Facile oxidation of alcohols to carboxylic acids in basic water medium by employing ruthenium picolinate cluster as an efficient catalyst

Article abstract of DOI:10.1002/aoc.4574

Selective transformation of alcohols into carboxylic acids is a crucial process in industry for the synthesis of bulk chemicals. Current methods for the production of acids involve oxygen under pressure or toxic reagents like ruthenium chlorite or iodate or chromium oxides. Herein, we report the preparation of [Ru₃(CO)₈(C₅H₄NCO₂)₂] cluster which is an efficient catalyst precursor for the conversion of primary alcohols into carboxylic acids under aerobic conditions. The catalytic process involves the use of NaOH in a water–isopropanol medium which gives a 90% yield of carboxylic acid (90% yield for benzoic acid in standard reaction). This clean process appears to be safe for the synthesis of various benzoic acids for both laboratory and also industrial purposes.

Full text of DOI:10.1002/aoc.4574

Received: 23 May 2018
DOI: 10.1002/aoc.4574
Revised: 28 July 2018
Accepted: 31 July 2018
F U L L P A P E R
Facile oxidation of alcohols to carboxylic acids in basic
water medium by employing ruthenium picolinate cluster
as an efficient catalyst
Ajeet Singh1
| Sandip K. Singh1 | Anoop K. Saini1 | Shaikh M. Mobin1,2,3
|
Pradeep Mathur1
1 Discipline of Chemistry, Simrol,
Selective transformation of alcohols into carboxylic acids is a crucial process in
industry for the synthesis of bulk chemicals. Current methods for the produc-
tion of acids involve oxygen under pressure or toxic reagents like ruthenium
chlorite or iodate or chromium oxides. Herein, we report the preparation of
[Ru3(CO)8(C5H4NCO2)2] cluster which is an efficient catalyst precursor for
the conversion of primary alcohols into carboxylic acids under aerobic condi-
tions. The catalytic process involves the use of NaOH in a water–isopropanol
medium which gives a 90% yield of carboxylic acid (90% yield for benzoic acid
in standard reaction). This clean process appears to be safe for the synthesis of
various benzoic acids for both laboratory and also industrial purposes.
Khandwa Road, Indore 453552, India
2 Discipline of Biosciences and Bio‐
Medical Engineering, Simrol, Khandwa
Road, Indore 453552, India
3 Discipline of Metallurgy Engineering and
Materials Science, Indian Institute of
Technology Indore, Simrol, Khandwa
Road, Indore 453552, India
Correspondence
Shaikh M. Mobin and Pradeep Mathur,
Discipline of Chemistry, Simrol, Khandwa
Road, Indore 453552, India.
Email: xray@iiti.ac.in; director@iiti.ac.in
KEYWORDS
Funding information
carboxylic acid, hydrobenzoin, monoclinic, picolinate ligands, Ru3(CO)12 cluster
Science and Engineering Research Board‐
Department of Science and Technology
(SERB‐DST), Grant/Award Number:
EMR/2016/001113
1 | INTRODUCTION
catalytic synthesis of carboxylic acid derivatives from
alcohols was initially performed with ruthenium hydride
Benzoic acid and its derivatives are important precursors
for the synthesis of useful organic compounds.[1–4] Sev-
eral hundred thousand tons of benzoic acid for industrial
applications is produced every year.[5,6] Benzoic acid is a
main component in food preservatives[7] mostly because
of its antifungal[8,9] and antimicrobial activities.[9] Its
derivatives are also useful for the production of plasti-
cizers,[10] alkyd resins[11,12] and polymers.[13,14]
In the past few decades, the use of transition metal
complexes has contributed tremendously to catalytic
organic synthesis.[15–21] Oxidations of alcohols to carbox-
ylic acids require various oxidants in large quantity, like
KMnO4, iodosobenzene, t‐BuOOH and chromium oxide,
and thus produce copious waste.[22] Whereas, the
complexes, polyoxometallates or PNN pincer com-
plexes.[23–26]
Rhodium‐catalysed oxidation of alcohol to carboxyl-
ate at high pH and using ketone as a hydrogen acceptor
under mild conditions was reported by Grützmacher
and co‐workers.[27] A heterogeneous copper system[28]
with NaOH at 320°C under high pressure has also been
used for catalytic oxidation of alcohols to carboxylates.[29]
For the oxidation of alcohols to carboxylic acids, a new
clean and atom‐economic approach has been introduced
by Milstein and co‐workers using water as the oxygen
donor in the presence of a base and using a ruthenium
hydride PNN pincer catalyst.[30] The reaction takes place
with dehydrogenation of alcohol to give coordinated
Appl Organometal Chem. 2018;e4574.
wileyonlinelibrary.com/journal/aoc
© 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4574

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SINGH ET AL.
FIGURE 1 Ruthenium‐based active
catalysts for carboxylic acid synthesis from
alcohols.
aldehyde to which water addition allows the formation of
carboxylic acid.[30] Prechtl and co‐workers also reported
carboxylic acid formation from alcohols using ruthenium
hydride PNP pincer catalyst (Figure 1(ii,b))[31] and Beller
and co‐workers converted renewable glycerol into 2‐
oxopropanoic acid using ruthenium hydride PNP pincer
complex (Figure 1(ii,a)).[32] By contrast, Möller and co‐
workers used a simple ruthenium (II)–N‐heterocyclic
carbene complex to perform this transformation
(Figure 1(iii)).[33] Peng and co‐workers used a ruthenium
complex containing a new 2,6‐bis(benzimidazole‐2‐yl)pyr-
idine pincer ligand for this catalytic transformation
(Figure 1(iv)),[34] whereas Gauvin and co‐workers[35] have
shown that recyclable PNP–ruthenium hydride catalysts,
prepared in situ by addition of PNP ligand to [Ru(H)(X)
(CO)(PPh3)3] (X = H, Cl), were efficient for the oxidation
of primary alcohols into carboxylates (Figure 1(ii,c)).[35]
Recently Bera and co‐workers reported that this oxidation
reaction could be efficiently performed using a non‐pincer
ruthenium hydride complex (Figure 1(v)).[36]
Most of the above mentioned efficient ruthenium cat-
alysts for the transformation of alcohol to carboxylate in
basic water involve ruthenium hydride or pincer ruthe-
nium catalysts. In this report, we describe the preparation
of
a
new ruthenium carbonyl cluster, namely
[Ru3(CO)8(C5H4NCO2)2] (1), containing two simple
TABLE 1 Screening of catalyst for transformation of benzyl alcohol to benzoic acid in basic water and dioxane as solventa
Catalytic oxidation
Entry
Component 1
Component 2
Adduct/cluster
reactionb
1
Ru3(CO)12
1
R
2
Ru3(CO)12
2
R
3
4
Ru3(CO)12
Ru3(CO)12
3
4
NR
NR
5
Ru3(CO)12
—
NR
aReaction conditions: benzyl alcohol (5 mmol), base (10 mmol), catalyst (1 mol%), H2O (500 μl), solvent (500 μl) were stirred at bath temperature of 98°C in an
oil bath in open atmosphere.
bR, reaction successful; NR, no reaction.

SINGH ET AL.
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their appropriate five‐membered chelation to Ru3(CO)12
which is not possible with nicotinic and isonicotinic acid
ligands. The chelation environment is confirmed by the
structure of cluster 1. It was authenticated by single‐crys-
tal X‐ray studies.
2.2 | Structural Description of Catalyst 1
Cluster 1 was obtained by reaction of Ru3(CO)12 with
simple chelation of picolinic acid in toluene at 110°C for
an hour. The molecular structure of 1 revealed the bind-
ing modes of picolinic acid ligand to Ru3(CO)12 and the
crystal structure is shown in Figure 2. The detailed struc-
tural parameters of complex 1 are presented in Table 2.
SCHEME 1
▪
chelating pyridine‐carboxylate ligands (Figure 1(vi)), as
an efficient catalyst, without pincer ligand, for the trans-
formation of a variety of alcohols into carboxylic acids
in basic water–isopropanol medium with good yields.
TABLE 2 Crystal data and structure refinement for complex 1
Identification code
Complex 1
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
a (Å)
C10H4NO6Ru1.5
385.75
2 | RESULTS AND DISCUSSION
2.1 | Catalyst Screening
293(2)
Monoclinic
Pn
The oxidation of benzyl alcohol into carboxylic acid was
carried out using a catalyst arising in situ from Ru3(CO)12
and a pyridine derivative containing a carboxylate group
picolinic acid (1a), pyridine‐2,6‐dicarboxylic acid (1b),
nicotinic acid (1c) and isonicotinic acid (1d) to afford
the adducts 1–4, respectively (Table 1). It was found that
adduct/cluster 1 and adduct 2 were active in the catalytic
transformation of alcohols to carboxylic acids using
NaOH in an open atmosphere for 14 h at bath tempera-
ture of 98°C in water–solvent (Scheme 1) likely due to
9.45480(10)
11.71470(10)
11.03310(10)
90
b (Å)
c (Å)
α (°)
β (°)
98.2050(10)
90
γ (°)
Volume (Å3)
1209.52(2)
4
Z
ρcalc (g cm−3
)
2.118
μ (mm−1
)
15.593
F (000)
740
Crystal size (mm3)
Radiation
0.34 × 0.33 × 0.29
Cu Kα (λ = 1.54184 Å)
7.546 to 142.5
2θ range for data collection (°)
Index ranges
−8 ≤ h ≤ 11, −14 ≤
k ≤ 14, −13 ≤ l ≤ 13
Reflections collected
6597
Independent reflections
3023 [Rint = 0.0467,
Rsigma = 0.0271]
Data/restraints/parameters
Goodness‐of‐fit on F 2
3023/2/334
1.091
Final R indexes [I ≥ 2σ(I)]
Final R indexes [all data]
R1 = 0.0487, wR2 = 0.1282
R1 = 0.0494, wR2 = 0.1343
1.52/−1.43
Largest diff. peak/hole (e Å−3
)
CCDC no.
1576762
FIGURE 2 Perspective view of cluster 1.

4 of 10
SINGH ET AL.
The structure of 1 is symmetric and it crystallized in
76.88°; the trans N–Ru–Ru angle is 158.93° in complex
1. Two carbonyls are attached to each ruthenium atom
bearing picolinate ligand. Overall two picolinate and
eight carbonyl ligands are attached to three ruthenium
atoms. Complex 1 has a glide plane perpendicular to [0,
1, 0] with glide component [1/2, 0, 1/2]. The order of
the glide plane is 2. Perspective view of the glide planes
is shown in the supporting information (Figure S1).
The distance between two ruthenium atoms (Ru1 and
Pn space group with monoclinic crystal system. In this
structure, the asymmetric unit consists of one picolinate
ligand attached to one ruthenium atom by the nitrogen
atom and one oxygen atom. The oxygen of the picolinate
ligand is bridging the two ruthenium atoms, each
adopting a distorted octahedral RuC2N1O2 coordination
sphere (Figure 2). The unique O–Ru–O cis bite angle is
76.33°, and similarly, the other O–Ru–O bite angle is
FIGURE 3 Hydrogen‐bonded one‐dimensional network in 1 along c‐axis.
TABLE 3 Optimization for synthesis of benzoic acid from benzyl alcohola
Yield (%)
Reaction
Base
Entry
Solvent
atmosphere
(10 mmol)
Time (h)
Conv. (%)
Benzoic acid
Hydrobenzoin
1
Dioxane
H2O/Ar
H2O/Ar
H2O/Ar
H2O/Ar
H2O/Ar
H2O/Ar
Ar
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
14
14
10
24
12
12
24
12
12
12
12
12
24
65
19
2
21
19
1
42
0
2
Methanol
Isopropanol
DMF
3
0
4
74
17
24
7
9
35
0
5
Chloroform
Acetonitrile
DMF
7
6
10
0
0
7
0
8
Water
Ar
0
0
0
9
Methanol
Ethanol
H2O/O2
H2O/O2
H2O/O2
H2O/O2
H2O/O2
69
82
90
40
34
69
81
90
27
2
0
10
11
12
13
0
Isopropanol
t‐Butanol
Isopropanolb
0
0
32
aReaction conditions: benzyl alcohol (5 mmol), base (10 mmol), catalyst 1 (1 mol%), H2O (500 μl), solvent (500 μl) were stirred at bath temperature of 98°C in an
oil bath in open atmosphere. Products were analysed using GC‐MS and 1H NMR.
bRoom temperature (25°C).

SINGH ET AL.
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Ru2) is 3.068 Å which is more than that in the tradi-
tional Ru3(CO)12 crystal structure (2.848 Å).[37] Ru1 and
Ru2 are bonded to Ru3 with bond lengths of 2.778 and
2.764 Å, respectively. The ruthenium atoms Ru1 and
Ru2 are attached to two oxygen atoms sharing the elec-
tron pair, i.e. lone pair (2.207 Å) and bond pair
(2.148 Å). Nitrogen donates its lone pair to Ru1 and
Ru2 atoms with bond length of 2.514 Å.
Complex 1 forms a one‐dimensional polymeric chain
using C─H⋅⋅⋅O interaction, i.e. H4⋅⋅⋅O5 with distance
2.705 Å, and H1⋅⋅⋅O2 and H8⋅⋅⋅O4 with distances of
2.364 and 2.478 Å, respectively (Figure 3). The one‐
dimensional chain extends to a two‐dimensional network
via π–π interaction between C6 and C10 with a distance
of 3.354 Å (supporting information, Figure S2).
2.3 | Catalytic Experiments
The oxidation reaction of benzyl alcohol (Scheme 1)
using 1 mol% of catalyst 1 was evaluated in water in the
presence of various solvents between 75 and 100°C. Using
dioxane or dimethylformamide (DMF) with water, a side
product, hydrobenzoin, was obtained along with benzoic
acid in inert (argon) atmosphere (Table 3, entries 1 and
TABLE 4 Comparative study of benzoic acid formation from benzylic alcohol using ruthenium complexes
Catalyst or
Entry
pre‐catalyst
Substrate
Reaction parameters
Yield (%)
Ref.
[30]
1
Alcohol
Catalyst, NaOH, water (reflux),
18 h, argon
84
[31,32,35]
2
3
4
Alcohol
1) Catalyst, NaOH, 120°C, 20 h
2) Catalyst, KOH, 125°C, 20 h
1) 67
2) 92
[33]
Alcohol
Catalyst, NaOH, water
(reflux), 24 h
92
82
[34]
Benzyl alcohol
Catalyst, CsOH, water
(reflux), 24 h (argon)
[36]
5
6
Benzyl alcohol
Benzyl alcohol
Catalyst, water, NaOH,
110°C, 6–24 h
100
90
Catalyst, NaOH, water,
isopropanol, 98°C, 12 h
This work

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SINGH ET AL.
4), whereas the same by‐product was obtained at the
lower temperature of standard condition (Table 3, entry
13). Using alcohols, chloroform and acetonitrile with
water in inert atmosphere gave only benzoic acid, but in
lower yields (Table 3, entries 2, 3, 5, 6). Neat solvents like
DMF and t‐butanol gave a lower yield in inert and open
environment, respectively (Table 3, entry 7 and Table S2,
entry 1). Using neat water in an argon atmosphere, with-
out any other solvent, and without base, the reaction did
not give any oxidized product (Table 3, entry 8 and Table
S2, entry 2, respectively) as catalyst 1 is not soluble in
neat water. In general, when the reactions were per-
formed either in water and alcohol medium (inert atmo-
sphere) or neat alcohol medium in open atmosphere,
both led to lower yield of product. In contrast, when the
reaction was performed in isopropanol and water (1:1)
as the medium in open air atmosphere, a higher yield
(90%) of benzoic acid was observed at 98°C (Table 3,
entry 11). This significant result proves the importance
of cluster 1 in catalysing the reaction of alcohol to carbox-
ylic acid in basic water in open atmosphere. Several alco-
hols along with water as reaction medium were also
studied, with isopropanol appearing as the most suitable
solvent for this reaction (Table 3, entries 10–13).
We evaluated various bases in the oxidation reaction,
K2CO3, KOH and NaOH. The most efficient bases were
found to be KOH and NaOH as they are effective for
de‐protonation in alcohol/solvent medium. Interestingly,
TABLE 5 Synthesis of carboxylic acid derivatives from alcoholsa
Entry
Reactant
Product
Conversion (%)
Yield by GC‐MS (%)b
1
70
66
2
3
43
90
41
34
4
5
6
75
20
95
71
19
25
7
98
65
8
9
44
54
34
34
aReaction conditions: alcohol (5 mmol), NaOH (10 mmol), catalyst 1 (1 mol%) were heated in an open atmosphere at bath temperature of 98°C. The reaction
time was 14 h. Derivatives of benzoic acid were obtained by 2 M HCl acid treatment of the reaction mixture. Products were analysed using GC‐MS, 1H NMR and
13C NMR.
bYields measured by GC‐MS are the average of three reactions with 5% error observed.

SINGH ET AL.
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FIGURE 4 Plausible mechanism for catalytic oxidation of alcohol to carboxylic acid using ruthenium cluster [Ru3(CO)8(C5H4NCO2)2].
NOTE: Editable chemdraw files are also attached in the next 2 pages
at room temperature, hydrobenzoin was formed in high
quantity and, as the temperature was increased (60°C),
the formation of benzoic acid was enhanced. The optimi-
zation studies of temperature proved that the reaction
was even possible at room temperature, 60 and 75°C
but with lower conversion of benzyl alcohol to benzoic
acid. This study proves that the catalyst 1 is also active
even at lower temperature.
Previous examples of the synthesis of benzoic acid from
alcohol as reported previously are summarized in Table 4.
So far the reported catalysts (Table 4, entries 1–5) are
either ruthenium hydride or ruthenium pincer complex
precursors which require much effort and sensitive envi-
ronment for their synthesis. In addition, the catalytic oxi-
dation also needs a higher temperature. However, 1 is
easily obtained by the simple chelation of picolinic acid
ligand to Ru3(CO)12 by refluxing in toluene for an hour.
Moreover, the reaction conditions for catalytic oxidation
are also comparatively mild.
The substrate scope of the oxidation reaction is
presented in Table 5. The catalytic oxidation is more
favourable for substituents with electron‐donating induc-
tive effect (Table 5, entries 1 and 4). Para‐substituted ben-
zyl alcohols are more easily oxidized than ortho‐

8 of 10
SINGH ET AL.
substituted benzyl alcohols likely because they are not
creating any steric hindrance. The reaction was also per-
formed with cyclic aliphatic compound; however, an infe-
rior yield was obtained (Table 5, entry 5). The p‐chloro‐
substituted benzyl alcohol gave a higher yield than p‐
bromo‐substituted benzyl alcohol because of stronger
C─Cl bond than C─Br bond, as benzoic acid is the other
by‐product along with p‐halobenzoic acid. To prove the
efficiency of catalyst 1 for aliphatic alcohol derivatives,
2‐phenylethan‐1‐ol and 2‐phenylpropan‐1‐ol were also
explored and desired carboxylic acids were formed. So,
the catalyst was also found to be active for aliphatic deriv-
atives. Furthermore, when pyridyl ring‐substituted com-
pounds were used instead of benzyl substituents, the
oxidation reaction did not occur, which is attributed to
pyridine ring interaction with ruthenium and deactiva-
tion of catalyst 1.
Several attempts were made to isolate the intermedi-
ate following various procedures[30,36,38,39] by reacting
catalyst and benzyl alcohol in aqueous methanol as well
as in CHCl3. Unfortunately, the intermediate could not
be isolated successfully. The role of the picolinic acid
anion is most likely to assist removal of CO and subse-
quent addition of PhCH2O− ligand.
The plausible oxidation mechanism is based on the
Milstein mechanism for ruthenium(II) pincer catalyst[30]
and here the catalytic transformation takes place at one
of the Ru centres bridged by two picolinate ligands as
Ru3(CO)12 itself does not catalyse the alcohol oxidation.
After CO elimination, there follows the initial coordina-
tion of the deprotonated alcohol (PhCH2O−) to one of
the two bridged Ru atoms (Figure 4, 1a). This is followed,
after CO de‐coordination, by hydride beta‐elimination
from the Ru–OCH2Ph species to give the coordinated
aldehyde HRu(O═CHPh) (1b).[30,36] Further reaction
with water gives a gem‐diolate complex and H2 elimina-
tion (1c). Beta‐hydride elimination gives the final carbox-
ylic acid product, and the RuH(CO) species (1d) is able to
deprotonate PhCH2OH to give 1a.
the primary alcohol to carboxylic acid at a relatively
low temperature (98°C) in water in open environment
(Scheme 1). Moreover, cluster 1 shows selectively high
yield (90%) in water and isopropanol as the reaction
medium. In the catalytic system, both water and oxygen
(from the open atmosphere) take part in the oxidation of
alcohol to carboxylic acid. These findings may open a
route to the design of new clusters for the transforma-
tion of alcohols to corresponding carboxylic acid
derivatives.
4 | EXPERIMENTAL
4.1 | Materials and Instrumentation
Ru3(CO)12, picolinic acid and alcohol derivatives were
purchased from Aldrich and TCI Chemicals. Reagents
used for purification and crystallization of products were
purchased from Rankem and Merck and used as
received. NMR spectra were recorded in CDCl3 with a
Bruker Avance (III) spectrometer (400 MHz). X‐ray
structural study of complex 1 was carried out using an
Agilent Technologies Supernova CCD system. Samples
were analysed using a Shimadzu QP2010 Ultra equipped
with Rtx‐5MS column (length 30 m, internal diameter
0.25 mm). The column oven programme was used as
40°C (hold 5 min) → 20°C min−1 → 280°C (hold
13 min) along with injection temperature of 280°C,
interface temperature of 300°C and ion source tempera-
ture of 220°C.
4.2 | Single‐Crystal X‐ray Diffraction
A graphite‐monochromated Cu Kα (λα = 1.54184 Å)
source at 25°C was used to collect data. The standard
phi–omega scan technique was used to collect data.
The interpretation of the collected data was done using
CrysAlisPro CCD software. The SHELXS‐97 direct
method was used to produce the crystal structures
and refinement was done by the full‐matrix least‐
squares method on F2.[40] Olex‐1.2 software was also
used.[41] All the C─H⋅⋅⋅π interactions,[42] molecular
drawings and mean plane analyses were obtained by
Diamond (version 3.1d) and Mercury (version 3.1).
The crystal structure and refinement data are shown
in Figure 2 and presented in Table 4, respectively.
And the bond distances and bond angles are presented
in Table S1.
3 | CONCLUSIONS
In summary, a new Ru3(CO)12‐based pyridine–acid clus-
ter, [Ru3(CO)8(C5H4NCO2)2], was synthesized by facile
addition of picolinic acid to Ru3(CO)12, which was char-
acterized using single‐crystal X‐ray diffraction. Complex/
catalyst 1 was evaluated for the catalytic oxidation of
alcohol to carboxylic acid (yield of 90%) using basic
water in open atmosphere. The crystal structure of com-
plex 1 revealed C─H⋅⋅⋅O and π–π interactions. Catalyst 1
is comparable with previously reported ruthenium
hydride or ruthenium pincer complexes as it converts
4.3 | Catalytic Reaction
Amounts of 5 mmol of benzyl alcohol and 10 mmol of
NaOH were mixed with 500 μl of water and 500 μl of

SINGH ET AL.
9 of 10
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isopropanol solvent media. Catalyst 1 (1 mol%) was
added. The reaction was performed at bath temperature
of 98°C in the atmospheric oxygen environment. After
14 h, the solvent was evaporated and a white precipitate
was observed. An amount of 5 ml of 2 M HCl was added
to the reaction mixture and stirred for 5 min. Then 5 ml
of ethyl acetate was added and extraction was done
using ethyl acetate (5 × 3 ml). Then after brine wash,
the recovered mixture was passed through a small col-
umn of sodium sulfate. After evaporation of the solvent,
white solid benzoic acid was obtained. The solid was
recrystallized using methanol and the NMR data show
benzoic acid formation. The yield of benzoic acid was
90% which was similar to the result observed using
GC‐MS.
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4.4 | Analysis of Products
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ACKNOWLEDGEMENTS
[20] W. Yang, L. Wei, T. Yan, M. Cai, Catal. Sci. Technol. 2017, 7,
1744.
Financial support from the Science and Engineering
Research Board‐Department of Science and Technology
(SERB‐DST project no. EMR/2016/001113), New Delhi,
and IIT Indore is gratefully acknowledged by S.M.M.,
and A.S. thanks UGC, New Delhi for providing a fellow-
ship and Sophisticated Instrumentation Centre (SIC),
IIT Indore. S.K.S. thanks IIT Indore for financial support.
P.M. gratefully acknowledges a J. C. Bose National
Fellowship.
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SUPPORTING INFORMATION
Additional supporting information may be found online
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How to cite this article: Singh A, Singh SK,
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alcohols to carboxylic acids in basic water medium
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