Photooxygenolysis of 3,6-di-tert-butyl-o-benzoquinone

Article abstract of DOI:10.1134/S1070428002120114

The photolysis of 3,6- and 3,5-di-tert-butyl-o-benzoquinones in benzene (λ > 380 nm, inert atmosphere) involves decarbonylation of the compounds to furnish respectively 2,5- and 2,4-di-tert-butylcyclopentadienones. The 2,5-isomer is stable, and the 2,4-di

Full text of DOI:10.1134/S1070428002120114

ISSN 1070-4280 Russian Journal of Organic Chemistry, 2006, Vol. 42, No. 2, pp. 227-229. Ó Pleiades Publishing, Inc. 2006.
Original Russian Text Ó V.B. Vol’eva, I.S. Belostotskaya, N.L. Komissarova, Z.A. Starikova, L.N. Kurkovskaya, 2006, published in Zhurnal
Organicheskoi Khimii, 2006, Vol. 42, no. 2, pp. 243-245.
Photooxygenolysis of 3,6-Di-tert-butyl-o-benzoquinone
V.B. Vol’eva, I.S. Belostotskaya, N.L. Komissarova, Z.A. Starikova, and L.N. Kurkovskaya
Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119991 Russia
e-mail: komissarova@polymer.chph.ras.ru
Received January 8, 2005
Abstract—The photolysis of 3,6- and 3,5-di-tert-butyl-o-benzoquinones in benzene (l > 380 nm, inert atmosphere)
involves decarbonylation of the compounds to furnish respectively 2,5- and 2,4-di-tert-butylcyclopentadienones.
The 2,5-isomer is stable, and the 2,4-di-tert-butylcyclopentadienone suffers a conversion into a Diels–Alder
adduct. The participation of oxygen inhibited the decarbonylation and changed the directon of the photolysis:
Here the products of the 3,5-di-tert-butyl-o-benzoquinones conversion were a di-tert-butylmuconic anhydride
and dipivalylethylene. It was concluded that a singlet oxygen was involved in the process which formed by
3
a triplet-triplet annihilation at the interaction of O with a triplet-excited initial quinone.
2
DOI: 10.1134/S1070428002120114
3
,6-Di-tert-butyl-o-benzoquinone (I) irradiated with
lived compound and even in the course of isolation it
transforms into a Diels–Alder dimer, 2,3a,5,7-tetra-tert-
butyl-3a,4,7,7a-tetrahydro-4,7-methanoindene-1,8-dione
(V). The latter process can be visually observed by the
disappearance of the characteristic orange-red cyclo-
pentadienone color.
light in the visible region (l > 380 nm) in the absence of
oxygen in benzene or hexane solution suffered a photo-
transformation uncommon for quinones: a decarbonyla-
tion affording 2,5-di-tert-butylcyclopentadienone (II), the
first example of a stable monomeric dialkyl-substituted
cyclopentadienone [1].
Dienone II sterically protected from the dimerization
of the [4+2]-cycloaddition type is capable to react as
a diene with less hindered dienophiles. For instance, in
the photolysis of quinone I in the presence of maleic
anhydride we isolated 1,8-di-tert-butyl-4-oxatricyclo-
%
XꢀW
%
XꢀW
2
2
2
KQ
&
2
*
*
[
5.2.1.0 2,6 ]-dec-8-ene-3,5,10-trione (VI).
%XꢀW
%
XꢀW
,
,,
%
&
%
XꢀW
2
2
The isomer 3,5-di-tert-butyl-o-benzoquinone (III)
reacts in the same fashion, but its decarbonylation product
,4-di-tert-butylcyclopentadienone (IV) is a short-
KQ
,
,
2
2
2
2
%XꢀW
2
2
%
XꢀW
XꢀW
2
2
9,
KQ
2
&
2
In photolysis carried out in the presence of oxygen the
formation of 1,2-dipivaloylethylene (VII) was observed
Wꢀ%X
Wꢀ%X
XꢀW
,,,
,9
%XꢀW
%
Wꢀ%X
2
,,
2
&2
Wꢀ%X & +& &+ & %XꢀW
&2
2
&2
%
XꢀW
2
2
%
XꢀW 2
%XꢀW
,,,
9
9,,
9
227

228
VOL’EVAet al.
1
whose precursor was a cyclic peroxide VIII, an adduct
of dienone II with oxygen.
compounds with O and of the nonradical reactions of
2
the same organic compounds with peroxides.
3
This process is a full analog of the reaction of 2,5-di-
phenylcyclopentadienone with a singlet oxygen that is used
as one among chemical tests for the singlet oxygen [2].
Apparently quinone I being indifferent to O but
2
1
capable to add O can be used as chemical indicator
for O along with cyclopentadienones. The ability of
quinone I to react with O combined with the high anti-
oxidant activity of the redox-conjugate 3,6-di-tert-butyl-
pyrocatechol (X) [5] permits an assignment of the redox-
couple pyrocatechol–quinone to the series of “universal”
antioxidants.
2
1
2
1
2
3
K
2
&2
2
2
3K
3K
2
3
K
EXPERIMENTAL
IR spectra were recorded on a spectrophotometer
Specord M-80 from KBr pellets, H NMR spectra were
3
K
& +& &+ & 3K
1
&2
2
2
registered on a spectrometer WH-250 (250 MHz), internal
reference TMS. Crystals of alkene VII were studied by
X-ray diffraction method. Colorless plates C H O
The data on the structure of compound VII are
presented on the figure.
1
2
20
2
In our case dienone II turned out to be an indicator of
a singlet oxygen formed in situ. The most probable
mechanism of its generation is a triplet-triplet annihilation
(M 196.28), triclinic, at 110 K a 5.609(6), b 5.933(6),
°
c 9.863(10) A, a 79.98(2), b 78.93(2), g 64.37(2)°,
°
3
3
V 288.9(5) A , space group P-1, Z 2, C 1.128 g/cm .
calc
3
at the interaction of O with a triplet-excited quinone
The experimental set of 2499 reflections was obtained
with diffractometer Bruker SMART CCD area detector
[7] at 110 K (lMoK -radiation, 2q 46°) from a single
2
3
3
1
[
3]: (I) + O ’ (I) + O . The quenching of quinone
2 0 2
triplets in this process with the simultaneous decrease in
the yield of the decarbonylation products (sum of
compounds II and VII) makes it possible to identify the
excited state of the quinone responsible for the
decarbonylation as a triplet state.
a
max
crystal of the size 0.30´0.15´0.05 mm. After averaging
the equivalent reflections we obtained 1027 independent
reflections (R 0.0972) used in solving and refining of
int
–1
the structure. The extinction (m 0.075 mm ) was not taken
into account, the values Tmax and Tmin (0.928 and
The participation of oxygen inhibits the decarbonylation
and changes the direction of the photoprocess. The main
pathway becomes photooxygenolysis giving as products
the above-mentioned 1,2-dipivaloylethylene (VII) and di-
tert-butylmuconic anhydride (IX), the prevailing product
0
.676 respectively ) were estimated using SADABS
routine [8]. The structure was solved by the direct
method, all the nonhydrogen atoms were localized in the
difference synthesis of the electron density and refined
by F2 in the anisotropic approximation; all hydrogen
1
hkl
arising from the reaction of O with quinone I.
2
atoms were placed into the geometrically calculated
positions and refined in the rider model with U(H) =
This reaction in comparison with the formation of
anhydride IX from quinone I and PhCO H or H O in
3
2
2
1
.2 U(C) where U(C) is the equivalent thermal factor of
acid medium supports the conclusion of Denny and Nickon
the carbon linked to the corresponding hydrogen atom.
The final values of the uncertainty factors are as follows:
R 0.0551 [calculated by F for 278 reflections with
[4] on similarity of oxidation results of certain organic
1
hkl
2
I >2s(I)], wR 0.0645 (calculated by F
for all 1027
2
hkl
ꢀ
ꢀ
2
reflections), GOOF 0.756.66 of refined parameter.
ꢀ
&
All calculations were carried out applying the software
package SHELXTL PLUS 5 [9].
ꢀ
ꢀ
&
ꢀ
&
ꢀ
&
ꢀ
&
ꢀ
&
ꢀ
&
ꢀ
&
ꢀ
ꢀ
ꢀ
&
&
3,6-Di-tert-butyl-o-benzoquinone (I) was prepared by
&
2
oxidation of pyrocatechol (X) with Ag O in ethyl ether
2
as described in [6].
Photolysis of 3,6-di-tert-butyl-o-benzoquinone (I)
under nitrogen atmosphere. A solution of 0.22 g of
quinone I in 20 ml of benzene was irradiated with light
Structure of 1,2-dipivaloylethylene (VII).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 42 No. 2 2006

PHOTOOXYGENOLYSIS OF 3,6-DI-tert-BUTYL-o-BENZOQUINONE
229
*
*
(
l > 380 nm) at room temperature under a nitrogen
1,8-Di-tert-butyl-4-oxatricyclo[5.2.1.0 2,6 ]-dec-
atmosphere till disappearance of quinone I traces. On
removing the solvent the crystalline residue was purified
by sublimation. We obtained 0.17 g (89%) of compound
8-ene-3,5,10-trione (VI). A mixture of 0.22 g of
quinone I and 0.1 g of maleic anhydride in 20 ml of
anhydrous benzene was irradiated under nitrogen atmo-
sphere till the quinone color disappeared. On evaporating
the solvent and crystallization of the residue from hexane
we obtained 0.23 g (81%) of adduct VI, mp 153–154°C.
–
1
II, mp 59–60°C. IR spectrum, n, cm : 1720 (C=O), 1590
1
(
(
C=C). H NMR spectrum, d, ppm: 1.06 s (9H), 6.21 s
1H). Found, %: C 81.16; H 10.46. C H O. Calculated,
1
3
20
%
: C 81.17; H 10.48.
1
H NMR spectrum, d, ppm: 1.00 s (9H), 2.92 s (1H),
Photolysis of 3,6-di-tert-butyl-o-benzoquinone (I)
5.34 s (1H). Found, %: C 70.10; H 7.88. C H O .
1
7
22
4
in the presence of atmospheric oxygen. The photho-
lysis of 0.22 g of quinone I was performed as described
above but at access of air. The chromatographic analysis
revealed the presence in the reaction mixture of a multi-
tude of products. We isolated preparatively 20 mg (10%)
of 1,2-dipivaloylethylene (VII) and 50 mg (20%) of di-
tert-butylmuconic anhydride (IX). Compound VII,
Calculated, %: C 70.34; H 7.64.
Adduct VI was also obtained by an independent
synthesis by boiling equimolar amounts of cyclopenta-
dienone II and maleic anhydride in benzene for 2 h.
REFERENCES
1
1. Vol’eva, V.B., Ershov, V.V., Belostotskaya, I.S., and
Komissarova, N.L., Izv. Akad. Nauk SSSR,Ser.Khim., 1974,
vol. 3, p. 739.
2. Einfuhrung in die Photochemie, Becker, H.G.O., Ed., Berlin:
Wissenschaften, 1976. Translated under the title Vvedenie
v fotokhimiyu organicheskikh soedinenii, Leningrad:
Khimiya, 1976.
mp 108–109°C (after sublimation). H NMR spectrum,
d, ppm: 1.4 s (9H), 7.1 s (1H). Found, %: C73.55; H 10.25.
C H O . Calculated, %: C 73.40; H 10.25. Anhydride
1
2
20
2
1
IX, mp 100–101°C. H NMR spectrum, d, ppm: 1.24 s
9H), 6.37 s (1H). Found, %: C 70.81; H 8.29. C H O .
(
14 20 3
Calculated, %: C 71.10; H 8.54.
Anhydride IX was also prepared by an independent
3. Barltrop, J.A. and Coyle, J.D., Excited States in Organic
synthesis by reacting quinone I with PhCO H at boiling
3
Chemistry, London: Wiley, 1975.
in benzene; it was isolated by TLC on Silufol UV-254
plates in a system hexane–ethyl ether, 4:1, v/v, yield 25%,
mp 100–101°C , the mixed sample of compound IX
prepared by both procedures melted without depression
of the melting point.
4. Denny, R.W. and Nickon,A., Org. Reactions., 1973, vol. 20,
p. 133.
5. Mazaletskaya, L.I., Karpukhina, G.V., Komissarova, N.L.,
and Belostotskaya, I.S., Izv.Akad.NaukSSSR,Ser.Khim.,
1982, vol. 3, p. 505.
Photolysis of 3,5-di-tert-butyl-o-benzoquinone
6. Komissarova, N.L., Belostotskaya, I.S., Dzhuaryan, E.V.,
(III). The photolysis conditions were similar to those
and Ershov, V.V., Izv.Akad.NaukSSSR,Ser.Khim., 1973,
vol. 6, p. 1380.
described above. On evaporation of benzene we obtained
colorless crystals of 2,3a,5,7-tetra-tert-butyl-3a,4,7,7a-
tetrahydro-4,7-methanoindene-1,8-dione (V), mp 150–
7. Bruker (1998b). SMART. Bruker Molecular Analysis
Research Tool. V. 5.059, Madison: Bruker, AXS.
1
1
0
(
51°C (from methanol). H NMR spectrum, d, ppm:
8
. Sheldrick, G.M., 1998a, SADABS, V. 2.01, Bruker/Siemens
Area Detector Absorption Correction Program, Madison:
Bruker,AXS.
.98 s (9H), 1.05 s (9H), 1.14 s (9H), 1.19 s (9H), 2.96 s
1H), 3.18 d (1H, J 1.1 Hz), 5.89 d (1H, J 1.1 Hz),
4
4
6
.77 s (1H). Found, %: C 81.51; H 10.50. C H O .
9. Sheldrick, G.M., 1998b. SHELXTL, V. 5.10, Structure
Determination Software Suite, Madison: Bruker, AXS.
2
6
40
2
Calculated, %: C 81.17; H 10.48.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 42 No. 2 2006