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Si(OCH ) ); 1.83 (q, 2H; =NÀCH ÀCH ÀCH ÀSi), 0.54 ppm (t, 2H; À
Synthesis of 4-(2-trimethoxysilylethyl)pyridine (6) and 2-(2-tri-
methoxysilylethyl)pyridine (7): Synthesis was carried out under an
argon atmosphere. Trichlorosilane (10.84 g, 80 mmol) was dissolved
in dry acetonitrile (250 mL) and 4-vinylpyridine or 2-vinylpyridine
3
3
1
2
2
2
3
CH ÀSi); C NMR (250 MHz, CDCl ): d=136.8 (ÀNÀCHÀNÀ), 128.1
2
3
(
ÀNÀCHÀCHÀN=), 120.7 (ÀNÀCHÀCHÀN=), 56.2 (ÀSi(OCH ) ), 55.7
3
3
(=NÀCH ÀCH À), 25.1 (=NÀCH ÀCH ÀCH ÀSi), 7.4 ppm (ÀCH ÀSi).
2
2
2
2
2
2
(8.41 g, 80 mmol) were added dropwise whilst stirring at room
Compound 2 was distilled at 1078C under vacuum (1 mbar). N-(3-
Propyltrimethoxysilane)-2-methylimidazole was obtained in a 78%
yield as a colorless and transparent liquid.
1
temperature. After the vinylpyridine had been completely added,
the reaction mixture was refluxed for 2 h. After cooling to ambient
temperature, a yellowish solution was obtained. Then the mixture
was cooled to approximately 08C and dry triethylamine (24.3 g,
H NMR (250 MHz, CDCl ): d=6.78 (s, 1H; ÀNÀCHÀCHÀN=), 6.71 (s,
3
1
H; ÀNÀCHÀCHÀN=), 3.71 (t, 2H; =NÀCH ÀCH À), 3.46 (s, 9H;
2
2
0
.24 mol) and dry methanol (25 mL) were added. The obtained col-
Si(OCH ) ), 2.26 (s, 3H; ÀNÀCÀCH ), 1.72 (q, 2H; =NÀCH ÀCH À
3
3
3
2
2
orless precipitate was filtered off under argon and the solvent was
removed under vacuum conditions. The crude product was
washed with THF (150 mL) and a colorless solid precipitated again.
The precipitate was filtered off and the solvent was removed
under vacuum conditions. For purification, the crude product was
distilled under vacuum conditions. Compound 6 was distilled at
111 8C under vacuum (1 mbar). 4-(2-Trimethoxysilylethyl)pyridine
13
CH ÀSi), 0.49 ppm (t, 2H, ÀCH ÀSi); C NMR (250 MHz, CDCl ): d=
2
2
3
1
44.2 (ÀNÀC(CH )ÀNÀ), 126.8 (ÀNÀCHÀCHÀN=), 119.0 (ÀNÀCHÀ
3
CHÀN=), 50.5 (ÀSi(OCH ) ), 48.0 (=NÀCH ÀCH À), 24.1 (=NÀCH À
3
3
2
2
2
CH ÀCH ÀSi), 12.8 (ÀCH ÀSi), 6.0 ppm (ÀNÀCÀCH ).
2
2
2
3
Compound 3 was distilled at 1388C under vacuum (1 mbar). N-(3-
Propyltrimethoxysilane)-2-isopropylimidazole was obtained in
1
a 76% yield as a colorless and transparent liquid. H NMR
was obtained in a 75% yield as a colorless and transparent liquid.
1
(
250 MHz, CDCl ): d=7.04 (d, 1H; ÀNÀCHÀCHÀN=), 6.88 (d, 1H, À
H NMR (500 MHz, CDCl
3
): d=7.97 (d, 2H; NÀCHÀCHÀ), 6.62 (d,
), 2.20 (t, 2H; SiÀCH ÀCH
À); C NMR (500 MHz, CDCl ): d=
152.2 (NÀCHÀCHÀCÀ), 148.6 (NÀCHÀCHÀ), 122.3 (NÀCHÀCHÀ), 49.3
(SiÀ(OCH ), 27.2 (SiÀCH ÀCH À), 9.2 ppm (SiÀCH ÀCH À); Si NMR
(IGATED, 500 MHz, CDCl ).
): d=À44.4 ppm (SiÀ(OCH
3
NÀCHÀCHÀN=), 3.95 (t, 2H; =NÀCH ÀCH À), 3.67 (s, 9H; Si(OCH ) ),
2H; NÀCHÀCHÀ), 3.04 (s, 9H; SiÀ(OCH
3
)
3
2
2
À
2
2
3 3
13
3
.09 (m, 1H; ÀNÀCÀCH), 1.95 (q, 2H; =NÀCH ÀCH ÀCH ÀSi), 1.44
), 0.45 ppm (t, 2H; SiÀCH ÀCH
2
2
3
2
2
2
13
(
(
d, 6H; CH ÀCHÀCH ), 0.72 ppm (t, 2H; ÀCH ÀSi);
C NMR
3
3
2
2
9
250 MHz, CDCl ): d=152.7 (ÀNÀC(CH)ÀNÀ), 126.9 (ÀNÀCHÀCHÀ
3
)
3
2
2
2
2
3
N=), 118.4 (ÀNÀCHÀCHÀN=), 50.5 (ÀSi(OCH ) ), 47.4 (=NÀCH ÀCH À
3
)
3 3
3
3
2
2
)
6
, 25.7 (CHÀ(CH ) ), 24.6 (=NÀCH ÀCH ÀCH ÀSi), 21.8 (CHÀ(CH ) ),
3
2
2
2
2
3 2
Compound 7 was distilled at 1068C under vacuum (1 mbar). 2-(2-
.1 ppm (ÀCH ÀSi).
2
Trimethoxysilylethyl)pyridine was obtained in a 33% yield as a col-
1
Synthesis of N-(3-propyltrimethoxysilane)pyrazole (4) and N-(3-
propyltrimethoxysilane)-3,5-dimethylpyrazole (5): Synthesis is
carried out under argon atmosphere. Sodium hydride (2.9 g,
orless and transparent liquid. H NMR (500 MHz, CDCl ): d=8.06
3
(d, 1H; NÀCHÀCHÀ), 7.11 (t, 1H; NÀCHÀCHÀCHÀ), 6.70 (d, 1H; NÀ
CÀCHÀ), 6.62 (t, 1H; NÀCHÀCHÀ), 3.10 (s, 9H; SiÀ(OCH ) ), 2.44 (t,
3
3
1
3
0
.12 mol) was dissolved in absolute THF (150 mL) and the mixture
2H; SiÀCH ÀCH À), 0.68 ppm (t, 2H; SiÀCH ÀCH À). C NMR
2
2
2
2
was cooled to approximately 08C with an ice bath. The respective
pyrazole (0.12 mol; for 4: 8.3 g of pyrazole; for 5: 11.5 g of 3,5-di-
methylpyrazole) was added portionwise whilst stirring. After the re-
spective pyrazole had been completely added, the ice bath was re-
moved and the mixture was maintained whilst stirring until no
more hydrogen gas was evacuated. Then 3-iodopropyltrimethoxy-
silane (23.12 g, 0.09 mol) was added and the mixture was main-
tained at reflux overnight. The slightly yellow suspension was fil-
tered off and the solvent removed under vacuum conditions. By
addition of absolute dichloromethane (150 mL), a colorless precipi-
tate appeared and was filtered off under an argon atmosphere. For
purification, the crude product was distilled under vacuum condi-
tions.
(500 MHz, CDCl ): d=162.5 (NÀCÀCHÀ), 148.2 (NÀCHÀCHÀCH),
3
135.3 (NÀCHÀCHÀCHÀ), 121.2 (NÀCÀCHÀ), 119.8 (NÀCHÀCHÀ), 49.3
(SiÀ(OCH ) ), 30.2 (SiÀCH ÀCH À), 8.41 ppm (SiÀCH ÀCH À);
3
3
2
2
2
2
29
Si NMR (IGATED, 500 MHz, CDCl ): d=À43.2 ppm (SiÀ(OCH ) ).
3
3 3
Synthesis of chloropropyl- or chloroethyl-modified silica nano-
particles: The previously prepared silica nanoparticle solution
(32 mL) was degassed under vacuum for several minutes to
remove excessive ammonia. Then, the respective 2-chloroalkyltri-
methoxysilane (14.29 mmol; 2.84 g of 3-chloropropyltrimethoxysi-
lane, 2.64 g of 2-chloroethyltrimethoxysilane) were added drop-
wise. The solution was stirred at room temperature for 24 h.
Synthesis of N-propylimidazole-modified silica nanoparticles
(
SiO ImR with R=H, Me, iPr): The previously prepared silica nano-
2
Compound 4 was distilled at 918C under vacuum (1 mbar). N-(3-
particle solution (32 mL) was degassed under vacuum for several
minutes to remove excessive ammonia. Then, the respective N-(3-
propyltrimethoxysilane)imidazole (14.29 mmol, 1–3) was added
dropwise. The solution was stirred at room temperature for 24 h.
Propyltrimethoxysilane)pyrazole was obtained with a yield of 82%
1
as a colorless and transparent liquid. H NMR (250 MHz, CDCl3):
d=7.60 (d, 1H, CH ÀNÀCHÀCHÀCHÀ), 7.48 (d, 1H; CH ÀNÀCHÀ
2
2
CHÀCHÀ), 6.33 (t, 1H; CH ÀNÀCHÀCHÀCHÀ), 4.22 (t, 2H; =NÀCH À
2
2
CH À), 3.65 (s, 9H; Si(OCH ) ), 2.08 (q, 2H; =NÀCH ÀCH ÀCH ÀSi),
Synthesis of N-propylpyrazole-modified silica nanoparticles
(SiO PyrazoleR with R=H, Me): The previously prepared silica
2 2
2
3 3
1
2
2
2
3
0
(
.72 ppm (t, 2H; ÀCH ÀSi); C NMR (250 MHz, CDCl ): d=140.0
2
3
CH ÀNÀCHÀCHÀCHÀ); 129.0 (CH ÀNÀCHÀCHÀCHÀ), 105.0 (CH À
nanoparticle solution (32 mL) was degassed under vacuum for sev-
eral minutes to remove excessive ammonia. Then, N-(3-propyltri-
methoxysilane)pyrazole (4) (3.3 g, 14.29 mmol) or N-(3-propyltrime-
thoxysilane)-3,5-dimethylpyrazole (5) (3.7 g, 14.29 mmol) was
added dropwise. The solution was stirred at room temperature for
24 h.
2
2
2
NÀCHÀCHÀCHÀ), 54.1 (=NÀCH ÀCH À), 50.4 (ÀSi(OCH ) ), 23.8 (=NÀ
2
2
3 3
CH ÀCH À), 6.0 ppm (ÀCH ÀSi).
2
2
2
Compound 5 was distilled at 1198C under vacuum (1 mbar). N-(3-
Propyltrimethoxysilane)-3,5-dimethylpyrazole was obtained in
1
a 63% yield as a colorless and transparent liquid. H NMR
(
250 MHz, CDCl ): d=5.85 (s, 1H; CH ÀNÀCÀCHÀ); 4.02 (t, 2H; =
Synthesis of 4-ethylpyridine- and 2-ethylpyridine-modified silica
3
2
NÀCH ÀCH À); 3.64 (s, 9H; Si(OCH ) ); 2.30 (d, 6H; ÀNÀCÀCH ), 1.99
nanoparticles (SiO 4-Py and SiO 2-Py, respectively): The previ-
2
2
3 3
3
2
2
1
3
(
(
q, 2H; =NÀCH ÀCH ÀCH ÀSi), 0.70 ppm (t, 2H; ÀCH ÀSi); C NMR
ously prepared silica nanoparticle solution (32 mL) was degassed
under vacuum for several minutes to remove excessive ammonia.
Then, 4-(2-trimethoxysilylethyl)pyridine (3.2 g, 14.29 mmol) or 2-(2-
trimethoxysilylethyl)pyridine are (3.2 g, 14.29 mmol) were added
dropwise. The solution was stirred at room temperature for 24 h.
2
2
2
2
250 MHz, CDCl ): d=146.9 (CH ÀNÀCÀCHÀCÀ); 138.4 (CH ÀNÀCÀ
3
2
2
CHÀCÀ), 104.6 (CH ÀNÀCÀCHÀCÀ), 50.7 (=NÀCH ÀCH À), 50.4 (À
2
2
2
Si(OCH ) ), 23.7 (=NÀCH ÀCH À), 13.3 (CH ÀNÀCÀCH ), 10.8 (CH À
3
3
2
2
2
3
2
NÀNÀCÀCH ), 6.0 ppm (ÀCH ÀSi).
3
2
Chem. Eur. J. 2014, 20, 10763 – 10774
10772
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim