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Synthesis and characterization of some novel silicon esters and their application as lubricant base stock solution.

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Full Paper
Received: 10 April 2009
Revised: 28 May 2009
Accepted: 29 May 2009
Published online in Wiley Interscience: 13 July 2009
(www.interscience.com) DOI 10.1002/aoc.1526
Synthesis and characterization of some novel
silicon esters and their application as lubricant
base stock solution
Kanak Saxena, C. S. Bisaria and A. K. Saxena∗
A series of functional organosilanes and their esters were synthesized by the hydrosilylation reaction of Si–H group-bearing
organosilicon derivatives with maleic anhydride using Speier’s catalyst and their esterification with long-chain alcohols in the
presence of stannous oxide. These products have been characterized using elemental analysis, FT-IR, 1 H, 13 C and 29 Si NMR.
Viscosity, density, pour point, flash point and tribological properties of these compounds have also been evaluated. These
c
esters have a pour point of <−60 ◦ C, a flash point of ∼200 ◦ C (closed-cup) and excellent load carrying capacity. Copyright 2009 John Wiley & Sons, Ltd.
Keywords: hydrosilylation; organosilane; Speier’s catalyst; pour point; flash point
Introduction
Synthetic esters are used widely as lubricants in aerospace, deep
sea environments and high altitudes as they have low pour points
and high flash points compared with mineral oils.[1 – 6] These
synthetic lubricants are prepared, in general, by the blending
of diesters and polyol esters which in turn are prepared by the
esterification reaction of dibasic acids and long-chain alcohols or
polyols and monobasic acids in the presence of mineral or organic
acid catalysts. However, due to the contamination of these
catalysts with esters, the materials are not completely neutral and
cause corrosion and also decrease the shelf-life of the lubricants.
A large number of patents have appeared on the manufacture of
completely neutral synthetic ester base stock solutions, especially
for aero-engine applications.[7 – 11] Such information in open
literature is very scarce. Despite the improved pour point and flash
point, it has been observed that the thermo-oxidative stability of
these synthetic esters[12,13] is not very promising, hence in certain
applications silicone oils have been used. However, due to poor
lubricating properties, the use of silicones is very restricted.[14 – 16]
To overcome the inherent problems of conventional lubricants
based on mineral oils, synthetic esters and silicone oil, it is
intended to synthesize some new esters to meet the desired
properties of both classes of materials, i.e. mineral oils/organic
esters and silicones. In view of this, in the present investigation we
have synthesized some novel branched chain complete neutral
organosilane and organodisiloxane esters as base stock solution
and evaluated their properties.
Experimental
grade, SD Fine Chemicals), isodecyl alcohol and bromobenzene
(LR grade, Ranbaxy) were used after distillation. Tetrahydrofuran
(LR grade, Ranbaxy), hexane (LR grade, E. Merck), diethylether
(LR grade, Ranbaxy), petroleum ether 60–80 ◦ C (AR grade, Samir
Tech-Chem Pvt Ltd) and benzene (LR grade, Ranbaxy) were
purified and dried before use as reported.[17]
Dibutylmethylsilane was prepared by the reaction of
dichloromethylsilane and butyl lithium in benzene under inert
atmosphere, yield 85.0%, b.p. 174–175 ◦ C, lit. b.p. 174–175 ◦ C.[18]
Butyldimethylsilane was synthesized by the reaction of
chlorodimethylsilane and butyl lithium in benzene under
inert atmosphere, yield 87.2%, b.p. 100–101 ◦ C, lit. b.p.
101–102 ◦ C.[18] Chlorodimethylsilane was hydrolyzed to afford
1,1,3,3-tetramethyldisiloxane, yield 82.5%, b.p. 71–72 ◦ C, lit. b.p.
72–73 ◦ C.[18]
Chloromethylphenylsilane was prepared by the Grignard
reaction of dichloromethylsilane and PhMgBr in diethylether.
Further chloromethylphenylsilane was hydrolysed to prepare 1,3dimethyl-1,3-diphenyldisiloxane, yield 78.4% b.p. 119–120 ◦ C at
2 mm pressure lit. b.p. 120 ◦ C at 2 mm pressure.[18]
Typical Procedure and Product Characterization
Hydrosilylation reaction of organosilane and organodisiloxane with
maleic anhydride
(i) Reaction of dibutylmethylsilane and maleic anhydride: a
solution of dibutylmethylsilane (12.5 ml, 0.06 mol), maleic anhydride (5.88 g, 0.06 mol) and Speier’s catalyst[19] (0.03 mol%)
in THF (50 ml) was combined in a round-bottom flask fitted
with a condenser and magnetic stirrer. The solution was refluxed with stirring for 6 h under a strictly inert atmosphere.
Chemicals
Appl. Organometal. Chem. 2009 , 23, 535–540
∗
Correspondence to: A. K. Saxena, DMSRDE, Applied Chemistry Division,
DMSRDE, DRDO, Kanpur-208013 India. E-mail: arvsaxena@gmail.com
Defence Materials and Stores Research and Development Establishment,
Kanpur 208013, India
c 2009 John Wiley & Sons, Ltd.
Copyright 535
Chlorodimethylsilane (Synthesis grade, E. Merck), dichloromethylsilane (99%, Aldrich), butyllithium (15% solution in hexane, Acros),
Mg (99.8%, Fluka), stannous oxide (99.99%, Aldrich) and maleic
anhydride (LR grade, SD Fine Chemicals) were used as received.
2-Ethylhexanol (LR grade, SD Fine Chemicals), 1-octanol (LR
K. Saxena, C. S. Bisaria and A. K. Saxena
Afterwards, the solvent was removed by distillation and the
residue was purified by column chromatography using silica gel (50 g for 1 ml) as stationary phase and petroleum
ether (60–80 ◦ C) as mobile phase, which gave the hydrosilylated product (HP1, C13 H24 O3 Si), yield 12.5 g, 81.3%. IR
(cm−1 ) 2958 (–CH3 ), 2923 (–CH2 –), 2873 (–CH–), 1850, 1781
(–CO–O–CO–, asy, sym), 1252 (–Si–CH2 –, –Si–CH3 ); 1 H
NMR (CDCl3 ) δ (ppm) −0.01 (s,–Si–CH3 ), 0.86 (q,–Si–CH2 –),
1.24 (t,–CH2 –CH3 ), 2.05 (m,–Si–CH2 –CH2 –CH2 –CH3 ),
3.62 (d,–CH2 –CO–), 4.71 (t,–Si–CH–CO–); 13 C NMR
(CDCl3 ) δ (ppm) −6.3 (–Si–CH3 ), 12.4 (–Si–CH2 –), 13.7
(–CH2 –CH3 ), 26.2 (–CH2 –CH2 –CH3 ), 26.6 (–Si–CH2 –CH2 –),
39.2 (–CH–CH2 –CO–), 48.1 (–Si–CH–CO–), 195.1 (–CO–);
29 Si NMR (CDCl ) δ (ppm) −61 (Bu MeSi–CH); elemental anal3
2
ysis (%) C 60.85, H 9.45, O 18.74, Si 10.89 (calcd 60.87, 9.44,
18.73, 10.90 respectively).
Similarly others reactions as mentioned below were carried out.
(ii) Reaction of butyldimethylsilane (15.0 ml, 0.09 mol), maleic
anhydride (8.82 g, 0.09 mol), Speier’s catalyst (0.03 mol%)
in THF (50 ml) yielded a product (HP2, C10 H18 O3 Si) 16.5 g,
85.6%. IR (cm−1 ) 2923 (–CH2 –), 2873 (–CH–), 1850, 1780
(–CO–O–CO–, asy, sym), 1251(–Si–CH2 –, –Si–CH3 ); 1 H
NMR (CDCl3 ) δ (ppm) 0.07 (s,–Si–CH3 ), 0.84 (t,–Si–CH2 –),
1.32 (t,–CH2 –CH3 ), 1.96 (m,–Si–CH2 –CH2 –CH2 –CH3 ),
2.58 (d,–CH2 –CO–), 4.16 (t,–Si–CH–CO–); 13 C NMR
(CDCl3 ) δ (ppm) −4.5 (–Si–CH3 ), 13.7 (–Si–CH2 –), 14.0
(–CH2 –CH3 ), 26.5 (–CH2 –CH2 –CH3 ), 26.8 (–Si–CH2 –CH2 –),
39.2 (–CH–CH2 –CO–), 48.1 (–Si–CH–CO–), 195.1 (–CO–);
29
Si NMR (CDCl3 ) δ (ppm) −57 (Me2 BuSi–CH–); elemental
analysis (%) C 56.04, H 8.41, O 22.42, Si 13.10 (calcd 56.02,
8.40, 22.40, 13.11 respectively).
(iii) Reaction of 1,3-dimethyl-1,3-diphenyldisiloxane (10.0 ml,
0.04 mol), maleic anhydride (7.84 g, 0.08 mol), Speier’s
catalyst (0.03 mol%) in THF (50 ml) yielded a product
(HP3, C22 H22 O7 Si2 ) 15.15 g, 83.4%. IR (cm−1 ) 2963 (–CH–),
2923 (–CH2 –), 1841, 1781 (–CO–O–CO–, asy, sym), 1495
(–Si–Ph), 1261 (–Si–CH3 ), 1054 (–SiOSi–); 1 H NMR (CDCl3 ) δ
(ppm) −0.01 (s,–Si–CH3 ), 0.84 (t,–Si–CH2 –), 7.3–7.5 (m, aromatic protons), 2.83 (d,–CH2 –CO–), 5.0 (t,–Si–CH–CO–); 13 C
NMR (CDCl3 ) δ (ppm) 0.6 (–Si–CH3 ), 35.2 (–CH–CH2 –CO–),
42.1 (–Si–CH–CO–), 127.3–133.2 (–Si–Ph–) 210.8 (–CO–);
29 Si NMR (CDCl ) δ (ppm) −120 [CH–Si(PhMe)–O]; elemental
3
analysis (%) C 58.14, H 4.86, O 24.66, Si 12.35 (calcd 58.12,
4.88, 24.65, 12.36 respectively).
(iv) Reaction of 1,1,3,3–tetramethyldisiloxane (14.0 ml, 0.07 mol),
maleic anhydride (13.72 g, 0.14 mol), Speier’s catalyst
(0.03 mol%) in THF (50 ml) yielded a product (HP4,
C12 H18 O7 Si2 ) 18.5 g, 80.0%. IR (cm−1 ) 2973 (–CH2 –),
2923 (–CH–), 1850, 1781 (–CO–O–CO–, asy, sym), 1255
(–Si–CH3 ), 1064 (–SiOSi–); 1 H NMR (CDCl3 ) δ (ppm) 0.01
(s,–Si–CH3 ), 2.84 (d,–CH2 –CO–), 4.49 (t,–Si–CH–CO–); 13 C
NMR (CDCl3 ) δ (ppm) −1.0 (–Si–CH3 ), 30.1 (–CH–CH2 –CO–),
37.2 (–Si–CH–CO–), 195.2 (–CO–); 29 Si NMR (CDCl3 ) δ (ppm)
−21 [CH–Si(Me2 )–O]; elemental analysis (%) C 43.59, H 5.50,
O 33.91, Si 17.01 (calcd 43.60, 5.49, 33.90, 17.00 respectively).
(ii)
(iii)
(iv)
Esterification reaction of hydrosilylated products with alcohols
536
(i) Reaction of HP1 with 2-ethylhexanol: a solution of HP1
(10.0 ml, 0.04 mol), 2-ethylhexanol (32.5 ml, 0.20 mol) and
metal oxide catalyst (3% of HP1) was combined in a round
bottom flask (250 ml) fitted with Dean’s Stark and refluxed
www.interscience.wiley.com/journal/aoc
(v)
for ∼6 h and cooled to room temperature. The solution
was filtered under pressure using millipore filters (11 µm) to
remove catalyst. The filtered solution was vacuum distillated
(3 torr, 70 ◦ C) to remove excess alcohol. The reaction product
(E1a, C29 H58 O4 Si) was purified by column chromatography
using silica gel (50 g for 1 ml) as stationary phase and a
mixture of petroleum ether (60–80 ◦ C) and ethyl acetate
(20 : 1) as mobile phase. Yield 19.0 g, 95.3%. IR (cm−1 ) 2959
(–CH3 ), 2927 (–CH2 –), 2874 (–CH–), 1736 (–COOR), 1252
(–Si–CH3 ); 1 H NMR (CDCl3 ) δ (ppm) 0.07 (s,–Si–CH3 ), 0.57
(t,–Si–CH2 –), 0.85–1.61 (m,–Si–CH2 –CH2 –CH2 –CH3 and
alkyl chain), 2.58 (d,–CH2 –CO–), 4.02 (d,–O–CH2 –), 4.17
(t,–Si–CH–CO–); 13 C NMR (CDCl3 ) δ (ppm) −6.3 (–Si–CH3 ),
15.4–33.2 (–Si–CH–CO–, –CH–CH2 –CO–, alkyl chain and
Si–Bu), 67.7 (–O–CH2 ), 166.3 (–CO–); 29 Si NMR (CDCl3 ) δ
(ppm) −61 (Bu2 MeSi–CH); elemental analysis (%) C 69.82,
H 11.71, O 12.81, Si 5.64 (calcd 69.80, 11.73, 12.83, 5.63
respectively).
Similarly other reactions as mentioned below were carried out.
Reaction of HP1 (10.0 ml, 0.04 mol), 1-octanol (32.5 ml,
0.20 mol) and stannous oxide (3% of HP1) yielded a
product (E1b, C29 H58 O4 Si) 19.3 g, 96.7%. IR (cm−1 ) 2957
(–CH3 ), 2927 (–CH2 –), 2857 (–CH–), 1736 (–COOR), 1252
(–Si–CH3 ); 1 H NMR (CDCl3 ) δ (ppm) 0.07 (s,–Si–CH3 ),
0.58 (t,–Si–CH2 –), 0.86–1.63 (m,–Si–CH2 –CH2 –CH2 –CH3
and alkyl chain), 2.59 (d,–CH2 –CO–), 4.07 (t,–O–CH2 –),
4.18 (t,–Si–CH –CO–); 13 C NMR (CDCl3 ) δ (ppm)
−6.3 (–Si–CH3 ),15.7–34.5 (–Si–CH–CO–, –CH–CH2 –CO–,
alkyl chain and–Si–Bu), 68.5 (–O–CH2 –), 167.2 (–CO–); 29 Si
NMR (CDCl3 ) δ (ppm) −53 (Bu2 MeSi–CH); elemental analysis
(%): C 69.81, H 11.72, O 12.85, Si 5.62 (calcd 69.80, 11.73,
12.83, 5.63 respectively).
Reaction of HP1 (10.0 ml, 0.04 mol), isodecyl alcohol (39.5 ml,
0.20 mol) and stannous oxide (3% of HP1) yielded a product
(E1c, C33 H66 O4 Si) 21.5, 96.4%. IR (cm−1 ) 2959 (–CH3 ), 2929
(–CH2 –), 2872 (–CH–), 1736 (–COOR), 1259 (–Si–CH3 ); 1 H
NMR (CDCl3 ) δ (ppm) 0.06 (s,–Si–CH3 ), 0.56 (t,–Si–CH2 –),
0.83–1.60 (m,–Si–CH2 –CH2 –CH2 –CH3 and alkyl chain),
2.58 (d,–CH2 –CO–), 4.05 (t,–O–CH2 –), 4.16 (–Si–CH–CO–);
13 C NMR (CDCl ) δ (ppm) −6.3 (–Si–CH ), 12.7–38.4
3
3
(–Si–CH–CO–, –CH–CH2 –CO–, alkyl chain and–Si–Bu),
65.7 (–O–CH2 –), 164.5 (–CO–); 29 Si NMR (CDCl3 ) δ (ppm)
−50 (Me2 BuSi–CH–); elemental analysis (%): C 71.42, H 11.97,
O 11.51, Si 5.08 (calcd 71.40, 11.99, 11.54, 5.06 respectively).
Reaction of HP2 (10.0 ml, 0.05 mol), 2-ethylhexanol (40.6 ml,
0.25 mol) and stannous oxide (3% of HP2) yielded a
product (E2a, C26 H52 O4 Si) 21.6 g, 94.6%. IR (cm−1 ) 2960
(–CH3 ), 2931 (–CH2 –), 2874 (–CH–), 1735 (–COOR), 1259
(–Si–CH3 ); 1 H NMR (CDCl3 ) δ (ppm) 0.06 (s,–Si–CH3 ),
0.57 (t,–Si–CH2 –), 0.86–1.64 (m,–Si–CH2 –CH2 –CH2 –CH3
and alkyl chain), 2.60 (d,–CH2 –CO–), 4.06 (d,–O–CH2 –),
4.17 (t,–Si–CH –CO–); 13 C NMR (CDCl3 ) δ (ppm) −4.5
(–Si–CH3 ), 13.5–36.2 (–Si–CH–CO–, –CH–CH2 –CO–,
alkyl chain and–Si–Bu), 65.4 (–O–CH2 –), 165.5(–CO–); 29 Si
NMR (CDCl3 ) δ (ppm) −57 (Me2 BuSi–CH–); elemental analysis (%): C 68.37, H 11.48, O 14.00, Si 6.14 (calcd 68.35, 11.48,
14.02, 6.15 respectively).
Reaction of HP2 (10.0 ml, 0.05 mol), 1-octanol (40.6 ml,
0.25 mol) and stannous oxide (3% of HP2) yielded a
product (E2b, C26 H52 O4 Si) 21.8 g, 95.5%. IR (cm−1 ) 2963
c 2009 John Wiley & Sons, Ltd.
Copyright Appl. Organometal. Chem. 2009, 23, 535–540
Synthesis and characterization of some novel silicon esters
(vi)
(vii)
(viii)
(ix)
Appl. Organometal. Chem. 2009, 23, 535–540
NMR (CDCl3 ) δ (ppm) −71 (CH–Si(PhMe)–O); elemental analysis (%): C 70.80, H 10.15, O 13.67, Si 5.35 (calcd 70.79, 10.16,
13.69, 5.34 respectively).
(x) Reaction of HP4 (10.0 ml, 0.03 mol), 2-ethylhexanol (48.7 ml,
0.30 mol) and stannous oxide (3% of HP4) yielded a
product (E4a, C44 H86 O9 Si2 ) 23.2 g, 94.8%. IR (cm−1 ) 2959
(–CH3 ), 2930 (–CH2 –), 2862 (–CH–), 1732 (–COOR), 1259
(–Si–CH3 ), 1070 (–SiOSi–); 1 H NMR (CDCl3 ) δ (ppm) 0.16
(s,–Si–CH3 ), 0.88–1.61 (m, alkyl chain), 2.48 (d,–CH2 –CO–),
4.09 (d,–O–CH2 –), 4.24 (t,–Si–CH–CO–); 13 C NMR
(CDCl3 ) δ (ppm) 1.0 (–Si–CH3 ), 15.7–36.2 (–Si–CH–CO–,
–CH–CH2 –CO–and alkyl chain), 65.7 (–O–CH2 –), 165.8
(–CO–); 29 Si NMR (CDCl3 ) δ (ppm) −8 (CH–Si(Me2 )–O);
elemental analysis (%): C 64.81, H 10.65, O 17.67, Si 6.90
(calcd 64.79, 10.64, 17.67, 6.89 respectively).
(xi) Reaction of HP4 (10.0 ml, 0.03 mol), 1-octanol (48.7 ml,
0.30 mol) and stannous oxide (3% of HP4) yielded a
product (E4b, C44 H86 O9 Si2 ) 23.44g, 95.8%. IR (cm−1 ) 2959
(–CH3 ), 2927 (–CH2 –), 2856(–CH–), 1735 (–COOR), 1259
(–Si–CH3 ), 1070 (–SiOSi–); 1 H NMR (CDCl3 ) δ (ppm) 0.12
(s,–Si–CH3 ), 0.86–1.65 (m, alkyl chain), 2.60 (d,–CH2 –CO–),
4.06 (t,–O–CH2 –), 4.16 (t,–Si–CH–CO–); 13 C NMR
(CDCl3 ) δ (ppm) 1.1 (–Si–CH3 ), 12.6–36.1 (–Si–CH–CO–,
–CH–CH2 –CO–and alkyl chain), 65.8 (–O–CH2 –), 165.4
(–CO–); 29 Si NMR (CDCl3 ) δ (ppm) −9 (CH–Si(Me2 )–O);
elemental analysis (%): C 64.80, H 10.65, O 17.65, Si 6.91
(calcd 64.79, 10.64, 17.67, 6.89 respectively).
(xii) Reaction of HP4 (10.0 ml, 0.03 mol), isodecyl alcohol
(59.3 ml, 0.30 mol) and stannous oxide (3% of HP4)
yielded a product (E4c, C52 H102 O9 Si2 ) 26.6 g, 95.6%.
IR (cm−1 ) 2959 (–CH3 ), 2930 (–CH2 –), 2872 (–CH–),
1735 (–COOR), 1258 (–Si–CH3 ), 1070 (–SiOSi–). 1 H
NMR (CDCl3 ) δ (ppm) 0.15 (s,–Si–CH3 ), 0.82–1.67 (m,
alkyl chain), 2.63 (d,–CH2 –CO–), 4.09 (t,–O–CH2 –), 4.20
(t,–Si–CH–CO–); 13 C NMR (CDCl3 ) δ (ppm) 1.1 (–Si–CH3 ),
10.2–38.1 (–Si–CH–CO–, –CH–CH2 –CO–and alkyl chain),
65.9 (–O–CH2 –), 165.5 (–CO–); 29 Si NMR (CDCl3 ) δ (ppm)
−12 (CH–Si(Me2 )–O); elemental analysis (%): C 67.34, H
11.08, O 15.54, Si 6.04 (calcd 67.32, 11.09, 15.53, 6.06 respectively).
Equipment and Analytical Measurements
Perkin Elmer FTIR Spectrometer RX1 was used to record IR spectra
using NaCl pellets. A Bruker Avance 400 MHz NMR spectrometer
was used for NMR studies using deutrated chloroform as solvent
and TMS as standard reference. A Vario EL III CHNOS elemental
analyzer was used for elemental analysis. Density, viscosity, pour
point and flash point were evaluated according to ASTM D1480,[20] ASTM D-445,[20] ASTM D-97[20] and ASTM D-3828[20]
methods, respectively. To investigate the load carrying capacities
Optimol Instruments SRV tester was used. At the temperature
50 ◦ C, frequency 50 Hz and stroke 1 mm, the load was increased
in multiples of 50 N and the machine run under this condition for
2 min until occurrence of seizure.
Results and Discussion
High-performance and multifunctional materials are always in
demand to meet the requirements of modern technological
advancements. Likewise, there is a growing demand for completely
c 2009 John Wiley & Sons, Ltd.
Copyright www.interscience.wiley.com/journal/aoc
537
(–CH3 ), 2927 (–CH2 –), 2857 (–CH–), 1735 (–COOR), 1260
(–Si–CH3 ); 1 H NMR (CDCl3 ) δ (ppm) 0.07 (s,–Si–CH3 ),
0.59 (t,–Si–CH2 –), 0.88–1.67 (m,–Si–CH2 –CH2 –CH2 –CH3
and alkyl chain), 2.65 (d,–CH2 –CO–), 4.06 (t,–O–CH2 –),
4.17 (t,–Si–CH–CO–); 13 C NMR (CDCl3 ) δ (ppm) −4.5
(–Si–CH3 ), 12.6–37.4 (–Si–CH–CO–, –CH–CH2 –CO–,
alkyl chain and–Si–Bu), 65.8 (–O–CH2 –), 165.4 (–CO–); 29 Si
NMR (CDCl3 ) δ (ppm) −53 (Me2 BuSi–CH–); elemental analysis (%): C 68.36, H 11.49, O 14.01, Si 6.15 (calcd 68.35, 11.48,
14.02, 6.15 respectively).
Reaction of HP2 (10.0 ml, 0.05 mol), isodecyl alcohol (49.4 ml,
0.25 mol) and stannous oxide (3% of HP2) yielded a product
(E2c, C30 H60 O4 Si) 24.7 g, 96.4%. IR (cm−1 ) 2959 (–CH3 ), 2929
(–CH2 –), 2872 (–CH–), 1736 (–COOR), 1258 (–Si–CH3 ); 1 H
NMR (CDCl3 ) δ (ppm) 0.08 (s,–Si–CH3 ), 0.58 (t,–Si–CH2 –),
0.85–1.67 (m,–Si–CH2 –CH2 –CH2 –CH3 and alkyl chain),
2.61 (d,–CH2 –CO–), 4.07 (t,–O–CH2 –), 4.17 (-Si–CH–CO–);
13 C NMR (CDCl ) δ (ppm) −4.5 (–Si–CH ), 10.8–40.2
3
3
(–Si–CH–CO–, –CH–CH2 –CO–, alkyl chain and–Si–Bu),
65.7 (–O–CH2 –), 165.6 (–CO–); 29 Si NMR (CDCl3 ) δ (ppm)
−48 (Me2 BuSi–CH–); elemental analysis (%): C 70.25, H 11.81,
O 12.46, Si 5.48 (calcd 70.24, 11.79, 12.48, 5.48 respectively).
Reaction of HP3 (10.0 ml, 0.02 mol), 2-ethylhexanol
(32.5 ml, 0.20 mol) and stannous oxide (3% of HP3)
yielded a product (E3a, C54 H90 O9 Si2 ) 18.0 g, 95.8%. IR
(cm−1 ) 3050–3070 (aromatic protons), 2960 (–CH3 ), 2930
(–CH2 ), 2873 (–CH–), 1736 (–COOR), 1461 (SiPh), 1261
(Si–CH3 ), 1076 (–SiOSi–); 1 H NMR (CDCl3 ) δ (ppm) 0.07
(s,–Si–CH3 ), 0.95–1.75 (m, alkyl chain), 2.69 (d,–CH2 –CO–),
4.08 (d,–O–CH2 –), 4.18 (t,–Si–CH–CO–), 7.41–7.62 (m,
aromatic protons); 13 C NMR (CDCl3 ) δ (ppm) 0.8 (–Si–CH3 )
12.4–32.2 (–Si–CH–CO–, –CH–CH2 –CO–and alkyl chain),
65.8 (–O–CH2 –), 127.5–133.4 (–Si–Ph), 165.5 (–CO–); 29 Si
NMR (CDCl3 ) δ (ppm) −56 (CH–Si(PhMe)–O); elemental analysis (%): C 69.03, H 9.65, O 15.34, Si 5.96 (calcd 69.02, 9.66,
15.33, 5.98 respectively).
Reaction of HP3 (10.0 ml, 0.02 mol), 1-octanol (32.5 ml,
0.20 mol) and stannous oxide (3% of HP3) yielded
a product (E3b, C54 H90 O9 Si2 ) 17.8 g, 94.8%. IR (cm−1 )
3050–3070 (aromatic protons), 2957 (–CH3 ), 2927 (–CH2 –),
2856 (–CH–), 1736 (–COOR), 1465 (–Si–Ph), 1262
(–Si–CH3 ), 1076 (–SiOSi–); 1 H NMR (CDCl3 ) δ (ppm) 0.07
(s,–Si–CH3 ), 0.93–1.75 (m, alkyl chain), 2.68 (d,–CH2 –CO–),
4.10 (t,–O–CH2 –), 4.18 (t,–Si–CH–CO–), 7.39–7.62 (m,
aromatic protons); 13 C NMR (CDCl3 ) δ (ppm) 0.8 (–Si–CH3 ),
12.6–32.4 (–Si–CH–CO–, –CH–CH2 –CO–and alkyl chain),
65.5 (–O–CH2 –), 127.5–133.2 (–Si–Ph), 165.2 (–CO–); 29 Si
NMR (CDCl3 ) δ (ppm) −59 [CH–Si(PhMe)–O]; elemental analysis (%): C 69.01, H 9.64, O 15.35, Si 5.98 (calcd 69.04, 9.66,
15.33, 5.98 respectively).
Reaction of HP3 (10.0 ml, 0.02 mol), isodecyl alcohol
(39.5 ml, 0.20 mol) and stannous oxide (3% of HP3)
yielded a product (E3c, C62 H106 O9 Si2 ) 20.1 g, 95.6%. IR
(cm−1 ) 3050–3070 (aromatic protons), 2958 (–CH3 ), 2928
(–CH2 –), 2872 (–CH–), 1735 (–COOR), 1466 (–Si–Ph), 1260
(–Si–CH3 ), 1077 (–SiOSi–); 1 H NMR (CDCl3 ) δ (ppm) 0.76
(s,–Si–CH3 ), 0.85–1.62 (m, alkyl chain), 2.52 (d,–CH2 –CO–),
4.02 (t,–O–CH2 –), 4.19 (t,–Si–CH–CO–), 6.56–7.12 (m,
aromatic protons); 13 C NMR (CDCl3 ) δ (ppm) 0.8 (–Si–CH3 ),
12.4–38.2 (–Si–CH–CO–, –CH–CH2 –CO–and alkyl chain),
65.8 (–O–CH2 –), 127.4–133.1 (–Si–Ph), 165.3 (–CO–); 29 Si
K. Saxena, C. S. Bisaria and A. K. Saxena
neutral high-performance lubricants for modern hyper planes,
rockets, missiles and submarines. Therefore, keeping in view the
limiting factors of mineral oils and synthetic esters lubricants,
it has been considered worthwhile to develop a convenient
high-yield synthesis of some novel organosilicon esters having
high flash point, low pour point and good load carrying
capacity.
These materials have been prepared in two steps as given
below:
filtration. There are patents available in which metal halides are
used as catalysts,[29 – 32] but in such cases halide ions are present
in products due to the hydrolysis of metal halogen bonds caused
by moisture. However, we used SnO, which did not contaminate
the product due to moisture. An added advantage herein is that
the catalyst is reusable if filtered under inert atmosphere. A possible mechanism of esterification using SnO as catalyst is given in
Scheme 3.
IR studies
1. Hydrosilylation reactions are very common to prepare functional organosilanes.[21 – 23] To carry out a hydrosilylation
reaction on unsaturated olefinic bonds, the Speier’s catalyst is one of the most favorable catalysts.[24 – 28] Therefore we
carried out hydrosilylation reaction of maleic anhydride with
Si–H group-bearing organosilanes and siloxanes in appropriate molar ratios in the presence of Speier’s catalyst using THF
as solvent (Scheme 1).
2. The esterification reaction of anhydride group-bearing
organosilicon derivatives with long chain aliphatic alcohols
was carried out using stannous oxide as catalyst (Scheme 2).
The completion of the reaction was monitored with the quantity of liberated water.
The process has an edge over the conventional processes where
organic or mineral acids are used as catalysts to facilitate the esterification reaction. In such cases, the removal of acid contaminants
in base stocks is a tedious process to afford completely neutral
base stocks, whereas in the present investigation the SnO has
been used as heterogenous catalyst which is easily removable by
The progress of hydrosilylation reaction of Si–H with maleic
anhydride was monitored with the disappearance of the νSi – H peak
at ∼2100 cm−1 and the νc c peak at 1594 cm−1 . The presence of
νs and νas at ∼1780 and ∼1850 cm−1 showed that the anhydride
group was intact. The siloxane products showed characteristic
absorption at ∼1060 cm−1 for νSi – O – Si .
Esters showed characteristic absorption at ∼1735 cm−1 due
to the νc o peak and absorptions due to anhydride group
disappeared at νs ∼ 1780 cm−1 and νas ∼ 1850 cm−1 .
Physical properties
Both the monosilanes and disiloxanes esters showed viscosities in
the range of 7–38 cst at 40 ◦ C. The viscosities of esters depend
on the alcohol used (Table 1). The esters of higher alcohols, e.g.
isodecyl alcohol, showed higher viscosity than esters of lower
alcohols, e.g. 2-ethylhexanol and 1-octanol.
The density of different esters was found to be in the
range of 0.89–0.95 at 25 ◦ C. Monosilane and disiloxane esters of 2-ethylhexanol and isodecyl alcohol showed pour
O
Me
Si
R′
R
Me
R
+
O
H
O
Si
H2PtCl6
R′
THF, reflux
O
O
Organosilane
or organosiloxane
HP 1 R = Bu R′ = Bu,
HP 3
O
Hydrosilylated product (HP)
Maleic anhydride
HP 2 R = Bu R′ = Me
R = Ph R′ = PhMeHSiO–
HP 4 R = Me R′ = Me2HSiO–
Scheme 1. Synthesis of hydrosilylated products.
O
Si
OR′′
SnO
HP
+
Hydrosilylated
R′′ OH
alcohol
OR′′
reflux
+
H 2O
O
silicon ester
Product
E 1a
HP = HP1 R′′ = X, E 1b HP = HP1 R′′ = Y, E 1c HP = HP1 R′′ = Z
E 2a
HP = HP2 R′′ = X, E 2b HP = HP2 R′′ = Y, E 2c HP = HP2 R′′ = Z
E 3a
HP = HP3 R′′ = X, E 3b HP = HP3 R′′ = Y, E 3c HP = HP3 R′′ = Z
E 4a
HP = HP4 R′′ = X, E 4b HP = HP4 R′′ = Y, E 4c HP = HP4 R′′ = Z
X = CH3(CH2) 3(CH2CH3)CHCH2–, Y = CH3(CH2) 6CH2–, Z = (CH3) 2CH(CH2)6CH2–
538
Scheme 2. Synthesis of silicon esters.
www.interscience.wiley.com/journal/aoc
c 2009 John Wiley & Sons, Ltd.
Copyright Appl. Organometal. Chem. 2009, 23, 535–540
Synthesis and characterization of some novel silicon esters
O
Sn
O
C
R
R
Me
Me
Si
O
Si
R′
δ δ
SnO
C
R′
O
Sn
O
C
R
Me
Si
R′
O
O
C
C
O
O
O
Sn
O
R
Me
H
O
Si
H
C O
O R′′
R′
R′′
O
C
C
O
O
Proton
transfer
Me
R
Si
R′
O
Me
Me
O
Si
C
C
R
R
O
R′
O
R′′
OH
C
C
Sn
O
O
H
O
O
R′′
OH
Me
O
Si
R′
O
Si
C
C
O
Sn
R
R′
δ δ
O
R′′ + SnO
OH
C
O
OH R′′
C
O
O
Sn
O
R′′
Me
O
Si
R′
C
O R′′
OH
Proton
transfer
O
Si
R′
C
O
R′′
OH2
Me
O
Si
R′
C
C
O
R′′ O Sn
O
C
O
R′′ O Sn
O
H
R
R
R
Me
C
O
R′′
O R′′
+ H2O + SnO
O
Scheme 3. Mechanism of esterification.
points of approximately <−60 ◦ C, whereas similar esters of 1octanol showed slightly higher pour points values ∼−35 ◦ C.
Such variation of pour points indicates that the branching
of alkyl chain of esters plays significant role in the pour
point. The linear chain increases the pour point dramatically;
consequently esters having branched alkyl chain have lower
pour points as compared with their linear chain analogous
members.[1 – 3,5,33]
The flash points of silicon esters as compared with organic esters
of the same alcohol are invariably high,[33,34] as shown in Table 1.
The flash point showed an increasing trend with the increase of
alkyl chain length, but the isomers, e.g. 2-ethylhexyl alcohol and
1-octanol, have nearly same flash points.
It is evident from the data of the SRV test (Table 1) that
silicon-based esters have higher load carrying capacities than
polysiloxane and approximately in the range of analogous
synthetic esters.[6,33 – 35]
Conclusion
Table 1. Physical properties and load carrying capacity results of
silicon esters
Compound
Viscosity
(cSt) (at
40 ◦ C)
Flash
point
(◦ C)
Pour
point
(◦ C)
Load
carrying
capacity (N)
0.94
0.94
0.92
0.95
0.95
0.93
0.89
0.91
0.91
0.92
0.92
0.91
13.65
20.25
35.73
23.44
21.85
38.69
7.74
14.34
26.40
14.79
14.34
24.12
183
177
205
175
183
200
165
170
205
175
187
200
<−61
−37
−55
<−60
−35
<−60
<−60
−41
<−60
<−60
−23
<−60
400
350
650
600
700
450
700
350
500
450
400
600
Appl. Organometal. Chem. 2009, 23, 535–540
Both the monosilane and disiloxane esters have shown good
lubricating properties and may serve as base stocks for preparing
high performance lubricants. Stannous oxide proved efficient
catalyst for esterification. Yields were very high.
Acknowledgments
Thanks are due to the Director, DMSRDE for necessary encouragement and providing laboratory facilities to facilitate the work. We
are also thankful to the scientists of the Fuel and Lubricant Division
of the Laboratory for SRV tests. We also extend our thanks to CAF
for NMR studies.
References
[1] T. A. Isbell, M. R. Edgcom, B. A. Lowery, Ind. Crops Prod. 2001, 13, 11.
[2] S. C. Cermak, T. A. Isbell, Ind. Crops Prod. 2003, 18, 183.
c 2009 John Wiley & Sons, Ltd.
Copyright www.interscience.wiley.com/journal/aoc
539
E 1a
E 1b
E 1c
E 2a
E 2b
E 2c
E 3a
E 3b
E 3c
E 4a
E 4b
E 4c
Density
(at
25 ◦ C)
K. Saxena, C. S. Bisaria and A. K. Saxena
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
S. C. Cermak, K. B. Brandon, T. A. Isbell, Ind. Crops Prod. 2006, 23, 54.
A. Patersson, Tribology 2007, 40, 638.
S. C. Cermak, T. A. Isbell, Ind. Crops Prod. 2002, 16, 119.
I. Minami, S. Mori, J. Synth. Lubric. 2005, 22, 105.
D. L. Cottle, D. W. Young, US Patent 2705724, 1955.
K. Koch, W. Breitzke, US Patent 4113642, 1978.
N. E. Schnur, US Patent 6551524, 2003.
C. S. Bisaria, A. K. Saxena, O. Prakash, G.N. Mathur, Indian Patent
1486/DEL, 2003.
A. K. Saxena, C. S. Bisaria, Indian Patent 1379/DEL, 2003.
T. I. Sarnavskaya, E. V. Lebedev, N. A. Kholodenko, T. E. Pivovarova,
Chem. Technol. Fuels Oils 1975, 11, 807.
D. Yang, Y. W. Kim, K. Chung, J. Han, J. Korean Ind. Eng. Chem., 2002,
13, 809.
M. J. Devine, E. R. Lamson, US Patent 3609079, 1971.
H. Alberts, S. Kussi, W. Grape, O. Schlak, US Patent 4652386, 1987.
W. C. Morro, L. E. Hakka, J. M. Brophy, M. J. R. Hebrard, J. C. Courtes,
US Patent 4059534, 1977.
A. I. Vogel, Practical Organic Chemistry, 3rd edn. Longman: London,
1971.
V. Bažant, V. Chvalosky, J. Rathousky, Handbook of Organosilicon
Compounds, Vol. 2, Part 1. Academic Press: New York, 1965.
J. L. Speier, J. A. Webster, G. H. Barnes, J. Am. Chem. Soc., 1957, 79,
974.
[20] American society of testing and materials, ASTM Standards on
Petroleum Products and Lubricants, Vol. I, 39th edn, Baltimore, MD,
December 1962.
[21] D. P. Dworak, M. D. Soucek, Macromolecules, 2004, 37, 9402.
[22] L. N. Lewis, K. G. Sy, P. E. Donahue, J. Organometall. Chem. 1992,
427, 165.
[23] V. I. Zhun, A. L. Tsvetkov, V. N. Sheludakov, Zh. Obshch. Khim.,
Chem. Abstr., 1989, 59, 30.
[24] A. Ranjan, C. S. Bisaria, A. K. Saxena, Ind. J. Technol. 1993, 31, 666.
[25] A. K. Saxena, C. S. Bisaria, L. M. Pande, Ind. J. Technol. 1991, 29, 310.
[26] S. E. Denmark, D. C. Forbes, Tetrahedron Lett. 1992, 33, 5037.
[27] A. Behr, F. Naendrup, D. Obst, Adv. Synth. Catal., 2002, 10, 344.
[28] N. Saghian, D. Gertner, J. Am. Oil Chem. Soc. 1974, 51, 363.
[29] I. Takahara, N. Kaminaka, M. Kadobayashi, US Patent 5760265, 1998.
[30] J. L. Mcginnis, US Patent 4480115, 1984.
[31] J. F. Knifton, US Patent 3933884, 1976.
[32] R. M. Hanes, W. D. Baugh, US Patent 4622416, 1986.
[33] L. E. Mirci, S. Boran, P. Luca, V. Boiangiu, J. Synthet. Lubric. 2005, 22,
161.
[34] H. Y. Shao, Y. M. Liu, X. S. Fu, T. H. Ren, J. Synthet. Lubric. 2005, 22,
259.
[35] W. Huang, J. Dong, F. Li, B. Chen, Tribology 2000, 33, 553.
540
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