New direct transformation reaction of SiF4 with methanol and aluminum with the aid of iodine to prepare tetramethoxysilane and aluminum fluoride

Article abstract of DOI:10.1016/j.jfluchem.2013.11.011

A new alcoholysis reaction of silicon tetrafluoride with methanol in the presence of aluminum can directly afford tetramethoxysilane and aluminum fluoride. The reaction conditions were investigated in detail to find that the catalytic amount of iodine was effective for the transformation.

Full text of DOI:10.1016/j.jfluchem.2013.11.011

Accepted Manuscript
Title: New direact transformation reaction of SiF with
4
methanol and aluminum with the aid of iodine to prepare
tetramethoxysilane and aluminum fluoride
Author: Zhong Huang Yuye Li Qiang Tian Zongfan Zhang
Xia Li Xuesong Liang Lusha Du
PII:
S0022-1139(13)00365-5
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.jfluchem.2013.11.011
FLUOR 8231
To appear in:
FLUOR
Received date:
Revised date:
Accepted date:
29-9-2013
13-11-2013
15-11-2013
Please cite this article as: Z. Huang, Y. Li, Q. Tian, Z. Zhang, X. Li, X. Liang, L. Du,
New direact transformation reaction of SiF with methanol and aluminum with the aid
4
of iodine to prepare tetramethoxysilane and aluminum fluoride, Journal of Fluorine
Chemistry (2013), http://dx.doi.org/10.1016/j.jfluchem.2013.11.011
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

*Graphical Abstract - Pictogram
Al
F
OCH3
Si
OCH3
activator (I2)
Al*
O
F
Si
F
+
3
H CO
OCH3
+
AlF3
H C
H
3
F
Page 1 of 21

*Graphical Abstract - Synopsis
New direact transformation reaction of SiF with methanol and aluminum with the aid of iodine
4
to prepare tetramethoxysilane and aluminum fluoride
Zhong Huang, Yuye Li, Qiang Tian, Zongfan Zhang, Xia Li, Xuesong Liang, Lusha Du
Pages No.-No.
Fine chemical industry center, Yunnan Chemical Research Institute, Yuntianhua Group Corporation
Limited, 1417 Dianchi Road, 650228, Kunming, Yunnan, China
We found a new alcoholysis reaction of silicon tetrafluoride with methanol in the presence of
aluminum. The reaction can directly afford tetramethoxysilane and aluminum fluoride in good yields.
Page 2 of 21

*Highlights (for review)
·
·
·
·
We report a new alcoholysis reaction of SiF , methanol and Al.
4
The reaction gives Si(OCH ) and AlF as the products in good yields.
3
4
3
The reaction was studied and the condition is mild.
The method easily transfers inorganic silicon of SiF to organic silicon compound.
4
Page 3 of 21

*Manuscript
New direact transformation reaction of SiF with methanol and aluminum with the aid of iodine to
4
prepare tetramethoxysilane and aluminum fluoride
1
Zhong Huang*, Yuye Li, Qiang Tian, Zongfan Zhang, Xia Li, Xuesong Liang, Lusha Du
Fine chemical industry center, Yunnan Chemical Research Institute, Yuntianhua Group Corporation
Limited, 1417 Dianchi Road, 650228, Kunming, Yunnan, China
Abstracts: A new alcoholysis reaction of silicon tetrafluoride with methanol in the presence of
aluminum can directly afford tetramethoxysilane and aluminum fluoride. The reaction conditions were
investigated in detail to find that the catalytic amount of iodine was effective for the transformation.
Keywords: Alcoholysis; Silicon tetrafluoride; Tetramethoxysilane
∗
Corresponding author at: Fine chemical industry center, Yunnan Chemical Research Institute, Yuntianhua
Group Corporation Limited, 1417 Dianchi Road, 650228, Kunming, Yunnan, China.
Tel.: +86(871)64313269; Fax: +86(871)64327017.
E-mail address: pifushu@163.com (Zhong Huang )
1
Page 4 of 21

1
. Introduction
Fluorosilicone resource is one of the main by-products in phosphate fertilizer industry, but has not
been efficiently used so far. This great and valuable resource not only has a negative effect on the
environment, but also brings a heavy economic burden to phosphate fertilizer industry.
Fluorine as a very important element is used in industry with a large scale, such as in new
materials, in new pesticides, in metallurgy, etc. However, fluorine becomes increasingly inadequate
because of the shortage of fluorspar which is the dominant source of fluorine. An alternative way to
meet the shortfall is to utilize the vast fluorine in the by-product of phosphate fertilizer industry, but it’s
very limited by technology.
Silicon tetrafluoride (SiF ) is the key by-product of phosphate fertilizer industry. It’s well-known
4
to us that the traditional method to utilize SiF is to generate fluorosilicic acid. Fluorosilicic acid is
4
usually used to prepare HF or other fluorides. One example is adding NH into fluorosilicic acid to
3
prepare SiO and NH F, and then NH F reacts with concentrated sulfuric acid to give HF and
2
4
4
(
NH ) SO . The method has some disadvantages such as that only fluorine atom is used and
4 2 4
by-products (SiO and (NH ) SO ) cannot be used, enhancing the manufacturing cost of enterprise and
2
4 2
4
giving potential contamination to the environment. SiF also could take part in the reaction with
4
alcohols and NH to produce (NH ) SiF and corresponding silicate esters [1,2], but only one third of
3
4 2
6
silicon atoms is transferred to be silicate esters and the rest of silicon atoms to be (NH ) SiF without
4
2
6
generating fluoride.
Therefore, it is urgent to find a different route, by which the fluorine and silicon can be
transformed at one step and the valuable products such as fluorides (AlF ) and silicones (silicate esters)
3
2
Page 5 of 21

can be obtained. AlF as an important chemical product has a great application in many fields,
3
especially in electrolytic aluminum industry. Silicate esters such as tetramethoxysilane and its polymers
are widely used as coupling agents, crosslinking agents and plasticizers. However, except some reports
on the structure of SiF [3-9], there are very few reports focused on the efficient method to use SiF , by
4
4
which fluorine atoms can be transferred to be fluorides and silicon atoms can be transferred to be
silicones.
Herein, we report a new reaction that provides two highly value-added products (AlF and
3
Si(OMe) ) from SiF directly by alcoholysis with MeOH in the presence of aluminum powder and
4
4
catalytic amount of I in good yields without producing worthless byproducts (Scheme 1). To the best
2
of our knowledge, this is the first report on the application of metal in the alcoholysis of SiF to
4
produce silicate esters.
I2
3
SiF + 12 CH OH + 4 Al
4 AlF + 3 Si(OCH ) + 6 H
3 3 4 2
4
3
Scheme 1. The reaction of SiF , MeOH and aluminum powder
4
2
2
. Results and Discussion
.1 Optimization of the reaction condition
At the very beginning, under the enlightenment of the reaction of SiCl with EtOH at room
4
temperature to give the products of HCl and tetraethoxysilane [10, 11], we tried the reaction of SiF4
with MeOH (or EtOH) for obtaining HF and tetramethoxysilane (or tetraethoxysilane). The result is
that no expected products were obtained even though many conditions were tried, such as enhancing
the reaction temperature and pressure. However, it was estimated that a certain compound may assist
the cleavage of stable SiF bonds to cause the desired reaction.
4
3
Page 6 of 21

We found that the aluminum powder could take part in the reaction of SiF with MeOH to give the
4
target products of AlF and tetramethoxysilane. Notably, the reaction can only conduct in the presence
3
of an activator (I ). Then, we used EtOH instead of MeOH under the same condition without
2
generating any target products. The reason is that the electron-withdrawing ability of proton of EtOH is
not strong enough.
At the beginning, the yield of AlF is only 80%, which is not very satisfactory in industry.
3
Therefore, we screened the reaction conditions. First, we explored the effect of the equivalent ratio of
SiF and aluminum (Table 1, Entries 1-9). It was found that the equivalent ratio has a critical influence
4
on the yield. In order to improve the yield of AlF , we took a large excess of SiF (the equivalent ratio
3
4
of SiF and Al is 1.5:1, Table 1, Entry 1), but it turned out that the result was not satisfactory. The yield
4
of AlF was only 85% and tetramethoxysilane was condensed to be a sol-gel form with difficulty to
3
separate the liquid phase and solid phase. The excess SiF is in favor of improving the yield, but it
4
causes the reaction system very acidic. Under this condition, the tetramethoxysilane can be easily
condensed to generate polysilicate. However, if equal amount of SiF and Al is used, the reaction is
4
also not satisfactory. For example, when the equivalent ratio was 1:1 (Table 1, Entry 6), the yields of
AlF and tetramethoxysilane were only 87% and 64%, respectively. The reason is that SiF is a gas at
3
4
o
room temperature, and easily volatilizes from SiF -MeOH solution at 40 C, resulting in that SiF in the
4
4
reaction system is inadequate. Experiments approved that slight excess of SiF is effective for the
4
completion of the reaction. For example, when the ratio of SiF and Al was slightly enhanced to
4
1
.1:1-1.2:1, the reaction worked well (Table 1, Entries 2-5, 7-9).
4
Page 7 of 21

a
Table 1. Optimization of the reaction condition
Entry Equiv. Ratio
SiF :Al)
Heating
Reaction Specification
Feed time
Yield of
Yield of
b
(
Temperature
Time
/h
of Al
of SiF /h AlF /%
Si(OCH )
3 4
4
4
3
o
c
/
C
/%
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
1.5:1
1.2:1
1.2:1
1.1:1
1.15:1
1:1
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
50 to reflux
50 to reflux
30 to reflux
40
6.5
6.5
6.5
6.5
6.5
6.5
6.5
8
8
8
8
8
8
8
8
8
8
8
8
8
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 80
FLPA180
FLPA250
FLX250
FLX325
4
85
90
91
92
92
87
94
94
93
94
92
93
86
90
65
83
95
95
95
a gel form
85
85
88
81
64
84
82
86
85
85
84
70
83
48
54
86
4.5
3.5
2.5
3
2.5
2.5
3
2.5
3.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
1.2:1
1.15:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
0
1
2
3
4
5
6
7
8
9
0
1
50
d
d
30 to reflux
50 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
87
83
Reactivity is very poor
Reactivity is very poor
8
a
All reactions were performed in a Laboratory-glass vessel BEP280/TypeII. I
noted. I , aluminum and anhydrous MeOH were charged. The mixture was stirred and heated to certain temperature. Then, a
solution of SiF -MeOH was added dropwise with a syringe pump.
The aluminum powder were classified by the preparation method. FLX means ball milling method, and FLPA means
2
(0.56% of aluminum mass) was loaded otherwise
2
4
b
atomization method.
c
The yield of tetramethoxysilane were reported with the silicon dioxide after hydrolysis.
d
2
The loading of I was reduced by a half to 0.28%.
With the above results in hand, we further proceeded to examine the scope of 1:1-1.2:1 ratio
(
Entries 2-8). After a number of screenings, we got the AlF product in an excellent yield (up to 94%)
3
when the ratio was 1.2:1. After acquiring the optimized ratio, we started to examine the effect of
reaction heating temperature on the result (Table 1, Entry 10-14). Comparing entry 9 with 13, and entry
1
1 with 14, we observed that a reflux process was necessary in the end step of the reaction. And the
o
o
o
heating temperature of 40 C was slightly better than 30 C and 50 C (Entry 9-12). Probably, too low
heating temperature could cause a smaller reaction rate, leading to a lower yield. Instead, too high
heating temperature could cause SiF volatilize too much, also resulting in the yield lower. Thus, the
4
o
optimum heating temperature condition is 40 C for about five hours, and then rises to reflux state.
5
Page 8 of 21

Consequently, considering on that I plays the key role in the reaction, the influence of the loading
2
of I on the reaction was investigated. In table 1, the loading of I is 0.56% of aluminum mass for the
2
2
most experiment. When we decreased the loading of I by a half (Entries 15 and 16), the yields of
2
products were much lower under the same condition (Entries 11 and 12). It indicates that the loading of
I2 must be suitable to give a satisfactory reaction result. A further investigation was made after the
screening of aluminum powder specifications to make sure the feasibility of lowing the I loading.
2
A series of aluminum powder with different specification was then examined (Table 1, Entries
1
7-21). It is shown that aluminum powder FLPA180 provided excellent results in terms of reaction
2
activity and yield (Entry 18, the specific surface area is 0.19 m /g). Perhaps, the small grain size
aluminum had a low activity because of its excessive oxidation on the surface (Entry 19, the specific
2
surface area of FLPA250 is 0.36 m /g). In contrast, too large grain size can also result in low yield
2
(
Entry 9, the specific surface area of FLPA40 is 0.05 m /g). Because the aluminum powder with a large
grain size has a small specific surface area, the probability of aluminum contacting with SiF and
4
MeOH becomes small, leading to a low reaction rate. Moreover, the preparation method of aluminum
had a great effect upon the reaction results (Entries 17-21). The aluminum powder FLX played very
poor in the reaction, and we could not observe the reaction phenomenon at all. The reason can also
relate with the oxidation on the surface of aluminum.
After selecting aluminum powder FLPA180 as the best, we found that the reaction time can be
shortened. Even if the reaction time was shortened to five hours, it was noted that the yields of AlF3
and tetramethoxysilane were not obvious diminished (Table 2, Entries 22-24). When the equivalent
ratio was 1.1:1 (Entry 23)，the reaction slightly went better than 1.2:1 (Entry 22) and 1.05:1 (Entry 24).
6
Page 9 of 21

Therefore, the equivalent ratio 1.1:1 was optimized to be the best. However, when the reaction time
was shortened to 4 h, the result was not satisfactory.
Finally, with the optimized reaction conditions in hand, we re-investigated the loading of I2.
When the loading was reduced to 0.39%, the reaction result was not affected (Table 2, Entry 25).
However, when the loading was reduced to 0.28% as experiments in Table 1 (Entries 15 and 16), the
reaction was also very poor (Table 2, Entry 26). Therefore, the loading of I was optimized to be 0.39%
2
of aluminum mass.
a
Table 2. Redefinition of reaction time, the ratio of materials, and I2
Entry
Equiv. Ratio
SiF :Al)
Heating
Temperature/ C time/h
Reaction Feed time Yield of
Yield of
o
b
(
of SiF /h
AlF /%
Si(OCH ) /%
4
4
3
3 4
2
2
2
2
2
2
3
4
5
6
1.2:1
1.1:1
1.05:1
1.1:1
1.1:1
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
5
5
5
5
5
2.5
2.5
2.5
2.5
2.5
95
96
95
96
85
86
81
86
c
d
The reaction is very poor
(0.56% of aluminum mass) was loaded otherwise
, aluminum and anhydrous MeOH were charged. The mixture was stirred and heated to certain temperature. Then, a
a
All reactions were performed in a Laboratory-glass vessel BEP280/TypeII. I
noted. I
2
2
solution of SiF
4
-MeOH was added dropwise with a syringe pump.
b
The yield of tetramethoxysilane were reported with the silicon dioxide after hydrolysis.
c
2
The loading of I was reduced to 0.39%.
d
The loading of I was reduced by a half to 0.28%.
2
As a result of screening the reaction condition, we got the AlF product in an excellent yield after
3
o
treating the crude product by calcinations under the temperature of at least 500 C. In order to prove
that the solid product is AlF , we tested the solid product by X-ray powder diffraction and X-ray
3
fluorescence. X-ray diffraction shows that the patterns of the solid are corresponding to the standard
files of AlF from ICDD, which belongs to P63/mmc space group (Figure 1). The X-ray fluorescence
3
shows that the quality of AlF could be better than the standard in industry (Table 3). Especially, the
3
content of F is up to 66.80%. It is noted that the yield of AlF can not be up to theoretical value. The
3
o
reason is that crude AlF must go through calcination under the temperature of at least 500 C to give
3
7
Page 10 of 21

the product AlF , and during the process, some AlF may suffer hydrolysis with the water in air,
3
3
leading to weight reduction.
Figure 1. The powder XRD of product AlF3
Table 3 The quality parameters for AlF3
2
-
parameters F/%
Al/%
Na/%
≤0.40
0.017
SiO /% Fe O /% SO4 /% P O /% Burn reduction/%
2
≤0.30
0.13
2
3
2
5
a
1
2
≥60
≥31.0
≤0.10
≤0.6
≤0.04
Not
≤1.0
b
66.80
31.87
0.014
0.015
0.5
detected
a
The standard of AF-1 of GB/T 4292-2007 in China.
b
3
The product AlF in the study.
2
.2 Discussion of the reaction mechanism
In order to clarify the reaction process, we did three experiments as follows: (a) SiF , Al and
4
MeOH, without I ; (b) Al, MeOH and I , without SiF ; (c) SiF , I and MeOH, without Al. No reaction
2
2
4
4
2
was found in all of these experiments. The results indicate that the four substrates are indispensable.
Because I was not detected after the reaction, I did not play a role as a catalyst but a similar role as in
2
2
preparing Grignard reagent. According to the literature [8] and our experiments, we conceived a
8
Page 11 of 21

possible process of the alcoholysis reaction (Scheme 2). Firstly, a complex 1 of SiF •4CH OH is
4
3
formed when SiF gas is passed into MeOH. In this complex, because of the coordination of MeOH
4
with silicon atom, the bond energy of F-Si is weakened and the bond becomes easier to be destructed.
Secondly, the aluminum powder is activated by I and labeled to be Al*, which then reacts with MeOH
2
under the aid of SiF . During the process, the H with positive charge of MeOH obtains electrons from
4
Al* to form hydrogen gas which then escapes from the reaction system, and the Al* loses three
-
electrons to combine with CH O to afford a complex 2. Thirdly, the complex 2 coordinates with
3
-
complexes 1 to generate intermediate 3. Fluorine atom is abstracted to Al with releasing CH O from
3
-
Al and bond forming between Si and CH O . During the process, a complex 5 is produced and the left
3
part of intermediate 3 is transformed to be complex 4. Finally, the complex 4 and 5 go through the
same process to generate the target products of tetramethoxysilane and AlF3.
9
Page 12 of 21

Al
F
F
F
I2
O
Si
+ H3C
H
F
Al*
H
H C
CH3
3
CH OH
3
O
H
O
H
F
F
F
F
CH3
SiF4
O
H
Si
O
H
OCH3
H C
3
H3C
H
O
O
Si
H2
*
CH3
F
F
F
Al ( OCH )
3 n-1
1
*
Al ( OCH3)n
F
2
O
H
CH3
O
3
H C
3
H
H
CH3
O
OCH3
H
H CO
OCH3
OCH3
*
3
F
O
+
AlF3
+
Si
F
Al ( OCH )
3 n-1
Si
CH3
H3CO
F
F
O
5
H
CH3
O
H C
3
H
4
Scheme 2. The possible mechanism of the reaction
3
. Conclusions
In summary, we found a novel alcoholysis reaction of SiF with MeOH in the presence of
4
aluminum powder and a catalytic amount of iodine. After the optimization of conditions, the reaction
afforded two high value-added products of AlF and tetramethoxysilane in good yields. The more
3
important is that the study may provide an effective method to overcome the difficulty of the use of
fluorosilicone resource for phosphate fertilizer companies. The study of alcoholysis reaction of SiF4
with MeOH and other alcohols is continued.
1
0
Page 13 of 21

4
4
. Experimental
.1 General
All reactions were performed in a Laboratory-glass vessel BEP280/TypeII. The fluoride,
aluminum and silicon element in AlF were measured on a Bruker S4 Pioneer XRF spectrometer. The
3
fluoride element in the liquid phase was recorded with a Fluorine Ion-selective measurement. The
tetramethoxysilane was determined on an Agilent 6890 series GC-MS spectrometer. X-ray diffraction
(
XRD) analysis was carried out by using a D/MAX 2500VB2+/PC and Cu Kα radiation (λ=1.54056 Å).
1
13
H and C NMR was recorded with a Bruker spectrometer at 500 MHz using TMS as internal standard.
The yields of tetramethoxysilane were reported with the silicon dioxide after hydrolysis. SiF , ammonia,
4
aluminum powder and anhydrous MeOH were used as purchased without purification.
4
.2 Typical procedure for the alcoholysis of SiF4
To a Laboratory-glass vessel (2 L) BEP280/TypeII, I (0.39% of aluminum mass), aluminum (24.8
2
g, 0.92 mol) and anhydrous MeOH (200 mL) were charged. The mixture was stirred and heated to 37
o
C. Then, a 28.6% solution of SiF -MeOH (275.6 g, 0.76 mol) was added with a syringe pump in 2.5 h
4
(
the velocity of flow was 1.84 g/min). After dropping of the SiF -MeOH solution, 100 of mL
4
o
anhydrous MeOH was added. The resulting solution was stirred at 40 C for 0.5 h. The temperature of
reaction mixture was then raised to reflux state and the reaction system was stirred for 2 h. The reaction
system was then cooled down to room temperature and the mixture was discharged from glass vessel.
11
Page 14 of 21

4.3 Typical procedure for the post-treatment of tetramethoxysilane and AlF3
A small amount of 10% NH -MeOH solution was added into the above reaction mixture until
3
reaction system was neutral. Then, this neutral material was distilled under reduced pressure (200 mbar)
o
at 80 C to collect distillate in an ice-water bath. The solid residue was washed with anhydrous MeOH.
The filtrates were merged with the distillate. Then the liquid was distilled under the pressure of 800
o
mbar until no distillate was present (the temperature of distillate was about 59 C). The distillate
portion was anhydrous MeOH containing a small amount of tetramethoxysilane, and the liquid residue
underwent distillation under reduced pressure (128 mbar) to give tetramethoxysilane as distillate (the
o
temperature of distillate was about 66 C, about 89 g). During the whole process, water must be strictly
o
o
avoided. The solid was dried at 90 C to a constant weight, and then went through calcination at 500 C
for 2 h to provide AlF (about 74.3 g).
3
o
4
.3.1 Tetramethoxysilane. Yield 85%; Colorless oil; Boiling point 113-116 C (800 mbar); Density (20
o
1
13
C) 1.07; H NMR (500 MHz, CDCl ): 3.56 (s, 12H); C NMR (500 MHz, CDCl ): 51.1; EI-MS
3
3
+
(
m/z, relative intensity): 152 (M , 70), 137 (16), 121 (100), 107 (18), 91 (43), 59 (8), 31 (4).
4
.3.2 Aluminum fluoride. Yield 96%; white solid.
Acknowledgments
The project is generously supported by Research Institutes Foundation of Yunnan Provincial
Science and Technology Department (Grant No. 2012CF028) and the Science and Technology
Innovation Project of Yuntianhua Group Corporation Limited (Grant No. 2013YTH04).
1
2
Page 15 of 21

References
[
[
1] A. A. Ennan, B. M. Kats, A. V. Skorichenko, Zh. Neorg. Khim. 44 (1971) 1429-1431.
2] K. S. Hannover, H. W. S. Hannover-Kirchrode, Process of producing silicic acid esters, U.S. Patent
2
814 635, 1959.
[
[
3] M. Atoji, W. N. Lipscomb, Acta Cryst. 7 (1954) 597.
4] A. V. Khoroshilov, S. A. Cherednichenko, A. V. Lizunov, S. N. Fedorova, Theor. Found. Chem.
Eng. 44 (2010) 569-573.
[
[
[
[
[
[
[
5] V. I. Nikitin, A. A. Ennan, Zh. Neorg. Khim. 25 (1980) 3391-3394.
6] M. Shimazu, Y. Suzaki, Japan J. Appl. Phys. 4 (1965) 819.
7] L. V. Ostapchuk, L. A. Gavrilova, A. A. Ennan, Zh. Neorg. Khim. 27 (1982) 344-347.
8] J. P. Guertin, M. Onyszchuk, Can. J. Chem. 41 (1963) 1477-1484.
9] V. O. Gel’mbol’dt, L. V. Koroeva, A. A. Ennan, Russ. J. Coord. Chem. 33 (2007) 160-167.
10] R. Z. Xie, W. J. Mao, Chem. World (1958) 512-513.
11] R. Wlodzimierz, Roczniki Chemii 29 (1955) 284-286.
1
3
Page 16 of 21

Schemes:
I2
3
SiF + 12 CH OH + 4 Al
4 AlF + 3 Si(OCH ) + 6 H
3 3 4
4
3
2
Al
F
F
F
I2
O
Si
+
H C
3
H
F
Al*
H
O
H C
CH3
3
CH OH
3
O
H
O
H
F
F
F
CH3
SiF4
O
H
Si
O
H
OCH3
H C
3
H C
F
H
O
3
H2
*
CH3
F
F
F
Al ( OCH )
3 n-1
1
*
i
S
Al ( OCH3)n
F
2
O
H
CH3
O
3
H C
3
H
H
CH3
O
OCH3
H
H CO
OCH3
OCH3
*
3
F
F
O
+
AlF3
+
Si
F
Al ( OCH3)n-1
Si
CH3
H CO
3
F
O
5
H
CH3
O
H C
3
H
4
1
4
Page 17 of 21

Figures:
1
5
Page 18 of 21

Scheme and figure captions
Scheme 1. The reaction of SiF , MeOH and aluminum powder
4
Scheme 2. The possible mechanism of the reaction
Figure 1. The powder XRD of product AlF3
1
6
Page 19 of 21

Tables
a
Table 1. Optimization of the reaction condition
Entry Equiv. Ratio
Heating
Reaction Specification
Feed time
Yield of
Yield of
b
(
SiF :Al)
Temperature
Time
/h
of Al
of SiF /h AlF /%
Si(OCH )
3 4
4
4
3
o
c
/
C
/%
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
1.5:1
1.2:1
1.2:1
1.1:1
1.15:1
1:1
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
50 to reflux
50 to reflux
30 to reflux
40
6.5
6.5
6.5
6.5
6.5
6.5
6.5
8
8
8
8
8
8
8
8
8
8
8
8
8
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 40
FLPA 80
FLPA180
FLPA250
FLX250
FLX325
4
85
90
91
92
92
87
94
94
93
94
92
93
86
90
65
83
95
95
95
a gel form
85
85
88
81
64
84
82
86
85
85
84
70
83
48
54
86
4.5
3.5
2.5
3
2.5
2.5
3
2.5
3.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
1.2:1
1.15:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
1.2:1
0
1
2
3
4
5
6
7
8
9
0
1
50
d
d
30 to reflux
50 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
87
83
Reactivity is very poor
Reactivity is very poor
8
a
All reactions were performed in a Laboratory-glass vessel BEP280/TypeII. I
noted. I , aluminum and anhydrous MeOH were charged. The mixture was stirred and heated to certain temperature. Then, a
solution of SiF -MeOH was added dropwise with a syringe pump.
The aluminum powder were classified by the preparation method. FLX means ball milling method, and FLPA means
2
(0.56% of aluminum mass) was loaded otherwise
2
4
b
atomization method.
c
The yield of tetramethoxysilane were reported with the silicon dioxide after hydrolysis.
d
The loading of I
2
was reduced by a half to 0.28%.
a
Table 2. Redefinition of reaction time, the ratio of materials, and I2
Entry
Equiv. Ratio
SiF :Al)
Heating
Temperature/ C time/h
Reaction Feed time Yield of
Yield of
o
b
(
of SiF /h
AlF /%
Si(OCH ) /%
4
4
3
3 4
2
2
2
2
2
2
3
4
5
6
1.2:1
1.1:1
1.05:1
1.1:1
1.1:1
40 to reflux
40 to reflux
40 to reflux
40 to reflux
40 to reflux
5
5
5
5
5
2.5
2.5
2.5
2.5
2.5
95
96
95
96
85
86
81
86
c
d
The reaction is very poor
(0.56% of aluminum mass) was loaded otherwise
, aluminum and anhydrous MeOH were charged. The mixture was stirred and heated to certain temperature. Then, a
solution of SiF -MeOH was added dropwise with a syringe pump.
The yield of tetramethoxysilane were reported with the silicon dioxide after hydrolysis.
a
All reactions were performed in a Laboratory-glass vessel BEP280/TypeII. I
noted. I
2
2
4
b
c
The loading of I
2
was reduced to 0.39%.
d
The loading of I was reduced by a half to 0.28%.
2
1
7
Page 20 of 21

Table 3 The quality parameters for AlF3
2
-
parameters F/%
Al/%
≥31.0
31.87
Na/%
≤0.40
0.017
SiO /% Fe O /% SO4 /% P O /% Burn reduction/%
2
≤0.30
0.13
2
3
2
5
a
1
2
≥60
≤0.10
≤0.6
≤0.04
Not
≤1.0
b
66.80
0.014
0.015
0.5
detected
a
The standard of AF-1 of GB/T 4292-2007 in China.
b
3
The product AlF in the study.
1
8
Page 21 of 21