Chloroarylation and thiocyanatoarylation of itaconic acid

Article abstract of DOI:10.1134/S1070363213020151

Under conditions of Meerwein reaction and anionarylation the aryldiazonium salts and itaconic acid form 2-chloro(thiocyanato)-2-benzylbutanedioic acids as the chloro- and thiocyianatoarylation products. The reaction is not accompanied by the decarboxylati

Full text of DOI:10.1134/S1070363213020151

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 2, pp. 325–328. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © V.S. Baranovskii, B.M. Petrushka, A.Yu. Fesak, B.D. Grishchuk, 2013, published in Zhurnal Obshchei Khimii, 2013, Vol. 83, No. 2,
pp. 271–274.
Chloroarylation and Thiocyanatoarylation of Itaconic Acid
V. S. Baranovskii, B. M. Petrushka, A. Yu. Fesak, and B. D. Grishchuk
Hnatiuk Ternopil National Pedagogical University, ul. M. Krivonosa 2, Ternopil, 46027 Ukraine
e-mail: baranovsky@tnpu.edu.ua
Received October 11, 2011
Abstract―Under conditions of Meerwein reaction and anionarylation the aryldiazonium salts and itaconic acid
form 2-chloro(thiocyanato)-2-benzylbutanedioic acids as the chloro- and thiocyianatoarylation products. The
reaction is not accompanied by the decarboxylation process and other transformations affecting the carboxy
groups of itaconic acid.
DOI: 10.1134/S1070363213020151
At present, a significant number of acrylic and
methacrylic acids derivatives has been investigated in
the anionarylation and Meerwein reaction conditions.
The preparative methods of obtaining the
anionarylation and arylation products starting from
unsaturated compounds are developed. Some
approaches to the synthesis of heterocycles based on
these processes are described [1–5].
benzylacrilic and arylitaconic acids in yields of ~20%
[6].
In continuation of the study on the derivatives of
α,β-unsaturated carboxylic acids [7–9] we examined
for the first time 2-methylenebutandioic (itaconic) acid
in the conditions of Meerwein reaction and
anionarylation.
A considerable interest in the synthetic and theo-
retical terms is the anionarylation of the unsaturated
dicarboxylic acids and their derivatives, which were
investigated only sporadically in the Meerwein reac-
tion [3].
Aryldiazonium chlorides were found to react readily
with itaconic acid in a water–acetone medium (1:2) at
20–25°C in the presence of copper(II) chloride as a
catalyst to form 2-chloro-2-benzylbutandioic acids I–
IV. The reaction proceeds with the nitrogen release
and the addition of an aryl group and chlorine atom at
the place of the double bond rupture.
The reactions of aryl diazonium chlorides with ita-
conic and aconitic acids are known to afford α-
N2Cl
OH
Cl
OH
O
O
+
O
_N2
O
OH
R
R
HO
I_IV
R = 2-CH3 (I), 4-CH3 (II), 4-CH3O (III), 4-Br (IV).
Aryldiazonium tetrafluoroborates react with
itaconic acid in the presence of potassium thiocyanate
and copper(II) tetrafluoroborate as a catalyst at –15 to
–10°С to form 2-thiocyanato-2-benzylbutandioic acids
V–X.
The yields of the products I–X are 54–75%. The
yields, melting points, and elemental analysis data of
the synthesized compounds I–X are presented in Table 1.
The chloroarylation and thiocyanatoarylation of
itaconic acid are also accompanied by a side formation
of chloroarenes (20–25%) and a mixture of thio- (3–
5%) and isothiocyanatoarenes (15–20%), respectively.
The optimal ratio aromatic diazonium salt–itaconic
acid–potassium thiocyanate–catalyst is 1.1:1:1.2:0.11.
325

326
BARANOVSKII et al.
N2BF4
OH
SCN
OH
O
O
+
+ KSCN
_N2, _KBF4
O
CH2
HO
O
CH2 OH
R
R
I_VI
R = H (V), 2-CH3 (VI), 3-CH3 (VII), 4-CH3 (VIII), 4-CH3O (IX), 4-Br (X).
Under the investigated conditions the chloroaryla-
tion and thiocyanatoarylation reactions were not
accompanied with the release of hydrogen chloride or
thiocyanate and decarboxylation of one COOH group,
which is consistent with the data of elemental analysis,
IR and mass spectroscopy of compounds I–X.
Thus, under the Meerwein reaction conditions the
itaconic acid gives exclusively the chloroarylation
products. The results presented in [5] concerning the
structure of the final products may be due to the fact
that the chloroarylated itaconic acid derivatives are
thermally unstable compounds, which during the
vacuum distillation can relatively easily eliminate
hydrogen chloride or undergo other destructive
changes.
The structure of the synthesized compounds was
1
confirmed by the IR and H NMR spectroscopy. The
IR spectra of compounds I–X contain the characteristic
absorption bands of carboxy (1696–1716 cm–1) and
The presence of two carboxy groups in the structure
of the unsaturated compounds does not affect the
regioselectivity of the chloro- and thiocyanatoarylation
and proves a sufficiently high activation of the
multiple carbon–carbon bond.
1
thiocyanate groups (2148–2164 cm–1). In the H NMR
spectra there are the signals of aromatic protons at
7.55–6.99 ppm. The protons of the methylene groups
associated with the aromatic rings, along with the
protons of the methylene groups of succinic acid
fragment are observed as the doublets of doublets in
the region of 3.34–2.89 ppm. The spectral data of
compounds I–X are presented in Table 2.
EXPERIMENTAL
The IR spectra were recorded on a Specord M80
1
instrument from the samples in mineral oil. The H
Table 1. Yields, melting points, and elemental analysis data of 2-chloro(thiocyanato)-2-benzylbutandioic acids I–X
Found, %
Calculated, %
Comp.
no.
Yield,
%
mp, °Са
Formula
Сl
N
–
S
–
Cl
N
–
S
–
58
56
54
62
67
61
55
70
75
58
170
199
192
182
125
171
118
128
127
156
13.88
C12H13O4Cl
C12H13O4Cl
C12H13O5Cl
C11H10BrO4Cl
С12H11NO4S
С13H13NO4S
С13H13NO4S
С13H13NO4S
С13H13NO5S
С12H10BrNO4S
13.81
I
13.90
–
–
13.81
–
–
II
13.09
–
–
13.00
–
–
III
IV
V
11.11
–
–
11.03
–
–
–
–
–
–
–
–
5.19
4.96
5.14
5.06
4.83
4.00
12.15
11.51
11.55
11.53
10.97
9.29
–
–
–
–
–
–
5.28
5.01
5.01
5.01
4.74
4.07
12.09
11.48
11.48
11.48
10.86
9.32
VI
VII
VIII
IX
X
a Compounds I–IV were recrystallized from ethanol, compounds V–X, from methanol.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 2 2013

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CHLOROARYLATION AND THIOCYANATOARYLATION OF ITACONIC ACID
Table 2. Parameters of IR and 1Н NMR spectra of 2-chloro(thiocyanato)-2-benzylbutandioic acids I–X
IR spectrum, ν, cm–1
Comp.
1Н NMR spectrum, δ, ppm
C–Cl
no.
С=О
(SCN)
672
1712
12.79 br.s (2Н, СООН), 7.29–7.13 m (4Н, С6Н4), 3.29 d.d [2H, СН2С(О)О], 2.89 d.d (2H, CH2С6Н4),
2.29 s (3Н, СН3)
I
668
1704
1700
1708
1712
1704
1700
1704
1708
12.77 br.s (2Н, СООН), 7.12 s (4Н, С6Н4), 3.30 d.d [2H, СН2С(О)О], 2.92 d.d (2H, CH2С6Н4), 2.27 s
(3Н, СН3)
II
676
12.80 br.s (2Н, СООН), 7.50 and 7.14 two d (4Н, С6Н4), 3.78 s (3Н, СН3О), 3.32 d.d [2H, СН2С(О)О],
2.94 d.d (2H, CH2С6Н4)
III
IV
VI
VII
VIII
IX
X
684
12.88 br.s (2Н, СООН), 7.53 and 7.18 two d (4Н, С6Н4), 3.34 d.d [2H, СН2С(О)О], 2.91 d.d (2H,
CH2С6Н4)
2152
2156
2160
2156
2148
12.64 br.s (2Н, СООН), 7.25–7.08 m (4Н, С6Н4), 3.20 d.d [2H, СН2С(О)О], 3.01 d.d (2H, CH2С6Н4),
2.30 s (3Н, СН3)
12.75 br.s (2Н, СООН), 7.20–6.99 m (4Н, С6Н4), 3.14 d.d [2H, СН2С(О)О], 2.98 d.d (2H, CH2С6Н4),
2.29 s (3Н, СН3)
12.82 br.s (2Н, СООН), 7.08 s (4Н, С6Н4), 3.11 d.d [2H, СН2С(О)О], 2.95 d.d (2H, CH2С6Н4), 2.26 s
(3Н, СН3)
12.71 br.s (2Н, СООН), 7.54 and 7.10 two d (4Н, С6Н4), 3.82 s (3Н, СН3О), 3.17 d.d [2H, СН2С(О)О],
2.96 d.d (2H, CH2С6Н4)
12.84 br.s (2Н, СООН), 7.51 and 7.15 two d (4Н, С6Н4), 3.19 d.d [2H, СН2С(О)О], 2.99 d.d (2H,
CH2С6Н4)
NMR spectra were obtained on a Varian Mercury
instrument (400 MHz) relative to internal TMS from
DMSO-d6 solutions. The mass spectra were registered
on an Agilent 6850/5973 N GC-mass spectrometer.
The individuality of the synthesized compounds was
established by TLC on Silufol UV-254 plates eluting
with a chloroform–methanol (ethanol)–acetone mixture
(2:1:1).
(0.004 mol) of copper(II) tetrafluoroborate hexahyd-
rate, and 3.9 g (0.04 mol) of potassium thiocyanate in
150 ml of a water–acetone (1:2.5) mixture was added
6.8 g (0.035 mol) of phenyldiazonium tetrafluoro-
borate within 1 h. The nitrogen release was observed at
–10°C for 1.5 h. After the nitrogen release completed
the reaction mixture was diluted with 100 ml of water,
and extracted with 100 ml of diethyl ether. The extract
was washed with water, dried with anhydrous calcium
chloride, concentrated, and cooled to –20°C. The
colorless crystals formed were recrystallized from
methanol. Yield 5.7 g (67%). Mass spectrum: m/z 255
[М+].
2-Chloro-2-(2-methylbenzyl)butanedioic acid (I).
To a mixture of 9.2 g (0.07 mol) of itaconic acid and
1.3 g (0.0077 mol) of copper(II) chloride dihydrate in
120 ml of a water–acetone (1:2) mixture was added a
solution of 11.9 g (0.077 mol) of o-tolyldiazonium
chloride within 30 min. The nitrogen release was
observed at 25°C for 2 h. After the nitrogen release
completed the reaction mixture was diluted with 100 ml
of water and extracted with 150 ml of diethyl ether.
The extract was washed with water, dried with
anhydrous calcium chloride, and concentrated. The
solid residue was eluted with benzene and recrystal-
lized from ethanol. Yield 11.1 g (58%). Mass
spectrum: m/z 246 [М]+.
Compounds VI–X were obtained similarly.
ACKNOWLEDGMENTS
This work was financially supported by the
Ministry of Science and Education of Ukraine.
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a mixture of 4.2 g (0.032 mol) of itaconic acid, 1.4 g
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BARANOVSKII et al.
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