10.1002/cctc.201900494
ChemCatChem
COMMUNICATION
ether, the reactant conversion and product selectivity were determined by
using GC (Agilent 7890) equipped with a flame ionization detector and a
DB-1301 column (30 m×0.25 mm), and the product yields are based on
isolated yields. The products were then characterized by 1H and 13C
NMR spectroscopy.
were investigated. Table 1 shows the scope of alcohols and
amines in HP-CeAlPO-5-catalyzed E-imines synthesis. Under
the optimized conditions, aniline was alkylated with various
benzyl alcohol derivatives (Table 1, 3a-3d). Substituted benzyl
alcohols with different functional groups (halides, alkyl, nitro,
trifluoromethyl) were isolated in excellent yields (80.6-89.1%,
Table 1, 3a-3d). In subsequent trials, various amines reacted
with 4-methoxyl-benzyl alcohol were also conducted. As can be
seen from Table 1 (3e-3m), 81.4-95.4% isolated yields of the
desired products were obtained over HP-CeAlPO-5. These data
indicate that substitutes with various electronic properties did not
have significant influence for the catalytic activity of HP-CeAlPO-
5 catalyst. Notably, the excellent isolated yields (81.4-87.9%) of
the corresponding imines by the ortho-substituted ones (Table 1,
3f, 3j, 3m) were obtained over HP-CeAlPO-5 catalyst. This is of
interest because these yields are difficult to obtain by reported
homogeneous Pd[2b] and Cu[4] catalysts as well as CeO2
catalyst[7].
Acknowledgements
Q. Ke was supported by Anhui Provincial Science Fund for Ex-
cellent Young Scholars (gxyqZD2018034). The work was sup-
ported by the National Science Foundation of China (grant
numbers 21476001, 21776002, 21306142). This work was also
supported by “Key Program for International S&T Cooperation
Projects of China” (No. YS2017YFGH001236) and the Natural
Science Foundation of Anhui Provincial Education Department
(KJ2017A056).
Keywords: Micropore • Stereoselective • E-imines • CeAlPO-5 •
Recycling ability of HP-CeAlPO-5 catalyst was examined by
conducting the cross-coupling reaction of benzyl alcohol with
aniline. Once the reaction was finished, the catalyst was filtered
with a mediate-rate filter paper, washed with toluene and reused
for other cycles, and the catalyst can be reused at least four
times without remarkable loss of the isolated yield (88.7-91.1%,
Table 1, 3a). Meanwhile, the inductively coupled plasma atomic
emission spectroscopy (ICP-AES) analyses showed that no
cerium species was detected in the solution after hot filtering
(<10 ppm). These results indicate that HP-CeAlPO-5 is an
intrinsically reusable heterogeneous zeolite catalyst.
N-benzylaniline
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Experimental Section
Catalytic activity test
A mixture of alcohol (1 mmol), toluene (2 mL), catalyst (50 mg, ~2.5wt%
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a 10 mL round-bottomed flask. The mixture was stirred at 40 °C for 2-4 h
under air atmosphere. After cooling to RT, the catalyst was separated by
filtration. The filtrate was diluted with diethyl ether (~5 mL) and washed
twice with water (~5 mL). Before purification of the products by silica-gel
chromatography with an eluent consisting of diethyl ether and petroleum
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