Synthesis of water- and oil-repellent organofluorosilicon compounds

Article abstract of DOI:10.1070/MC2006v016n03ABEH002340

We have synthesised organofluorosilicon compounds that impart higher water- and oil-repellent properties to construction materials than known organosilicon compounds.

Full text of DOI:10.1070/MC2006v016n03ABEH002340

Mendeleev
Communications
Mendeleev Commun., 2006, 16(3), 190–192
Synthesis of water- and oil-repellent organofluorosilicon compounds
a
a
b
b
b
Alexander A. Yarosh,* Stanislav P. Krukovsky, Tatiana A. Pryakhina, Valery M. Kotov, Boris G. Zavin
a
and Alexey M. Sakharov
a
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 495 135 6379; e-mail: yar@ioc.ac.ru
b
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 495 135 5085
DOI: 10.1070/MC2006v016n03ABEH002340
We have synthesised organofluorosilicon compounds that impart higher water- and oil-repellent properties to construction
materials than known organosilicon compounds.
In most cases, cultural monuments and buildings are protected
from adverse environmental effects by means of functionally
substituted organosilicon compounds that impart water-repellent
properties to protected surfaces. However, these compounds
have no oil-repellent properties since they undergo swelling or
dissolution in organic compounds that occur in the atmosphere
due to motor-car exhausts and other anthropogenic emissions.
Organofluorine compounds have low surface tension and are,
as a rule, poorly soluble in organic solvents. Therefore, they
possess higher hydrophobic and oleophobic properties than
1
90 Mendeleev Commun. 2006

Mendeleev Commun., 2006, 16(3), 190–192
organosilicon compounds. However, organofluorine compounds
H(CF ) CH O(CH ) Si(OEt) (OCH CF CF H)
2
2
2
2 3
2
2
2
2
cannot interact with the inorganic surfaces of construction
materials in the same way as functionally substituted organo-
silicon compounds.
For this reason, compounds that incorporate both organo-
silicon and organofluorine fragments are of interest. Owing to
the organosilicon fragment, they can be reliably attached to con-
struction material surfaces, whereas the organofluorine fragment
will ensure the hydrophobic and oleophobic protection of the
object.
7
H(CF ) CH O(CH ) Si(OEt)(OCH CF CF H)
2
2
2
2
2 3
2
2
2
8
An alternative method to obtain compound 6 (total yield 44%)
involves the reaction of a fluoroalkoxide with allyl bromide and
the hydrosilylation of compound 9 with trichlorosilane followed
by ethoxylation with triethyl orthoformate (Scheme 4):
BrCH CH=CH2
HSiCl3
2
This paper presents several ways to synthesise organofluoro-
H(CF ) CH ONa
H(CF ) CH OCH CH=CH
2 2 2 2 2
2
2
2
1
–4
silicon compounds.
9
Perfluoroacyloxyalkylethoxysilanes were obtained from per-
fluorocarboxylic acid fluorides and unsaturated alcohols fol-
lowed by hydrosilylation (Scheme 1):†
3
HC(OEt)3
H(CF ) CH O(CH ) SiCl
H(CF ) CH O(CH ) Si(OEt)
2 2 2 2 3 3
2
2
2
2 3
3
1
0
6
Scheme 4
R COF + HOCH CH=CH
R COOCH CH=CH
f
2
2
f
2
2
Perfluoroacylaminoalkylethoxysilanes were synthesised accord-
ing to Scheme 5.‡
1
a–c
2
3a–c
HSi(OEt)3
R COOCH CH CH Si(OEt)
f
2
2
2
3
MeOH
R COF
R COOMe
f
f
4
a–c
NH (CH ) Si(OEt)
3
2
2
3
a R = C F
f
6
13
R CONH(CH ) Si(OEt)
3
f
2 3
b R = C F OCF(CF )CF OCF(CF )
f
3
7
3
2
3
11a–c
c R = CF O[CF(CF )O] (CF O) [CF(CF )CF O] CF(CF )
f
3
3
x
2
y
3
2
z
3
a R = C F OCF(CF )CF OCF(CF )
f
3
7
3
2
3
Scheme 1
b R = CF O[CF(CF )O] (CF O) [CF(CF )CF O] CF(CF )
f
3
3
x
2
y
3
2
z
3
According to GLC data, the yields of esters 3a–c were up to
c R = CF O(CF CF O) CF
f 3 2 2 5 2
~
95%. The structures of the products were confirmed by NMR
Scheme 5
spectra.
The hydrosilylation of compounds 3a–c with triethoxy-
The reactions were monitored by IR spectroscopy. The gradual
disappearance of bands at 1870 (acyl fluoride C=O) and 1780 cm
–1
silane was carried out in the presence of catalytic amounts of
H PtCl ·6H O at temperatures above 100 °C. The product
(ester C=O) was observed, along with the appearance of a band
at 1740 cm–1 (amide C=O). The yield of compounds 11a–c was
~70% with respect to the original acyl fluoride. The structures
of the products were confirmed by H and C NMR spectra.
The protective properties of compounds 11a–c were estimated
with their 5% solutions in Freon-113, which were used to treat
specimens of construction materials. The efficiency of these
compounds was estimated by the contact angles of water and
decalin on the specimens, frost resistance, salt resistance, vapour
permeability and water absorption. The test results for certain
2
6
2
yields were about 60%. An alternative method to obtain com-
pounds 4a–c is the hydrosilylation of compounds 3a–c with
trichlorosilane at 80 °C. Compounds 5a–c were ethoxylated with
triethyl orthoformate at room temperature (Scheme 2), yield 80%:
1
13
HSiCl3
R COOCH CH=CH
R COO(CH ) SiCl
f 2 3 3
f
2
2
3a–c
5a–c
3
HC(OEt)3
R COO(CH ) Si(OEt) + 3EtCl + 3HCOOEt
§
f
2
3
3
compounds are presented in Table 1. The organosilicon liquid
4
a–c
‡
Scheme 2
Synthesis of compounds 11a–c. Acyl fluoride RfCOF (56 mmol) was
placed in a flask equipped with a stirrer, a condenser, a thermometer and
a dropping funnel, and MeOH (58 mmol) was added with stirring. The
reaction was carried out for 2 h at 50 °C. The mixture was washed with a
Polyfluoroalkoxyalkylalkoxysilanes were synthesised from
fluorinated alcohols and J-chloropropyltriethoxysilane (Scheme 3):
5
% solution of sodium carbonate and dried over calcined Na SO . After
2 4
Na
that, J-aminopropyltriethoxysilane (60 mmol) was added at 20 °C. The
yields of compounds 11a–c were 90–95%. Bp 140–144 °C (1 Torr) for
11a and 121–123 °C (1 Torr) for 4b. Compound 11c was used without
H(CF ) CH OH
H(CF ) CH ONa
2 2 2
2
2
2
3
Cl(CH ) Si(OEt)
2
3
H(CF ) CH O(CH ) Si(OEt)
3
2
2
2
2 3
rectification.
6
§ Tests with organofluorosilicon compounds. Limestone specimens were
Scheme 3
immersed into a 5% solution of an organofluorosilicon compound in
Freon-113 for 1 min, dried to constant mass and weighed.
According to 1H and 13C NMR data, the ethoxy groups
at the Si atom are replaced with polyfluoroalkoxy groups under
the synthesis conditions of compound 6 to give compounds
Determination of water absorption. The specimens were immersed in
water for 2, 8 and 24 h and weighed. The results on water absorption are
presented in Table 1.
Determination of frost-resistance. The tests were carried out according
to GOST (State Standard) no. 7025-67. The specimens were immersed
in water for 2 h and then for 2 h into a freezing chamber at –20 °C, then
again immersed in water for thawing, and weighed.
Bioresistance assessment. Limestone specimens (5×5×1 cm) were
treated with 5% solutions of compounds 11a and 11c and then
contaminated, along with blank specimens, with the suspensions of
Ulocladium sp., Aspargillius versicolor, Aspargillius niger and other
fungi spores. The contaminated specimens were placed in a desiccator
containing water at the bottom and kept at a constant temperature of
27 °C and an air relative humidity of 90%. The growth of fungi on the
specimens was monitored using an MBS-9 microscope. After 58 days,
the blank limestone specimens were entirely covered with branching
mycelium, whereas only limited spore production was observed on
the pretreated specimens. According to GOST 9.048-89, these results
correspond to a bioresistance of 1 to 2 grades.
7
and 8:
†
Synthesis of compounds 4a–c. Acyl fluoride R COF 1a–c (56 mmol)
f
was placed in a flask equipped with a stirrer, a condenser, a thermometer
and a dropping funnel, and allyl alcohol (58 mmol) was added with
stirring. The reaction was carried out for 2 h at 35 °C. The yields of
compounds 3a–c were 80–88%.
The hydrosilylation of compounds 3a–c was carried out for 5 h at
5
0 °C in a stream of argon in the presence of H PtCl ·6H O (20 mmol).
2 6 2
The yields were 50–60%. Bp 82–85 °C (1 Torr) for 4a and 125–128 °C
(
1 Torr) for 4b. Compound 4c was used without rectification.
1
3
For 4a: C NMR, d: 9.24; 21.73 and 70.39 [O(CH ) Si], 17.31 and
2
3
5
8.53 (EtOSi), 158.5 (C=O), 85–125 (carbon atoms of the fluorinated
2
9
13
29
radical). Si NMR, d: –7.46. The C and Si NMR spectra of com-
pounds 4b and 4c are identical and differ only in the F NMR spectra
19
characteristic of the corresponding organofluorine substituents.
Mendeleev Commun. 2006 191

Mendeleev Commun., 2006, 16(3), 190–192
Table 1 Physico-chemical characteristics of limestone specimens after treatment with 5% solutions of hydrophobising compounds.
Water absorption
in 2 h (%)
Water absorption
in 8 h (%)
Water absorption
in 24 h (%)
Hydrophobic
effect (%)
Water contact
angle, q/°
Decalin contact
angle, q/°
Compound
Original specimen
GKZh-94
Disboxan-450
Compound 11a
Compound 11b
Compound 11c
6.34
0.39
—
0.36
0.18
0.58
6.62
1.36
2.0
0.48
0.38
0.95
6.96
1.83
—
1.88
1.38
2.24
0
0
98
120
130
138
128
0
51
54
110
115
110
79.45
69.79
92.75
94.26
85.64
GKZh-94 and the organosilicon composition Disboxan-450
Lacufa, Germany) applied to limestone specimens were used
for comparison. The water resistance, frost resistance and salt
resistance of hydrophobised specimens were determined accord-
ing to the NORMAL, RILEM 11.8a, RILEM 11.8b, GOST
pretreated with Disboxan-450 degraded after 15 cycles in a
similar salt-resistance test.
(
The laboratory assay for the bioresistance of new compounds
was carried out in GosNIIRestavratsii (State Research Restora-
tion Institute); the bioresistance was evaluated using a six-grade
scale. It was found that the bioresistance of pretreated limestone
specimens was 1 to 2 grades 58 days after the contamination.
Compounds 11a–c do not possess anti-fungal properties, but
they are not digested or hardly digested by microorganisms.
Hence, such compounds can be recommended for prolonged
protection from attacks of construction materials with mould,
fungi and algae. Environmental tests carried out with a number
of cultural monuments made of limestone, cement, marble and
granite showed that no algae and fungi grew on them even eight
years after treatment with the test compounds.
7
025-67, GOST 2309-80 and GOST 25898-83 procedures, as
5
–6
well as by other methods.
When a hydrophobic coating is applied to construction mate-
rials, a protective layer that hinders the ingress of water is
formed on their surfaces. Such a coating can partially prevent
water evaporation from the material. Therefore, hydrophobised
specimens are tested for changes in their vapour permeability in
comparison with non-treated ones. The vapour permeability of
the specimens was determined according to GOST 25898-83.
The decrease in the vapour permeability of plaster specimens
hydrophobised with compounds 11a–c was ~5%, which com-
plies with the requirements for hydrophobising coatings.
The hydrophobic effect was calculated by dividing (i) the
difference between the values of water absorption for non-treated
and treated specimens by (ii) the water absorption for the non-
treated specimen after exposure to water for 8 h (Table 1).
The frost resistance is the ability of a material saturated
with water to withstand repeated alternating freezing in air and
thawing in water. Water freezing in the pores of a construction
material causes its degradation. The salt resistance of construc-
tion materials is determined as the ability to withstand repeated
immersion of specimens in a solution of salts at 20 °C followed
by drying at 60°. Accelerated tests for frost resistance and salt
resistance are carried out using hydrophobised specimens prepared
from brick-cement plaster.
This study was supported by OJSC ‘Moscow Committee for
Science and Technologies’.
References
1
S. P. Krukovsky, A. A. Yarosh, V. M. Kotov, T. A. Pryakhina, V. N. Yarosh,
B. G. Zavin, V. N. Pisarenko, V. M. Svetlakov and V. E. Blinov, RF Patent
2
,149,151, 2000.
2
S. P. Krukovsky, A. A. Yarosh, V. M. Kotov, T. A. Pryakhina, V. N. Yarosh,
B. G. Zavin, V. N. Pisarenko, V. M. Svetlakov and V. E. Blinov, RF Patent
2,151,151, 2000.
3 S. P. Krukovsky, A. A. Yarosh, A. A. Glazkov, D. V. Batizat and T. N.
Redina, J. Fluorine Chem., 1999, 96, 31.
4
A. A. Yarosh, T. A. Pryakhina, V. M. Kotov, B. G. Zavin and S. P.
nd
Krukovsky, The 2 International Conference ‘Chemistry, Technology
and Applications of Fluorocompounds’ (STAF-97), St. Petersburg, 1997,
P2-24, p. 96.
The hydrophobisation of plaster specimens coated with lime
wash was carried out by analogy with the hydrophobisation of
limestone. It was found that even after 90 freezing–thawing
cycles on plaster specimens treated with 5% solutions of com-
pounds 11a–c, lime wash did not fall off, whereas blank specimens
lost colour after 2 cycles and degraded after 15 cycles. A similar
behaviour was observed in the salt-resistance tests of plaster
specimens. Blank specimens started to degrade intensely after
5
A. A. Yarosh, S. P. Krukovsky, B. G. Zavin, V. M. Kotov, T. A. Pryakhina
and V. N. Yarosh, Abstracts of the 10 All-Russian Conference ‘Organo-
th
silicon Compounds: Synthesis, Properties and Applications’, 2005, abstract
3C23 (in Russian).
6 A. A. Yarosh, S. P. Krukovsky, A. M. Sakharov, B. G. Zavin, V. M. Kotov,
T. A. Pryakhina and V. N. Yarosh, International Conference ‘Art et
Chimie, Les Polymers’, Actes du Congres, Paris, 2002, pp. 115–117.
3
1
test cycles, whereas the specimens pretreated with compounds
1a–c started to degrade after 27–28 cycles. The specimens
Received: 20th February 2006; Com. 06/2683
1
92 Mendeleev Commun. 2006