10.1002/chem.201805942
Chemistry - A European Journal
FULL PAPER
Syntheses of alkoxysilylated cyclohexasiloxane (6MR-1)
glass tubes. Tetramethylsilane (TMS) was used as an internal reference
at 0 ppm. CDCl3 or EtOH-d6 was used to obtain lock signals. A small
amount of Cr(acac)3 (acac: acetylacetonate) was added as a relaxation
agent for 29Si nuclei except for 4MR-1 and 6MR-1. 29Si NMR spectra were
measured with a 45° pulse and a recycle delay of 10, 20, or 30 s. HR-MS)
analysis was conducted by using an Exactive Plus (Thermo Fisher
Scientific) instrument. Low resolution ESI-MS analysis was conducted by
using a JMS-T100 CS AccuTOF (JEOL) instrument. The samples were
dissolved in methanol. MALDI-TOF MS spectra were recorded on a Bruker
Autoflex instrument with dithranol as a matrix. GPC was carried out using
a LC-9100 NEXT with a recycling preparative HPLC system using a
refractive index detector (Japan Analytical Industry Co., Ltd.). Two types
of cross-linked polystyrene-divinylbenzene copolymer packed columns
(YMC-GPC T2000 and YMC-GPC T4000; exclusion limits of 2,000 and
4,000, respectively, and theoretical plate > 20,000) were used with
chloroform as the eluent at a flow rate of 7.0 mL min−1 for 4MR-1, 6MR-1,
crude product derived from 6MR-1, and dimethylvinylsilylated derivatives
derived from 4MR-3. Two types of cross-linked polystyrene-
divinylbenzene packed columns (JAIGEL-1HH and JAIGEL-2HH;
exclusion limits of 1,000 and 5,000, respectively) were used with
chloroform as the eluent at a flow rate of 7.0 mL min−1 for 4MR-2, 4MR-3,
and trimethylsilylated derivatives derived from 4MR-3 and 5.0 mL min−1 for
crude products derived from 4MR-2.
Cyclohexasiloxane with dimethylethoxysilyl groups (denoted as 6MR-1)
was
prepared
by
silylation
of
nickel/sodium-containing
oligophenylmetallasiloxane,[32] which was reported to give cis-
hexa[(phenyl)(hydroxy)]cyclohexasiloxane, in a similar manner as 4MR-1.
The dried crystals of nickel/sodium-containing oligophenylmetallasiloxane
(0.8659 g, 0.3717 mmol) were reacted with the silylating agent (obtained
by partial ethoxylation of 10.7 mL Me2SiCl2) in the mixture of dehydrated
toluene (20 mL) and dehydrated pyridine (10 mL). 6MR-1 was obtained as
a
colorless brittle solid (yield: 82%, based on {[(C6H5-
SiO2)6]2Ni4Na4(NaOH)2}(n-C4H9OH)3(H2O)3[32]). Spectroscopic data for
6MR-1 (Figure S5): 1H NMR (500.13 MHz, CDCl3, 25 °C, TMS): δ = 6.88–
7.23 (m, 30H, C6H5), 3.63 (q, J = 7.1 Hz, 12H; OCH2CH3), 1.07 (t, J = 6.9
Hz, 18H; OCH2CH3), 0.173 ppm (s, 36H; CH3); 13C NMR (125.76 MHz,
CDCl3, 25 °C, TMS): δ = 134.21 (CH), 132.83 (CH), 129.54 (CH), 127.23
(CH), 57.85 (OCH2CH3), 18.23 (OCH2CH3), −0.82 ppm (CH3); 29Si (99.36
MHz, CDCl3, 25 °C, TMS): δ = −11.6 (D1, 6Si; OSiMe2(OEt)), −82.1 ppm
(T3, 6Si; O3SiPh); HR-MS (electrospray ionization, 2 kV): calcd. for
C60H96O18Si12Na+ [M + Na]+: 1463.3720; found: 1463.3673.
NMR analyses of the hydrolysis and condensation processes of 4MR-
1 and 6MR-1.
4MR-1 and 6MR-1 were dissolved in mixtures of dehydrated EtOH and
deuterated EtOH (70 vol% EtOH-d6). Then, water and 6M HCl aq. were
added to the solutions. The molar ratio 4MR-1:(EtOH + EtOH-d6):H2O:HCl
Acknowledgements
was 1:32:4:0.004, and 6MR-1:(EtOH
1:48:6:0.004. The mixtures were put in NMR glass tubes and analyzed by
29Si NMR after certain periods of time.
+
EtOH-d6):H2O:HCl was
The authors are grateful to Dr. N. Sugimura (Materials
Characterization Central Lab., Waseda Univ.) for HR-MS
measurements. This work was supported in part by JSPS
KAKENHI (Grant-in-Aid for Scientific Research (B), No.
15H03879)
Hydrolysis and intramolecular condensation of 4MR-1, 4MR-2, and
6MR-1
Keywords: cage siloxanes • POSS • siloxane • building block •
4MR-1, 4MR-2, and 6MR-1 were dissolved in EtOH. Then, water and 6M
HCl aq. were added to the solutions. The molar ratio (4MR-1, 4MR-2, and
6MR-1):EtOH:HCl was 1:300:0.4, and the H2O/SiOEt molar ratios were
adjusted to 10. The mixtures were stirred at room temperature for more
than 12 h, and volatile components were removed in vacuo. After drying
at 80 °C for 2 h, crude products were obtained as colorless solids. In the
case of 4MR-1, precipitation occurred during hydrolysis. In a separate vial,
water was added as a poor solvent to promote further precipitation, and
the precipitates were recovered by filtration and dried to form white
powders.
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of chlorotrimethylsilane or chlorodimethylvinylsilane was added to
terminate the silanol groups (molar ratio was chlorosilane:4MR-3 = 500:1).
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Characterization
Solution 1H, 13C, and 29Si NMR spectra were recorded on a JNM-ECZ 500
(JEOL) spectrometer with resonance frequencies of 500.13 MHz, 125.76
MHz, and 99.36 MHz, respectively, at ambient temperature using 5-mm
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