Expedient method for oxidation of alcohol by hydrogen peroxide in the presence of amberlite IRA 400 resin (basic) as phase-transfer catalyst

Article abstract of DOI:10.1080/00397910801916090

Amberlite IRA 400 (strongly basic), a classical polymer imparts phase-transfer catalysis in the oxidation of primary and secondary alcohols by hydrogen peroxide to give excellent yields of the corresponding carbonyl compounds or carboxylic acids in acetonitrile solvent at reflux temperature in 4-6 h. The catalytic system is inert to other susceptible oxidation sites such as carbon-carbon double bonds. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910801916090

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Expedient Method for Oxidation of Alcohol
by Hydrogen Peroxide in the Presence
of Amberlite IRA 400 Resin (Basic) as
Phase‐Transfer Catalyst
Nishi Bhati a , Kuladip Sarma a & Amrit Goswami a
a Synthetic Organic Chemistry Division, North East Institute of Science and
Technology, Jorhat, Assam, India
Version of record first published: 25 Apr 2008.
To cite this article: Nishi Bhati , Kuladip Sarma & Amrit Goswami (2008): Expedient Method for Oxidation of
Alcohol by Hydrogen Peroxide in the Presence of Amberlite IRA 400 Resin (Basic) as Phase‐Transfer Catalyst,
Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
38:9, 1416-1424
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Synthetic Communicationsw, 38: 1416–1424, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910801916090
Expedient Method for Oxidation of Alcohol
by Hydrogen Peroxide in the Presence
of Amberlite IRA 400 Resin (Basic) as
Phase-Transfer Catalyst
Nishi Bhati, Kuladip Sarma, and Amrit Goswami
Synthetic Organic Chemistry Division, North East Institute of Science
and Technology, Jorhat, Assam, India
Abstract: Amberlite IRA 400 (strongly basic), a classical polymer imparts phase-
transfer catalysis in the oxidation of primary and secondary alcohols by hydrogen
peroxide to give excellent yields of the corresponding carbonyl compounds or car-
boxylic acids in acetonitrile solvent at reflux temperature in 4–6 h. The catalytic
system is inert to other susceptible oxidation sites such as carbon–carbon double bonds
Keywords: Amberlite resin, oxidation, progesterone, sodium tungstate
Catalytic oxidation of alcohols to the corresponding carbonyl compounds and car-
boxylic acids is a highly desirable functional group transformation both in indus-
trial chemistry as well as in organic synthesis because of the wide-ranging utility
of these products as important precursors and intermediates for many drugs,
vitamins, and fragrances.[1,2] Historically such oxidations were carried out with
toxic oxo chromium(V) reagents,[3] pyridinium chlorochromate,[4] hypochlor-
ites,[5] permanganate,[6] oxidants, etc. Subsequent developments involved the
use of other oxidizing agents activated by different transition metals,[7,8] heavy
metals,[9] halides,[10] dimethyl sulphoxide (DMSO),[11] hypervalent iodines
such as Des-Martin-Periodate,[12] etc. However, these reagents are either toxic,
hazardous to handle, cannot be stored because of their explosive nature, or
Received October 17, 2007
Address correspondence to Amrit Goswami, Synthetic Organic Chemistry Division,
North East Institute of Science and Technology, Jorhat, Assam, India 785 006. E-mail:
amritg_2007@rediffmail.com
1416

Oxidation of Alcohol
1417
sensitive to other susceptible sites apart from the target, and in some cases it is
cumbersome to recover the catalyst from the products. Quite a few reports[13–
16]
have appeared using oxygen or hydrogen peroxide under different catalytic
conditions for such purposes, but these are not devoid of many problems.
Keeping in mind the different problems associated with the reported methods
and taking the mandatory environmental considerations into account, it was
deemed desirable to have a recyclable catalytic system for oxidation of primary
and secondary alcohols using hydrogen peroxide as the oxidant because it is con-
venient and cheap and produces water as the only by-product.
RESULTS AND DISCUSSIONS
Because hydrogen peroxide is the desired green oxidant of choice[17] and also
because of our success[18] in the oxidative transformation of functional group,
we wanted to study the much-sought-after oxidation of primary and secondary
alcohols with hydrogen peroxide under the influence of a suitable catalytic
system that is recyclable and hence economical, mild and efficient. Among
the polyoxometallic compounds, sodium tungstate is considered as ecologi-
cally benign[19] and suitable to activate hydrogen peroxide (Scheme 1).
Therefore, we studied the oxidation of several primary and secondary
aliphatic and aromatic alcohols with hydrogen peroxide (30%) using sodium
tungstate in the presence of strongly basic amberlite IRA-400 resin in chloride
form. The use of basic amberlite IRA-400 resin has two advantages. First, it
acts as a phase-transfer catalyst (PTC), and second, it can very easily be
separated out from the reaction mixture as it remains in the solid form. The
molar ratio of the substrate–hydrogen peroxide–sodium tungstate was 10:40–
60:1. Sodium tungstate needs activation prior to its participation in the
oxidation reaction. Reaction was therefore performed by first stirring together
sodium tungstate and hydrogen peroxide (30%) in the presence of a little
dilute sulfuric acid for about 30 min at room temperature at pH 1.5 followed
by addition of the substrate, amberlite resin, and more of hydrogen peroxide in
acetonitrile. It was refluxed for 4–6 h to give a good yield of the carbonyl
products. The catalyst Na2WO4 was first oxidized by hydrogen peroxide to bis-
peroxotungstate complex (A), which is feebly active towards alcohols
(Scheme 2). However, at pH 1.5, this peroxo complex was converted to the
Scheme 1.

1418
N. Bhati, K. Sarma, and A. Goswami
Scheme 2.
monoprotonated active form (B), which remains in equilibrium with the diproto-
nated form (C). The diprotonated bisperoxo complex (C) present as minor
component is reactive in the homogenous phase but unable to move into the
organic phase. The dominant active monoprotonated complex (B) formed at
pH 1.5 moves into the organic phase by the exchange of its anionic part with
the chloride anion of the basic resin (QþCl2, Qþ ¼ ammonium cation on
styrene divinylbenzene matrix) and oxidized the substrate alcohol to the corre-
sponding carbonyl compound. The requirement of acidic pH is therefore
advocated for the formation of the active monoprotonated bisperoxotungstate
complex (B), and the basic resin has no role to play at this stage but is
essential at the later stage to bring it to the organic phase through exchange
and carry forward the oxidation.
When this reaction was carried out[20] in the presence of a strongly acidic
resin (amberlite IR 120 resin, sulphonic acid group on styrene divinylbenzene
matrix), the entire reaction followed a different course to form phenolic
compounds from the benzylic alcohols, which is under further investigation.
The reaction was studied in a series of solvents to check the efficiency in
terms of product yield, time duration, and temperature (Table 1) with three
Table 1. Oxidation of alcohols to carbonyls in different solvent systems using
Na2WO4, H2O2 (30%) and amberlite IRA-400 resin (strongly basic)
Yield (%)b
Entry
Solvent
Time (h)
Temperature (8C)
7
10
14
1
2
3
4
5
Dichloromethanea
Dichloroethane
Acetonitrile
Ionic liquid
Water
120
8–16
4–6
42
80
80
50
90
—
81
86
75
73
—
87
93
80
79
—
90
96
83
81
7–10
12–16
aProducts were not isolated.
bIsolated yield.

Oxidation of Alcohol
1419
Table 2. Oxidation of primary and secondary alcohols to carbonyls and carboxylic acids
Reaction condition
Alcohol–H2O2–
Na2WO4
Time Yield
(%)b
Entry
Substrate
Producta
(h)
1
2
Benzyl alcohol Benzaldehyde
4-Methoxybenzyl 4-Methoxy
10:50:1
10:50:1
4
4
83
79
alcohol
4-Nitrobenzyl
alcohol
benzaldehyde
4-Nitro
benzaldehyde
4-Chloro
benzaldehyde
3
4
10:50:1
10:50:1
4
4
81
80
4-Chlorobenzyl
alcohol
5
6
7
8
Cinnamyl alcohol Cinnamaldehyde
10:50:1
10:40:1
10:40:1
10:40:1
4
5
5
6
73
84
86
78
Cyclopentanol
Cyclohexanol
2,6-Dimethyl
cyclohexanol
4-tert-Butyl
cyclohexanol
1-Phenyl ethanol
1-(4-iso-Butyl)-
phenyl ethanol
Benzoin
Cyclopentanone
Cyclohexanone
2,6-Dimethyl
cyclohexanone
4-tert-Butyl
9
10:40:1
6
63
cyclohexanone
Acetophenone
4-Isobutyl
10
11
10:60:1
10:60:1
5
6
93
87
acetophenone
Benzil
12
13
14
15
16
17
18
10:40:1
10:60:1
10:60:1
10:60:1
10:60:1
10:60:1
10:60:1
6
6
4
6
6
6
6
87
73
Cholesterol
Benzhydrol
Octanol
5-Cholesten-3-one
Benzophenone
Octanoic acid
Hexanoic acid
(+)-Camphor
2-Methylbutyric
acid
96
85c
90c
61
Hexanol
Borneol
2-Methyl-1-
butanol
81
19
20
4-Hydroxy-3-
methoxybenzyl
alcohol
Vanillin
10:60:1
10:60:1
4
5
75
73
Pregnenelone
Pregn-5-ene-3,20-
dione
aThe products were identified by comparison of physical and spectroscopic data with
the authentic samples.[8b,10d,21,22]
bIsolated yield.
cRemaining ester.
representative substrates, viz cyclohexanol, 1-phenylethanol, and benzhydrol
(7, 10, and 14, Table 2). Although the reaction does not take place at all in
dichloromethane, it gives the best yield in acetonitrile at reflux temperature
in half the time (4–6 h) as water and dichloroethane (8–16 h). On the other
hand, the reaction in ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate

1420
N. Bhati, K. Sarma, and A. Goswami
was completed within 7–10 h at 50 8C with 75–83% yield. It is clear from
Table 2 that most substrates underwent direct oxidation to give the correspond-
ing aldehydes, ketones, acids, and esters in excellent yields. The oxidation of
aliphatic as well as aromatic secondary alcohols (6–12, 14, Table 2)
proceeded with high efficiency to give ketones, and the primary aromatic
alcohols proceeded with moderate efficiency to give aldehydes (1–5, 17, 19,
Table 2). The primary aliphatic alcohols (15, 16, 18, Table 2) underwent
oxidation to provide synthetically and commercially useful acids or esters.
The resin that functions as the PTC does not require any regeneration and
hence can be used along with the aqueous layer containing the metal catalyst
for more than five runs without any appreciable loss of activity, as no structural
change was observed. This is confirmed from the observation of superimposable
IR spectra of fresh IRA amberlite 400 resin, and the resin was isolated after use
more than five times (Fig. 1). The polymeric basic amberlite resin PTC with
sodium tungstate as the activator for hydrogen peroxides has the advantage
that C55C double bond present in any alcohol substrates is left untouched
(5 and 20, Table 2). The untouchability of the C55C bond by this oxidizing
system is further observed when the synthesis of an important pregnan series
steroidal hormone progesterone (20d) was undertaken as a part of our
continued effort[23] for preparation of different corticosteroid drug intermedi-
ates. Thus, during the oxidation of the secondary hydroxyl group in the
3-position of pregnenolone (20b) by the Oppenauer reaction (Scheme 3), the
5,6 double bond is shifted to the 4,5 position (appeared at dH 5.70 ppm) to
give progesterone[24] with the stable a,b conjugated enone form. However,
when pregnenolone (20b) was oxidized with hydrogen peroxide and sodium
Figure 1. Superimposable IR spectra of fresh amberlite IRA 400 resin (basic) (A) and
the resin isolated after use (B).

Oxidation of Alcohol
1421
Scheme 3. Synthesis of progesterone and pregn-5-ene-3,20-dione: (i) Pd-C/H2, rt,
8 h; (ii) KHSO4–SiO2–MeOH, 64 8C, 4 h.[26]; (iii) H2O2–Na2WO4–amberlite IRA-
400 (resin), 80 8C 6 h; (iv) Oppenauer oxidation; (v) (COOH)2–EtOH, 3 h.[25a]
tungstate with amberlite basic resin, no shift of this double bond at the 5,6
position (appeared at dH 5.23 ppm) was observed in the product pregn-5-ene-
3,20-dione (20c). Pregn-5-ene-3,20-dione is a very important intermediate for
preparation of different 17a-substituted 5-ene-3,20-dione corticosteroid[25]
drugs.
In summary, we have described an expedient method for oxidation of
primary and secondary alcohols by hydrogen peroxide using amberlite IRA
400 resin in chloride form (strongly basic) and sodium tungstate as catalyst.
This method is high yielding, clean, safe, operationally simple, and cost-
effective and can be exploited successfully for large-scale industrial pro-
duction of carbonyl compounds by recycling the catalytic system.
REPRESENTATIVE EXPERIMENTAL PROCEDURE
Sodium tungstate (0.329 g, 1 mmol) was stirred with dil. H2SO4 (0.5 mL, pH
1.5) and H2O2 (30%, 6.8 mL, 0.06 mol) in a 50-mL flask for 30 min. Then
resin (0.1 g, ,1% of the total reaction volume) and diphenylmethanol
(1.84 g, 10 mmol) in acetonitrile (15 mL) were added to the reaction
mixture. The resultant was then heated to 80 8C. The aliquots of the
reaction mixture were taken at different time intervals and monitored by gas
and thin-layer chromatography (TLC). After about 4 h the reaction mixture
was cooled to room temperature. The solid resin was filtered, and the
solvent removed under reduced pressure. The residual aqueous layer was
extracted in ethyl acetate (50 mL) and then washed with water
(3 ꢀ 10 mL), at which time no residual peroxide was detected in the
organic phase. It was dried over anhydrous sodium sulphate and concentrated
under reduced pressure. The residual crude reaction mixture was purified by
silica-gel column chromatography using 20% ethyl acetate in pet. ether
(40–60 8C) as eluent to give the pure ketone benzophenone (1.75 g, 95%).
The catalyst (amberlite resin) was washed thoroughly with ethyl acetate and
dried at 100 8C for 2 h. The same catalyst and aqueous layer were then used

1422
N. Bhati, K. Sarma, and A. Goswami
for other different substrates. The reaction carried out under triphase catalysis
in other organic ionic solvents and water was worked up in an analogous
manner to isolate the products from the organic phase. Similarly the other
substrate alcohols were oxidized to the corresponding carbonyl derivatives
(Table 2).
ACKNOWLEDGMENTS
We gratefully acknowledge the Department of Science and Technology (DST),
New Delhi, for the research grant and P. G. Rao, director, Regional Research
Laboratory, Jorhat, for providing the facility to carry out the work. One of
the authors (N. B.) also appreciates DST, New Delhi, for granting a fellowship
under the Woman Scientist Scheme-A (WOS-A) program.
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