Adamantane-containing esters as potential components of thermostable lubricating oils

Article abstract of DOI:10.1134/S0965544113060029

Some esters of dimethyladamantanedicarboxylic acids with aliphatic alcohols and the ester of dimethyladamantanedicarbinol with an aliphatic acid have been synthesized, and their properties have been studied; their viscosity-temperature properties and ther

Full text of DOI:10.1134/S0965544113060029

ISSN 0965ꢀ5441, Petroleum Chemistry, 2013, Vol. 53, No. 6, pp. 418–422. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © E.I. Bagrii, G.B. Maravin, 2013, published in Neftekhimiya, 2013, Vol. 53, No. 6, pp. 467–472.
AdamantaneꢀContaining Esters as Potential Components
of Thermostable Lubricating Oils
E. I. Bagrii and G. B. Maravin
Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russia
eꢀmail: bagrii@ips.ac.ru
Received April 22, 2013
Abstract—Some esters of dimethyladamantanedicarboxylic acids with aliphatic alcohols and the ester of
dimethyladamantanedicarbinol with an aliphatic acid have been synthesized, and their properties have been
studied; their viscosity–temperature properties and thermoꢀoxidative stability as potential components of
highꢀtemperature lubricating oils have been examined .
Keywords: alkyladamantanes, 2,2,4ꢀtrimethylpentane, destructive alkylation, alkyladamantane oils, esters,
thermostable oils
DOI: 10.1134/S0965544113060029
Increasing the power of engine units for modern alkyl (methyl and ethyl) groups at the bridgehead posiꢀ
vehicles or the output of power devices for industrial
plants and equipment and simultaneous improving
their efficiency, environmental safety, and dimension
characteristics require continuous improving the qualꢀ
ity of lubricants, first of all, enhancing their thermal
and thermoꢀoxidative stabilities. The mineral oils used
for the purpose, which maximum operating temperaꢀ
tions of the adamantane core are mainly produced in
the former case when aluminum halideꢀbased cataꢀ
lysts are used, whereas thermodynamically less stable
alkyladamantane isomers bearing the alkyl groups at
the secondary carbon atoms form in significant
amounts along with the aforementioned compounds
on solid alumina and zeoliteꢀcontaining catalysts.
ture is no more than 150°C, do not meet the demands
of the current engine building industry for a long time;
in this connection, thermostable synthetic oils, based
on of organic acid esters with neopentyl alcohol and
operable at a temperature of 200–225
are being under development now.
Higher alkyladamantanes that match oil distillates
by molecular mass can be prepared using the known
adamantane and lowerꢀalkyladamantanes alkylation
methods, which in particular are surveyed in the
monograph [9]. One of the methods is based on the
destructive adamantane alkylation reaction with
isooctane in the presence of aluminum chloride,
which was pioneered by E.I. Bagrii et al. [10, 11] and
is essentially a version of the known Ipatieff reaction
involving adamantane instead of benzene as a subꢀ
strate. The difference between these versions is that
tertꢀbutylbenzenes are produced in the case of an aroꢀ
matic substrate and isoꢀbutyladamantanes in the case
of adamantanes. This fact suggests that a likely alkylaꢀ
tion agent is the carbocationic fragment of the heteroꢀ
lytic degradation of 2,2,4ꢀtrimethylpentane (tertꢀbutyl
cation) for aromatic compounds and the anionic speꢀ
cies for adamantanes, i.e., the reaction takes place in
°C and higher
Among the starting compounds used for manufacꢀ
turing the basestock of thermally stable lubricants,
adamantane derivatives, such as higher alkyladamanꢀ
tanes and esters of adamantanepolyacids or adamanꢀ
tylpolyols, are of considerable interest [1–4]. The
starting compounds adamantane and lower alkyladaꢀ
mantanes became quite available substances because
numerous methods for their production, including
industrial processes, have been worked out. To proꢀ
duce them by isomerization, using petrochemical
feedstock (hydrogenated cyclopentadiene and methꢀ
ylcyclopentadiene dimers, the Schleyer method [5])
and coke byproducts (perhydroacenaphthene, perhyꢀ
drofluorene, the Schneider method [6]). Both alumiꢀ
num halides [5, 6] and alumina, aluminosilicates, and
zeoliteꢀcontaining materials [7, 8] can be used as catꢀ
alysts. It is noteworthy that alkyladamantanes with situ immediately after the formation of the cations:
418

ADAMANTANEꢀCONTAINING ESTERS AS POTENTIAL COMPONENTS
CH3
419
CH3
C CH3
CH3 Cꢀ
CH3
CH3
CH3
CH3
CH3
AIX
3
CH3
C
CH2
CH CH3
.
ᮎ
CH3
ADH
CH3
CH2 CH
CH3
CH3
CH CH2
However, it should be noted that the same result that prevents the friction couple from wear, thereby
will be obtained if the alkylation involves isobutylene, increasing the lubricant service life by a factor of 1.8.
which is produced by stabilization of the initially genꢀ
erated anion: owing to the electronꢀdonating effect of
two methyl groups, a certain excess electron density
concentrates on the methylene group of isobutylene
and it is this group that will attacks the adamantantyl
cation.
In context of these results, it was interesting to
examine closer the influence of the composition and
structure of adamantane derivatives on their thermal
stability, as well other properties, in relation to their
potential use as components of thermostable lubricatꢀ
ing oils.
In this paper we report the results of study on the
synthesis and properties of some new compounds,
namely, diesters of alkyladamantanedicarboxylic acids
with aliphatic alcohols and diesters of alkyladamanꢀ
tanedicarbinol with aliphatic acids.
The facts that the reaction proceeds rapidly at a relꢀ
atively low temperature (45–50°C) and that the prodꢀ
ucts barely contain condensation or polymerization
substances support the mechanism in question. Howꢀ
ever, the mechanism of this interesting reaction
demands closer examination to finally elucidate the
issue.
When excess isooctane is used, triꢀ and tetrasubstiꢀ
tuted isobutyladamantanes bearing substituents at the
tertiary carbon atoms of the core are the main prodꢀ
ucts. In practical application of the reaction, it should
be borne in mind that during a longer contact with the
EXPERIMENTAL
In this work the following two types of esters were
synthesized and examined:
CH3
catalyst isobutyl groups isomerize to
because of a higher thermodynamic stability of
butyladamantanes. It is of alkyladamantanes that the
latter property is characteristic [9].
nꢀbutyl groups
O
R O C
nꢀ
C O R
O
CH3
This method based on the destructive alkylation
reaction of adamantane with isooctane was used by
Podehradska et al [12] to build up pilot batches of triꢀ
isobutylꢀ and tetraisobutyladamantane mixtures and
to assess their potential use as lubricants. It was conꢀ
cluded that tetraisobutyladamantane oil could be used
as cable oil owing to its high electrical insulating propꢀ
erties; whereas triisobutyladamantane oil was not recꢀ
ommended for use in freon compressors because of its
insufficient thermal stability.
R = C4H9 (I); C5H11 (II); C8H17 (III); C16H33 (IV)
CH3
O
O
H2C
R1 C O
CH2
O C R1
CH3
R1 = C5H11 (V)
Monoesters of adamantanecarboxylic acids, lauryl
alkyladamantanecarboxylates and neopentyl alkyladꢀ
amantanecarboxylates, were proved to be more stable
as well as methyladamantanylcarbinol monoesters
(monoalkyladamantanyl)methyl laurates. In [13] one
Synthesis of 5,7ꢀDimethyladamantaneꢀ1,3ꢀ
dicarboxylic Acids (R = H)
The reaction mixture containing sulfuric acid
of the authors with coworkers found that monoadaꢀ (1000 mL, 94%) and an activator reagent (100 mL)
mantanecarboxylic acid esters are very effective antiꢀ was cooled to 28 , and 1,3ꢀdimethyladamantane
°C
wear additives for lubricant compositions based on (50 g) was slowly, portionwise added to the mixture.
polysiloxane fluids. The working capacity of lubricants The reaction mixture was vigorously stirred and forꢀ
in ball bearings of lowꢀpower micromotors increases mic acid (100 mL, 99%) was slowly added dropwise
owing to these additives. The positive effect is due to within 2 h, then the mixture was agitated for 3 h at
the fact that adamantanecarboxylic esters are room temperature. The reaction mixture was poured
adsorbed on friction surfaces to form a protective layer onto ice. The precipitate formed was filtered off,
PETROLEUM CHEMISTRY Vol. 53
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420
BAGRII, MARAVIN
washed with water until the filtrate was neutral, dried liquid nitrogen, whereas temperature of a heating bath
in air, and recrystallized from aqueous ethanol. The was 200°C. The yield of the
acid yield was 90% of theory. Mp 270°C. Found (%): (43%). Mp 39°C.
C 66.65; H 8.03. Calculated for С14Н20О4 (%):
C 66.61; H 7.94.
nꢀhexadecyl ester was 24 g
Synthesis of Diester of 5,7ꢀDimethylꢀ1,3ꢀ
Dihydroxymethyladamantane and Isovaleric Acid (V)
Diꢀnꢀbutylꢀ5,7ꢀdimethyladamantaneꢀ1,3ꢀ
dicarboxylate (I)
(A) Dimethylꢀ5,7ꢀdimethyladamantaneꢀ1,3ꢀdicarꢀ
boxylate. In a oneꢀneck flask fitted with a Dean–Stark
trap, unpurified 5,7ꢀdimethyladamantaneꢀ1,3ꢀdicarꢀ
boxylic acid (41 g) prepared as described above was
suspended in benzene (0.4 L) and boiled for 2 h to
remove the aqueous layer. Methanol (0.1 L) and oleum
(0.002 L, 30%) were added and boiled for another 2 h.
The solution was cooled, transferred into a separating
funnel with the subsequent addition of 0.1 L of a 10%
ammonium solution, and shaken; the aqueous layer
was separated; the benzene layer was filtered through a
In a oneꢀneck flask fitted with a Dean–Stark trap
and a reflux condenser 5,7ꢀdimethyladamantaneꢀ1,3ꢀ
dicarboxylic acid (20 g, 0.079 mol), benzene (150 mL)
and nꢀbutanol (12.9 g, 0.174 mol, 16 mL) were susꢀ
pended, concentrated sulfuric acid (0.37 g, 0.2 mL)
was added to the suspension, and the mixture was
refluxed 6 h until the calculated amount of water
(2.9 mL) was removed. To a benzene solution of the
dibutyl ester obtained, a solution of sodium hydroxide
(0.3 g, 0.0038 mol) in water (3 mL) was added, the
mixture was intensively shaken, and the resulted emulꢀ
sion was filtered through a layer of alumina of activity
Brockmann grade II alumina column (d = 10 cm, h =
2 cm); and the adsorbent was washed with 0.4 L of
benzene. The combined benzene solution was evapoꢀ
rated to dryness in vacuum, the residue was crystalꢀ
lized from hexane, and dried in vacuum, to afford
34.7 g (36% based on starting 1,3ꢀdimethyladamanꢀ
tane) of dimethyl 5,7ꢀdimethyladamantaneꢀ1,3ꢀ
dicarboxylate. Mp 90°C, pure for chromatography.
(B) 5,7ꢀDimethylꢀ1,3ꢀdihydroxymethyladamanꢀ
tane. Lithium aluminum hydride (11.4 g, 0.3 mol) was
added within 2 h with vigorous stirring to a solution of
dimethyl 5,7ꢀdimethyladamantaneꢀ1,3ꢀdicarboxylate
(28 g, 0.1 mol) in dry ether (0.5 L) at temperature of
+3 to +5°C. The solution was stirred for 3 h at room
temperature, then an AlCl3 saturated solution (0.2 L)
was slowly added with cooling, the mixture was transꢀ
ferred to a separating funnel, the aqueous layer was
separated, and the organic layer was washed with water
(0.5 L) and dried with sodium sulfate (0.2 kg). Ether
was removed to dryness in vacuum, and the residue
grade II (d = 5 cm, h = 2 cm) followed by elution with
another portion of benzene (150 mL). The benzene
solution was evaporated to dryness in vacuum, and the
oily residue was distilled to isolate the main fraction
with bp 126–128°C at 0.2 mmHg, affording 24.9 g
(86.2%) of diꢀnꢀbutyl 5,7ꢀdimethyladamantaneꢀ1,3ꢀ
dicarboxylate. nD20 = 1.4739, IR spectrum: 1725 cm–1
(C=O). Found (%): C 73.2; H 11.7. Calculated for
С22Н36О4 (%): C 72.5; H 10.0. GLC: 30 m capillary
column, SEꢀ30, 250°C (isothermal mode), t = 460 s.
Diamylꢀ5,7ꢀDimethyladamantaneꢀ1,3ꢀ
Dicarboxylate (II)
Compound II was prepared by analogy with dibutyl
ester (I) using amyl alcohol (15.4 g) instead of
ꢀbutanol. The yield of ester was 21.5 g (71.4%).
Bp 139–140°C at 0.15 mmHg. n2D0 = 1.4740, IR specꢀ
trum: 1725 cm–1 (C=O). Found (%): C 73.6; H 10.6.
Calculated for С24Н40О4 (%): C 73.4; H 10.3. GLC:
n
was crystallized from
nꢀheptane to obtain 20.5 g
(91.4%) of 5,7ꢀdimethylꢀ1,3ꢀdihydroxymethyladaꢀ
mantane, which was used without further purification
for preparing the isovaleric acid ester.
t
= 714 s.
(C) Diester of 5,7ꢀdimethylꢀ1,3ꢀdihydroxymethyꢀ
ladamantane and isovaleric acid (V)
.
A oneꢀneck roundꢀbottom flask of a 1ꢀL capacity
was charged with 5,7ꢀdimethylꢀ1,3ꢀdihydroxymethyꢀ
ladamantane (15 g, 0.067 mol), isovaleric acid (20.5 g,
0.2 mol, 21.8 mL), benzene (150 mL), and tolueneꢀ
sulfonic acid (0.2 g). The mixture was refluxed for 4 h
to remove water (2.5 g), cooled, and filtered through a
column with Al2O3; the alumina cake was washed with
benzene (150 mL). The combined benzene solution
was evaporated to dryness in vacuum, the oily residue
was distilled in vacuum to obtain 16.3 g (61.7%) of 5,7ꢀ
dimethyldi(1,3ꢀhydroxymethyladamantyl) diisovalerꢀ
Diisooctylꢀ5,7ꢀDimethyladamantaneꢀ1,3ꢀ
Dicarboxylate (III)
Compound (III) was prepared by analogy with
dibutyl ester (I) using isooctyl alcohol (22.7 g) instead
of nꢀbutanol. The yield of the isooctyl ester was 14 g
(37%). Bp 240–246°C at 0.2 mmHg. n2D0 = 1.4823.
DiꢀnꢀHexadecyl 5,7ꢀDimethyladamantaneꢀ1,3ꢀ
Dicarboxylate (IV)
Compound IV was prepared by analogy with dibuꢀ
ate. Bp 125°C at 0.08 mmHg. n2D0 = 1.4754. Found
tyl ester (I) using
nꢀhexadecyl alcohol (42.3 g), replacꢀ
(%): C 73.5; H 10.7. Calculated for С24Н40О4 (%): C
ing the vacuum distillation stage by molecular subliꢀ
mation in a sublimator onto a substrate cooled with 73.4; H 10.8.
PETROLEUM CHEMISTRY Vol. 53
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ADAMANTANEꢀCONTAINING ESTERS AS POTENTIAL COMPONENTS
Table 1. 1H NMR spectrum of DAADC (II) Table 2. 13C NMR spectrum of DAADC (II)
Chemical shift, ppm Proton quantity Group number
421
Chemical shift, ppm
Group number
13.72
22.03
ε
0.87
1.13
1.29
1.47
1.59
1.85
4.02
7.27
12H
2H
8H
8H
4H
2H
4H
all CH3 groups
δ
6
27.83 + 28.08
29.73
two methyl groups on core
γ + δ
5 + 7
β + γ
1 + 3
2
4 + 8 + 9 + 10
31.13
β
38.60
2
α
42.63
44.03
4 + 9
6
CHCl3
49.60
64.18
α
77.03
CDCl3
COO
The chemicals used were of the analytical grade.
Purity of the compounds obtained was controlled by
GLC (30ꢀm capillary column, SEꢀ30 stationary
176.27
phase, 250°C, isothermal mode). The structure of the
compounds and their purity were also confirmed by
spectral methods (gas chromatography–mass specꢀ
tures thermoꢀoxidative stability were measured
according to GOST 1928ꢀ87 and GOST 23175ꢀ74,
respectively [14].
1
trometry and H and 13C NMR spectroscopy). The
mass spectrum and the NMR spectrum of diamyl 5,7ꢀ
dimethyladamantaneꢀ1,3ꢀdicarboxylate (DAADC)
(II) as an example are given below in Tables 1 and 2,
respectively. The gas chromatography–mass specꢀ
trometry study was performed on a Thermo Focus
DSC2 instrument (a Varian VFꢀ5ms capillary column,
RESULTS AND DISCUSSION
The viscosity properties of the adamantaneꢀconꢀ
taining esters synthesized are collated in Table 3 with
the known thermostable oil IPMꢀ10, which has a close
viscosity value.
As follows from these data, the compounds (samꢀ
ples I and II) are superior to the standard highꢀtemꢀ
perature oil IPMꢀ10 in viscosity–temperature characꢀ
teristics. The dynamic viscosity of compound II within
30 m length, 0.25 mm inner diameter, 0.25
thickness, carrier gas helium, injector temperature
270 ) operating in the temperature programming
mode from 30 to 30 at a heating rate of 15°C/min
µ
m layer
°С
°
С
with isothermal holding at the final temperature for
10 min. The mass spectrometer operating mode : ionꢀ
ization energy of 70 eV, source temperature of 230°С,
a scan interval from 10 to 800 dalton with a scan rate
of 2 scan/s, the unit mass resolution over the entire
mass range.
the temperature range of +10 to –40°C increases by
slightly more than a factor of 3, whereas the viscosity
of the standard oil increases by a factor of 30 times; low
viscosity values at negative temperatures are particuꢀ
larly attractive. Moreover, the sample exhibits
higher thermoꢀoxidative stability compared with the
standard oil.
It is noteworthy that small changes in the structure
of the compound (on passing from compound II to
compound V) prepared from adamantyl alcohol,
di(hydroxymethyl)dimethyladamantane, and aliꢀ
phatic acid result in sharp alteration in the pattern of
change in viscosity properties; non only the absolute
value of viscosity increases, but and temperature–visꢀ
cosity relationship becomes much less favorable. It is
interesting to compare the properties of the test comꢀ
pounds obtained with those of ester compounds with a
close structure in which the adamantyl core is directly
bound with oxygen atom (methylene linker is absent),
i.e., esters of adamantanols and aliphatic acids
(Table 4). Such compounds were synthesized and
studied by Kosaku and Hiromichi [15].
Mass spectrum of compound II: M 392, m/z
(abundance): 324 (16.56); 323, Mꢀ69 (89,84); 277
(38.78); 253 (100.0); 207 (26.78); 189 (22.54); 161
(41.48); 151 (18.39); 107 (21.47); 43 (19.03).
1H NMR spectra were taken on a Bruker MSLꢀ300
spectrometer (Table 1), and 13C NMR spectra on a
Bruker Avanceꢀ700 spectrometer, a CDCl3 solution,
room temperature (Table 2). The numbering of the
atoms and group in II is given below:
CH3
7
10
1
8
6
β
δ
O
3
O
2
5
C5H11 O C
C
O
CH3
α
γ
9
4
CH3
The kinematic viscosity of the esters was deterꢀ
mined at 100
33ꢀ82, and the dynamic viscosity at various temperaꢀ absolute viscosity value of the substances increases
The Japanese investigators have shown that in the
°C according to GOST (State Standard) series of adamantyl caprylates studied, not only the
PETROLEUM CHEMISTRY Vol. 53
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422
BAGRII, MARAVIN
Table 3. Viscosityꢀtemperature characteristics of adamantaneꢀcontaining esters
Dynamic viscosity, mPa at
T, °C
Compound
designation
2
£
1
υ
10
0
–10
–20
–30
–40
I
3.08
3.61
5.77
3.16
64.28
77.91
266.8
31.73
74.02
91.55
101.3
128.5
590.2
90.7
229.8
138.3
951.0
173.6
358.4
206.5
4733
570.7
300.2
9525
14
34
26
25
II
V
368.65
51.70
IPMꢀ10
397.0
960.4
1
2
2
Kinematic viscosity at 100°C, mm /s; Thermoꢀoxidative stability in thin layer, min.
Table 4. Properties of adamantaneꢀcontaining esters
Compound Adamantaneꢀ1,3ꢀdiol dicaprylate [15]
Diamylꢀ5,7ꢀdimethyladamantaneꢀ1,3ꢀ
dicarboxylate (II)
CH
3
O
C
C7H15
C
O
O
O
C C7H15
O
C 5 H 11
O
C
O
O
C 5 H 11
CH
3
Molecular mass
Kinematic viscosity at 100
DTA data: temperature of exotherm
420
5.57
313
392
3.61
302
°
C, mm2/s
in air, C
°
2. Y. Inamoto, K. Nakayama, H. Takenaka, and
H. Kimura, JP Patent No. 7 321 103 (1973).
(with the viscosity index remaining almost
unchanged), but their thermoꢀoxidative stability is
also enhanced as the number of ester substituents at
the tertiary carbon atoms of the adamantane core
increases (from 1 to 3). So, the temperature of the exoꢀ
thermal peak in air for adamantyl monoꢀ, diꢀ, and triꢀ
caprylates was 223, 313, and 331, respectively.
3. J. Podehradska, J. Humhej, and Z. Zdarecky, Sb. Vys.
Sk. Chem.ꢀTechnol. Praze 39, 205 (1978).
4. J. Podehradska and L. Vodicka, Sb. Vys. Sk. Chem.ꢀ
Technol. Praze 47, D101 (1984).
5. P. R. Schleyer, J. Am. Chem. Soc. 79, 3292 (1957).
6. A. Schneider, R. W. Warren, and E. J. Janovsky, J. Am.
Thus, the ester derivatives of adamantane and alkyꢀ
ladamantanes are quite promising as components of
thermostable lubricants. It is significant that comꢀ
pounds with a desired viscosity value depending on the
task for particular equipment or application area can
be prepared by varying the number and nature of subꢀ
stituents, with the thermoꢀoxidative stability and enviꢀ
ronmental safety of the oils remaining at a high level.
Moreover, the thermoꢀoxidative properties of such
compounds have good prospects for optimization.
Chem. Soc. 86, 5365 (1964).
7. E. I. Bagrii and P. I. Sanin, USSR Inventor’s Certificate
No. 239,302; Byull. Izobret., No. 25, 241 (1971).
8. E. I. Bagrii and P. I. Sanin, US Patent, 3,637,876
(1972).
9. E. I. Bagrii, Adamantanes: Preparation, Properties, and
Use (Nauka, Moscow, 1989) [in Russian].
10. E. I. Bagrii, P. I. Sanin, and T. Yu. Frid, USSR Invenꢀ
tor’s Certificate No. 302,008; Byull. Izobret., No.28,193
(1972).
11. E. I. Bagrii, T. Yu. Frid, and P. I. Sanin, Izv. Akad. Nauk
SSSR, Ser. Khim., No. 2, 498 (1970).
ACKNOWLEDGMENTS
12. J. Podehradska, L. Vodicka, and V. Stepina, J. Synth.
The authors thank R. S. Borisov for recording and
interpreting the mass spectra and M.P. Filatova and
P.V. Dubovskii for recording the NMR spectra.
Lubr. 6,123 (1989).
13. A. D. Apryatkin, E. I. Bagrii, and T. N. Dolgopolova,
USSR Inventor’s Certificate No. 1,593,205 (1990).
14. Petroleum Products: Testing Methods (Gosstandart
SSSR, Moscow, 1982, 1987) [in Russian].
REFERENCES
15. H. Kosaku and S. Hiromichi, US Patent No. 4,963,292
(1990).
1. I. N. Duling and A. Schneider, US Patent No. 3 398 165
(1968).
Translated by S. Lebedev
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2013