Halogenation of N-substituted para-quinone monoimine and para-quinone monooxime esters: VI. Regular trends in chlorination and bromination of N-arylsulfonyl-1,4-benzoquinone monoimines alkyl-substituted in the quinoid ring

Article abstract of DOI:10.1134/S107042800605006X

Reactions of halogens with N-arylsulfonyl-1,4-benzoquinone monoimines occur with the formation of a halogenonium ion that either transforms into a carbocation where the first halogen atom adds to the carbon in the ortho-position relative to the carbonyl c

Full text of DOI:10.1134/S107042800605006X

ISSN 1070-4280 Russian Journal of Organic Chemistry, 2006, Vol. 42, No. 5, pp. 683-688. Ó Pleiades Publishing, Inc. 2006.
Original Russian Text Ó A.P. Avdeenko, S.A. Konovalova, O.N. Ludchenko, 2006, published in Zhurnal Organicheskoi Khimii, 2006, Vol. 42,
No. 5, pp. 702-707.
Halogenation of N-Substituted para-Quinone Monoimine
and para-Quinone Monooxime Esters: VI.* Regular Trends
in Chlorination and Bromination
of N-Arylsulfonyl-1,4-benzoquinone Monoimines
Alkyl-Substituted in the Quinoid Ring
A.P.Avdeenko, S.A. Konovalova, and O.N. Ludchenko
Donbass State Machine Building Academy, Kramatorsk, 84313 Ukraine
e-mail: chimist@dgma.donetsk.ua
Received November 23, 2004
Abstract—Reactions of halogens with N-arylsulfonyl-1,4-benzoquinone monoimines occur with the formation
of a halogenonium ion that either transforms into a carbocation where the first halogen atom adds to the carbon
in the ortho-position relative to the carbonyl carbon, or the halogenonium ion adds directly the second halogen
atom.
DOI: 10.1134/S107042800605006X
This research continues the investigation of the
halogenation processes of N-arylsulfonyl-1,4-benzo-
quinone monoimines alkyl-substituted in the quinoid ring.
In the preceding publications of this series [1–3] the
features of the halogenation of various N-aroyl(aryl-
sulfonyl)oximino-2,5-cyclohexadien-1-ones and N-aryl-
sulfonyl-1,4-benzoquinone monoimines were considered,
the main reaction paths and regularities were revealed.
conditions the halogenation of quinone imines Ia and Ib
gave rise mainly to stable 4-arylsulfonylimino-5,6-dihalo-
2,3-dimethyl-2-cyclohexen-1-ones IIa, IIb, IIIa, and
IIIb, and only at the bromination in CHCl3 N-phenyl-
sulfonyl-4-amino-6-bromo-2,3-dimethylphenol (IV) was
isolated (Scheme 1).
The chlorination of 4-arylsulfonylamido-2,3-dimethyl-
phenols Va and Vb depending on the experimental
As the last object for the study in this series we
selected N-arylsulfonyl-2,3-dimethyl-1,4-benzoquinone
monoimines Ia and Ib in order to establish finally the
halogenation mechanism of N-arylsulfonyl-1,4-benzo-
quinone monoimines. Similarly to N-arylsulfonyl-3-methyl-
1,4-benzoquinone monoimines [3] quinone imines Ia and
Ib exist in solution in the form of a single isomer but to
the anti-bond C=C of the quinoid ring in these compounds
one more substituent, Me group, is attached, even more
increasing the steric hindrance to the halogen addition
across this bond. Therefore the halogen addition should
occur strictly regiospecifically at the C=C bond of the
quinoid ring lacking substituents.
Scheme 1.
Hr
C
Hr
Cyt
6ꢀTP I
P
Cyt
Hr
Hr
Cyt
C
,, ꢀꢁ,,Eꢀꢁ,,, ꢀꢁ,,,E
6ꢀTP I
P
Hr
Hr
,Dꢀꢁ,E
7ꢀ
QuTP IC
PC
8C8y
The halogenation of quinone imines Ia and Ib was
performed in various solvents (CHCl3, CH3CO2H,
CH3CO2H–DMF mixture, 5:1), and at different ratios
quinone imine I–halogen. Depending on the experimental
7ꢀ
,9
Ar = Ph (a), 4-MeC6H4 (b); Hlg = Cl (II), Br (III).
* For communication V, see [1].
683

AVDEENKO et al.
684
Scheme 2.
+OJ
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,, ꢀꢁ,,Eꢀꢁ,,, ꢀꢁ,,,E
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Ar = Ph (a), 4-MeC6H4 (b); Hlg = Cl (VI, VIII), Br (IV, IX).
The bromination of aminophenols Va and Vb in CHCl3
or CH3CO2H yielded only aminophenol IV, in the mixture
DMF–CH3CO2H, 1:5, at the ratio initial compound–
bromine 1:1 formed aminophenol VI; and at the ratio 1:5
compounds of cyclohexene structure IIIa and IIIb were
obtained. The structure of aminophenols IV and VI was
confirmed by the 1H NMR spectra recorded after oxida-
tion of the aminophenols to the corresponding quinone
imines VIII and IX for the 1H NMR spectra of the latter
were more informative. The signal from the H5 atom of
quinone imines VIII and IX is observed in the spectra as
a singlet in a downfield region characteristic of hydrogen
atoms in the ortho-position with respect to the imine
carbon.
conditions afforded 4-arylsulfonylimino-2,3-dimethyl-5,6-
dichloro-2-cyclohexen-1-ones IIa and IIb, 4-phenylsul-
fonylamido-2,3-dimethyl-6-chlorophenol (VI), and 4-aryl-
sulfonylimino-5,6-dimethyl-2,5,6-trichloro-2-cyclohexen-
1-ones VIIa and VIIb (Scheme 2).
Aminophenol VI was obtained only in chloroform at
the ratio substrate Va–chlorine 1:1. In this case the
electrophilic substitution is likely to occur (the chlorine
enters into the meta-position with respect to the most
electron-withdrawing group). Then under the action of
the second chlorine molecule aminophenol VI is oxidized
to give quinone imine VIII, and the next chlorine molecule
adds to form a compound of cyclohexene structure VIIa.
The latter stage was proved by an independent synthesis,
the chlorination of quinone imine VIII. Compound VIII
was obtained by oxidation of aminophenol VI with lead
tetraacetate. In the same way was synthesized quinone
imine IX.
The structure of aminophenols IV and VI was
confirmed by their independent synthesis by hydrohalo-
genation of quinone imines I. The compounds obtained
were identical to aminophenols IV and VI prepared by
the halogenation.
In CH3CO2H and the mixture DMF–CH3CO2H, 1:5,
the aminophenols Va and Vb are oxidized with chlorine
to the corresponding quinone imines, add a single chlorine
molecule forming compounds of cyclohexene structure
IIa and IIb (which were isolated at the ratios initial
susbtance–chlorine 1:1, 1:2), eliminate an HCl molecule,
and add the second molecule of Cl2 furnishing compounds
VIIa and VIIb. This scheme is supported by the fact,
that the reduced form VI is not isolated in the reactions
carried out in CH3CO2H and the mixture DMF–
CH3CO2H, 1:5.
In order to prove the last stages of the chlorination
and to obtain products with a higher extent of the bromina-
tion we performed the halogenation of aminophenols IV
and VI, and quinone imines VIII and IX (Scheme 3).
We succeeded to obtain by bromination of aminophenol
IV a compound of cyclohexene structure X which we
failed to isolated at the bromination of aminophenol Va.
The halogenation of quinone imines VIII and IX
provided mixtures of compounds VIIa, XI and X, XII
respectively. Thus the halogen molecule added both at
RUSSIAN JOURNAL OF ORGANI C CHEMISTRY Vol. 42 No. 5 2006

HALOGENATION OF N-SUBSTITUTED para-QUINONE MONOIMINE:VI.
685
Scheme 3.
the C=C linked to a halogen atom and to the C=C bond
with two methyl substituents notwithstanding the steric
hindrances (Scheme 3).
Hr Cyt
Cyt
Hr
Cyt
Calculations by PM3 method show that in quinone
imine Ia the bond C5=C6 is less polarized and therefore
more active (see the table), and at the same time as in
the case of N-arylsulfonyl-3-methyl-1,4-benzoquinone
monoimines [3] it is more sterically accessible. Hence
the steric and electronic factors operate in the same
direction, and therefore the halogen addition products
obtained from quinone imines I resulted from the reaction
only at the C5=C6 bond. In quinone imine VIII the
difference in polarization of the C2=C3 and C5=C6 bonds
is less pronounced (see the table), and besides a sub-
stituent, chlorine atom, is attached to the C5=C6 bond.
Accordingly the chlorination of quinone imine VIII gave
rise to products of chlorine addition to either of the C=C
bonds of the quinoid ring, compounds VII and XI.
,9ꢀꢁ9,
QuTP I
P
Cyt
9,, ꢀꢁ;
Hr Hr
Cyt
9,,,ꢀꢁ,;
QuTP I
P
C
Cyt
CytCyt
;,ꢀꢁ;,,
Hlg = Cl (VII, XI), Br (X, XII).
stability of the cyclohexene structures arising from the
halogen addition to the C=C bond of the quinoid ring
depends on the configurational stability of the nitrogen
atom: the configurationally rigid compounds are stable,
the configurationally labile, unstable. A firm stage
sequence of the halogen addition to p-benzoquinone
monoimines was established. The cyclohexene structures,
products of a single halogen molecule addition to the C=C
bond of the quinoid ring, were isolated for the first time.
Depending on the nature of the solvent these structures
may undergo either a prototropic rearrangement into an
aminophenol, or they suffer a regioselective dehydrohalo-
genation affording two quinone imines. Aminophenols
obtained as a result of the prototropic rearrangements
are oxidized with a halogen molecule followed by
a halogen or a hydrogen halide molecule addition, and
the quinone imines either add a halogen molecule with
subsequent dehydrohalogenation etc., or add a hydrogen
halide molecule and further are oxidized by a halogen
molecule etc. The reaction of N-arylsulfonyl-4-amino-
phenols with halogens occurs either as an electrophilic
substitution or the initial aminophenol is oxidized into
quinone imine. Further transformations are similar to those
described above.
The composition and structure of compounds syn-
thesized were proved by elemental analysis, IR, 1H and
13C NMR spectra. The 1H NMR spectra were registered
only for compounds of the quinoid and cyclohexene
structure since they were more informative. To confirm
the structures of compounds IIa and VIIa we recorded
their 13C NMR spectra.
Thus based on experiments reported here and in
[1–3] the following regular trends can be formulated for
the halogens reactions with N-arylsulfonyl-1,4-benzo-
quinone monoimines. para-Benzoquinone monoimines
existing as a single isomer due to steric hindrance to the
nitrogen inversion add a halogen molecule predominantly
to the syn-bond C=C of the quinoid ring; introduction to
this bond of a bulky substituent (i-Pr group) does not
block the reaction across the bond. Nonsymmetrically
substituted p-benzoquinone monoimines where inversion
of the nitrogen occurs add the halogen atm regio-
specifically exclusively to the less sterically hindered C=C
bond of the quinoid ring. Introduction of substituents of
different character (donors or acceptors) into the quinoid
ring of the p-benzoquinone monoimines where the
nitrogen atom undergoes inversion results in the halogen
addition to the bond linked to a donor substituent. The
To elucidate the halogenation mechanism of N-aryl-
sulfonyl-1,4-benzoquinone monoimines we carried out the
bromination of quinone imine Ia in the presence of LiCl.
Atomic charges (q, e.u.) on C2, C3, C5, and C6 of quinoid ring in quinone imines Ia and VIII calculated by PM3 method
&RPSGꢀꢁQRꢀꢁ
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aDq = |qC2 – qC3|; bDq = |qC5 – qC6|; cDq = Dq – Dq .
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RUSSIAN JOURNAL OF ORGANI C CHEMISTRY Vol. 42 No. 5 2006

AVDEENKO et al.
(('ꢂ ꢅꢄxEꢃ€‚y
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686
Scheme 4.
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The resulting product was a mixture of isomers IIIa and
XIII (Scheme 4).
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The structure of compounds obtained was established
from the 1H NMR spectra considering the chemical shifts
of atoms H5 and H6 in 6-bromo-2,3-dimethyl-4-phenyl-
sulfonylimino-5-chloro-2-cyclohexen-1-one (XIII) as
compared to those in the spectra of 5,6-dibromo-2,3-
dimethyl-4-phenylsulfonylimino-2-cyclohexen-1-one
(IIIa) and 2,3-dimethyl-4-phenyl-sulfonylimino-5,6-
dichloro-2-cyclohexen-1-one (IIa). The ratio of com-
pounds IIIa and XIII in the mixture obtained was in the
range 45:55.
Energy diagram of the bromination process of N-phenyl-
sulfonyl-1,4-benzoquinone monoimine (XIV) in the presence
–
of Cl ions.
We carried out by the PM3 procedure the geometry
optimization for the above ions of N-phenylsulfonyl-1,4-
benzoquinone monoimine (XIV). Bromonium ion A1 with
a bromine atom attached to the syn-bond C=C of the
quinoid ring has a lower enthalpy of formation than
bromonium ion A2 with a bromine atom added to the anti-
bond C=C with respect to the substituent at the nitrogen;
thus bromonium ion A1 is more energetically feasible (see
the figure). This result is well consistent with the
experiment: The halogen addition occurs mainly at the
the syn-bond C=C of the quinoid ring.
Thus at the bromination of quinone imine Ia in the
–
presence of Cl ions the main reaction product is the
cyclohexene structure containing a chlorine atom at the
C5 (ortho-position relative to the imine carbon atom) and
a bromine atom at C6 (ortho-position with respect to the
carbonyl carbon). In bromination of p-benzoquinone
monooximes esters in the presence of LiCl a cyclohexene
structure was obtained with a bromine atom at C5 (ortho-
position with respect to oximine carbom atom) and a
chlorine atom attached to C6 (ortho-position with respect
to the carbonyl carbon) [2].
The optimization of bromonium ion A finally leads to
cation B. The comparison of enthalpy of formation for
cations A–C demonstrated that from the energy viewpoint
carbocation B is the most favorable (see the figure),
and its structure corresponds to that of the final reaction
product.
According to the classical theory of a bromine molecule
addition to a C=C bond a p-complex forms in the first
stage transforming into a bromonium ion A. Then depend-
ing on the reaction conditions this ion either directly reacts
with a bromide anion or initially converts into cation B or
C that in its turn adds the bromide anion.
Therefore the experimental data and calculations
suggest, that the bromination of benzoquinone monoimines
presumable proceeds via bromonium ion A subsequently
transforming into cation B that has the smallest enthalpy
of formation among the ions considered, or exclusively
through bromonium ion A not involving other cations,
namely, along the most energetically favorable pathway
7ꢀ
–
(see the figure). The intermediate structure D (Cl ion
I
P
attached to the bromonium ion) posseses the smallest
enthalpy of formation among the species considered. The
optimization of intermediate structure D (cis-
configuration) gives finally compound E.
I
P
QuTP
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QuTP
C
C
C
C
%
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The least possible route is the bromination through
intermediate cation C for its enthalpy of formation is the
largest, and compound F that should have formed in this
case as a result of bromination was not isolated.
I
P
QuTP
C
7ꢀ C
&
RUSSIAN JOURNAL OF ORGANI C CHEMISTRY Vol. 42 No. 5 2006

HALOGENATION OF N-SUBSTITUTED para-QUINONE MONOIMINE:VI.
687
EXPERIMENTAL
H6) 3.3 Hz], 7.37–7.94 d.d (4H b Ts), 2.47 s (3H, Me,
Ts). Found, %: Cl 19.28, 19.36. C15H15Cl2NO3S.
Calculated, %: Cl 19.68.
IR spectra were recorded on a spectrophotometer
UR-20 from KBr pellets. 1H and 13C were registered on
a spectrometer Varian VXR-300 (1H 300, 13C 75.4 MHz)
in CDCl3 relative to TMS.
2,3-Dimethyl-4-phenylsulfonylamido-6-chloro-
phenol (VI). Yield 68%, mp 198–199°C. Found, %:
Cl 11.39, 11.43. C14H14ClNO3S. Calculated, %: Cl 11.37.
The reaction mixtures were analyzed by TLC on Silufol
UV-254 plates (eluent benzene–ethyl acetate, 10:1,
development under UV irradiation).
5,6-Dimethyl-4-phenylsulfonylimino-2,5,6-
trichloro-2-cyclohexen-1-one (VIIa). Yield 75%, mp
117–118°C. 1H NMR spectrum, d, ppm: 1.88 s (3H, Me6),
1.98 s (3H, Me5), 8.34 s (1H, H3), 7.57–8.03 m (5H,
Ph). 13C NMR spectrum, d, ppm: 19.55 (Me3), 20.94
(Me2), 70.44 (C3), 72.93 (C2), 128.74 (C5), 141.77 (C6),
167.24 (C4), 181.66 (C1). Found, %: Cl 28.10, 28.15.
C14H12Cl3NO3S. Calculated, %: Cl 27.94.
Quinone imines Ia, Ib and aminophenols Va, Vb
were synthesized by procedures from [4]. Recrystal-
lization from CH3CO2H. Yield of compound Ia 87%,
mp 97–99°C. Found, %: N 4.95, 5.02. C14H13NO3S.
Calculated, %: N 5.09. Yield of compound Ib 84%,
mp 86–88°C. Found, %: N 4.82, 4.91. C15H15NO3S.
Calculated, %: N 4.84. Yield of compound Va 92%,
mp 206–207°C. Found, %: N 4.97, 5.07. C14H15NO3S.
Calculated, %: N 5.05. Yield of compound Vb 88%, mp
212–214°C. Found, %: N 4.75, 4.87. C15H17NO3S.
5,6-Dimethyl-4-tosylimino-2,5,6-trichloro-2-
cyclohexen-1-one (VIIb). Yield 82%, mp 132–133°C.
1H NMR spectrum, d, ppm: 1.87 s (3H, Me6), 1.97 s
(3H, Me5), 8.35 s (1H, H3), 7.37–7.94 d.d (4H, Ts),
2.47 s (3H, Me, Ts). Found, %: Cl 27.02, 27.10.
C15H14Cl3NO3S. Calculated, %: Cl 26.95.
1
Calculated, %: N 4.81. H NMR spectra, d, ppm: Ia:
2.06 br.s (3H, Me3), 2.05 br.s (3H, Me2), 6.64 d (1H,
H6), 8.14 d [1H, H5, J(H5, H6) 10.2 Hz], 7.56–8.04 m
(5H, Ph); Ib: 2.04 br.s (3H, Me2), 2.05 br.s (3H, Me3),
6.62 d (1H, H6), 8.15 d [1H, H5, J(H5, H6) 10.5 Hz],
2.47 s (3H, Me b Ts), 7.36–7.92 d.d (4H, Ts).
2,3-Dimethyl-N-phenylsulfonyl-6-chloro-1,4-
benzoquinone monoimine (VIII). Yield 68%, mp 127–
1
128°C. H NMR spectrum, d, ppm: 2.05 q (3H, Me2),
2.12 q (3H, Me3), 8.37 s (1H, H5), 7.57–8.04 m (5H,
Ph). Found, %: Cl 11.40, 11.45. C14H12ClNO3S.
Calculated, %: Cl 11.44.
Chlorination of quinone imines Ia, Ib, VIII, and
aminophenols Va, Vb, VI. Through a solution of 2 mmol
of compound Ia, Ib, Va, Vb, VI, or VIII in 3 ml of
CHCl3, CH3CO2H, DMF, or a mixture DMF–CH3CO2H,
1:5, was passed a stream of dry chlorine at a rate 15–20
ml/min at 25–30°C. The ratio initial substance–chlorine
was controlled by the weight gain, and it was varied in
the range 1:1–1:3. In several hours the reaction products
were filtered off. All compounds obtained were
recrystallized from acetic acid.
2,3-Dimethyl-4-phenylsulfonylimino-5,6,6-
trichloro-2-cyclohexen-1-one (XI). 1H NMR
spectrum, d, ppm: 2.07 d (3H, Me2), 2.17 d (3H, Me3),
6.61 s (1H, H5), 7.57–8.06 m (5H in Ph).
Bromination of quinone imines Ia, Ib, IX, and
aminophenol IV, Va, Vb. To a solution of 2 mmol of
compound Ia, Ib, IV, Va, Vb, or IX in 3 ml of CHCl3,
CH3CO2H, DMF, DMF–CH3CO2H, 1:5, was added
dropwise at stirring a solution of bromine in the
appropriate solvent to the desired ratio initial compound–
bromine (1:1, 1:3, 1:5, 1:8). The reaction products obtained
in several hours were filtered off, washed with acetic
acid, and recrystallized from acetic acid.
2,3-Dimethyl-4-phenylsulfonylimino-5,6-di-
chloro-2-cyclohexen-1-one (IIa). Yield 85%, mp 156–
157°C. H NMR spectrum, d, ppm: 2.07 br.s (3H, Me2),
2.10 br.s (3H, Me3), 4.58 d (1H, H6), 6.32 d [1H, H5,
J(H5,H6) 3.3 Hz], 7.56–8.06 m (5H, Ph). 13C NMR
spectrum, d, ppm: 13.71 (Me3), 15.75 (Me2), 50.79 (C5),
55.14 (C6), 141.54 (C2), 144.05 (C3), 168.41 (C4), 187.11
(C1). Found, %: Cl 20.40, 20.55. C14H13Cl2NO3S.
Calculated, %: Cl 20.48.
1
5,6-Dibromo-2,3-dimethyl-4-phenylsulfonyl-
imino-2-cyclohexen-1-one (IIIa). Yield 75%, mp 138–
1
139°C. H NMR spectrum, d, ppm: 2.07 br.s (3H, Me2),
2.11 br.s (3H, Me3), 4.76 d (1H, H6), 6.43 d [1H, H5,
J(H5, H6) 3.3 Hz], 7.56–8.06 m (5H, Ph). Found, %: Br
36.83, 36.94. C14H13Br2NO3S. Calculated, %: Br 36.73.
2,3-Dimethyl-4-tosylimino-5,6-dichloro-2-
cyclohexen-1-one (IIb). Yield 80%, mp 107–108°C.
1H NMR spectrum, d, ppm: 2.06 br.s (3H, Me2), 2.09
br.s (3H, Me3), 4.57 d (1H, H6), 6.34 d [1H, H5, J(H5,
5,6-Dibromo-2,3-dimethyl-4-tosylsulfonylimino-
2-cyclohexen-1-one (IIIb). Yield 81%, mp 127–128°C.
RUSSIAN JOURNAL OF ORGANI C CHEMISTRY Vol. 42 No. 5 2006

AVDEENKO et al.
688
1H NMR spectrum, d, ppm: 2.06 br.s (3H,Me2), 2.10 br.s
(3H, Me3), 4.76 d (1H, H6), 6.45 d [1H, H5, J(H5, H6)
3.6 Hz], 7.36–7.95 d.d (4H, Ts), 2.47 s (3H, Me, Ts).
Found, %: Br 35.48, 35.55. C15H15Br2NO3S. Calculated,
%: Br 35.58.
REFERENCES
1. Avdeenko, A.P. and Konovalova, S.A., Zh. Org. Khim., 2006,
vol. 42, p. 669
2. Avdeenko, A.P. and Konovalova, S.A., Il’chenko,A.Ya., and
Glinyanaya, N.M., Zh. Org. Khim., 2006, vol. 42, p. 64.
3. Avdeenko,A.P. and Konovalova, S.A., Zh. Org. Khim., 2006,
vol. 42, p. 364.
6-Bromo-2,3-dimethyl-4-phenylsulfonyl-
amidophenol (IV). Yield 90%, mp 200–201°C. Found,
%: Br 22.45, 22.54. C14H14BrNO3S. Calculated, %:
Br 22.43.
4. Burmistrov, S.I. and Titov, E.A., Zh. Obshch. Khim., 1952,
vol. 22, p. 999.
6-Bromo-2,3-dimethyl-N-phenylsulfonyl-1,4-
benzoquinone monoimine (IX). Yield 67%, mp 127–
128°C.
5. Adams, R. and Reifschneider, W., Bull. Soc. Chim., 1958,
p. 23;Adams, R. and Blomstrom, D., J. Am. Chem. Soc., 1953,
vol. 75, p. 3405.
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