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984
J. Am. Chem. Soc. 1996, 118, 3984-3985
Ozone from Iron(III) Porphyrin, Nitrite Ion, and
Oxygen
we address the question: Can dioxygen be a substrate in these
reactions?
As a consequence of related studies of the reactions of
oxygen-heme protein adducts with simple N-O bonded
species, it became clear that the character of the reactions in
air and under argon was markedly different. Thus, the auto-
Charles E. Castro
The EnVironmental Toxicology Graduate Program
UniVersity of California, RiVerside, California 92521
CEC Consulting, 1090 Madison Place
-
catalytic reaction of oxymyoglobin with NO2 in air requires
1
2
intermediates that are not apparent under argon. This led to
the speculation that ozone may be an entity driving the
autocatalysis. Perhaps like CO and NO, oxygen could be a
substrate in reaction 1?
Laguna Beach, California 92651
ReceiVed June 22, 1995
To test this unlikely hypothesis, octaethylporphyrin iron(III)
chloride and potassium crown ether (18-crown-6) nitrite were
reacted in an oxygen atmosphere with three substances that have
been established to be inert under argon. That is, they are not
substrates in reaction 1. These ozone scavengers are nitrite ion
and the two olefins 2,3-dimethyl-2-butene and 2-methyl-2-
butene. Reaction conditions were the same as those described
Ozone is well known as an extremely powerful oxidant. Its
decomposition to oxygen proceeds with the release of 143 kJ/
mol, and it reacts with a broad range of inorganic and organic
1,2
structural types.
It is formed in the atmosphere by the
photolysis of O2 and NO2. The resulting oxygen atoms combine
with O2 to produce O3. The combination of certain peroxy
radicals may also result in O3.3 In addition to photolysis, ozone
1
0
previously except that they were carried our under oxygen.
can be synthesized from dioxygen by electrolysis, electrical
discharge, ionizing radiation, and UHF fields. The actual
chemistry of these processes is complex and not fully under-
stood.2 In contrast, the chemical generation of ozone is rare.
However, small quantities have been reported to occur upon
-
-5
In the first reaction, an excess of NO2 (5.2 × 10 mol of
K+ (18-crown-6) NO2 ) was allowed to react with ClFe(III)-
-
,3
-5
OEP (2 × 10 mol) in 4 mL of N-methylpyrrolidone (NMP)
- 1% acetic acid. The thoroughly oxygen-purged, sealed,
stirred reaction was concentrated to dryness in vacuo after 16
h. The recovery of combined nitrite and nitrate from an aqueous
4
the addition of hydrogen peroxide to selenic acid, the decom-
5
position of potassium peroxydisulfate by acid, the reaction of
6
13
-
-
fluorine with aqueous KOH, and the oxidation of thin films of
extract was 73%. The ratio of NO3 to NO2 was 0.5 ( .1
7
-
aluminum. Presumably oxygen atoms are generated to some
(theoretical, 0.6). The generation of NO3 was confirmed by
extent in these reactions.
IR analysis of a portion of the concentrated aqueous extract.
2
8
-1
The oxidations of iodide to iodine and nitrite to nitrate are
common tests for the presence of ozone in trace quantities.
However, the most characteristic reaction of ozone is its reaction
with olefins.2 The sequence ozonolysis followed by reduction
of the ozonides with zinc in acetic acid, to aldehydes and
ketones, is the classic method for locating the position of double
Strong bands corresponding to nitrate (1350 cm ) and nitrite
-
1
14a
(1275 cm ) were observed.
With the olefin traps, a large excess of the olefin was
-
employed to compete with the potential NO2 reaction with
ozone. Two mL of NMP-1% HOAc and two mL of olefin
-
5
-5
containing 2 × 10 mol of ClFe(III)OEP and 2.6 × 10 mol
9
+
-
bonds in unknown structures. This procedure has been
of K(18-crown-6) NO2 were stirred in an oxygen atmosphere
for 16 h. The reaction mixture was briefly purged with argon
and reduced with zinc dust (0.2-0.4 g) and acetic acid
(additional 0.5 mL) for 3 h. The low-temperature (bp < 60
°C) reaction distillate was analyzed by gas chromatography
(GC), infrared, and GC-mass spectroscopy. With 2,3-dimethyl-
supplanted by modern NMR analyses, but it represents an
excellent means of establishing the transient presence of ozone
in a reaction mixture.
We have recently reported a series of facile oxygen atom
-
transfers from iron(III) porphyrin NO2 adducts to a broad range
of substrates under argon10 (eq 1, S ) substrate). Typical
reactions entail oxygen insertion into carbon-hydrogen bonds,
15
2-butene, the yield of acetone was 100 ( 10% calculated on
the basis of 2 mol of acetone per mol of PFe charged. The
III
reaction distillate exhibited a strong carbonyl absorption at 1722
S
-1
III
-
II
cm corresponding exactly to that of acetone in tetramethyl-
PFe + NO2 h PFeNO2
9
8 PFe NO + SO
(1)
ethylene.
With 2-methyl-2-butene, the yield of acetone following the
reaction and reduction with Zn/HOAc and distillation was 90%,
but the acetaldehyde recovery (GC) was lower (50%).16 Both
acetone and acetaldehyde from these reactions were confirmed
olefin epoxidation, and oxygen atom transfers to sulfides,
phosphines, carbon monoxide, and nitric oxide. The driving
force for these reactions resides in the enormous thermodynamic
stability of the porphyrin iron(II)-NO adducts.11 In this work
1
7
by GC-MS.
(
1) Cotton, F. A.; Wilkinson, G. AdVanced Inorganic Chemistry, 5th ed.;
John Wiley and Sons: New York, 1988; pp 452-454.
2) Razumaovskii, S. D.; Zaikov, G. E. Ozone and its Reactions with
Organic Compounds; Elsevier: New York, 1984.
3) Horvath, M.; Bilitzky, L.; Huffner, J. Ozone; Elsevier: New York,
(12) Wade, R. S.; Castro, C. E. Chem. Res. Toxicol., submitted for
publication.
(
(13) (a) Chow, T. J.; Johnstone, M. S. Anal. Chem. Acta 1962, 27, 441.
(b) A possible additional source of nitrate in this milieu, following reaction
2, would be the reaction of PFeNO with O2 (cf. ref 12).
(
1
985.
-
(
4) Blums, A.; Sauka, J. J. LatV. PSR Zinat. Akad. Vestis Kim. Ser. 1970,
(14) (a) The same reaction under argon yielded no NO3 . Similarly a
2
47.
reaction under oxygen, but without porphyrin, produced no nitrate. (b) All
control reactions were run and worked up in a manner identical to that
described in the text and consisted of runs (i) with substrate and oxygen,
but no porphyrin; (ii) porphyrin, oxygen, and substrate, but no nitrite; (iii)
porphyrin, nitrite, and substrate, but no oxygen (reactions under argon).
No reaction occurred under any of these conditions. In all cases, only nitrite
salt and unreacted olefin were recovered. In particular, neither nitrate,
acetone, or acetaldehyde was detected in any control run.
(
5) Sauka, J.; Blums, A.; Morica, V.; Brezina, V. LatV. PSR Zinat. Akad.
Vestis Kim. Ser. 1968, 392.
(
(
(
6) Briner, E.; Tolun, R. HelV. Chim. Acta 1948, 31, 937.
7) Gen, M. Y.; Petrov, Y. I. Dokl. Akad. Nauk SSSR 1960, 135, 1361.
8) Kontrakis, P.; Wolfson, J. M.; Bunyaviroch, A.; Fruehlich, S. E.;
Hirono, K.; Mulik, J. D. Anal. Chem. 1993, 65, 209-214.
(
9) March, J. B. AdVanced Organic Chemistry, 3rd ed.; John Wiley and
Sons: New York, 1985; p 1066 ff.
(15) A 2 ft × 1/8 in. Porapak P column at 85 °C/30 mL/min He was
employed. Acetone and (2.0 min) tetramethylethylene (2.8-6 min were
the only peaks present and corresponded exactly to an authentic standard.
(16) A 5 ft × 1/8 in. Porapak T column at 125 °C/40 mL/min He was
employed: acetaldehyde (4 min), trimethylethylene (9-12 min), acetone
(15 min). Consistent injection of acetaldehyde was difficult. Estimation
of the combined yield of acetone and acetaldehyde via IR of the distillate
(
10) Castro, C. E.; O’Shea, S. K. J. Org. Chem. 1995, 60, 1922.
(
11) (a) Jongeward, K. A.; Magde, D.; Taube, J.; Marsters, J. C.; Traylor,
T. G.; Sharma, V. S. J. Am. Chem. Soc. 1988, 110, 380. (b) Blackmore,
R. S.; Greenwood, G.; Gibson, Q. H. J. Biol. Chem. 1991, 266, 19245. (c)
Carver, T. E.; et al. J. Biol. Chem. 1990, 265, 20007. (c) Petrich, J. W.; et
al. Biochemistry 1991, 30, 3975-3987. (d) Hishino, M.; Ozawa, K.; Seki,
H.; Ford, P. C. J. Am. Chem. Soc. 1993, 115, 9568.
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1
(1718-1720 cm ) and comparison with a standard were 90 ( 10%.
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002-7863/96/1518-3984$12.00/0 © 1996 American Chemical Society