3
2
A. Noschese et al. / Journal of Catalysis 340 (2016) 30–40
Table 1
Reduction of NB catalyzed by Au-Cd, Au-Cb, Au-C
c
, Au-C
e
at 35 °C.
Entrya
Catalyst
Time (min)
Conversionb (mol%)
Selectivityb (%)
AOB
AB
AN
1
2
3
4
5
Au-Cd
Au-Cb
60
60
60
45
90
>99
85
66
>99
86
–
–
>99
2.9
2.5
>99
5
66
55
–
16
6.9
–
Au-C
Au-C
–
c
e
67
14
a
Reaction conditions: NB (2.54 mmol; 0.42 M), gold catalyst (50 mg; NB/Au molar ratio = 500); NaBH
4
(15.2 mmol; 2.53 M), 35 °C, methanol (6 mL), N
2
protective
atmosphere (1 bar).
b
Conversion and selectivity evaluated by GC–MS using anisole as internal standard.
0
0
(
[
d, 2H, J = 8.7 Hz), 3.55 (br s, 2H)]; 3,3 ,4,4 -tetrachloroazobenzene
(250 MHz, CD Cl ): 7.94 (d, 2H, J = 2.1 Hz), 7.75 (dd, 2H,
= 8.4 Hz, J = 2.4 Hz), 7.57 (d, 2H, J = 8.4 Hz)]; 1,2-bis(3,4-dichlor
ophenyl)hydrazine [(250 MHz, CD Cl ): 7.13 (d, 2H, J = 8.8 Hz),
.87 (d, 2H, J = 2.6 Hz), 6.63 (dd, 2H, J = 8.8 Hz, J = 2.6 Hz)]; 1,2-
chloro-4-aniline [(250 MHz, CD Cl ): 7.05 (d, 1H, J = 8.6 Hz), 6.71
d, 1H, J = 2.7 Hz), 6.48 (dd, 1H, J = 8.6 Hz, J = 2.7 Hz), 3.59 (br s,
H)]. WAXD patterns were obtained in reflection mode with an
2
2
J
1
2
2
2
6
1
2
2
2
(
2
1
2
automatic Bruker D8 powder diffractometer using the Ni-filtered
Cu K radiation. TEM analysis was carried out with a JEOL (JEM
010) electron microscope operating at 300 kV, with a point-to-
a
3
point resolution of 0.17 nm (at Scherzer defocus). Specimens were
sonicated in 2-propanol, and then transferred (10 mL) onto a cop-
per grid covered with a lacey carbon film supplied from Assing. The
size distribution profile of the AuNPs was manually calculated
using the software Photoshop CC2014. SEM analysis was carried
out with
FE-SEM). AAS analysis was performed on a PerkinElmer AAnalyst
00 spectrophotometer using an Au hollow cathode lamp
Perkin–Elmer). ICP-OES was performed on a Perkin–Elmer Optima
7000 DV instrument. GC–MS analysis was carried out on a GC–MS
890A/5975C chromatograph from Agilent Technologies equipped
with an DB 17MS column (phenyl/methyl-polysiloxane, 30 m,
.25 mm ID) and a mass-selective detector. The surface areas of
the polymer matrix were determined by nitrogen absorption at
7 K of the AuNPs-sPSB powders degassed at 40 °C under vacuum
a scanning electron microscope (Zeiss Sigma-VP
1
(
Fig. 1. WAXD spectra of: (a) Au-Cd; (b) Au-Cb; (c) Au-Cc; (d) Au-Ce. The size of the
AuNPs was determined by the Scherrer method using the h111i reflection of the
crystalline AuNPs at 2h = 38.2°.
7
1
-propanol (P99.5%), 1-butanol (98%), acetone (P99%), sodium
0
borohydride (>98%), anisole (99%), nitrobenzene (>99.5%),
4-nitrobenzyl alcohol (99%), 4-nitrobenzaldehyde (98%),
4-nitroaniline (P99%), 4-nitrotoluene (99%), 4-nitroanisole (99%),
4-chloronitrobenzene (99%), 1,2-dichloro-4-nitrobenzene (99%),
4-nitrobenzoic acid (>98%), 4-nitrophenol (P99%,) were purchased
7
for 24 h using a Nova Quantachrome 4200e. The specific surface
area was calculated using the BET method.
from commercial sources (Carlo Erba, TCI, Sigma–Aldrich, Labscan
and Romil) and used as received. Deuterated solvents were pur-
chased from Euriso-Top or Sigma–Aldrich and used as received.
2
.3. Synthesis of the Au-Cd, Au-Cb, Au-Cc and Au-Ce catalysts
The
polybutadiene copolymer (sPSB) and the corresponding catalysts
Au-Cd, Au-Cb, Au-C and Au-C (the greek symbol stands for the
multiblock
syndiotactic
polystyrene-co-1,4-cis-
2.2. Instrumentation and methods
c
e
crystalline form of the host polymer phase) were synthesized as
previously reported [15,16,22]. Briefly: a 1 L round-bottomed
three-necked flask equipped with a magnetic stirring bar was
charged with anhydrous THF (650 mL) and finely grounded sPSB
The NMR characterization of the reaction products was per-
formed on Avance Bruker spectrometers (600, 400, 300 and
1
2
4
50 MHz for H) using the following 1H NMR diagnostic signals:
-aminobenzyl alcohol [(300 MHz, CD Cl ): 7.04 (d, 2H,
2
2
(4.9 g; x
ature and then heated to reflux for 1 h to reach the complete swel-
ling of the polymer. HAuCl O (0.210 g; 0.56 mmol) was added
ꢀ3H
S
= 0.88). The mixture was stirred for 24 h at room temper-
J = 8.0 Hz), 6.60 (d, 2H, J = 8.0 Hz), 4.40 (s, 2H), 3.52 (br s, 2H)];
4
4
2
-aminoaniline [(250 MHz, CD
2
Cl
2
), 6.55 (s, 4H), 3.77 (br s, 2H)];
4
2
-toluidine [(400 MHz, CD Cl
H, J = 8.2 Hz), 3.88 (br s, 2H), 2.14 (s, 2H)]; 4,4 -
2
2
), 6.86 (d, 2H, J = 8.0 Hz), 6.55 (d,
at room temperature and the resulting slurry kept under stirring
for 24 h, then refluxed for 1 h. A THF solution of sodium triethyl-
borohydride (10 mL, 1.0 M) was added at 25 °C producing a rapid
change of the color from pale yellow to red. The polymer was
rapidly coagulated in a plenty of methanol, recovered by filtration,
washed with fresh methanol and dried in vacuo at room tempera-
ture. The resulting catalyst Au-Cd was analyzed by AAS and ICP-
OES to assess the gold content of 2% w/w. The annealing of Au-Cd
0
dimethoxyazobenzene [(300 MHz, CD
H), 3.79(s, 6H)]; 4-anisidine [(300 MHz, CD
2
Cl
2
), 8.16 (m, 4H), 6.92 (m,
Cl ), 6.6 (m, 4H),
.64 (s, 3H), 3.55 (br s, 2H)]; 4,4 -dichloroazoxybenzene
Cl ): 8.19 (d, 2H, J = 8.4 Hz), 8.10 (d, 2H,
J = 8.8 Hz), 7.45 (d, 2H, J = 8.4 Hz), 7.39 (d, 2H, J = 8.8 Hz)];
-chloroaniline [(300 MHz, CD Cl ): 6.95 (d, 2H, J = 8.7 Hz), 6.59
4
3
[
2
2
0
(300 MHz, CD
2
2
4
2
2