Synthesis of 1,3,4-trimethylcyclohex-3-en-1-carboxylic acid allyl ester

Article abstract of DOI:10.1134/S107042721201034X

The process of diene cyclization of 2,3-dimethylbutadiene with allyl methacrylicate was investigated. Effects of temperature, reaction duration, and ratio of reagents on the yield of 1,3,4-trimethylcyclohex-3-en-1-carboxylic acid allyl ester was studied.

Full text of DOI:10.1134/S107042721201034X

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 1, pp. 164−166. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © I.S. Polevaya, N.M. Karpyak, M.D. Fedevich, O.I. Marshalok, I.J. Pyrig, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85,
No. 1, pp. 171−173.
BRIEF
COMMUNICATIONS
Synthesis
of 1,3,4-Trimethylcyclohex-3-en-1-Carboxylic Acid Allyl Ester
I. S. Polevaya, N. M. Karpyak, M. D. Fedevich,
O. I. Marshalok, and I. J. Pyrig
Lviv Polytechnical National University, Lviv, Ukraine
Received November 12, 2010
Abstract—The process of diene cyclization of 2,3-dimethylbutadiene with allyl methacrylicate was investigated.
Effects of temperature, reaction duration, and ratio of reagents on the yield of 1,3,4-trimethylcyclohex-3-en-1-
carboxylic acid allyl ester was studied. Optimal conditions of passing the process were found.
DOI: 10.1134/S107042721201034X
Esters of alkyl-substutited cyclohexenecarboxylic ac-
ids are valuable raw material for the synthesis of a number
of compounds including medical preparations, some of
which inhibit cholesterin biosynthesis and noticeably
reduce its level in blood [1]. Furthermore esters of alkyl-
substutited cyclohexenecarboxylic acids are used for the
synthesis of tertiary alcohols applied in perfumery com-
positions [2]. Owing to the dielectric anisotropy, esters
are used as components of liquid-crystal compositions for
electro-optical instruments. They are also widely applied
as softening modifiers of epoxy resins. Multifunctional
monomers of various structures with a certain complex
physicochemical characteristics are obtained on the ba-
sis of esters of alkyl-substutited cyclohexenecarboxylic
acids [3].
of DMB with methyl metacrylate, using a solution of
methyl metacrylate and DMB in toluene. The mixture
is stirred, put in a glass ampoule, and heated up within
12 h at 140°С in the presence of pyrogallol. The yield
of the ester is 70% [3]. No published information on the
procedures of preparation of 1,3,4-trimethylcyclohex-
3-en-1-carboxylic acid allyl esters (TMCHC AE) is
available.
The aim of this work was the extension of the assort-
ment of esters of cyclohexenecarboxylic acids due to
obtaining new monomers, unsaturated esters of alkyl-
substutited cyclohexenecarboxylic acids.
To prepare TMCHCAE, we have chosen its synthesis
from DMB with methacrylic acid allyl ester (MA AE)
has been selected.
In the literature there are data on the cyclization
of some dienes with acrylates. Ethyl ester of
3,4-dimethylcyclohex-3-en-1-carboxylic acid is
obtained by the reaction of 2,3-dimethylbutadiene
(DMB) with ethyl acrylate by the Diels–Alder reaction
[2]. Methyl ester of 2-methylcyclohex-3-en-1-carboxylic
acid is obtained by the condensation of piperylene
with methyl acrylate, using equimolar amounts of
piperylene and methyl acrylate. The mixture is stirred,
put in an autoclave, and heated up for 6 h at 200°С in
the presence of hydroquinone. The yield of the ester
is 65% [1]. Methyl ester of 1,3,4-trimethylcyclohex-
3-en-1-carboxylic acid is obtained by the cyclization
EXPERIMENTAL
In the work we have studied the process of TMCHC
AE preparation by DMB diene cyclization with MAAE
according to the reaction according to the scheme
To obtain TMCHCAE, we used DMB synthesized by
a catalytic dehydration of 2,3-dimethyl-2,3-butanediol [4,
5] and chemically-pure grade MAAE.
Reaction products were analyzed on a “Chrom-5”
chromatograph with a DTP thermal conduction detector
and a chromatograph column of 1 m in length and diam-
164

SYNTHESIS OF 1,3,4-TRIMETHYLCYCLOHEX-3-EN-1-CARBOXYLIC ACID ALLYL ESTER
165
Scheme.
O
CH2
H3C
H3C
C
C
C
O
CH2
CH
CH2
C
+
CH3
CH2
CH2
O
H2
C
C
O
C
C
CH2
H3C
H3C
C
H2
H
CH3
CH2
C
H2
Fig. 1. Dependence of TMCHC AE yield Р (%) on the process
time τ (min) at the equimolar ratio of reagents. Т (°С): (1) 170,
(2) 160, (3) 150, (4) 140, (5) 130, (6) 120.
eter 3 mm filled with polisorb-1. A detector current was
37 mA; temperature of the column 120, of the detector
150, and of an evaporator 150°С; gas-carrier hydrogen,
its consumption 22 ml min–1, the sample volume 1 μl.
Signal recording and handling chromatograms were car-
ried out on a computer.
To determine optimal conditions of obtaining TMCHC
AE, we have studied the effect of the cyclization tempera-
ture, of the time of interacting mother substances, and of
their ratio on the product yield. The results obtained are
given in Figs. 1 and 2.
As the reaction temperature increases from 130 up to
160°С the yield of the product for 5 h reaction increases
from 54 up to 68% at the equimolar ratio of reagents. At
the further temperature increase no essential increase in
the target product yield is observed, furthermore at higher
temperatures the possibility of the reaction mixture po-
lymerization increases. The dependences of TMCHCAE
yield on temperature and time are presented in the table.
It follows from these data that the optimal temperature
of the TMCHC AE synthesis is 160°С.
Fig. 2. Dependence of TMCHC AE yield Р (%) on the process
time τ (min) at temperature 160°С. DMB:MAAE ratio: (1) 1 :
20, (2) 1 : 10, (3) 1 : 5, (4) 1 : 2, (5) 1 : 1.
We have studied the effect of DMB : MA AE molar
ratio (from equimolar up to 20-fold excess) at the optimal
temperature of 160°С on the yield of the target product
(Fig. 2). It was found that the application of excess MA
AE does not result in essential increase in the target
product yield. Therefore the equimolar ratio of reagents
providing the process manufacturability is optimal.
1
61.09. Н NMR spectrum was recorded on a Bruker
AM-300 spectrometer (300 MHz) in СDCl3, internal
standard TMS. Н NMR spectrum completely agrees
1
with the AE TMCHC structure. The spectrum contains
signals at 1.38, 1.82, 1.82, 1.84, 1.91, 2.01, 2.09, 2.15,
2.40, 4.75, 5.23, 5.24, and 6.06 ppm. Protons of the allyl
fragment are recorded at 6.06 ppm as a multiplet, at 5.23
and 5.24 ppm as a triplet, and at 4.75 ppm as a doublet.
Six aromatic protons of the cyclohexene fragment give
four doublet signals at 1.84, 1.91, 2.01, 2.09, 2.15, and
2.40 ppm. Methyl groups of the aromatic cycle in posi-
tions 1, 3, and 4 resonate as two singlets at 1.38, 1.82,
and 1.82 ppm.
The maximal TMCHC AE yield for the 5 h process
at the temperature of 150–160°С and equimolar ratio of
reagents is 66–68%.
Synthesized TMCHC AE has the following physi-
cochemical characteristics: mp 102°С at 3 mm Hg;
nD20 1.4758; d420 0.9565; MR: found 61.31, calculated
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 1 2012

166
POLEVAYA et al.
vol. 70, pp. 2502–2503.
CONCLUSION
2. Petrov, A.A. and Sopov, N.P., Zh. Obshch. Khim., 1948,
Allyl ester of 1,3,4-trimethylcyclohex-3-en-1-carboxyl-
ic acid was synthesized at the equimolar ratio of reagents.
vol. 18, no. 10, pp. 1781–1788.
3. Monnin, J., Angew. Chem., 1957, vol. 23, no. 69, pp. 762–
763.
REFERENCES
4. UA Patent 46772, IPC C 07 C 11/00.
5. UA Patent 52884, IPC C 07 C 11/00.
1. Meek, J.S. and Ragsdale, J.W., J. Am. Chem. Soc., 1948,
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 1 2012