Synthesis of 3,4-dibromo-3,4,4-trichloro-1-phenylbutan-1-one and 1-aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones from 3,4,4-trichlorobut-3-enoic acid

Article abstract of DOI:10.1134/S107042800711005X

Bromination of 3,4,4-trichlorobut-3-enoic acid in boiling carbon tetrachloride led to the formation of 2-bromo-3,4,4-trichlorobut-3-enoic acid as a result of replacement of hydrogen in the CH₂ group. The reaction at 40°C involved the double C=C

Full text of DOI:10.1134/S107042800711005X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 11, pp. 1617–1621. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © V.I. Potkin, S.K. Petkevich, R.V. Kaberdin, P.V. Kurma, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 11,
pp. 1621–1625.
Synthesis of 3,4-Dibromo-3,4,4-trichloro-1-phenylbutan-1-one
and 1-Aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones
from 3,4,4-Trichlorobut-3-enoic Acid
V. I. Potkin, S. K. Petkevich, R. V. Kaberdin, and P. V. Kurman
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 13, Minsk, 220072 Belarus
e-mail: potkin@ifoch.bas-net.by
Received September 16, 2006
Abstract—Bromination of 3,4,4-trichlorobut-3-enoic acid in boiling carbon tetrachloride led to the formation
of 2-bromo-3,4,4-trichlorobut-3-enoic acid as a result of replacement of hydrogen in the CH2 group. The
reaction at 40°C involved the double C=C bond to give 3,4-dibromo-3,4,4-trichlorobutanoic acid. The
brominated acids were converted into the corresponding chlorides which were used to acylate benzene, toluene,
and bromobenzene according to Friedel–Crafts. The acylation was not selective, and only the reaction of
3,4-dibromo-3,4,4-trichlorobutanoyl chloride with benzene gave 3,4-dibromo-3,4,4-trichloro-1-phenylbutan-1-
one as the only product. 1-Aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones were synthesized by bromination of
the corresponding 1-aryl-3,4,4-trichlorobut-3-en-1-ones which were prepared previously by Friedel–Crafts
acylation of substituted benzenes with 3,4,4-trichlorobut-3-enoyl chloride.
DOI: 10.1134/S107042800711005X
Accessible 3,4,4-trichlorobut-3-enoic acid (I)
which is readily obtained from trichloroethylene dimer
[1] contains several potential reaction centers and is
a convenient starting material for the synthesis of
various polyfunctional compounds [2, 3]. We previ-
ously reported on the chlorination of acid I with
quantitative formation of pentachlorobutanoic acid [3];
however, its bromination has not been studied so far.
Nevertheless, bromine-and chlorine-containing carbox-
ylic acids attract interest from both preparative (due
to the presence of reactive C–Br bonds in their
molecules) and practical viewpoints. Polyhalogenated
carboxylic acids exhibit a broad spectrum of useful
properties, in particular they are extractants for rare-
earth elements, promotors of Ziegler–Natta catalysts,
flammable inhibitors, and biologically active sub-
stances [4–8].
bon tetrachloride was complete in 72 h; it involved
replacement of hydrogen in the CH2 group and resulted
in the formation of 57% of 2-bromo-3,4,4-trichlorobut-
3-enoic acid (II). We also isolated 3,4-dibromo-3,4,4-
trichlorobutanoic acid (III) as by-product (yield 4%);
it was formed via bromine addition at the double C=C
bond in the initial acid. When the bromination in
carbon tetrachloride was carried out at 40°C, the re-
action was complete in 48 h, and bromine addition
product III was isolated in 53% yield, while the yield
of substitutive bromination product II did not exceed
5%. In this case, the reaction required initiation by
irradiation with a filament lamp (no bromination
occurred in the dark). By contrast, the substitutive
bromination in boiling carbon tetrachloride was equal-
ly successful in the dark and on exposure to light.
Compounds II and III are characterized by consider-
ably different solubilities, and they were separated by
fractional crystallization from hexane.
The goal of the present work was to study the
bromination of 3,4,4-trichlorobut-3-enoic acid (I) and
possible way of synthesis of polychlorobromo-sub-
stituted acids and ketones.
Unlike acid I, the bromination of acid chloride IV
in carbon tetrachloride both under reflux and at room
temperature resulted in replacement of hydrogen in the
CH2 group with formation of 2-bromo-3,4,4-trichloro-
but-3-enoyl chloride (V). From the preparative view-
We previously found that the bromination of acid I
follows different pathways, depending on the reaction
conditions. The reaction with bromine in boiling car-
1617

POTKIN et al.
1618
Scheme 1.
Cl
Cl
Cl
Cl
Cl
Cl
Br2, CCl4
reflux, 72 h
SOCl2
COOH
COCl
Br
Br
II
V
Br2, CCl4
40°C, 48 h
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Br
Cl
Cl
Br
Br
Br
Br
SOCl2
COOH
PhH, AlCl3
Br
COOH
COCl
COPh
Cl
Cl
Cl
I
III
VI
VII
Br2, CCl4, reflux, 30 h
RC6H5, AlCl3
V
Cl
Cl
Cl
SOCl2
Cl
Cl
COCl
IV
Cl
COC6H4R
VIII–X
Cl
Cl
Cl
O
Br2, CCl4, 40°C, 1 h
VIII–X
Br
XI–XIII
C6H4R
VIII, XI, R = H; IX, XII, R = 4-Me; X, XIII, R = 4-Br.
C–Cl and C–Br bonds in compounds II, III and V, VI,
respectively.
point, it is advisable to carry out the reaction under
reflux. In this case, the reaction is complete in 30 h,
and compound V is formed in 65% yield. The reaction
at room temperature required 10 days to be complete.
Dibromo acid III was converted into the correspond-
ing chloride VI in 97% yield by standard procedure,
i.e., by treatment with thionyl chloride. Acid chloride
V was synthesized in a similar way from acid II, but
the yield of V did not exceed 75%.
1
The H NMR spectrum of acid III contained
a singlet at δ 3.86 ppm from protons of the CH2 group
and a broadened singlet from the acidic proton at
δ 11.31 ppm. In the 1H NMR spectrum of VI, the CH2
signal appeared as a singlet at δ 4.34 ppm. Acid II
displayed in the spectrum a singlet at δ 5.93 ppm from
the CHBr proton (δ 6.13 ppm in the spectrum of
chloride V) and a broadened singlet at δ 10.97 ppm
due to the COOH group.
The structure of bromo-substituted carboxylic acids
II and III and the corresponding acid chlorides V and
VI was determined on the basis of their elemental anal-
No molecular ion peaks were observed in the mass
spectra of both acids II and III and acid chlorides V
and VI. Fragmentation of these compounds under elec-
tron impact involves elimination of hydrogen chloride,
bromine atoms, decarboxylation (II, III), and subse-
quent profound decomposition with rupture of C–C
bonds. The intensity ratios for the isotope clusters were
consistent with the presence of four halogen atoms in
molecules II and V and five halogen atoms in III and
VI [9, 10].
1
yses and IR, H NMR, and mass spectra. In addition,
the molecular weights of acids II and III were deter-
mined by titrimetry. In the IR spectra of acids II and
III, stretching vibrations of the carbonyl groups
appeared as strong absorption bands at 1738 and
1718 cm–1, respectively. The C=O bands in the spectra
of acid chlorides V and VI were located at higher
frequencies, at 1801 and 1817 cm–1, respectively.
Stretching vibrations of the double C=C bond in II
and V gave rise to absorption bands at 1589 and
1585 cm–1. IR absorption bands in the regions 692–814
and 596–648 cm–1 were assigned to vibrations of the
Friedel–Crafts acylation of benzene with 3,4-di-
bromo-3,4,4-trichlorobutanoyl chloride (VI) gave 66%
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

SYNTHESIS OF 3,4-DIBROMO-3,4,4-TRICHLORO-1-PHENYLBUTAN-1-ONE
1619
of 3,4-dibromo-3,4,4-trichloro-1-phenylbutan-1-one
(VII), whereas the acylation with the same reagent of
substituted benzenes, such as toluene, p-xylene, and
p-bromobenzene, was not selective (complex mixtures
of products were formed). Presumably, the process was
accompanied by dehydrobromination, rearrangements
with migration of bromine atom, and arylation of the
ketones thus formed. The 1H NMR spectra of the reac-
tion mixtures (after removal of excess aromatic sub-
strates) contained a singlet at δ 6.7 ppm from the CHBr
and vinylic =CH protons and a singlet at δ 4.26 ppm,
which may be assigned to CHPh proton. Furthermore,
the signal intensity ratio for aromatic protons and
aliphatic protons in the acyl fragment indicated the
presence of two aromatic rings in the molecule of one
of the products. Likewise, the acylation of benzene and
its derivatives with 2-bromo-3,4,4-trichlorobut-3-enoyl
chloride (V) was accompanied by analogous processes,
Stretching vibrations of the C=O bonds in ketones
XI–XIII were characterized by strong IR absorption
bands at 1698–1706 cm–1, and bands in the regions
1584–1602 and 1572–1580 cm–1 were assigned to vi-
brations of the C=C bonds. Ketones XI–XIII showed
1
in the H NMR spectra singlets at δ 6.63–6.70 ppm
from the CHBr protons, which unambiguously indicat-
ed that the reaction occurred as replacement of hydro-
gen in the CH2 group by bromine. Aromatic protons
resonated in the region δ 7.27–7.95 ppm. In the mass
spectra of ketones VII and XI–XIII we observed no
molecular ion peaks; the fragment ion peaks corre-
sponded to elimination of halogen atoms and hydrogen
chloride, followed by decomposition of the carbon
skeleton.
Ketones VII and XI–XIII attract interest as con-
venient synthons for the preparation of polyfunctional
compounds; it is known that halogenated ketones are
used in the synthesis of antihelminthics, insecticides,
and other biologically active substances [11, 12].
1
as followed from similarity of the H NMR spectra of
the product mixtures obtained in the acylation with
acid chlorides V and VI. The IR spectra of the reaction
mixtures contained several strong carbonyl absorption
bands in the region 1690–1702 cm–1, which also
confirmed formation of several products. The product
mixtures were difficult to separate, and we failed to
isolate individual compounds therefrom.
EXPERIMENTAL
The IR spectra were recorded in KBr on a Protege-
460 spectrometer with Fourier transform. The 1H NMR
spectra were measured on a Tesla-567A instrument
(100 MHz) from solutions in CDCl3 using tetramethyl-
silane as internal reference. The mass spectra (electron
impact, 70 eV) were obtained on a Hewlett–Packard
HP 5890/5972 GC–MS system (HP-5MS capillary col-
umn, 30 m×0.25 mm, film thickness 0.25 μm, 5% of
phenylmethylsilicone; injector temperature 250°C).
The molecular weights of acids II and III were deter-
mined by titration with a 0.1 N alcoholic solution of
sodium hydroxide.
The structure of 3,4-dibromo-3,4,4-trichloro-1-
phenylbutan-1-one (VII) was confirmed by its ana-
lytical and spectral data. In the IR spectrum of VII, the
carbonyl band was located at 1699 cm–1, stretching
vibrations of the aromatic C=C bonds appeared at
1580 and 1595 cm–1, and vibrations of the C–Cl and
C–Br bonds were characterized by absorption bands in
the regions 689–799 and 548–623 cm–1, respectively.
1
The H NMR spectrum of ketone VII contained
a singlet at δ 4.38 ppm due to methylene protons, and
aromatic protons gave rise to multiplets in the region
δ 7.30–8.12 ppm.
2-Bromo-3,4,4-trichlorobut-3-enoic acid (II).
A mixture of 10 g (53.8 mmol) of 3,4,4-trichlorobut-3-
enoic acid (I) and 3 ml (58.4 mmol) of bromine in
50 ml of anhydrous carbon tetrachloride was heated for
72 h under reflux. The mixture was washed with
an aqueous solution of Na2SO3 to remove residual
bromine and with water and dried over sodium sulfate.
The solvent was removed under reduced pressure,
50 ml of hexane was added to the solid residue, the
mixture was heated to the boiling point, the undis-
solved material was filtered off, the filtrate was cooled
to 0°C, and the precipitate was filtered off, washed
with cold hexane, and dried under reduced pressure.
Yield 8.06 g (57%), mp 83–85°C. IR spectrum, ν,
cm–1: 2500–3300 (COOH); 1738 (C=O); 1589 (C=C);
With a view to obtain polyhalogenated aryl ketones
we examined bromination of 1-aryl-3,4,4-trichlorobut-
3-en-1-ones VIII–X which were synthesized previous-
ly by Friedel–Crafts acylation of the corresponding
benzenes with acid chloride IV [3]. Reactions of com-
pounds VIII–X with bromine in carbon tetrachloride
both at room temperature and under reflux involved
replacement of hydrogen in the CH2 group. Under the
optimal conditions (40°C, 1 h), the corresponding
1-aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones XI–
XIII were obtained in 92–98% yield. Their structure
was determined on the basis of their IR, 1H NMR, and
mass spectra and elemental analyses.
1
722, 814 (C–Cl); 648 (C–Br). H NMR spectrum, δ,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

POTKIN et al.
1620
ppm: 5.93 s (1H, CHBr), 10.97 br.s (1H, COOH).
Found, %: C 18.08; H 0.90; Hlg 69.78. M 265. Cal-
culated, %: C 17.91; H 0.75; Hlg 69.42. M 268.32.
3,4-Dibromo-3,4,4-trichloro-1-phenylbutan-1-
one (VII). Acid chloride VI, 8.5 g (23 mmol), was
mixed with 3.7 g (27.8 mmol) of anhydrous alumi-
num(III) chloride, 5.45 g (69.8 mmol) of anhydrous
benzene was added to the resulting complex, and the
mixture was stirred for 4 h at 20°C and for 2 h at 45°C,
diluted with 15 ml of methylene chloride, and poured
into 100 ml of 0.1 N hydrochloric acid. The organic
phase was separated, washed with water, a solution of
sodium carbonate, and water again, and dried over
MgSO4. The solvent was distilled off, and the residue
was recrystallized from hexane. Yield 6.22 g (66%),
mp 88–90°C. IR spectrum, ν, cm–1: 1699 (C=O); 1595,
1580 (C=C); 799, 748, 689 (C–Cl); 548, 623 (C–Br).
1H NMR spectrum, δ, ppm: 4.38 s (2H, CH2), 7.50–
7.60 m (3H, Harom), 7.90–8.10 m (2H, Harom). Found,
%: C 29.18; H 2.08; Hlg 64.71. [M – 2Br – HCl]+ 212.
Calculated, %: C 29.34; H 1.72; Hlg 65.02. M 409.33.
The material insoluble in hexane was 3,4-dibromo-
3,4,4-trichlorobutanoic acid (III); it was purified by
recrystallization from carbon tetrachloride. Yield 4%,
mp 148–150°C. IR spectrum, ν, cm–1: 2450–3200
(COOH); 1718 (C=O); 692, 773, 805 (C–Cl); 596
1
(C–Br). H NMR spectrum, δ, ppm: 3.86 s (2H, CH2),
11.31 br.s (1H, COOH). Found, %: C 13.61; H 1.23,
Hlg 75.98. M 347. Calculated, %: C 13.76; H 0.87;
Hlg 76.21. M 349.23.
Following an analogous procedure, the reaction was
carried out at 40°C (reaction time 48 h) under irradia-
tion with a filament lamp. The products were separated
in a similar way.
2-Bromo-3,4,4-trichlorobut-3-enoyl chloride (V).
A solution of 18.5 g (89 mmol) of 3,4,4-trichlorobut-3-
enoyl chloride (IV) and 5 ml (97.3 mmol) of bromine
in 50 ml of anhydrous carbon tetrachloride was heated
for 30 h under reflux. The solvent was distilled off
under atmospheric pressure, and the residue was
distilled under reduced pressure. Yield 16.6 g (65%),
bp 76–77°C (2 mm), d420 = 1.836. IR spectrum, ν, cm–1:
1801 (C=O); 1585 (C=C); 729, 701 (C–Cl); 599
General procedure for the bromination of
1-aryl-3,4,4-trichlorobut-3-en-1-ones VIII–X. Bro-
mine, 45 mmol, was added dropwise under stirring to
a solution of 40 mmol of ketone VIII–X in 40 ml of
anhydrous carbon tetrachloride, heated to 40°C. The
mixture was then heated to 60°C, stirred for 30 min at
that temperature, washed with a solution of Na2SO3 to
remove excess bromine and with water until neutral
reaction, and dried over CaCl2. The solvent was re-
moved, and the solid residue was purified by recrys-
tallization from hexane (compound XI) or methanol
(XII, XIII).
1
(C–Br). H NMR spectrum, δ, ppm: 6.13 s (1H,
CHBr). Found, %: C 16.90; H 0.76; Hlg 76.95. [M –
HCl]+ 248. Calculated, %: C 16.75; H 0.35; Hlg 77.32.
M 286.77.
3,4-Dibromo-3,4,4-trichlorobutanoyl chloride
(VI). Thionyl chloride, 5 ml (69.6 mmol), was added
dropwise to a solution of 8 g (22.9 mmol) of acid III in
30 ml of anhydrous carbon tetrachloride, and the mix-
ture was stirred for 30 min and heated under reflux
until hydrogen chloride no longer evolved (test with
a litmus paper). The solvent and excess thionyl
chloride were distilled off first under atmospheric
pressure and then under reduced pressure (1 mm). The
residue was 8.25 g (98%) of compound VI which
required no additional purification, d420 = 2.008. IR
spectrum, ν, cm–1: 1817 (C=O); 694, 758, 788 (C–Cl);
2-Bromo-3,4,4-trichloro-1-phenylbut-3-en-1-one
(XI). Yield 98%, mp 65–66°C. IR spectrum, ν, cm–1:
1706 (C=O); 1582, 1592 (C=C); 709, 750, 847 (C–Cl);
1
551 (C–Br). H NMR spectrum, δ, ppm: 6.70 s (1H,
CHBr), 7.49–7.65 m (3H, Harom), 7.86–7.95 m (2H,
H
arom). Found, %: C 36.90; H 2.03; Hlg 56.55. [M –
HCl]+ 290. Calculated, %: C 36.57; H 1.84; Hlg 56.71.
M 328.42.
2-Bromo-3,4,4-trichloro-1-(4-methylphenyl)but-
3-en-1-one (XII). Yield 96%, mp 95–97°C. IR spec-
trum, ν, cm–1: 1698 (C=O); 1580, 1602 (C=C); 707,
1
599, 623 (C–Br). H NMR spectrum, δ, ppm: 4.34 s
1
752, 822 (C–Cl); 545 (C–Br). H NMR spectrum, δ,
(2H, CH2). Found, %: C 12.90; H 0.99; Hlg 81.81.
[M – 2Br]+ 206. Calculated, %: C 13.07; H 0.55;
Hlg 82.03. M 367.68.
ppm: 2.45 s (3H, Me), 6.68 s (1H, CHBr) 7.27 d and
7.35 d (1H each, Harom), 7.78 d and 7.86 d (1H each,
H
arom). Found, %: C 38.54; H 2.58; Hlg 54.70.
An analogous procedure was used to obtain
2-bromo-3,4,4-trichlorobut-3-enoyl chloride (V) (yield
75%); the product was identical to a sample prepared
by bromination of 3,4,4-trichlorobut-3-enoyl chloride
(IV) as described above.
[M – HCl]+ 302. Calculated, %: C 38.58; H 2.35;
Hlg 54.39. M 340.45.
2-Bromo-1-(4-bromophenyl)-3,4,4-trichlorobut-
3-en-1-one (XIII). Yield 92%, mp 96–98°C. IR spec-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

SYNTHESIS OF 3,4-DIBROMO-3,4,4-TRICHLORO-1-PHENYLBUTAN-1-ONE
1621
trum, ν, cm–1: 1698 (C=O); 1572, 1584 (C=C); 716,
764, 825 (C–Cl); 546 (C–Br). H NMR spectrum, δ,
5. Haglid Frank, R., US Patent no. 3803189, 1974; Ref.
Zh., Khim., 1975, no. 5O363P.
1
6. Maahs, G. and Rombusch, K., FRG Patent Appl.
no. 2921220, 1980; Chem. Abstr., 1981, vol. 94,
no. 83622u.
7. Maahs, G. and Rombusch, K., FRG Patent Appl.
no. 2925012, 1980; Chem. Abstr., 1981, vol. 94,
no. 156335q.
ppm: 6.63 s (1H, CHBr) 7.70 br.s (2H, Harom), 7.75 br.s
(2H, Harom). Found, %: C 29.72; H 1.65; Hlg 65.39.
[M – HCl]+ 368. Calculated, %: C 29.49; H 1.24;
Hlg 65.35. M 407.32.
REFERENCES
8. FRG Patent Appl. no. 1534599, 1968; Chem. Abstr.,
1969, vol. 71, p. 13992r.
1. Petkevich, S.K., Dikusar, E.A., Potkin, V.I., Kaber-
din, R.V., Moiseichuk, K.L., Yuvchenko, A.P., and Kur-
man, P.V., Russ. J. Gen. Chem., 2004, vol. 74, p. 586.
2. Petkevich, S.K., Potkin, V.I., and Kaberdin, R.V., Russ. J.
Org. Chem., 2004, vol. 40, p. 1146.
9. Takhistov, V.V., Prakticheskaya mass spektrometriya
organicheskikh soedinenii (Practical Mass Spectrometry
of Organic Compounds), Leningrad: Leningr. Gos.
Univ., 1977, p. 268.
10. Takhistov, V.V., Rodin, A.A., and Maksimova, B.N.,
3. Potkin, V.I., Kaberdin, R.V., Petkevich, S.K., and Kur-
Usp. Khim., 1991, vol. 60, p. 2143.
man, P.V., Russ. J. Org. Chem., 2002, vol. 38, p. 1099.
11. Pilgram, K. and Kendall Hass, D., J. Med. Chem., 1975,
vol. 18, p. 1204.
12. Mirskova, A.N., Levkovskaya, G.G., Lidina, P.V., and
4.Shcheglov, Yu.V., Nikishin, G.I., Dyusenov, M.I., Musi-
kaev, D.A., Yakovets, V.I., and Yakovets, V.P., USSR
Inventor’s Certificate no. 218563, 1967; Byull. Izobret.,
1968, no. 17.
Voronkov, M.G., Khim.-Farm. Zh., 1977, no. 3, p. 74.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007