Supported RAPTA Complex Catalyst for Organic Reactions
tometer with a CuKa source in the 2q range 10–808. The data were
collected with a step of 1.08minÀ1. Transmission electron microsco-
py (TEM) micrographs were recorded on a MET-JEOL 2000 EX-II mi-
croscope at an operating voltage of 200 kV. The particles were dis-
persed in ethanol by sonication, loaded on a carbon coated
copper grid, and then allowed to dry at room temperature before
recording the micrographs. ICP-MS analyses of the catalyst before
as well as after the reactions were performed on an Agilent HP
7500c instrument. 5 mg of each sample was dissolved in 2.5 mL of
concentrated aqua regia and the volume was adjusted to 50 mL in
a volumetric flask. This solution was then used for the elemental
analysis using 5 ppb of Rh as internal standard. All reagents were
obtained from commercial suppliers and used without any further
purification, with the exception of the phosphane ligand 1,3,5-
triaza-7-phosphatricyclo[3.3.1.13,7]decane (PTA),[25] the dimeric pre-
cursor [{RuCl(m-Cl)(h6-p-cymene)}2],[26] the mononuclear complex
[RuCl2(h6-p-cymene)(PTA)] (4),[27] and the (Z)-2-en-4-yn-1-ol deriva-
tives,[28] which were prepared by following methods reported else-
where.
PTA-functionalized magnetic nanoferrites (2): 1 (4 g, 9 mmol) and
the silica-coated nanoferrite (4 g) were dispersed by sonication in
of CHCl3 (100 mL) and the mixture was heated at reflux for 48 h.
Then, the product 2 was separated magnetically, washed with
CHCl3 (3ꢃ50 mL), and dried under vacuum at 608C for 2 h. The
weight percentage of P in the solid was found to be 10% by ICP-
MS analysis. Ferrite 2 was characterized by XRD, TEM, and FTIR
spectroscopy (see the Supporting Information).
RAPTA-functionalized magnetic nanoferrites (3): 2 (2 g) was dis-
persed in methanol (20 mL) under N2 atmosphere. A solution of
[{RuCl(m-Cl)(h6-p-cymene)}2] (2.5 g; 4.1 mmol) in methanol (100 mL)
was added to it and the mixture was stirred at room temperature
for 24 h. The resulting product 3 was separated magnetically,
washed with methanol (3ꢃ30 mL) and dried under vacuum. The
weight percentages of P and Ru in the solid were found by ICP-MS
analysis to be 1.2 and 1.6 wt%, respectively. Ferrite 3 was charac-
terized by XRD, TEM, and FTIR, spectroscopy (Figure 2).
Catalytic hydration of nitriles
Under
a
nitrogen atmosphere, nanoferrite
3
(100 mg,
Synthesis of catalysts
1.58 mol% Ru), water (3 mL) and the corresponding nitrile
(1 mmol) were introduced into a crimp-sealed thick-walled glass
tube equipped with a pressure sensor and a magnetic stirrer. The
reaction tube was placed inside the cavity of a CEM Discover fo-
cused microwave synthesis system, operated at 1508C (tempera-
ture monitored by a built-in infrared sensor), 100 W, and 100–
120 psi (1 psi=6.89 kPa) for the indicated time in each case. The
course of the reaction was monitored by regular sampling and
analysis by GC. After completion of the reaction, the mixture
turned clear and the catalyst was deposited on the magnetic bar
within 30–45 s, being easily removed from reaction mixture using
an external magnet. After separation of catalyst, the clear liquid
was cooled slowly and analytically pure crystals of the amides that
deposited were isolated from the water medium by simple decant-
ation/filtration. Identity of the resulting amides was assessed by
Fe3O4 magnetic nanoparticles: Iron(II) chloride tetrahydrate (10.0 g;
50 mmol) and iron(III) chloride hexahydrate (16.2 g; 60 mmol) were
separately dissolved in water (100 mL) by stirring at room tempera-
ture. The two solutions were then mixed and stirred for 15 min.
Ammonium hydroxide (25%) was added slowly to adjust the pH of
the solution to 9–10. The reaction mixture was continually stirred
for 4 h at room temperature. The precipitated nanoparticles were
separated magnetically, washed with water until the pH reached 7,
and then dried under a vacuum at 608C for 2 h. Yield: 9.25 g.
Silica coating of the Fe3O4 magnetic nanoparticles: The above syn-
thesized Fe3O4 ferrite (2 g, 8.64 mmol) was dispersed in isopropa-
nol (500 mL) and the mixture was sonicated for 30 min. To this so-
lution, concentrated ammonium hydroxide (25%; 50 mL) was then
added, followed by the dropwise addition of a solution of tetrae-
thylorthosilicate (1 mL, 4.5 mmol) in isopropanol (100 mL) over 1 h.
The solution was stirred for 6 h at room temperature. The silica-
coated magnetic nanoparticles were recovered by centrifugation,
washed thrice with water (50 mL) and thrice with ethanol (50 mL),
and then dried under vacuum at 608C for 2 h. Yield: 1.95 g.
1
comparison of their H and 13C{1H} NMR spectra with those previ-
ously described, and by their fragmentations in GC/MS. Analytical
and spectroscopic data for new compounds are as follows (1H and
13C{1H} NMR spectra are included in the Supporting Information
file):
Ethyl 4-carbamoylbenzoate: White solid; IR (KBr): n˜ =3390 (m),
2922 (s), 2550 (m), 2358 (m), 1964 (w), 1926 (w), 1652 (s), 1567 (m),
1520 (m), 1458 (s), 1376 (s), 1288 (s), 1180 (m), 1131 (m), 1111 (m),
1023 (m), 1013 (m), 974 (w), 905 (w), 871 (m), 768 (w), 724 (m),
621 cmÀ1 (w); MS (EI 70 eV): m/z (%)=193 (27) [M+], 177 (36), 148
1-(3-(trimethoxysilyl)propyl)-3,5-diaza-1-azonia-7-phosphatricy-
clo[3.3.1.13,7]decane iodide (1): PTA (2 g, 12.7 mmol) and (3-iodo-
propyl)trimethoxysilane (3.15 mL, 15.3 mmol) was taken up in dry
acetonitrile (100 mL) under nitrogen atmosphere and heated at
reflux for 48 h with stirring. The solvent was then evaporated and
the resulting solid residue was washed with hexane (3ꢃ30 mL)
and dried under vacuum to afford the desired product 1 as a
white powder (5.34 g, 94%). IR (KBr): n˜ =3404 (m), 2964 (m), 2910
(m), 1684 (m), 1460 (s), 1406 (m), 1388 (m), 1346 (w), 1325 (w),
1313 (s), 1281 (s), 1279 (m), 1263 (m), 1248 (m), 1190 (w), 1146 (w),
1120 (s), 1093 (s), 1023 (s), 983 (m), 935 (w), 921 (s), 898 (m), 815
1
(100), 121 (18), 103 (41), 76 (61), 50 (45), 29 (46); H NMR (CD3OD):
d=1.39 (t, 3H, 3J(H,H)=7.1 Hz, OCH2CH3), 4.38 (q, 2H, 3J(H,H)=
3
7.1 Hz, OCH2CH3), 7.94 (d, 2H, J(H,H)=8.5 Hz, Ar), 8.08 ppm (d, 2H,
3J(H,H)=8.5 Hz, Ar); 13C{1H} NMR (CD3OD): d=12.7 (s, OCH2CH3),
60.6 (s, OCH2CH3), 126.9 and 128.6 (s, CH of Ar), 132.6 (s,
CC(=O)OEt), 137.3 (s, CC(=O)NH2), 165.3 (s, CC(=O)OEt), 169.4 ppm
(s, CC(=O)NH2). Elemental analysis calcd (%) for C10H11NO3: C 62.17,
H 5.74, N 7.25; found: C 62.30, H 5.81, N 7.28.
1
(s), 767 (s), 747 (m), 732 (m), 687 (w), 635 (w), 556 cmÀ1 (s); H NMR
(D2O): d=2.75 (s, 9H, Si(OCH3)), 3.91 (m, 8H, PCH2N and N(CH2)3Si),
4.40 (m, 4H, NCH2N and N(CH2)3Si), 4.58 (m, 2H, NCH2N), 4.82 ppm
(m, 4H, PCH2N+ and NCH2N+); 13C{1H} NMR (D2O): d=45.2 (s, 2C)
and 56.4 (s, N(CH2)3Si), 45.5 (s, 2C, PCH2N), 50.1 (s, Si(OCH3)), 56.8 (s,
PCH2N+), 69.2 (s, 2C, NCH2N), 80.1 ppm (s, NCH2N+); 31P{1H} NMR
(D2O): d=À85.80 ppm (s). Elemental analysis calcd (%) for
C12H27N3O3IPSi: C 32.22, H 6.08, N 9.39; found: C 32.41, H 6.13,
4-((Trimethylsilyl)ethynyl)benzamide: White solid; IR (KBr): n˜ =3388
(s), 3185 (s), 2921 (s), 2852 (s), 2744 (w), 2360 (w), 2157 (m), 1943
(w), 1656 (s), 1605 (s), 1550 (m), 1505 (w), 1460 (m), 1403 (s), 1304
(w), 1284 (w), 1252 (m), 1223 (w), 1178 (w), 1139 (m), 1118 (w),
1084 (w), 1015 (w), 843 (s), 778 (s), 759 (s), 698 (w), 668 (w), 650
1
(m), 589 cmÀ1 (m); H NMR (CD3OD): d=0.24 (s, 9H, Si(CH3)3), 7.49
N 9.44. 31P{1H}, H, and 13C{1H} NMR and IR spectra can be found in
(d, 2H, 3J(H,H)=8.0 Hz, Ar), 7.83 ppm (d, 2H, 3J(H,H)=8.0 Hz, Ar);
13C{1H} NMR (CD3OD): d=À2.5 (s, Si(CH3)3), 98.9 (s, CCꢂCSi(CH3)3),
1
the Supporting Information.
ChemSusChem 2011, 4, 104 – 111
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
109