The reaction of condensation of furfural with mercaptoacetic acid esters

Article abstract of DOI:10.1134/S1070427213050297

The condensation reaction of furfural with various mercaptoacetic acid esters was studied. The reaction products were tested for their corrosion protective properties in M-16 cylinder oil used for marine diesel engines. It was found that the resulting 2-d

Full text of DOI:10.1134/S1070427213050297

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 5, pp. 787−789. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © P.G. Asadova, G.Z. Guseinov, M.A. Allakhverdiev, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 5, pp. 840−843.
MACROMOLECULAR COMPOUNDS
AND POLYMERIC MATERIALS
The Reaction of Condensation of Furfural
with Mercaptoacetic Acid Esters
P. G. Asadova, G. Z. Guseinov, and M. A. Allakhverdiev
Baku State University, Baku, Azerbaijan
e-mail: mirze_a@mail.ru
Received January 14, 2013
Abstract—The condensation reaction of furfural with various mercaptoacetic acid esters was studied. The reaction
products were tested for their corrosion protective properties in M-16 cylinder oil used for marine diesel engines.
It was found that the resulting 2-di(alkoxycarbonylmethylthio)methylfuranes at 2% concentration completely
suppress corrosion of lead plates.
DOI: 10.1134/S1070427213050297
Furfural (furan-2-aldehyde) which is produced com-
mercially from pentosan feedstock is known to be the
most readily available compound in the furan series [1].
Furfural derivatives are extensively used for preparation
of many technically significant products: plasticizers,
insecticides, fragrances, medicinal substances, furan
resins, etc. [2, 3]. Among furfural derivatives, sulfur-
and nitrogen-containing compounds have a prominent
place. For example, reactions of furoic acid chlorides
with mercaptoaryl- and alkylthiazoles gave sulfur- and
nitrogen-containing derivatives of furfural, which were
suggested as rubber vulcanization accelerators [2].
Here, we studied the reactions between furfural and
various mercaptoacetic acid esters with a view of syn-
thesizing new sulfur-containing furfural derivatives that
could be used as lubricant additives.
It was expected that a sulfide sulfur, an ester group,
and a furan moiety occurring in these compounds
simultaneously would confer to them useful, in particular
antioxidant and corrosion protective, functional
properties.
EXPERIMENTAL
The new sulfur-containing derivatives of furfural
were synthesized by furfural condensation with various
alkyl esters of mercaptoacetic acid, catalyzed by small
amounts of dilute hydrochloric acid. The condensation
reaction scheme was as follows:
It should be noted that there is continuously growing
interest in cyclic compounds containing a furan moiety
and various functional groups. Not only conventional
preparative but also combinatorial chemistry method are
used for synthesis of these compounds [4–6].
HCl
_H2O
CHO + 2HS
CH2
C
O
OR
CH(S
CH2
C
O
OR)2
O
O
Hg, d420 1.325 g cm–3.The esters used in this study were
obtained by HCl-catalyzed reactions of mercaptoacetic
acid with the corresponding aliphatic alcohols, taken
in a 1 : 1.2 molar ratio. The reaction was carried out in
a three-necked flask equipped with a thermometer, a
where R = i-C3H7 (I), n-C4H9 (II), n-C5H11 (III), n-C7H15
(IV), n-C9H19 (V).
The reactants, furfural and mercaptoacetic acid,
were freshly distilled prior to use; furfural: bp 161.7°C,
d420 1.159 g cm–3; mercaptoacetic acid: bp 124°C/30 mm
787

788
ASADOVA et al.
stirrer, and a reflux condenser. The calculated amounts
of mercaptoacetic acid and aliphatic alcohol and a few
drops of concentrated hydrochloric acid were charged
into the flask under stirring, and the resulting mixture
was refluxed for 10 h. Upon completion of the reaction
the resulting mass was diluted with benzene (1 : 3),
transferred to a separation funnel, and washed several
times with water. The organic layer was separated, dried
over sodium sulfate, and subjected to distillation. Table 1
summarizes the characteristics of the mercaptoacetic acid
esters synthesized.Mercaptoacetic acid esters are color-
less liquids, highly soluble in organic solvents. Their
structure was confirmed by IR spectroscopy.The conden-
sation reaction of furfural with the mercaptoacetic acid
esters synthesized was also carried out in a three-necked
flask equipped with a thermometer, a stirrer, a dropping
funnel, and a reflux condenser. The calculated amounts
of furfural and catalyst, dilute hydrochloric acid, were
charged into the flask, and the resulting mixture was
stirred and then thoroughly cooled (to 0–6°C). Next, the
calculated amount of mercaptoacetic acid ester was fed
from the dropping funnel at this temperature for 1 h, after
which the mixture was further stirred at 15–6°C for 2 h.
We examined the yields of the target compounds I–V
as influenced by various factors (reactant ratio, nature of
mercaptoacetic acid ester, temperature, reaction time)
and determined the best conditions for their synthesis:
temperature from 0 to –5°C, catalyst (HCl) amount 2%
(for the mixture taken), and furfural:ester molar ratio 1 : 2.
Table 2 lists the characteristics of the target products
synthesized, 2-di(alkoxycarbonylmethylthio)methyl-
furanes I–V.
The structure of the sulfur-containing furfural deriva-
tives synthesized was confirmed by NMR spectroscopy,
with compounds I and II as examples. The NMR spectra
were recorded on a Bruker-300 (Bruker, FRG) instrument
with tetramethylsilane as internal standard.
1
Compound I. Н NMR spectrum (CCl4), δ, ppm:
25 d (12Н, 4СН3, 3JН–Н = 6.28 Hz), 3.15 and 3.35 d (4Н,
2SСН2), 4.98 m (2Н, ОСН), 5.41 s (1Н, SCH), 6.3 and
6.31 d (2Н, 2СН=, 3JН–Н = 3.25 Hz), 7.45 s (1Н, =СНО).
13С NMR spectrum (CCl4), δ, ppm: 22, 33, 47, 69, 108,
110, 149, 150, 168.
1
Compound II. Н NMR spectrum (CCl4), δ, ppm:
0.9 t (6Н, 2СН3, 3JН–Н = 6.38 Hz), 1.35 m (4Н, 2СН2),
1.6 m (4Н, 2СН2), 3.15 and 3.42 d (4Н, 2SCH2), 4.05 t
Upon completion of the reaction the condensate was
1 : 2 (w/w) diluted with benzene, transferred to a sepa-
ration funnel, and washed several times with water. The
organic layer was separated, dried over sodium sulfate,
and subjected to vacuum distillation.
(4Н, 2ОСН2), 5.45 (1Н, SCH), 6.3 d (2Н, 2СН=, 3JН–Н
=
3.27 Hz), 7.35 s (1Н, =СНО). 13С NMR spectrum (CCl4),
δ, ppm: 14, 19, 30, 33, 38, 46, 65, 108, 110, 149, 150, 168.
To test the suitability of the compounds synthesized as
Table 1. Characteristics of mercaptoacetic acid esters
R
bp, °C/P, mm Hg
165–166
Yield, %
57.0
nD20
d420, g cm–3
1.0408
i-C3H7
n-C4H9
n-C5H11
n-C7H15
1.4509
1.4568
1.4574
1.4590
193–194
54.3
1.0268
202–204
59.6
1.0276
105–107/1
56.0
1.0115
n-C9H19
118–119/ 1
60.0
1.4609
0.9532
Table 2. Characteristics of target compounds
Compound
bp, °C/2 mm Hg
83–85
Yield, %
nD20
d420, g cm–3
1.1814
I
70.0
64.7
1.5180
1.5120
II
90–93
1.1433
III
IV
117–120
127–129
62.0
60.5
1.5090
1.5074
1.1326
1.1070
V
135–137
60.0
1.5012
1.0117
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 86 No. 5 2013

THE REACTION OF CONDENSATION
789
Table 3. Results of testing compounds I–V in M-16 cylinder
oil
required protective properties: Its corrosivity toward lead
is 256 g m–2.
Thus, our tests showed that the sulfur-containing
compounds synthesized by condensation of furfural
with mercaptoacetic acid esters are suitable as corrosion
protective additives for M-16 cylinder oil used in marine
diesel engines.
Concentration in Corrosivity toward
Compound
oil, %
lead, g m–2
I
II
1
2
3.5
0
1
2
10.7
3.3
CONCLUSIONS
III
IV
V
1
2
11.6
2.7
(1) Hydrochloric acid-catalyzed condensation reac-
tions of furfural with various mercaptoacetic acid esters
were studied.
1
2
12.0
1.3
1
2
12.4
2.1
(2) The 2-di(alkoxycarbonylmethylthio)methylfuranes
synthesized were tested at 1 and 2% concentrations as
corrosion protective additives to M-16 cylinder oil used in
marine diesel engines. It was found that they possess high
corrosion protective properties and virtually completely
suppress corrosion of lead plates.
Neat oil
(no additive)
–
256
corrosion protective additives in oils, we prepared their
compositions with M-16 cylinder oil used in marine diesel
engines and carried out tests with lead plates on a DK-
NAMI instrument at 140°C. The results are summarized
in Table 3.Studies of the furfural condensation reaction
with various mercaptoacetic acid esters showed that, de-
pending on the length of the radical R in the ester group,
the target 2-di(alkoxycarbonylmethylthio)methylfuranes
were obtained in a 60 to 70% yield, i.e., with increasing
length of the radical R the yield tends to decrease, as ex-
pected (Table 2). The nD20 and d420 characteristics exhibit
similar trends. The compounds synthesized are viscous
yellow substances, highly soluble in lubricating oils.
Table 3 shows that all the sulfur-containing compounds
synthesized possess high corrosion protective properties
with respect to lead plates. At 1% concentration of these
compounds in M-16 oil the corrosivity was estimated
at 3.5–12.4 g m–2, and at 2% concentration corrosion
was virtually completely suppressed. As for neat M-16
cylinder oil (without additives), it does not possess the
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RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 86 No. 5 2013