Conditions of synthesis and properties of dimethacrylate derivatives containing a fragment of a dimerized fatty acid

Article abstract of DOI:10.1134/S1070427212080150

A series of dimethacrylate esters of a dimerized fatty acid were prepared. The dependence of their formation rate on the kind of the glycol used was examined. The correlation between the molecular-weight characteristics of the esters and their synthesis conditions is discussed.

Full text of DOI:10.1134/S1070427212080150

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 8, pp. 1225−1231. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © E.V. Fomina, L.P. Korovin, V.A. Fomin, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 8, pp. 1288−1294.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Conditions of Synthesis and Properties of Dimethacrylate
Derivatives Containing a Fragment
of a Dimerized Fatty Acid
E. V. Fomina, L. P. Korovin, and V. A. Fomin
Kargin Research Institute of Polymers, Dzerzhinsk, Nizhni Novgorod oblast, Russia
e-mail: niip@kis.ru
Received January 10, 2012
Abstract—A series of dimethacrylate esters of a dimerized fatty acid were prepared. The dependence of their
formation rate on the kind of the glycol used was examined. The correlation between the molecular-weight char-
acteristics of the esters and their synthesis conditions is discussed.
DOI: 10.1134/S1070427212080150
Recently there has been particular interest in products
based on a dimerized fatty acid (DFA) [1–4]. Thanks to
the high reactivity of DFA, it is possible to prepare a wide
range of products finding use in diverse fields of industry
[5–7]. The unique physicochemical properties and ser-
vice characteristics of DFA derivatives, determined by
the presence of bulky cycloaliphatic substituents in acid
residues, make their studies topical.
The goal of this study was to synthesize new DFA
dimethacrylate derivatives and to examine how their
properties depend on the starting reactants and on the
conditions of synthesis and isolation.
EXPERIMENTAL
We used the following chemicals: Pripol-1013 dimer-
ized fatty acid (linoleic acid dimer containing no less than
97% main substance, CAS no. 61788-89-4); DFAdichlo-
ride (DFADC) synthesized according to [9]; methacrylic
acid [MAA, TU (Technical Specification) 6-01-914–79];
freshly distilled glycols and their monoesters: ethylene
glycol [EG, GOST (State Standard) 19710–83], diethyl-
ene glycol (DEG, GOST 10136–77), triethylene glycol
(TEG, TU 6-01-5–88 with revisions 1, 2), butylene glycol
(BG, TU 64-5-105–86), ethylene glycol monomethac-
rylate (EGM, TU 6-01-1240–80), and propylene glycol
monomethacrylate [PGM, STP (Enterprise Standard)
70–2005, Research Institute of Polymers]; preliminar-
ily distilled toluene (GOST 5789–78) and triethylamine
(GOST 9966–88); hydroquinone (GOST 2549–60); p-
methoxyphenol (TU 6-09-1248–71); p-toluenesulfonic
Another important factor making DFAattractive is its
production from renewable plant materials.
Previously [8–11] we reported on the synthesis of DFA
oligo- and (co)polyamides, which are base raw materi-
als for preparing hot-melt adhesives with high adhesion
characteristics.
As a continuation of studies in the field of synthesis
of DFA derivatives, it was interesting to introduce into
a molecule containing a bulky DFAfragment methacrylate
groups capable of subsequent polymerization in the
presence of free-radical initiators or under UV irradiation,
to obtain polymeric adhesives with internal plasticization.
Combination of properties of the DFA cycloaliphatic
substituent and high capability of methacrylates for
polymerization will expand the applications of DFA acid (p-TSA, TU 6-09-3668–77); sodium hydroxide
derivatives as adhesives and binders in production of
various composite materials, anaerobic sealants, and
casting compounds.
(GOST 4328–77 with revisions 1, 2); sodium chloride
(GOST 4233–77); distilled water (GOST 6709–72); and
copper(I) chloride (GOST 4164–79).
1225

1226
FOMINA et al.
columns with the sorbent porosity of 105, 3 × 104, 104,
103, and 250 Å (Waters). As detectors we used an R-403
differential refractometer (Waters) and an LCD 2563
photometer (λ = 254 nm). The eluent was tetrahydrofuran
(THF). The chromatograph was calibrated using polysty-
rene (PS) references.
The structures of the synthesized DFAdimethacrylate
esters were analyzed by IR and NMR spectroscopy. The
IR spectra were recorded with a Specord М 82 spectro-
photometer in the range 4000–400 cm–1 from a sample
drop pressed between KBr plates. The NMR spectra were
taken with a Bruker DPX-200 spectrometer operating
1
at 200 MHz for Н and 50 MHz for 13С. The samples
The saponification, acid, and ester numbers of the
products were determined according to [12, 13].
were dissolved in CDCl3. The internal reference was
tetramethylsilane.
We examined several procedures for preparing DFA
dimethacrylates under different conditions. The scheme
of one-step esterification starting from DFA, glycol, and
MAA can be presented as follows:
The molecular-weight distribution (MWD) of the
dimethacrylate esters was determined by gel perme-
ation chromatography (GPC) with a set of five Styragel
(CH2)7
(CH2)5
COOH
(CH2)7
CH2
COOH
CH
2HO
R
OH
+
+
2CH2
C
COOH
CH
(CH2)4
C(O)
CH3
I_IV
CH3
CH3
CH3
(CH2)7
O
R
O
C(O)
C
CH2
4H2O,
+
(CH2)7
CH2
C(O)
CH
O
R
O
C(O)
C
CH2
CH
(CH2)4
CH3
CH3
(CH2)5
CH3
V_VIII
R = (СН2)2 (I, V); СН2СН2ОСН2СН2 (II, VI); СН2СН2ОСН2СН2ОСН2СН2 (III, VII); (СН2)4 (IV, VIII).
conversion, but it is accompanied by pronounced tarring,
so that light diester V cannot be prepared in high yield in
this case because of large loss in the isolation step.
To prepare dimethacrylate ester V from DFA, MAA,
and ethylene glycol, a reactor equipped with a stirrer and
a Dean–Stark trap with a reflux condenser was charged
with the calculated amounts of the reactants (molar ratio
DFA : MAA : ethylene glycol = 1 : 2.2 : 2.2), and also
with hydroquinone (1 wt % of MAA), Cu2Cl2 (1 wt %
of MAA), and p-TSA (2.5 wt % of the sum of the reac-
tants). The mixture was heated with vigorous stirring to
108–120°С until the water evolution ceased. The reaction
progress was monitored by the amount of the released
water (Fig. 1) and by the acid numbers characterizing the
change in the content of the starting acids in the reaction
mixture (Fig. 2).
The observed deceleration of the reaction between
P, %
As shown in Fig. 1 (curve 1), the reaction proceeds,
on the average, within 10 h. More than a half of the
stoichiometric amount of water is released in the first
hour, after which the reaction decelerates and practically
ceases. Performing the reaction for the time exceeding
10 h leads to only a slight increase in the reactant
τ, h
Fig. 1. Reactant conversion P in synthesis of dimethacrylates
as a function of time τ. Dimethacrylate: (1) V, (2) VI, (3) VII,
and (4) VIII; the same for Fig. 2.
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CONDITIONS OF SYNTHESIS AND PROPERTIES OF DIMETHACRYLATE DERIVATIVES
1227
DFA, MAA, and ethylene glycol on reaching 85% con-
version with respect to the released water is confirmed by
measurements of the acid number of the reaction mixture
(Fig. 2, curve 1), which decreases only to 3.8 (mg KОН)
g–1 and then does not decrease further.
a vacuum (1.33–0.67 kPa) for 1–2 h at 50–60°С. The
properties of the synthesized dimethacrylate ester V are
given in Table 1.
It was interesting to study how the structure of the
glycol component affects the characteristics of the di-
methacrylates obtained and simultaneously to determine
the optimal conditions for DFA esterification. For this
purpose, with synthesized DFA dimethacrylates with
DEG, TEG, and BG fragments.
After the synthesis completion, the reaction mixture
was purified to remove excess MAA and ethylene
glycol and residual amounts of the catalyst, after which
it was transferred into a separation funnel and washed
with water. The washing was accompanied by strong
emulsification, which considerably complicated the
separation of the organic and aqueous phases. With
the aim to improve the phase separation, the reaction
mixture was diluted by a factor of 2 with toluene, with
the subsequent washing performed with 10% aqueous
NaCl. The emulsion formed underwent separation in
20–30 h. After washing, we determined the acid number
of the mixture and neutralized the residual acidity with
the calculated amount of NaOH. Excess alkali may lead to
saponification of DFAdimethacrylate, which, in turn, may
cause strong emulsification of the system due to formation
of DFA sodium salts. The neutralized reaction mixture
was also washed with a 10% aqueous NaCl solution and
then with distilled water to neutral reaction.
Dimethacrylate esters VI–VIII were prepared simi-
larly to V from DFA, MAA, and the above glycols.
When monitoring the reaction water evolution and the
variation of the acid numbers (Fig. 2), we found that the
esterification rate sharply increases with an increase in
the distance between the hydroxy groups in the glycols:
BG > TEG > DEG > EG. This may be due to the fact that,
with an increase in the number of methylene or ethylene
oxide fragments in the glycol structure, the position of its
OH groups becomes more and more favorable kinetically
[14].
It should also be noted that, in the synthesis of the
dimethacrylates with DEG, TEG, or BG, the phase
separation of the washed reaction mixture and aqueous
layer occurred faster than in the synthesis of the diester
with ethylene glycol.
The toluene solution of DFA dimethacrylate ester,
separated from the aqueous layer, was filtered through
a fabric filter, after which 0.05 wt % hydroquinone was
added, and the toluene was distilled off at 50–60°C/8.0–
1.33 kPa. The dimethacrylate was additionally kept in
In our further experiments, we synthesized the di-
methacrylates by the reaction of DFA or DFA DC with
ethylene glycol monomethacrylate or propylene glycol
monomethacrylate:
(CH2)7
COХ
(CH2)7
CH2
COХ
2HO
R1
O
C(O)
+
C
CH2
CH
CH
(CH2)4
CH3
CH3
(CH2)5
CH3
IХ, Х
CH3
R1
O
C(O)
(CH2)7
C(O)
O
C
CH2
2HХ,
+
R1
(CH2)4
O
(CH2)7
CH2
C(O)
O
C(O)
C
CH2
CH
CH
CH3
CH3
(CH2)5
CH3
ХI_ХIV
where X = ОН, R1 – СН2СН2 (IX, XI); –СН–СН2 (X, XII); Х = Cl, R1 – СН2СН2 (IX, XIII); –СН–СН2 (X, XIV).
|
|
СН3
СН3
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1228
FOMINA et al.
as follows. To a calculated amount of EGM or PGM,
dissolved in excess toluene in the presence of triethylamine
(TEA) as acid acceptor, we added dropwise with stirring
a toluene solution of DFA DC at the molar ratio glycol
monomethacrylate : DFA DC : TEA = 2.2 : 1 : 2.8.
The mixture was vigorously stirred for 1 h at 20°С,
after which it was heated at 40°С for an additional 2 h.
After cooling, the mixture was filtered to remove TEA
hydrochloride, and the filtrate was transferred into
a separation funnel in which it was washed 5–6 times
with water to neutral reaction. To the washed solution,
we added 0.01–0.04 wt % p-methoxyphenol, after which
the toluene was distilled off.
τ, h
High reactivity of DFA dichloride allowed the con-
densation to be performed at a lower temperature and in
a shorter time, compared to azeotropic esterification, and
the DFA dimethacrylates to be obtained in high yield.
Fig. 2. Total acid numberAN of the reaction mixture in synthesis
of dimethacrylates as a function of time τ.
The data we obtained show that it is appropriate to
prepare DFA dimethacrylates using compounds IX and
X, because introduction of a ready glycol monomethac-
rylate into the reaction system considerably simplifies the
condensation process.
All the synthesized dimethacrylates are viscous trans-
parent liquids with the color from yellow to dark brown
and with a weak methacrylate odor. The physicochemical
and chemical properties of V–VIII and XI–XIV and the
IR and NMR data for them are given in Table 1.
Dimethacrylates XI and XII were prepared at the
molar ratio DFA : glycol monomethacrylate = 1 : 2.4 in
toluene in the presence of a catalyst, p-TSA.
It seems also important to study the molecular-weight
characteristics of the DFA dimethacrylates prepared and
their dependence on the synthesis conditions.
The reaction of DFA with EGM completes in 4.5–5 h
on reaching 95–96% conversion. Thus, in esterification
of the dimerized acid with glycol monomethacrylate the
reaction time is considerably shorter (by a factor of 2)
than in the system with EG and methacrylic acid, the yield
of dimethacrylate XI is approximately 10% higher than
that of V, and the product is washed with faster phase
separation.
It is known [15–17] that the structure of the
oligoester acrylates formed does not always meet the
expectations, despite agreement between the calculated
and experimentally determined characetristics. Probably,
deeper condensation of the bifunctional components
(glycol, DFA) leads to the formation of a wide range of
mono- and oligomeric products, and the dimethacrylates
formed are actually polydisperse multicomponent
mixtures.
At the same time, dimethacrylate XII in the reaction
with PGM is formed slowly. The reaction completes in
10–11 h on reaching 95.6% conversion. In this case, the
decreased reaction rate is due to specific features of the
structure and reactivity of PGM containing a secondary
hydroxy group.
In this connection, we examined the molecular-weight
characteristics of the DFA methacrylates prepared from
different starting compounds. Depending on the synthesis
conditions, the products can be subdivided into three
groups: V–VIII; XI and XII; and XIII and XIV.
The formation of DFA dimethacrylates occurs at
elevated temperatures (108–120°С) and therefore is
accompanied by formation of certain amounts of by-
products and tars. Therefore, it was of interest to examine
the possibility of preparing FDA dimethacrylates under
milder conditions, e.g., by nonequilibrium condensation
with DFA dichloride [10].
The molecular-weight characteristics of the
compounds prepared were studied by gel permeation
chromatography. The GPC data show that FDA
dimethacrylates V–VIII are not monodisperse. The
gel chromatogram of dimethacrylate VIII, shown in
Fig. 3a, reflects its complex oligomer composition:
Along with the expected main compound, it contains
compounds of lower and higher molecular weights, which
Synthesis of dimethacrylates XIII and XIV from
DFA DC and glycol monomethacrylates was performed
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CONDITIONS OF SYNTHESIS AND PROPERTIES OF DIMETHACRYLATE DERIVATIVES
1229
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FOMINA et al.
Table 2. Molecular parameters of DFA dimethacrylate esters
(a)
Number-
average
molecular
weight Mn
Weight-
average
molecular
weight Mw
Polydispersity
index Mw/Mn
Compd.
V
1900
1800
2000
2200
900
3300
3000
3100
4300
1200
1100
1200
1100
1.74
1.67
1.56
1.95
1.33
1.29
1.26
1.22
VI
VTHF, arb. units
VII
VIII
XI
(b)
XII
XIII
XIV
850
950
900
VTHF, arb. units
Our tests showed that the use of FDA dimethacrylate
derivatives V–VIII and XI–XIV as components of
anaerobic adhesive formulations for thread joints of
elements not only enhances by a factor of 1.4–2.0 the
gluing strength on oiled surfaces, but also ensures
high level of preservation of the unscrewing moment,
compared to the known commercially available sealant.
Fig. 3. Gel chromatograms of dimethacrylate esters (a) VIII
and (b) XI. (VTHF) THF volume and (М) PS molecular weight.
Detector: (1) refractometric and (2) spectrophotometric.
is confirmed by high polydispersity index (Table 2).
Diesters V–VII are characterized by the same molecular-
weight distribution. In turn, the gel chromatogram of
dimethacrylate XI (Fig. 3b) suggests formation of the
practically monodisperse product. The other esters XII–
XIV prepared by reactions of glycol monomethacrylates
with DFA or DFA DC have also fairly homogeneous
composition (Table 2).
CONCLUSIONS
(1) Dimethacrylate esters of dimerized fatty acid,
containing bulky cycloaliphatic groups imparting high
adhesion properties to these compounds, were synthesized
by high- and low-temperature oligoesterification.
(2) The esterification rate and the molecular-weight
characteristics of the dimerized fatty acid dimethacrylate
derivatives largely depend on the structure of the reactants
(glycols, glycol monometharylates).
The dependence we obtained is primarily determined
by the nature and functionality of the starting reactants
and by mild esterification conditions. A decrease in the
number of functional groups, in combination with the low
reaction temperature, leads to a decrease in the probability
of side reactions, whereas high activity of the starting
chloride and better accessibility of the reaction sites favor
predominant formation of the expected dimethacrylates.
REFERENCES
1. Feng, G., Qu, H., Cui, Y. et al., J. Polym. Res., 2007,
vol. 14, no. 2, pp. 115–119.
2. Heidarian, J., Chasem, N., and Wan Daud, W.A., Macromol.
Chem. Phys., 2005, vol. 206, no. 6, pp. 658–663.
The synthesized DFA dimethacrylate derivatives
V–VIII and XI–XIV are of considerable interest as
components of various adhesive formulations, sealing and
binding materials, and insulation casting or impregnation
compounds.
3. Fomina, E.V., Klei. Germet. Tekhnol., 2011, no. 11,
pp. 12–19.
4. Fomina, E.V., Klei. Germet. Tekhnol., 2011, no. 12,
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 8 2012

CONDITIONS OF SYNTHESIS AND PROPERTIES OF DIMETHACRYLATE DERIVATIVES
1231
Compounds), Leningrad: Khimiya, 1972.
pp. 9–17.
13. TU (Technical Specification) 6-01-1217–79: Oligoester
5. US Patent 6111055.
6. US Patent 6617394.
7. RF Patent 2074214.
Acrylate MDF-2.
14. Berlin, A.A., Kefeli, T.Ya., and Korolev, G.V.,
Poliefirakrilaty (Polyester Acrylates), Moscow: Nauka,
1967.
8. Fomina, E.V., Chervyakova, G.N., Kurskii, Yu.A., and
Sineokov, A.P., Zh. Prikl. Khim., 2005, vol. 78, no. 7,
pp. 1142–1145.
15. Mezhikovskii, S.M., Arinshtein, A.E., and Deberdeev, R.
Ya., Oligomernoe sostoyanie veshchestva (Oligomeric
State of a Substance), Moscow: Nauka, 2005.
9. Fomina, E.V., Kurskii, Yu.A., Beloded, L.N., and
Chervyakova, G.N., Zh. Prikl. Khim., 2006, vol. 79, no. 5,
pp. 787–791.
16. Korovin, L.P., Krom, E.N., Kartashov, V.R., et al., Izv.
Vyssh. Uchebn. Zaved., Khim. Khim. Tekhnol., 1974,
vol. 17, no. 12, pp. 1847–1851.
10. Fomina, E.V., Kurskii, Yu.A., Chervyakova, G.N., and
Sineokov, A.P., Zh. Prikl. Khim., 2008, vol. 81, no. 4,
pp. 621–626.
17. Fomin, V.A. and Guzeev, V.V., Sintez, svoistva i primenenie
oligoefirakrilatov: Materialy plenarnykh dokladov VIII
Mezhdunarodnoi konferentsii po khimii i fizikokhimii
oligomerov “Oligomery-2002” (Synthesis, Properties, and
Use of Oligoester Acrylates: Plenary Lectures at VIII Int.
Conf. on Chemistry and Physical Chemistry of Oligomers
“Oligomers-2002”), Chernogolovka, 2002.
11. Fomina, E.V., Perevaryukha, M.A., and Safonova, N.N.,
Klei. Germet. Tekhnol., 2006, no. 1, pp. 17–20.
12. Toroptseva,A.M., Belogorodskaya, K.V., and Bondarenko,
V.M., Laboratornyi praktikum po khimii i tekhnologii
vysokomolekulyarnykh soedinenii (Practical Laboratory
Course of Chemistry and Technology of Macromolecular
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 8 2012