Mendeleev
Communications
Mendeleev Commun., 2017, 27, 371–373
Chemiluminescence in decomposition of bridged
1,2,4,5-tetraoxanes catalyzed by ferrocene
a
a
b
c
Dim I. Galimov,* Dilara R. Gazeeva, Ramil G. Bulgakov and Alexander O. Terent’ev
a
b
c
Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, 450075 Ufa, Russian Federation.
Fax: +7 347 284 2750; e-mail: galimovdi@mail.ru
Institute of Molecule and Crystal Physics, Ufa Scientific Centre of the Russian Academy of Sciences,
4
50054 Ufa, Russian Federation. Fax: +7 347 292 1417; e-mail: profbulgakov@yandex.ru
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow,
Russian Federation. Fax: +7 499 135 5328; e-mail: terentev@ioc.ac.ru
DOI: 10.1016/j.mencom.2017.07.016
Chemiluminescence was observed in ferrocene-catalyzed
decomposition of bridged 1,2,4,5-tetraoxanes, namely,
Me
Me
+ Cp2Fe
Cp2Fe
O
O
O
O
O
O
–
2,3,5,6-tetraoxabicyclo[2.2.1]heptanes. The chemi- and photo-
O
O
O
O
chemi-
luminescence
Me
Me +
luminescence spectra revealed the main products and lumine-
scence emitters to be b-diketones. The reaction intermediate,
the OOH radical, was found to catalyze the decomposition
of the 1,2,4,5-tetraoxanes.
Me
+ HO2
O2
Me
–
R
R
R
R = CH2CO2Et, (CH2)4Me, CH2CN, Ph, CH2CO2H
The chemiluminescence (CL) method is a highly informative
and convenient tool for studying the mechanisms and kinetics of
reactions of various peroxides, viz., organic peroxides, including
in the presence of Cp Fe is a catalytic process. In fact, according
2
–3
to iodometric titration data, reactions of TOX (10 mmol dm ) with
–3
even small amounts of ferrocene ([Cp Fe] = 0.05–1 mmol dm )
2
0
1–3
4
dioxetanes, and organometallic peroxides. 1,2,4,5-Tetraoxanes
TOXs) containing two peroxy groups in the six-membered hetero-
result in nearly complete (³95%) TOX decomposition in 2 h at
(
348 K in O atmosphere. The conversion in thermal decomposi-
2
cycle possess a broad spectrum of biological activity, including
antimalarial and antihelmintic ones, and among peroxides they are
tion of these TOXs under similar conditions does not exceed 8%.
5
Discovery of the catalytic action of Cp Fe appears important
2
ii/iii
most promising for practical purpose. Despite the considerable
progress reached in the studies on TOX chemistry, it should be
admitted that the mechanism of their therapeutic effect is still a
since catalytic redox reactions involving Fe ions also occur in
5
the living biosystem of the human organism.
Taking into consideration the similar structures and chemical
properties of TOX, the regularities of CL and the products of
catalytic decomposition of TOX with ferrocene were studied
for TOX 1 (Scheme 1), which gives the most intense CL, as an
example. It has been found by spectral methods that TOX 1
decomposition affords ethyl 4-acetyl-5-oxohexanoate as the main
5
,6
matter of discussion. It is believed that the key step of chemical
action of TOX involves cleavage of the peroxy bond induced by
ii
Fe ions of human blood heme. In continuation of studies on the
ii
regularities of TOX decomposition in reactions with Fe com-
pounds, this paper reports the first results of studies on the CL
emerging in Cp Fe-catalyzed TOX decomposition (Cp = C H ).
‡
(~70% according to GC MS) product. Based on the charac-
2
5
5
The CL caused by emission of TOX decomposition products was
7
Me
first detected in TOX thermal decomposition, as well as in the
Me
Cp2Fe+
O
O
ii
8,9
O
O
reaction of TOX with inorganic Fe compounds. Decomposi-
O
O
O
O
O
+ Cp2Fe
tion of TOX catalyzed by zinc tetraphenylporphyrin was also
MeCN–H2O
48 K
found to result in CL,10 where excited zinc(ii)–porphyrin moiety
Me
Me
3
served as the emitter.
R
R
†
The standard experimental procedure is described in detail
1
2
3
4
R = CH2CO2Et
R = (CH2)4Me
R = CH2CN
R = Ph
1
4,15
elsewhere.
It has been found that, unlike the reactions with
O
O
3
O
*
ii 8,9
inorganic salts of Fe , decomposition of all of the TOXs studied
Me
Me + Me
Me
†
2 2
5 R = CH CO H
The studied TOXs (99%) were synthesized at N. D. Zelinsky Institute
R
R
11,12
of Organic Chemistry (Moscow) according to published procedure.
Ferrocene (Aldrich, 98%, 102-54-5), MeCN (Sigma-Aldrich, 99.8%,
5-05-8), Rhodamine 6G (Rd6G, Sigma, 989-38-8), 9,10-dibromoanthracene
DBA) and 9,10-diphenylanthracene (DPA) were of ‘chemically pure’
Chemiluminescence
at 380±20 nm
7
(
Scheme 1
1
3
grade. Water and gases (Ar, O ) were purified prior to use.
2
–3
‡
1
A solution of TOX in MeCN (40 mmol dm , 0.5 ml), a solution of Rd6G
Ethyl 4-acetyl-5-oxohexanoate. H NMR (500 MHz, CDCl ) d: 1.30
(m, Me), 1.60 (s, 2Me), 1.95 (d, CH ), 2.50 (m, CH ), 2.71 (m, CH), 4.20
(m, CH2). 13C NMR (125 MHz, CDCl ) d: 9.81 (s, 2Me), 14.23 (s, Me),
3
–3
in H O (4 mmol dm , 0.5 ml) or H O (0.5 ml) were loaded into a Pyrex reactor
2
2
2 2
(d = 20 mm, V = 10 ml) in an argon or oxygen atmosphere. After that, the
3
volume of the reaction solution was adjusted to 1.8 ml with water (0.5 ml)
19.12 (s, CH ), 31.77 (s, CH ), 58.20 (s, CH), 60.88 (s, CH ), 172.37 (s,
OCO). MS, m/z (%): 200 (1) [M] , 158 (15), 113 (37), 84 (23), 71 (15),
55 (15), 43 (100).
2
2
2
–
+
and MeCN (0.3 ml). Further, a solution of Cp Fe in MeCN (10 mmol dm
2
3
,
0.2 ml) was syringed through a penicillin stopper and, CL was recorded.
©
2017 Mendeleev Communications. Published by ELSEVIER B.V.
–
371 –
on behalf of the N. D. Zelinsky Institute of Organic Chemistry of the
Russian Academy of Sciences.