Biomimetic oxidation of ibuprofen with hydrogen peroxide catalysed by Horseradish peroxidase (HRP) and 5,10,15,20- tetrakis-(2',6'-dichloro-3'- sulphonatophenyl)porphyrinatoiron(III) and manganese(III) hydrates in AOT reverse micelles

Article abstract of DOI:10.1016/S0968-0896(99)00202-3

The oxidation of ibuprofen with H₂O₂ catalysed by Horseradish peroxidase (HRP), Cl₈TPPS₄Fe(III)(OH₂)₂ and Cl₈TPPS₄Mn(III)(OH₂)₂ in AOT reverse micelles gives 2-(4'-isobutyl-phenyl)ethanol (5) and p-isobutyl acetophenone (6) in moderate yields. The reaction of ibuprofen (2) with H₂O₂ catalysed by HRP form carbon radicals by the oxidative decarboxylation, which on reaction with molecular oxygen to form hydroperoxy intermediate, responsible for the formation of the products 5 and 6. The yields of different oxidation products depend on the pH, the water to surfactant ratio (Wo), concentration of Cl₈TPPS₄Fe(III)(OH₂)₂ and Cl₈TPPS₄Mn(III)(OH₂)₂ and amount of molecular oxygen present in AOT reverse micelles. The formation of 2-(4'-isobutyl phenyl)ethanol (5) may be explained by the hydrogen abstraction from ibuprofen by high valent oxo- manganese(IV) radical cation, followed by decarboxylation and subsequent recombination of either free hydroxy radical or hydroxy iron(III)/manganese(III) porphyrins. The over-oxidation of 5 with high valent oxo-manganese, Mn(IV)radical cation intermediate form 6 in AOT reverse micelles by abstraction and recombination mechanism. (C) 1999 Elsevier Science Ltd.

Full text of DOI:10.1016/S0968-0896(99)00202-3

Bioorganic & Medicinal Chemistry 7 (1999) 2629±2634
Biomimetic Oxidation of Ibuprofen with Hydrogen Peroxide
Catalysed by Horseradish Peroxidase (HRP) and 5,10,15,20-
Tetrakis-(20,60-dichloro-30-sulphonatophenyl)porphyrinatoiron(III)
and Manganese(III) Hydrates in AOT Reverse Micelles
S. M. S. Chauhan* and B. B. Sahoo
Department of Chemistry, University of Delhi, Delhi 110 007, India
Received 1 March 1999; accepted 17 July 1999
AbstractÐThe oxidation of ibuprofen with H2O2 catalysed by Horseradish peroxidase (HRP), Cl8TPPS4Fe(III)(OH2)2 and
Cl8TPPS4Mn(III)(OH2)2 in AOT reverse micelles gives 2-(40-isobutyl-phenyl)ethanol (5) and p-isobutyl acetophenone (6) in moderate
yields. The reaction of ibuprofen (2) with H2O2 catalysed by HRP form carbon radicals by the oxidative decarboxylation, which on
reaction with molecular oxygen to form hydroperoxy intermediate, responsible for the formation of the products 5 and 6. The yields
of di€erent oxidation products depend on the pH, the water to surfactant ratio (Wo), concentration of Cl8TPPS4Fe(III)(OH2)2 and
Cl8TPPS4Mn(III)(OH2)2 and amount of molecular oxygen present in AOT reverse micelles. The formation of 2-(40-isobutyl
phenyl)ethanol (5) may be explained by the hydrogen abstraction from ibuprofen by high valent oxo-manganese(IV) radical cation,
followed by decarboxylation and subsequent recombination of either free hydroxy radical or hydroxy iron(III)/manganese(III)
porphyrins. The over-oxidation of 5 with high valent oxo-manganese, Mn(IV)radical cation intermediate form 6 in AOT reverse
micelles by abstraction and recombination mechanism. # 1999 Elsevier Science Ltd. All rights reserved.
Introduction
enzymatic reactions.10,11 Reverse micelles act as func-
tional modulators and accelerate the reactivity of heme
peroxidase and other enzymes.12±17
Ibuprofen and related aryl propionic acids are impor-
tant non-steroidal anti-in¯ammatory drugs.1 They inhi-
bit selected cyclooxygenase reactions in the biosynthesis
of prostaglandins from archidonate.2±5 Cyclooxygenase
catalyses the conversion of archidonic acid to PGG2
and reduction of PGG2 to PGH2. Both reactions are
catalysed by formation of transient higher oxidation
states of the heme enzymes. Ibuprofen and related aryl
propionic acids inhibit cyclooxygenase reaction but not
the peroxidase activity.6,7 The reaction of Horseradish
peroxidase (HRP) with hydrogen peroxide forms a high
valent oxo-iron(IV) radical cation which is reduced to
high valent oxo-iron(IV) intermediate by accepting
electrons from substrate leading to formation of sub-
strate radicals. The coupling, disproportionation and
other reactions of substrate radicals are responsible for
the formation of ®nal products.8,9 Reverse micelles are
simplest models of natural membrane and they form
variable reaction media depending on the ratio of water
to surfactant and governs the eciency of chemical and
The oxidation of indole-3-acetic acid with hydrogen per-
oxide catalysed by 5,10,15,20-tetrakis-(20,60-dichloro-30-
sulphonatophenyl)porphyrinatoiron(III)hydrates gives
indole-3-carbinol and corresponding aldehyde in AOT
reverse micelles18 in di€erent reaction conditions. Herein,
we report the biomimetic oxidation of ibuprofen with
H2O2 catalysed by HRP and 5,10,15,20-tetrakis(20,60-
dichloro-30-sulphonatophenyl)porphyrinatoiron(III) and
manganese(III) hydrates in AOT reverse micelles in dif-
ferent reaction conditions, to elucidate the molecular
mechanism of heme peroxidase and related enzymes.
Results
Formation of type I intermediate by the reaction of HRP
with hydrogen peroxide (H2O2) and the subsequent catalytic
reaction with ibuprofen (2) in AOT reverse micelles
Formation of reactive intermediate (type I of HRP) by
the reaction of HRP with hydrogen peroxide (H2O2) has
* Corresponding author. Fax: +91-11-7256593; e-mail: smschau-
han@chemistry.du.ac.in
0968-0896/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(99)00202-3

2630
S. M. S. Chauhan, B. B. Sahoo / Bioorg. Med. Chem. 7 (1999) 2629±2634
been reported in aqueous solution.7,8 The reaction of
H2O2 to HRP, at 40ꢀC in AOT reverse micelles,
results in the decrease of the Soret absorbance of HRP
and formation of a new peak at 412 rim. The spectrum
of this new species is analogous to type I form of
Horseradish peroxidase, i.e. oxo-iron(IV) radical cation
intermediate.2 The new peak at 412 nm does not appear
in the presence of BPH at low temperature in AOT
reverse micelles. The reaction of ibuprofen (2) with
hydrogen peroxide (H2O2) catalysed by HRP in AOT
reverse micelles (Wo=10) at pH 4.0 in 1 h gives 2-(40-
isobutylphenyl)ethanol (5) and p-isobutyl-acetophenone
(6) in 42 and 12% yields, respectively. The oxidation
products of ibuprofen (2) with H2O2 depend on the pH
and presence of molecular oxygen in AOT reverse
micelles. The sterically hindered p-tert-butyl phenol
(BPH) quenches the oxidation of ibuprofen with H2O2±
HRP system in AOT reverse micelles. The reaction of
ibuprofen with H2O2 catalysed by HRP in AOT reverse
micelles at pH 4.0 (Wo=10) is completely quenched by
using BPH in 1:1 and 0.5:1 molar ratio with HRP. In
case of HRP and quencher (0.25:1), 5 and 6 are formed
in 7% and 1% yields respectively.
Formation of high valent radical cation intermediate by
the reaction of hydrogen peroxide (H2O2) with CI8TP-
PS4Fe(III)(OH)2)2 and Cl8TPPS4Mn(III)(OH2)2 and
the subsequent catalytic reaction with ibuprofen (2) in
AOT reverse micelles at di€erent pH
Figure 1. Formation of high valent oxo-manganese(IV)radical cation
from the reaction of H2O2 with Cl8TPPS4Mn(III)Cl (1) in AOT reverse
micelle at di€erent pH. All the reactions were performed at 40ꢀC in
7
phosphate bu€er (pH 7.0, 9.2 and 11.0). Cl8TPPS4Mn(III)Cl, 1.8Â10
mol; H2O2, 1.0Â10 5 mol; AOT, 3 cm3.
The reaction of hydrogen peroxide with iron(III) and
manganese(III) porphyrin in aqueous solution,21 AOT
reverse micelles22,23 and latex24,37 have been studied.
But the detailed kinetics of the reaction of Cl8TPPS4
Mn(OH2)2 with H2O2 at di€erent pH and the study of
active intermediate at low temperature ( 40ꢀC) in AOT
reverse micelles has not yet been studied. Spectra of 1 at
di€erent pH (4<pH<11) in presence of H2O2 at 40ꢀC
are recorded as shown in Figure 1. In the absence of
oxidising agent, the manganese porphyrins are stable in
aqueous solution. The absorbance maximum at 469 nm
is the Soret of Mn(III) porphyrins. However, upon
addition of H2O2 the absorption spectrum changes and a
new species is formed at low temperature ( 40ꢀC). The
absorption maxima at 469 nm decreases and a new band
at 424 nm on addition of H2O2 becomes sharper and
increased in intensity. The intensity of 424 nm band is
higher at pH 9.2 as compared to at pH 7.0 and 4.0.
Again at pH 11.0, the intensity of 424 nm band is low-
ered. Manganese(IV) porphyrin may be present in the
form of a m-oxo-dimer in which there is anti-ferromag-
netic coupling between two manganese(IV) atoms. The
formation of m-oxo-dimers is well known in iron por-
phyrins as well as manganese(III) porphyrins in extre-
mely alkaline solution.25,26 The peak at 424 mn may be
assigned for the high valent oxo-manganese species, at
low temperature in AOT reverse micelles. In the pre-
sence of BPH, there is no formation of the new species
showing absorbance at 424 nm.
whereas in basic bu€er solution, it forms Cl8TP-
PS4Mn(III)(OH2)(OH) and Cl8TPPS4Mn(III)(OH)2.29,30
The reaction of 2 with H2O2 catalysed by Cl8TP-
PS4Fe(III)(OH2)2 in AOT reverse micelle (Wo=12) at
pH 4.0 in 1h gives 5 and 6 in 45 and 12% yields,
respectively. Further the reaction of 2 with H2O2 cata-
lyzed by Cl8TPPS4Mn(III)(OH2)2 (1a) gives 5 and 6 in
40% and 10% yields, respectively. The reaction of 2
with H2O2 catalysed by 1a in aqueous acetate bu€er pH
4.0 gives 5 and 6 only in 2 and 0% yields, respectively.
The yields of the oxidation products increases with
increase of Wo upto 12, then decreases with further
increase in Wo at pH 4.0 in acetate bu€er. The depen-
dence of Wo in the formation of 5 is shown in Figure 2.
The formation of 2-(40-isobutylphenyl)ethylchloride
(2%) is observed with the reaction of ibuprofen (2) in
saturated sodium chloride with hydrogen peroxide
(H2O2) catalysed by Cl8TPPS4Mn(III)(OH2)2 in AOT
reverse micelles. The sterically hindered p-tert-butyl
phenol (BPH) also quenches the oxidation of ibuprofen
with H2O2-Cl8TPPS4Mn(III)(OH2)2 system in AOT
reverse micelles. The reaction of ibuprofen with H2O2
catalysed by Cl8TPPS4Mn(III)(OH2)2 in AOT reverse
micelle at pH 4.0 (Wo=10) is completely quenched by
using BPH in 1:1 and 0.5:1 molar ratio with porphyrin
whereas the reaction is partially quenched by using BPH
in 0.25:1 molar ratio with porphyrin. In case of
Cl8TPPS4Fe(III)(OH2)2 5 and 6 are formed in 10 and
1% yields, respectively, while in Cl8TPPS4Mn(III)
(OH2)2, 5 and 6 are formed in 12 and 1% yields,
respectively. Similar reactions have been performed at
The reaction of Cl8TPPS4Mn(III)Cl (1) with acidic
aqueous bu€er solution (pH 4.0) exchanges the axial
chloride ligand forming Cl8TPPS4Mn(III)(OH2)2, (1a)

S. M. S. Chauhan, B. B. Sahoo / Bioorg. Med. Chem. 7 (1999) 2629±2634
2631
pH 7.0, 9.2, 12.0 and results are presented in Figure 2.
All the products have been characterized by compar-
ison with authentic samples and their HPLC retention
time. The reaction of ibuprofen ester (7) with H2O2
catalyzed by Cl8TPPS4Mn(III)(OH2)2 at Wo=12 in
AOT reverse micelle at pH 4.0, 7.0 and 9.2 does not
give any decarboxylated product.
carbon radical (4). The carbon radical (4) reacts with
molecular oxygen to form peroxy radical species (10)
which abstracts Hꢁ from solvent or ibuprofen (substrate)
leads to formation of hydroperoxide intermediate (11).
The homolytic cleavage of hydroperoxide, form the
alcohol 5 and elimination of H2O gives the ketone 6
(Scheme 1). The formation of this type of product has
been reported during the reaction of indole-3-acetic acid
with HRP in aqueous phosphate bu€er.33
The incorporation and UV±visible spectroscopic study
of [Cl8TPPS4Mn(III)(OH2)2] (1a), ibuprofen (2) and p-
tert-butyl phenol (BPH) in AOT reverse micelle have
been done by following the literature procedures.19,20
The comparison of UV-visible spectra in phosphate
bu€er and methanol of 1a indicate that 1a resides in the
interphase of AOT reverse micelles. Ibuprofen and p-
tert-butyl phenol (BPH) resides in the interphase of
AOT reverse micelles, inferred by the comparison of its
UV-visible spectra in reverse micelles with those in
phosphate bu€er (pH 7.0), methanol and chloroform.
The maximum absorbance of ibuprofen was obtained at
water to surfactant ratio, Wo=24 of AOT reverse
micelles.
The yield of 5 becomes maximum at Wo=10 with H2O2
catalysed by HRP in AOT reverse micelles and then
decreases at higher Wo. These results indicate that at
water/surfactant, Wo=10, HRP has the right geometry
for the maximum activity for the above oxidation reac-
tion which is comparable with the maximum activity of
HRP at Wo=12 in AOT reverse micelles during the
oxidation of pyrogallol to purpurogallin.27 In the
absence of oxygen the formation of 5 and 6 is not
observed in the AOT reverse micelles. The activity of
HRP is quenched in the presence of BPH at Wo=10, in
AOT reverse micelle.
The reactions of selected water soluble iron(III)por-
phyrins and H2O2 with organic substrates form the
same products, obtained by the reactions of HRP and
H2O2 in AOT reverse micelles in same reaction condi-
tions.28 The product formation (path A, Scheme 2) may
be explained by abstraction of hydrogen radicals by
high valent oxo-manganese(IV)porphyrins (8a) from
ibuprofen (2) and subsequent decarboxylation from the
radical species (3) form ibuprofen carbon radical (4).
The recombination of 4 with chelated hydroxyl equiva-
lent (8b) or free hydroxyl radical gave 2-(40-iso-
butylphenyl)ethanol (5). Further, the over-oxidation of
5 with high valent radical cation (8a) form 6 by
abstraction and recombination mechanism (Scheme 2).
This kind of abstraction and recombination mechanism
has been proposed for the oxidation of alcohols to
Discussion
The reaction of H2O2 and HRP in AOT reverse micelles
forms high valent radical cation (type 1) intermediate,
which accept one electron from the ibuprofen (2) at its
heme edge without direct contact with the oxygen atom
of the oxo-iron and it self-converts to type II inter-
mediate of HRP. The ibuprofen radical cation loses H+
to form the carboxylate radical (3) species which on
subsequent decarboxylation leads to the ibuprofen
Figure 2. Formation of 5 from 2 and H2O2 catalyzed by HRP and
water soluble porphyrins in AOT reverse miscelles at di€erent pH and
water:surfactant ratio, Wo. All the reactions were performed at room
temperature in acetate bu€er (pH 4.0), phosphate bu€er (pH 7.0, 9.2
and 12). Cl8TPPS4Mn(III)Cl, 1.8Â10 7 mol; Cl8TPPS4Fe(III)Cl, 1.9Â
7
5
10 mol; H2O2, 1.0Â10 mol; AOT, 3 cm3.
Scheme 1.

2632
S. M. S. Chauhan, B. B. Sahoo / Bioorg. Med. Chem. 7 (1999) 2629±2634
Scheme 2.
aldehyde/ketone with mono-oxygen donors catalysed by
metalloporphyrins in organic22,23 and aqueous solu-
tion.34 An alternative pathway (path B) is the reaction
of H2O2 and ibuprofen (acid) form peroxy acid complex
(9) reversible, which on homolytic cleavage in presence
of metalloporphyrin form 3. The decarboxylation of 3
form 4, which is responsible for the formation of 5 and
6 (Scheme 2). Further the reaction of the peroxy acid (9)
also reacts with metalloporphyrin, forms high valent
oxo-radical cation heterolytically, which leads to ®nal
products in AOT reverse micelles. The formation of
carbon radical after CO2 elimination has been observed
directly in homogeneous medium.31 The formation of 2-
(40-isobutylphenyl)ethylchloride (12) in 2% yield may be
explained by the reaction of carbon radical with chlor-
ine radical, which is generated by the reaction of Cl
with HOÁ, in AOT reverse micelles.
tion of both ibuprofen (2) and Cl8TPPS4Mn(III)(OH2)2
(1a), for maximum interactions and high yields of di€er-
ent oxidation products. The AOT reverse micelles are
more ecient reaction media than aqueous phosphate
bu€er in above oxidative decarboxylation and sub-
sequent formation of oxidative products of ibuprofen in
di€erent reaction conditions.
Conclusion
The hydrogen abstraction followed by decarboxylation
of ibuprofen and subsequent product formation by
reaction of ibuprofen with hydrogen peroxide catalysed
by HRP and 5,10,15,20-tetrakis(20,60-dichloro-30-sul-
phonatophenyl)porphyrinatoiron(III) and manganese
(III) hydrates depend upon pH and water to surfactant
ratio (Wo) and presence of oxygen in the AOT reverse
miscelles. The percentage yields of the products increa-
ses at lower pH as compared to higher pH in AOT
reverse micelles. The high valent oxo-iron(IV) and man-
ganese(IV) radical cation species are easily quenched by
the sterically hindered p-tert-butyl phenol (BPH) in AOT
reverse micelles and no oxidation products are formed in
the presence of BPH. Although the same products are
This type of oxidative decarboxylation of selected acids
has been reported by the reaction with iodosylbenzene
catalysed by iron(III)porphyrin in organic solvents.31,32
The yield of 5 and 6 is maximum at Wo=12 and again
decreases with increasing Wo and pH in AOT reverse
micelle. Hence the aqueous core of AOT reverse micelle
(Wo=12) has appropriate diameter for the incorpora-

S. M. S. Chauhan, B. B. Sahoo / Bioorg. Med. Chem. 7 (1999) 2629±2634
2633
formed by the reaction of ibuprofen and H2O2 catalysed
by water soluble iron(III) and manganese(III)porphyr-
ins, as formed by the reaction of ibuprofen with H2O2
catalysed by HRP, but their mechanism of formations
are di€erent. Thus the above chemical model systems,
metalloporphyrins/H2O2 mimick the formation of dif-
ferent products as obtained by the reaction of ibuprofen
with H2O2 and HRP in aerobic organized media.
bu€er (pH 4.0, 10.0 mL) was injected into the stirred
solution followed by H2O2 (30%, 0.2 mmol, 10.8 mL).
The initially turbid reaction mixture gradually becomes
clear in about 5 min, indicating the completion of the
micellization process, was stirred for 1.5 h in the pre-
sence of dissolved oxygen atmosphere. The reaction
mixture was concentrated and extracted with methanol
and the extract was quenched by adding BPH and sub-
jected to HPLC analysis for identi®cation and quanti®-
cation of products.
Experimental
Oxidation of ibuprofen (2) with H2O2 catalysed by Cl8
TPPS4Fe(III)(OH2)2 and Cl8TPPS4Mn(III)(OH2)2 in
AOT reverse micelles
Materials and Methods
UV±vis spectra were recorded using a Shimadzu UV-260
spectrophotometer. IR spectra were recorded using a
Perkin±Elmer FTIR spectrum 2000 spectrophotometer.
EIMS spectra were recorded on Jeol SX/102DA-6000
(6kV, 10 mA) spectrophotometer. The oxidation pro-
ducts of ibuprofen were identi®ed and quanti®ed by
using Waters HPLC equipped with a photodiode array
detector (Model 991) on a m-Bondapak C18 column
(3.9Â300 mm) using methanol (100%) as eluent at a ¯ow
rate of 0.2 mL/min monitored at 265 rim and compar-
ison of both UV spectra and retention time with that of
authentic samples. 1H NMR spectra were recorded on a
Bruker 300 MHz spectrophotometer.
The oxidation of ibuprofen in AOT reverse micelles was
studied by minor modi®cations of the known meth-
ods.21,28,37 Ibuprofen (0.3 mol) was added to a solution
of AOT in iso-octane (6 mL, Wo=12) containing 10 mL
of Cl8TPPS4Fe(III)(OH2)2 and Cl8TPPS4Mn(III)(OH2)2
(3.6 mmol). Hydrogen peroxide (30%, 0.2 mmol, 10.8
mL) was added to above solution and stirred for 1 h at
room temperature in presence of inert atmosphere. The
products were extracted with methanol (15 mL) and the
extract was quenched by adding BPH and then sub-
jected to HPLC analysts for identi®cation and quanti®-
cation of products, The same procedure was followed
for reactions at di€erent water to surfactant ratio (Wo)
and at di€erent pH. The results are presented in Figure
2. In an another experiment saturated NaCI solution
(5.4 mL) was injected to the POR/H2O2/AOT system
and stirred for 1 h at room temperature. The products
were extracted with methanol (15 mL) and the extract
was subjected to HPLC analysis.
Sodium bis-(2-ethylhexyl)sulphosuccinate (Aerosol-OT)
was puri®ed by published procedure35 before use. Ibu-
profen was obtained from Ranbaxy, India and puri®ed.
The aqueous hydrogen peroxide (30% v/v) was
obtained from CDH India and used without further
puri®cation. 5,10,15,20-tetrakis(20,60-dichloro-30-sulpho-
natophenyl)porphyrin (Cl8TPPS4) was prepared by sul-
phonation of Cl8TPP with oleum at 130ꢀC by following
the literature procedure.36 UV±visible lmax nm (emax in
methanol): 425.5 (0.74), 521.5 (0.03), 555.0 (0.01), 600.0
Oxidation of ibuprofen ester (7) with H2O2 catalysed by
1 in AOT reverse micelles
1
(0.01) and 658.0 (0.01). HNMR (D2O) d ppm: 8.77 (s,
Ibuprofen ester (7) was prepared from ibuprofen (2) by
re¯uxing in dry methanol for 3±4 h with catalytic amount
of concd H2SO4, Yield: (82%), FTIR n (®lm)/cm 1 2955,
2871, 2361, 1904, 1739, 1612, 1512, 1377, 1334, 1207,
1165, 1068, 852, 798 and 727. 1H NMR (CDCl3); d ppm
0.92 (d, 6H, J=6.5 Hz), 1.43 (d, 3H, J=6.5 Hz), 1.80 (in,
lH), 2.05 (m, M), 2.60 (d, 2H, J=7.2 Hz), 3.70 (s, 3H) and
7.10 (m, 4H). EIMS (m/z): 220 (M+), 205 (M+±CH3), 161
(100%, M+±COOCH3). The oxidation of ibuprofen ester
was studied by the same procedure as ibuprofen.
SH, pyrrolic protons), 8.62 (in, 4H, aromatic protons)
and 8.00 (m, 4H, aromatic protons). 5,10,15,20-tetra-
kis(20,60 -dichloro-30 -sulphonatophenyl)-porphyrinato-
manganese(III)hydrate [Cl8TPPS4Mn(III)(OH2)2] (1a)
was prepared by re¯uxing the water-soluble free base
porphyrin with a 40-fold excess of manganese(II) chlo-
ride in DMF (10 mL) following the literature proce-
dure.37 UV±visible lmax nm (emax in water): 370.2 (0.19),
395.6 (0.14), 418.2 (0.19), 464.0 (0.28), 560.2 (0.04).
5,10,15,20-tetrakis(20,60 -dichloro-30 -sulphonatophenyl)
porphyrinatoiron(III)hydrate [Cl8TPPS4Fe(III)(OH2)2]
(1a) was prepared by re¯uxing the water-soluble free
base porphyrin with a 40-fold excess of ferrous(II)
chloride in DMF (10 mL) following the literature pro-
cedures.21,28,38 UV±visible lmax nm (emax in water):
400.0 (0.34), 416.5 (0.72), 466 (0.08) and 512.5 (0.06).
Synthesis of p-isobutyl-acetophenone (6)
The isobutyl benzene was acylated by Ac2O and anhy-
drous AlCl3 by following the literature procedure39 to give
the title compound. In a typical experiment, a mix of
Ac2O (0.01 M, 1.0 mL) and isobutylbenzene (0.01 M,
1.3 mL) was added to anhydrous AlCl3 in dry CH2Cl2 at
5ꢀC to +5ꢀC in ꢂ4 h, and the mixture was stirred for
30 min, allowed to warm to 25±8ꢀ, and worked up to give
p-isobutyl-acetophenone (6). Yield ꢂ70%, FTIR n (®lm)/
cm 1: 3063, 2923, 2360, 1685, 1599, 1449, 1359, 1266,
1180, 1078, 1024, 955, 760 and 690. 1H NMR (300 MHz,
CDCl3) d ppm: 0.89 (d, 6H, J=6.6 Hz), 1.84 (m, 1H), 2.54
(d, 2H, J=7.3Hz), 2.62 (s, 3H), 7.24 (d, 2H, J=8.9 Hz),
Reaction of ibuprofen (2) with H2O2 catalysed by HRP
in AOT reverse micelle
To a solution of AOT in isooctane (0.05 M, 10 mL) was
added the ibuprofen solution (6 m mol) and the mixture
was stirred vigorously till the ibuprofen was dissolved
approximately 3 min. A solution of HRP in phosphate

2634
S. M. S. Chauhan, B. B. Sahoo / Bioorg. Med. Chem. 7 (1999) 2629±2634
7.36 (d, 2H, J=8.9Hz); EIMS (m/z): 176 (M+), 161
(100%, M+±CH3).
7. de Montellano, P. R. O. Acc. Chem. Res. 1987, 20, 289.
8. Dolphin, D. Isr. J. Chem. 1981, 21, 67.
9. Maranon, M. J. R.; Van Huystee, R. B. Phytochem. 1994,
37, 1217.
10. De, T. K.; Maitra, A. Ad. Colloid. Interface Sci. 1995, 59, 95.
11. Bru, R.; Sanchez-Ferrer, A.; Garcia-Carmona, F. Biochem.
J. 1995, 310, 721.
12. Schwuger, M. J.; Stickdorn, K.; Schomacker, R. Chem.
Rev. 1995, 95, 849.
13. Hamachi, I.; Noda, S.; Kunitake, T. J. Am. Chem. Soc.
1991, 113, 9625.
14. Hamachi, I.; Fujita, A.; Kunitake, T. J. Inorg. Biochem.
1993, 51, 327.
15. Klyachko, N. L.; Levashov, A. V.; Martinek, K. Mol. Biol.
1984, 18, 1019.
16. Martinek, K.; Levashov, A. V.; Khmelnitsky, Yu.L.;
Klyachko, N. L.; Berezin, I. V. Science 1982, 218, 889.
17. Chauhan, S. M. S.; Kalra, B.; Gulati, A. J. Surf Sci. and
Tech. 1997, 13, 49.
Synthesis of 2-(40-isobutylphenyl)ethanol (5)
The 2-(40-isobutyl phenyl)ethanol (5) was prepared by the
hydrogenation of p-isobutylacetophenone (6) in presence
of 10% Pd/C in dry methanol by following the literature
procedure40 under 100 psig of H at 30ꢀC for 1h with 95%
conversion. FTIR n (®lm)/cm 1: 3401, 2956, 2923, 2852,
2361, 1606, 1510, 1463, 1377, 1266, 1163, 909, 848 and
1
720. H NMR (300 MHz, CDCl3) d ppm: 0.90 (d, 6H,
J=6.5 Hz), 1.85 (m, 1H), 1.95 (d, 3H, J=6.5 Hz), 2.65 (d,
2H, J=7.2 Hz), 4.27 (q, 1H, J=6.5 Hz), 7.26 (d, 2H,
J=8.8Hz), 7.39 (d, 2H, J=8.8 Hz); EIMS (m/z): 179
(M++I), 178 (M+), 160 (100%, M+±H2O).
18. Chauhan, S. M. S.; Mohapatra, P. P.; Kalra, B.; Kohli, T.
S.; Satapathy, S. J. Mol. Cat. A: Chem. 1996, 113, 239.
19. Chauhan, S. M. S.; Satapathy, S. Proc. Ind. Acad. Sci.
(Chem. Sci.) 1991, 103, 645.
20. Chauhan, S. M. S. J. Ind. Chem. Soc. 1996, 73, 637.
21. Panicucci, R.; Bruice, T. C. J. Am. Chem. Soc. 1990, 112,
6063.
22. Larpent, C.; Patin, H. J. Mol. Catal. A: Chem. 1992, 72,
315.
23. Bri€raud, T.; Larpent, C.; Patin, H. J. Chem. Soc. Chem.
Commun. 1990, 1193.
24. Lindsey, J. S.; Wagner, R. W. J. Org. Chem. 1989, 54, 828.
25. Fleischer, E. B.; Palmer, J. M.; Srivastava, T. S.; Chatter-
jee, A. J. Am. Chem. Soc. 1971, 93, 3162.
26. Spreer, L. O.; Leone, A.; Maliyackel, A. C.; Otvos, J. W.;
Calvin, M. Inorg. Chem. 1988, 27, 2401.
Synthesis of 2-(4-isobutyl phenyl)ethylchloride (12)
The 2-(40-isobutyl phenyl)ethylchloride (12) was prepared
by the chlorination of 2-(40-isobutyl phenyl)ethanol using
thionyl chloride. Pyridine (1.0 mL) and 2-(40-isobutyl
phenyl)ethanol (0.01 M, 1.8 mL) was stirred for 15 min at
room temperature followed by addition of thionyl chlo-
ride (1.2 mL) drop by drop for 1 h. Then the resulting
solution was re¯uxed for another 2 h, in which pyridinium
hydrochloride separates and the excess thionyl chloride
was evaporated with repeated azeotropic distillation in
benzene under reduced pressure, which gives the oily layer
of 2-(40-isobutyl phenyl)ethylchloride (12) in 87% con-
version. FTIR n (®lm)/cm 1: 2956, 2926, 2054, 1579, 1475,
1
1380, 1268, 1194, 903, and 753. H NMR (300 MHz,
27. Das, S.; Maitra, A. N. Colloids and Surfaces 1989, 35, 101.
28. Chauhan, S. M. S.; Ray, P. C.; Satapathy, S.; Vijayar-
ahavan, B. Ind. J. Chem. 1992, 31B, 837.
29. Harriman, A.; Porter, G. J. Chem. Soc. Farady Trans. 2
1979, 75, 1532, 1543.
30. Jeon, S.; Bruice, T. C. Inorg. Chem. 1992, 31, 4843.
31. Komuro, M.; Higuchi, T.; Hirobe, M. Bioorg. Med. Chem.
1995, 3, 550.
CDCl3) d ppm: 0.90 (d, 6H, J=6.3 Hz), 1.85 (m, 1H), 2.00
(d, 3H, J=6.3 Hz), 2,65 (d, 2H, J=7.2 Hz), 4.40 (q, 1H,
J=6.3 Hz), 7.26 (d, 2H, J=8.8 Hz), 7.39 (d, 2H, J=8.8
Hz); EIMS (m/z): 196 (M+), 161 (100%, M+±35Cl), 159
(M+±37Cl).
Acknowledgements
32. Komuro, M.; Nagatasu, Y.; Higuchi, T.; Hirobe, M. Tet-
rahedron Lett. 1992, 33, 4949.
33. Kobayashi, S.; Sugioka, K.; Nakano, H.; Nakano, M.;
Tero-Kubota, S. Biochemistry 1984, 23, 4589.
34. Chauhan, S. M. S.; Gupta, M.; Gulati, A.; Nizar, P. N. H.
Ind. J. Chem. 1996, 35B, 1267.
35. Chauhan, S. M. S.; Gulati, A.; Sahay, A.; Nizar, P. N. H.
J. Mol. Cad. A: Chem 1995, 105, 159.
We are grateful to Department of Science and Technol-
ogy (DST), Govt. of India and Council for Scienti®c
and Industrial Research (CSIR), New Delhi, India, for
®nancial support.
36. Dolphin, D.; Nakano, T.; Maioni, T. E.; Kirk, T. K.;
Farrell, R. In Lignin Enzymic and Microbial Degradation;
Odier E. (Ed.); INRA, Paris, 1987; p. 157.
References
1. Zaks, A.; Dodds, D. R. Drug Discovery Today 1997, 2, 513.
2. Smith, W. L.; Marnett, L. J. Biochem. Biophys. Acta. 1991,
1083, 1.
37. Turk, H.; Ford, W. T. J. Org. Chem. 1991, 56, 1253.
38. Leanord, D. R.; Lindsay Smith, J. R. J. Chem. Soc. Perkin
Trans. 2 1990, 1917.
3. Yamamoto, S. Biochem. Biophys. Acta. 1992, 1128, 117.
4. Karthein, R.; Dietz, R.; Nastainczyk, W.; Ruf, H. H. Eur. J
Biochem. 1988, 171, 313.
5. Smith, W. L.; Marnett, L. J.; Dewitt, D. L. Pharmacol.
Ther. 1991, 49, 143.
39. Lucia, B. D.; Elmer, S. G.; Gheorghe, B.; Ileana, F.; Radu,
I. M. Rom, 64,337(Cl CO7C49/78) 16 June 1979, Appi 84,
889, 21 Feb 1976; Chem Abs. 1981, 95, 678.
40. Varadaraj, E.; Kenneth, G. F.; Alan, M. M.; Graham,
N. M.; Edward, G. J.; Lee, S. B.; Gary, L. M. Eur. Pat. Appl,
EP 400, 892 (Cl C07C57/30), 5 Dec 1990, US Appl. 357, 381,
24 May, 1989, Chem Abs. 1991, 114, 781.
6. Dunford, H. B.; Stillman, J. S. Coord. Chem. Rev. 1976, 19,
187.