Chlorination of 3,6-di-tert-butyl-1,2-benzoquinone in two-phase catalytic system

Article abstract of DOI:10.1134/S1070428011070086

Chlorination of 3,6-di-tert-butyl-1,2-benzoquinone in a two-phase catalytic system (CH₂Cl₂, HCl-H₂O, H₂O ₂, Bu₄NCl) led to halogen addition at the C=C bond, and subsequent dehydrochlorinati

Full text of DOI:10.1134/S1070428011070086

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 7, pp. 1015–1017. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © T.I. Prokof’eva, V.B. Vol’eva, I.S. Belostotskaya, N.L. Komissarova, A.V. Malkova, 2011, published in Zhurnal Organicheskoi
Khimii, 2011, Vol. 47, No. 7, pp. 1001–1003.
Chlorination of 3,6-Di-tert-butyl-1,2-benzoquinone
in Two-Phase Catalytic System
T. I. Prokof’eva, V. B. Vol’eva, I. S. Belostotskaya, N. L. Komissarova, and A. V. Malkova
Emanuel’Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 119334 Russia
e-mail: komissarova@polymer.chph.ras.ru
Received October 12, 2010
Abstract—Chlorination of 3,6-di-tert-butyl-1,2-benzoquinone in a two-phase catalytic system (CH2Cl2, HCl–
H2O, H2O2, Bu4NCl) led to halogen addition at the C=C bond, and subsequent dehydrochlorination of the
adduct gave 3,6-di-tert-butyl-4-chloro-1,2-benzoquinone. Chlorination of the latter afforded 3,6-di-tert-butyl-
4,5-dichloro-1,2-benzoquinone.
DOI: 10.1134/S1070428011070086
As a rule, direct chlorination of alkyl-substituted
pyrocatechols is not used for selective synthesis of
monochloro derivatives because of side oxidation, de-
alkylation, and polyhalogenation processes. Monosub-
stituted derivatives are obtained most frequently via
dipolar 1,4-addition of hydrogen chloride to redox-
conjugated quinone. For example, 3,5-di-tert-butyl-6-
chlorobenzene-1,2-diol (I) is synthesized from 3,5-di-
tert-butylbenzene-1,2-diol through the corresponding
quinone (Scheme 1).
However, analogous scheme cannot be applied to
the isomeric 3,6-di-tert-butylbenzene-1,2-diol (II)–
3,6-di-tert-butyl-1,2-benzoquinone (III) couple. Qui-
none III reacts with dry hydrogen chloride according
to redox pattern with formation of initial pyrocatechol
II [1] (Scheme 2). The reaction of III with aqueous
HCl gives 3,6-di-tert-butyl-2-hydroxy-1,4-benzoqui-
none (IV) as a result of hydration [2] (Scheme 3).
Scheme 3.
Bu-t
Bu-t
Scheme 1.
O
O
OH
OH
Aq. HCl
t-Bu
OH
OH
t-Bu
O
O
[O]
HO
Bu-t
Bu-t
Bu-t
Bu-t
III
Cl
Bu-t
t-Bu
OH
OH
HCl
O
[O]
O
OH
Bu-t
Bu-t
I
IV
Scheme 2.
We succeeded in synthesizing 3,6-di-tert-butyl-4-
chloro-1,2-benzoquinone (V) through intermediate ad-
duct of quinone III with chlorine, which was generated
in situ with the aid of hydrogen peroxide in a two-
phase catalytic system containing quinone III in meth-
ylene chloride or carbon tetrachloride and aqueous
HCl and Bu4NCl. Compound III failed to react with
Bu-t
Bu-t
O
OH
OH
HCl, Et2O
·
+
2Cl
O
Bu-t
Bu-t
III
II
1015

PROKOF’EVA et al.
1016
HCl or H2O in a nonpolar solvent. Chlorine liberated
in the reaction of HCl with H2O2 is transferred by
Bu4NCl (phase-transfer catalysis) to the organic phase
where it reacts with quinone III to produce the corre-
sponding adduct at the double bond, 3,6-di-tert-butyl-
5,6-dichlorocyclohex-3-ene-1,2-dione (VI). Dehydro-
chlorination of VI by the action of triethylamine
affords chloro-substituted quinone V which can be
reduced to the corresponding pyrocatechol with zinc in
acetic acid (Scheme 4).
reaction system was necessary, otherwise SO2Cl2 was
inactive. The proposed reaction scheme implied pro-
tonation of SO2Cl2 to generate cationoid species
responsible for electrophilic attack on the quinone
(Scheme 6).
Scheme 6.
Bu-t
Bu-t
O
O
Cl
O
O
Cl
OH
O
+
S
Cl
Scheme 4.
Bu-t
Bu-t
Bu-t
Cl
Bu-t
Aq. HCl, H2O2
Bu4NCl, CH2Cl2
III
O
O
Cl
O
Cl
Bu-t
Cl
O
O
ClS(O)OH
–SO2, –H+
Bu-t
Bu-t
VI
O
III
Bu-t
VI
Bu-t
Bu-t
Cl
O
Cl
OH
OH
Et2NH
–Et2NH·HCl
Zn, AcOH
With account taken of the data obtained in the
present work, a more probable reaction scheme is that
implying radical rather than ionic mechanism of forma-
tion of adducts VI and VII, according to which pro-
tonation of SO2Cl2 promotes its redox dehalogenation
(Scheme 7). The process may be both intra- and inter-
molecular with participation of acid catalyst.
O
Bu-t
Bu-t
V
Analogous reaction sequence with quinone V as
starting compound involves intermediate formation of
3,6-di-tert-butyl-4,5,6-trichlorocyclohex-3-ene-1,2-
dione (VII) and yields 3,6-di-tert-butyl-4,5-dichloro-
1,2-benzoquinone (VIII) (Scheme 5).
Scheme 7.
Cl–
Cl
OH
Cl
OH
O
Scheme 5.
Cl–
S
S
Bu-t
Cl
O
Cl
Cl
Bu-t
Aq. HCl, H2O2
Bu4NCl, CH2Cl2
Cl
O
O
Cl
Cl
O
·
2 Cl
+
ClS(O)OH
HCl + SO2
O
The proposed radical mechanism for the formation
of adducts VI and VII is also consistent with the
ability of quinone III to form adducts with radical
species at the endocyclic double C=C bonds, which
was demonstrated in other reactions, for example, in
the reaction of III with dihalocarbenes and in the di-
merization of III [4, 5].
Bu-t
Bu-t
VII
V
Bu-t
Cl
Cl
O
–HCl
O
Thus selective monohalogenation of the redox
couple pyrocatechol (II)–quinone (III) or substituted
analogs can be performed through intermediate qui-
none adducts with halogen generated in situ. These
adducts do not undergo uncontrolled transformations,
and their dehydrohalogenation selectively yields the
corresponding mono- and dihalo-substituted quinones.
Bu-t
VIII
Analogous syntheses of quinones V and VIII were
reported in [3] where intermediate adducts VI and VII
were obtained by reaction of quinone III or V with
SO2Cl2. Here, the presence of a proton donor in the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 7 2011

CHLORINATION OF 3,6-DI-tert-BUTYL-1,2-BENZOQUINONE
1017
EXPERIMENTAL
described above for compound VI. Light yellow crys-
tals, mp 86°C. 1H NMR spectrum, δ, ppm: 1.37 s (9H),
1.40 s (9H), 4.83 s (1H). Found, %: C 51.65; H 5.82.
C14H19Cl3O2. Calculated, %: C 51.63; H 5.89.
1
The H NMR spectra were recorded on a WH-250
spectrometer at 250 MHz) from solutions in carbon
tetrachloride using TMS as internal reference.
3,6-Di-tert-butyl-4,5-dichlorocyclohexa-3,5-di-
ene-1,2-dione (VIII) was synthesized from adduct VII
as described above for quinone V. Dark red crystals,
Compounds V–VIII were isolated in almost quan-
titative yields (≥95%).
1
mp 48°C. H NMR spectrum: δ 1.40 ppm, s. Found,
3,6-Di-tert-butyl-5,6-dichlorocyclohex-3-ene-1,2-
dione (VI). Quinone III [6], 1.1 g, was dissolved in
20 ml of methylene chloride (c = 5×10–3 M), 20 ml of
concentrated hydrochloric acid and 0.55 g (2×10–3 M)
of tetrabutylammonium chloride were added, and
hydrogen peroxide was then added under vigorous
stirring until dark brown color typical of the initial
quinone disappeared. The organic phase was separated,
washed with water, dried over Na2SO4, and evaporat-
ed, and the residue was recrystallized from heptane.
%: C 58.04; H 6.27. C14H18Cl2O2. Calculated, %:
C 58.13; H 6.29.
REFERENCES
1. Belostotskaya, I.S., Vol’eva, V.B., Komissarova, N.L.,
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stotskaya, I.S., and Ershov, V.V., Izv. Ross. Akad. Nauk,
Ser. Khim., 1981, p. 2110.
1
Light yellow crystals, mp 154°C. H NMR spectrum,
δ, ppm: 1.25 s (9H), 1.40 s (9H), 5.10 d (1H, J =
6.4 Hz), 6.83 d (1H, J = 6.4 Hz). Found, %: C 57.70;
H 6.91. C14H20Cl2O2. Calculated, %: C 57.73; H 6.94.
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3,6-Di-tert-butyl-4-chlorocyclohexa-3,5-diene-
1,2-dione (V). Diethylamine, 0.44 g (6×10–3 M), was
added to a solution of 1.46 g (5×10–3 M) of adduct VI
in pentane, the precipitate was filtered off, the filtrate
was washed with water, dried over Na2SO4, and evap-
orated, and the residue was recrystallized from hexane.
Dark red crystals, mp 50–51°C [6].
3,6-Di-tert-butyl-4,5,6-trichlorocyclohex-3-ene-
1,2-dione (VII) was synthesized from quinone V as
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 7 2011