420
IKAEV et al.
Alkylation of diethyl hydrogen phosphite followed
the procedure described in [8]:
modifier; M, molar weight of the modifier; Mx, molar
weight of the leaving groups in the modifier molecule;
F, mean number of bonds formed by the modifier
molecule with the surface, equal to 1 for monofunc-
tional silanes and 1.5 for bi- and trifunctional silanes
[10]).
2 (С2Н5О)2Р(О)Н + 2Na → 2 (С2Н5О)2Р(О)Na + Н2,
С4Н9X + (С2Н5О)2Р(О)Na → (С2Н5О)2Р(О)С4Н9 + NaX.
Evaluation of the hydrolytic stability of the modified
supports. Tests were performed with aqueous solutions
of H2SO4 (pH 1, 4), NaOH, and Na2CO3 (pH 7, 10,
12).
A 250-ml two-necked flask equipped with a mag-
netic stirrer and a reflux condenser was charged with
250 ml of anhydrous diethyl ether and 48 ml of diethyl
hydrogen phosphite. Sodium metal (5.75 g) was
gradually added. After sodium dissolved completely, a
dropping funnel was attached to the flask and the
calculated amount of 1-bromobutane (26 g) was
gradually added. After adding the whole amount of the
reagent the mixture was stirred for an additional 8 h.
The resulting diethyl butane-1-phosphonate was dis-
tilled in a vacuum, bp 84ºC (13 mm Hg). Yield 75%.
Two weighed portions (1 g) of the modified oxide
were placed in test tubes, and each was charged with
10 ml of a solution with appropriate pH value. The test
tubes were stoppered and allowed to stand for 24 h
with intermittent shaking. Then the supernatant was
decanted, and the powders were transferred with
distilled water onto a filter and washed with distilled
water (10×20 ml). The samples were dried in an oven
at 110ºC for 24 h.
Modification of tin dioxide with diethyl butane-1-
phosphonate. Traditional method. Modification of
tin dioxide was performed in a three-necked flask
equipped with a power-driven stirrer and a reflux
condenser. The flask was charged with 1 g of the sup-
port and 100 ml of absolute toluene. The mixture was
heated to reflux, and the modifier was added. The
modifier was taken in an amount corresponding to the
grafting density of 10 nm–2. Then the powder was
washed and dried by the standard procedure.
Impregnation method. A round-bottom flask was
charged with a weighted portion of tin dioxide. Then
hexane was added in a volume equal to the double vol-
ume of tin dioxide. After that, the modifer was added
in an amount corresponding to 50 modifier molecules
per 1 nm2 of the tin dioxide surface. The solvent was
removed on a rotary evaporator, and the resulting
powder was heated at 120ºC for 24 h, after which it
was washed and dried by the standard procedure.
elemental analysis. Elemental analysis of modified
samples of tin dioxide was performed on a Carlo Erba
device (Italy). The carbon content of the tin dioxide
samples was determined by combustion of the sub-
stance in a fast oxygen stream, after Korshun and
Klimova [9]. The amount of the modifier on the sur-
face (nm–2) was calculated by the formula
Thermal studies were performed with a Netzsch STA
449 C device in an argon atmosphere. The temperature
range was 20–500ºC, and the heating rate, 10 deg min–1.
REFERENCES
1. Moses, P.R., Wier, L.M., and Murray, R.W., Anal.
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N = [(6.02·105·РС)/(1200 nС – РСМ')](1/Ssp),
where PC is the carbon content (%); nC, amount of
carbon atoms in the modifier molecule; Ssp, specific
surface area of the support; M' (g mol–1) = M – nMx +
17n – 18F (M' is the reduced molar weight of the
10. Modifitsirovannye kremnezemy v sorbtsii, katalize i
khromatografii (Modified Silicas in Sorption, Catalysis,
and Chromatography), Lisichkin, G.V., Ed., Moscow:
Khimiya, 1986.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008