylene (10 mM), catalyst (3 mol %). TMSCl (2 mL) in benzene/n-butanol (60 mL, 10:0.6, v/vꢂ at 40 ꢀC for 8 h. bDetermined
by GC analysis. cIsolated yield. dRatio of 1, 3, 5-isomer and 1, 2, 4-isomer, detected by GCMS. eThe diameter of the Pd particles was 28–34 ꢁm. f Some unidentified
brown oil was also isolated. gSome unidentified compounds were also detected (0.15%). hThe reaction was at 80 ꢀC under argon for 16 h, some unidentified oil was also
observed. i20 h was needed instead of 8 h.
S2.3.4. Preparation of Chitosan Functionalized
Graphene (CSGR-OH)
S3. CATALYTIC PERFORMANCE OF THE
PD NPs/CSGR COMPOSITES
Experimental results revealed that in addition to 1a, other
acetylenes with different functional groups such as esters
(ethyl propiolate, 1b), bromines (3-bromo-1-propyne, 1c),
and aromatic rings (phenylacetylene, 1d, tested as a refer-
ence) groups are tolerated. Catalyzed by Pd NPs/CSGR-
NH2 (Cat. 1), the reactions of 1b, 1c and 1d proceeded
smoothly with yields of 99.1%, 98.5%, 97.8%, respec-
tively, all exclusively producing 1, 3, 5-isomers (entries
6–8, Table S1), indicating that the catalysts can provide
A stock solution of chitosan in aqueous acetic acid
was prepared by dissolving 2 g chitosan in 200 mL
of aqueous acetic acid. Grafting of chitosan onto the
graphene surface was conducted by using EDC (1-ethyl-
3-(3-dimethylaminopropyl) carbodiimide and NHS (N-
hydroxysuccinimide) as coupling agents, in which GO
were dispersed in deionized water followed by reaction
with a mixture of EDC and NHS (EDC/NHS = 1:2.5) for
2 h to activate the carboxylic acid groups on the graphene
superior regiocontrol in the cyclotrimerization reaction.
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oxide. Subsequently, the desired amount of chitosan solu-
IP: 130.63.180.147 On: Wed, 13 Aug 2014 19:28:34
tion was added into the GO dispersion with vigorous stir-
Copyright: American Scientific Publishers
S4. CHARACTERIZATION OF PD NPs/CSGR
CATALYST
ꢀ
ring. Then the mixture was carried out at 88 C for 24 h
under N2. After reaction, the reaction mixture was cen-
trifuged, and washed with ethanol and distilled water for
several times, the obtained brown black solid was collected
S5. PROOFS FOR THE
CYCLOTRIMERIZATION PRODUCTS
ꢀ
and dried at 65 C under vacuum for 24 h, the intermedi-
Trimethyl-1, 3, 5-tricarboxylate (2a) Solid, mp 145–
ate was called CSGR-OH. In this step, most of the epoxy
groups and other oxygen-bearing groups on the graphene
oxide surface were also reduced.
ꢀ
1
ꢀ
148 C. H NMR (600 MHz, CDCl3, 27 C): ꢇ 3.9854
(s, 9H), 8.8480 (s, 3H); 13C NMR (150 MHz, CDCl3,
27 C): ꢇ 52.6623, 76.8961, 77.1067, 77.3174, 131.2712,
ꢀ
134.6224, 165.4435; MS m/z: 253, 252, 222, 221, 193,
147, 102, 75; IR (KBr, cm−1ꢂ: 3093, 3022, 2964, 2847,
1725, 1435, 1260, 1002, 873, 744, 718, 493.
Trimethyl-1, 2, 4-tricarboxylate (3a) Solid, mp 38–
ꢀ
ꢀ
40 C. 1H NMR (600 MHz, CDCl3, 27 C): ꢇ 3.8804
(s, 3H), 3.8953 (s, 3H), 3.9148 (s, 3H), 7.6918–7.7158
(s, 1H), 8.1367–8.1464 (d, 1H), 8.3537–8.3777 (d, 11H);
13C NMR (150 MHz, CDCl3, 27 ꢀC): ꢇ 52.8443,
52.9113, 76.9440, 77.1546, 77.3652, 128.9158, 130.2658,
131.6638, 132.2670, 132.4872, 165.3382, 166.8223,
167.5691; MS m/z: 253, 252, 222, 221, 193, 103, 75,
59; IR (KBr, cm−1ꢂ: 3009, 2951, 2899, 2847, 1731, 1435,
1299, 1241, 1112, 1067, 989, 860, 751, 577, 493.
Triethyl-1, 3, 5-tricarboxylate (2b) Solid, mp 134–
140 ꢀC. 1H NMR (600 MHz, CDCl3, 27 ꢀC): 1.4338–
1.4579 (m, 9H), 4.4469–4.4710 (m, 6H), 8.8411 (s, 3H);
13C NMR (150 MHz, CDCl3, 27 ꢀC): ꢇ 14.3346,
61.7105, 76.9152, 77.1259, 77.3461, 131.5106, 134.4213,
Fig. S2. FTIR spectra of (a) phthaloyl chitosan; (b) ECSGR and (c) Pd
NPs/ECSGR.
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J. Nanosci. Nanotechnol. 11, 5159–5168, 2011