Synthesis of acetamide derivatives using S-MWCNT and S-MC as an efficient heterogeneous catalysts

Article abstract of DOI:10.1166/jnn.2018.14563

Sulphate modified multiwalled carbon nanotubes (S-MWCNT) and Mesoporous carbon (S-MC) catalysts were prepared by wet impregnation method. These materials were characterized by different analytical techniques such as Powder-XRD, BET surface area analysis, SEM-EDS and TEM analysis to evaluate their bulk and surface properties. Surface acidity of the catalyst was measured by TPD-NH3 technique, as well as n-butyl amine titration. The estimated surface acidity of S-MWCNT and S-MC using n-butyl amine titration was found to be 0.82 and 1.75 mmol/g respectively. The catalytic activity of these materials was investigated in the synthesis of acetamide derivatives using aromatic acids with substituted aromatic amines in a liquid phase reaction. The reaction conditions were optimized to achieve good % yield of the products. In general S-MC catalyst exhibited good catalytic activity and gave higher % yield of the respective acetamides than S-MWCNT. This is attributed to higher surface acidity of S-MC, however the catalyst was found to be non-recyclable. S-MWCNT exhibited moderate % yield and 100% selectivity towards the formation of products. S-MWCNT catalyst was recycled up to 5 times with a consistent % yield of the respective acetamide derivatives. The synthesized acetamide derivatives were analyzed by M.P, 1HNMR techniques.

Full text of DOI:10.1166/jnn.2018.14563

Article
Journal of
Nanoscience and Nanotechnology
Vol. 18, 426–433, 2018
Copyright © 2018 American Scientific Publishers
All rights reserved
Printed in the United States of America
www.aspbs.com/jnn
Synthesis of Acetamide Derivatives using S-MWCNT and
S-MC as an Efficient Heterogeneous Catalysts
1
1ꢀ2
3
1ꢀ∗
K. U. Minchitha , H. N. Hareesh , N. Nagaraju , and N. Kathyayini
1Centre for Incubation, Innovation Research and Consultancy (CIIRC), Jyothy Institute of Technology,
Tataguni off Kanakapura Road, 560082, Bengaluru, India
Visvesvaraya Technological University-Research Resource Centre, Jnanna Sangama Belagavi, 590018, Karnataka, India
2
3
Department of Chemistry, St. Joseph’s College P. G. Centre, 46, Langford Road, Shanthinagar Bangalore 560027, Karnataka, India
Sulphate modified multiwalled carbon nanotubes (S-MWCNT) and Mesoporous carbon (S-MC) cat-
alysts were prepared by wet impregnation method. These materials were characterized by different
analytical techniques such as Powder-XRD, BET surface area analysis, SEM–EDS and TEM anal-
ysis to evaluate their bulk and surface properties. Surface acidity of the catalyst was measured by
TPD-NH technique, as well as n-butyl amine titration. The estimated surface acidity of S-MWCNT
3
and S-MC using n-butyl amine titration was found to be 0.82 and 1.75 mmol/g respectively. The
catalytic activity of these materials was investigated in the synthesis of acetamide derivatives using
aromatic acids with substituted aromatic amines in a liquid phase reaction. The reaction conditions
were optimized to achieve good % yield of the products. In general S-MC catalyst exhibited good
catalytic activity andI gP a: v 1e 0 h9 i.g2 h3 e 6r . 5% 3. y1 i e3 l1d Oo fn :t h Se a rt e, s2 p2e cD t iev ec 2a 0c e1 t8a m0 i8d : e3 s7 :t 3h 7a n S-MWCNT. This is
attributed to higher surfac eC ao cp i dy irt iyg ho ft : SA - Mm Ce ,r i hc oa wn e Sv ec ri et nh et if icca tPa ul y bs lt i sw ha es r sf ound to be non-recyclable.
Delivered by Ingenta
S-MWCNT exhibited moderate % yield and 100% selectivity towards the formation of products.
S-MWCNT catalyst was recycled up to 5 times with a consistent % yield of the respective acetamide
1
derivatives. The synthesized acetamide derivatives were analyzed by M.P, HNMR techniques.
Keywords: Multiwalled Carbon Nanotubes, Mesoporous Carbon, Acetamide Derivatives,
Aromatic Amines, Aromatic Acids.
1
. INTRODUCTION
commonly used as catalysts/supports in various organic
1
0
Currently Nanotechnology is the most vital feature which
involves integration of different branches of science and
technology. In the present scenario of research and devel-
opment synthesis, design and fabrication of nanostructured
materials and tuning their materials properties known as
transformations. There are some unique properties of
carbon materials which make them suitable for their
application in numerous catalytic processes. These prop-
erties include (a) chemical stability or chemical inert-
ness, (b) high specific area, (c) eco-friendly in nature,
(d) their tunable porosity and unique surface chem-
istry. Since carbon materials are obtained in different
forms such as tubes, fibers, granules, monoliths, fabrics
and pellets, they can be conveniently used in various
1
–5
nanoarchitectonics is employed in various fields. Among
different nanomaterials, nanocarbons such as graphene,
carbon nanotubes and fullerenes are the most important
representative allotropes which are employed for nanoar-
chitectronics in electronics, biomedical applications, drug
delivery, bioimaging, sensors, batteries, energy storage
systems, nanoelectrocatalysis and also in heterogeneous
catalysis.6
1
1ꢀ12
catalytic reactions.
Modification of carbon materials
with anions, transition metals and transition metal oxides
are widely studied and have exhibited good catalytic
–9
13
activity in many organic reactions such as alkylation,
1
4
15
16
In heterogeneous catalysis, carbon materials such as
mesoporous carbon (MC), activated carbon (AC) as well
as carbon nanotubes (CNTs) and their modified forms are
condensation, transesterification, dimerization, ami-
dation, benzylation18 and esterification etc.
1
7
19
In particular modified MC and CNTs are currently being
used as catalysts supports in organic transformation reac-
tions. Modified MC is known for its catalytic activity due
∗
Author to whom correspondence should be addressed.
426
J. Nanosci. Nanotechnol. 2018, Vol. 18, No. 1
1533-4880/2018/18/426/008
doi:10.1166/jnn.2018.14563

Minchitha et al.
Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
to high surface area, large pore volume, optimal pore size
and ordered pore structure. According to literature, Daiya
MWCNT and MC are abbreviated as S-MWCNT and S-
MC respectively.
2
0
Song et al., prepared aryl sulphonic acid functionalized
MC and used in the synthesis of ethyl levulinate from
2.3. Characterization of S-MWCNT and S-MC
2
1
levulinic acid and furfuryl alcohol. Lingtao and his co-
workers prepared phosphoric acid modified MC and used
as novel solid acid catalysts in the synthesis of methyl
oleate from oleic acid and methanol in esterification reac-
tion. Another Interesting carbon material is CNTs which
exhibits remarkable catalytic activity, when it is used as
supports in organic reactions. This is attributed to its
unique properties such as electrical and thermal conductiv-
ity; uniform pore size distribution, high length to diameter
The prepared catalytic materials were characterized by
appropriate analytical techniques. Powder X-ray diffrac-
tion (Powder-XRD) patterns were recorded on a Panalyti-
cal Xpert pro X-ray diffractometer using Cu Kꢁ radiation
ꢀ
ꢀ
(
ꢂ = 0ꢃ154 nm) in the 2ꢄ range of 5 to 70 at 40 kV
ꢀ
with a scanning rate of 2 /min. Brunauer, Emmett and
Teller (BET) surface area was determined from Quan-
tachrome Nova-1000 surface analyzer. Morphology and
elemental composition of the materials were determined by
Scanning Electron Microscopy-Energy Dispersive X-ray
Spectroscopy (SEM–EDS) techniques using Quanta 200
FEI instrument. Transmission Electron Microscopy (TEM)
images were recorded on Tecnai instrument. Surface acid-
ity of the materials was determined using Temperature-
2
2
23
aspect ratio and high surface area. Zhou et al., have pre-
pared functionalized MWCNT supported TiO and used it
2
in the transesterification of dimethyl carbonate with phenol
2
4
to synthesize methyl phenol carbonate. Xianbing et al.,
have modified MWCNT via carboxylic acid formation and
studied esterification of glycerol with acetic acid. Further
sulphuric acid modified MC and MWCNT are being devel-
oped as catalysts supports in the synthesis of organic fine
chemicals due to easy separation and recovery from the
reaction mixture as well as their convenient reusability was
Programmed Desorption-Ammonia (TPD-NH ꢅ analyzer
3
using Mayura analytical instrument as well as n-butyl
amine back titration method.
2
5
2.4. Catalytic Activity Studies of S-MWCNT
and S-MC
The catalytic activity of S-MWCNT and S-MC catalysts
were investigated in the synthesis of acetamide derivatives
using substituted aromatic amines (aniline, benzyl amine,
also reported.
Amide formation is one of the most important reactions
in pharmaceutical industry. The amide bond is a key func-
tional group in organic chemistry. It plays an important
role in the synthesis of wide ran gI Pe :o 1f 0c 9h e. 2m 3i 6c a. 5l s3 i. n1 c3 l 1u dOi nng : Sat, 22 Dec 2018 08:37:37
Copyright: American S pc ai er an -t ci fhi cl o Pr ou ba lni si lhi ne er sand para-methoxy aniline) and aro-
peptides, polymers, proteins and pharmaceutical agents.
Delivered bymI na tgi ce na ct ai ds (phenyl acetic acid, phenylthio acetic acid and
Keeping in view the importance of the above mentioned
factors, we have modified MWCNT and MC with sul-
phuric acid by wet impregnation technique and used in
the synthesis of various acetamide derivatives. Further cat-
alytic activity studies and reusability of the catalysts were
also investigated.
Indole 3-acetic acid) in a liquid phase reaction. In a typical
procedure of synthesis of acetamide derivatives, mixture of
aromatic acid and substituted aromatic amine in 1:1 molar
ꢀ
ratio was refluxed at 110 C using 50 mg of catalyst with
10 mL of toluene as solvent in a 100 mL R B flask fit-
ted with water cooled condenser. After a definite period
of time, the reaction mixture was cooled to room tempera-
ture and filtered to separate the solid catalyst. The product
was recovered from the filtrate using sodium bicarbon-
ate and ethyl acetate. The separated acetamide derivative
2
. EXPERIMENTAL DETAILS
2
.1. Materials
Multiwalled carbon nanotubes were procured from
Nanocyl, Belgium, mesoporous carbon was obtained from
Sigma Aldrich. Sulphuric acid, aniline, benzyl amine,
para-chloro aniline, para-methoxy aniline, phenyl acetic
acid, phenylthio acetic acid and Indole 3-acetic acid, ethyl
acetate, sodium bicarbonate and petroleum ether were pro-
cured from Merck Pvt. India Ltd and used as received.
1
was confirmed from TLC, MP, HNMR techniques. Fur-
ther optimization of the reaction conditions was made by
using different amounts of the catalysts, varying the tem-
perature, duration of the reaction. The effect of different
solvents in the synthesis of acetamide derivatives was also
checked.
2
.2. Preparation of Catalytic Materials
3
. RESULTS AND DISCUSSION
In a typical procedure of synthesis of sulphate modi-
fied carbon based catalysts supports, 3 g of commercially
available multiwalled carbon nanotubes (MWCNT) and
mesoporous carbon (MC) was weighed accurately and
mixed well with 3 mL of 3 M H SO in an agate mor-
tar for 1 h. The obtained paste was dried in a hot air
oven at 110 C for 12 h. Further, catalytic materials were
mixed well to get homogeneous powder. Sulphate modified
3
.1. Characterization of the Catalysts
PXRD Analysis: Powder X-ray diffraction patterns of
S-MWCNT and S-MC are given in Figure 1. MWCNT
exhibited a strong symmetrical diffraction peak at 2ꢄ =
2
4
ꢀ
25 . This 2ꢄ value corresponds to diffraction from hexago-
ꢀ
nal (002) planes of graphitic structure of MWCNT (JCPDS
car files, no 41-1487). The low intensity peak at 43.2 is
ꢀ
J. Nanosci. Nanotechnol. 18, 426–433, 2018
427

Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
Minchitha et al.
(002)
2
2
1
1
500
000
500
000
S-MC
(100)
500
0
0
10
20
30
40
50
60
70
80
2
θ
100
8
6
4
2
0
0
0
0
0
S-MWCNT
(002)
(100)
Figure 2. TPD-NH profile of S-MWCNT and S-MC catalysts.
0
10
20
30
40
50
60
70
80
3
2
θ (deg.)
acidic sites on the surface of the catalyst.27 The ammo-
nia desorption peak can therefore be used to represent the
concentration of the acidic sites on the surface of a cat-
Figure 1. PXRD pattern of S-MWCNT and S-MC catalysts.
attributed to diffraction from (100) plane.26 Similar obser-
vations were observed in case of MC catalysts. However
after acid treatment, the diffraction pattern of S-MWCNT
was considerably altered with respect to 2ꢄ value and
its intensity. After the acid treatment of S-MC, it was
noticed that there was not much difference in the diffrac-
tion peaks observed for (002) and (100) planes. However
alyst. The TPD-NH profile of S-MC catalyst contained
3
two desorption peaks in the ranges of 200–250 and 270–
ꢀ
360 C which indicated the presence of both weak and
moderately strong acidic sites. In case of S-MWCNT cat-
alyst, the TPD-NH
the range of 300 to 400 C which indicated the presence
of strong acid sites.
profile contained a desorption peak in
3
ꢀ
ꢀ
the diffraction peaks at 2ꢄ = 25 and 43.2 was slightly
SEM images and EDS profiles: SEM images and the
EDS profiles of S-MWCNT and S-MC are given in
IP: 109.236.53.131 On: Sat, 22 Dec 2018 08:37:37
shifted.
Copyright: American Scientific Publishers
BET surface area and surface acidity mea sDu re el imv ee nr et :d byFI ing gu er en t3a . SEM images of S-MWCNT and S-MC revealed
BET surface area, pore volume, pore diameter and surface
acidity of S-MWCNT and S-MC are given in Table I. Sur-
face area, pore volume of S-MWCNT values is higher than
S-MC and pore diameter as well as surface acidity values
are higher in S-MC. The higher surface acidity of S-MC
may be due to interaction of sulphate groups with porous
structure of MC.
that, the catalytic materials retained their original struc-
tures as tubular (MWCNT) and spears (MC) with signifi-
cant surface changes. The EDS profiles of S-MWCNT and
S-MC show the presence of elemental sulphur as 8.45
and 9.40 atomic weight % respectively along with carbon
and oxygen.
TEM images: The TEM images of S-MWCNT and
S-MC catalysts are given in Figure 4. These images clearly
indicate that the tubular structure of MWCNT is retained
even upon sulphuric acid treatment. However the tubes in
S-MWCNT are found to be thick due to acid treatment.
In case of S-MC catalyst there is no significant difference
in the structure but on the surface of mesoporous carbon
black patches appeared due to acid treatment.
TPD-NH profile: Temperature programmed desorption
3
of ammonia for S-MWCNT and S-MC are given in
Figure 2, where these catalysts supports were subjected to
ꢀ
ꢀ
heat treatment in the temperature range 50 C to 600 C.
It has been reported that, NH desorption peaks obtained
3
ꢀ
for the catalysts in the range of 50 to 250 C correspond
to weakly acidic sites on their surface and moderate acetic
ꢀ
sites within the range of 250 to 350 C. Furthermore,
ꢀ
NH desorption peaks above 350 C correspond to strongly
3.2. Catalytic Activity Studies
3
The catalytic activity of S-MWCNT and S-MC was inves-
tigated in the synthesis of acetamide derivatives using aro-
matic acids (phenyl acetic acid, phenylthio acetic acid
and Indole 3-acetic acid) with substituted aromatic amines
Table I. BET surface area, pore volume, pore diameter and surface
acidity of S-MWCNT and S-MC.
Catalyst
name
Surface area Pore volume
Pore
diameter Å
Surface acidity
mmol/g ( )
(
aniline, benzyl amine, para-chloro aniline and para-
2
∗
m /g
cc/g
methoxy aniline) in a liquid phase reaction (Table II).
The obtained products were analyzed using NMR tech-
nique. The structural details of the obtained compounds
are listed in Table II and it is matching with the reported
S-MWCNT
S-MC
53.64
25.63
0.18
0.05
13.91
78.51
0.82
1.75
∗
Note: Total surface acidity of the catalysts were measured using n-butyl amine
2
8–31
back titration method.
literatures.
428
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Minchitha et al.
Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
c)
(
(
a)
(
d)
(
b)
Figure 3. SEM images of (a) S-MWCNT and (b) S-MC catalysts and EDS profiles of (c) S-MWCNT and (d) S-MC.
IP: 109.236.53.131 On: Sat, 22 Dec 2018 08:37:37
Copyright: American Scientific Publishers
3
1
.3. Spectral Data
5. N-phenyl-2-(phenylthio)acetamide: (Table II, entry 5):
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1
1
. N-Diphenyl acetamide: (Table II, entry 1): HNMR
HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 10.18 (s, 1H), 7.53
6
(
8
1
400 MHz, DMSO-d ꢅ: ꢆ: 10.10 (s, 1H), 7.57 (dꢀJ =
(dꢀJ = 7ꢃ2 Hz, 2H), 7ꢃ38–7ꢃ25 (m, 6H), 7ꢃ19–7ꢃ15
(m, 1H), 7.03 (tꢀJ = 6ꢃ8 Hz, 1H), 3.83 (s, 2H).
6
ꢃ0 Hz, 2H), 7ꢃ31 − 7ꢃ19 (m, 7H), 7.09 (tꢀJ = 7ꢃ2 Hz,
H), 3.60 (s, 2H).
. N-benzyl-2-phenylacetamide: (Table II, entry 2):
6. N-benzyl-2-(phenylthio)acetamide: (Table II, entry 6):
1
2
HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 8.59 (s, 1H),
6
1
HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 8.50 (s, 1H),
7ꢃ34–7ꢃ23 (m, 6H), 7ꢃ21–7ꢃ12 (m, 4 Hz), 4.25 (s, 2H),
3.69 (s, 2H).
6
7
3
ꢃ30–7ꢃ14 (m, 10H), 4.24 (s, 2H), 3.29 (s, 2H).
7
. N-(4-chlorophenyl)-2-(phenylthio) acetamide: (Table II,
. N-(4-chlorophenyl)-2-phenylacetamide: (Table II,
1
1
entry 7): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 8.61 (s, 1H),
entry 3): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 8.53 (s, 1H),
7
4
entry 4): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 9.97 (s, 1H),
7
6
6
7
(
8
ꢃ33–7ꢃ25 (m, 6 Hz), 7ꢃ19–7ꢃ12 (m, 3H) 4.23 (s, 2H), 3.68
s, 2H).
N-(4-methoxyphenyl)-2-(phenylthio) acetamide: (Table II,
ꢃ39–7ꢃ19 (m, 9H), 4.22 (s, 2H).
. N-(4-methoxyphenyl)-2-phenylacetamide: (Table II,
1
.
6
1
entry 8): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 10.01 (s, 1H),
.47 (dꢀJ = 9ꢃ2 Hz, 2H), 7ꢃ29–7ꢃ20 (m, 5H), 6.84
6
7
7
.44 (dꢀJ = 6ꢃ8 Hz, 2H), 7. 38 (dꢀJ = 1ꢃ6 Hz, 2H),
(
dꢀJ = 8ꢃ8 Hz, 2H), 3.67 (s, 3H), 3.56 (s, 2H).
.30 (tꢀJ = 7ꢃ6 Hz, 2H), 7.18 (tꢀJ = 7ꢃ6 Hz, 1H), 6.88
(
9
dꢀJ = 6ꢃ8 Hz, 2H), 3.79 (s, 2H), 3.68 (s, 3H).
. 2-(1H-indol-3-yl)- N-phenylacetamide: (Table II,
(
a)
(b)
1
entry 9): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 10.88
6
(
(
(
s, 1H), 10.06 (s, 1H), 7.59 (dꢀJ = 8ꢃ0 Hz, 2H), 7.33
dꢀJ = 8ꢃ0 Hz, 1H), 7ꢃ27–7ꢃ20 (m, 3H), 7ꢃ06–6ꢃ93
m, 3H), 3.70 (s, 2H).
1
0. N-benzyl-2-(1H-indol-3-yl)acetamide:
(Table
II,
1
entry 10): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 10.84
6
1
00 mm
100 mm
(
(
s, 1H), 8.37 (s. 1H), 7.53 (dꢀJ = 8ꢃ0 Hz, 1H), 7.32
dꢀJ = 8ꢃ0 Hz, 1H), 7ꢃ27–7ꢃ17 (m, 6H), 7ꢃ06–7ꢃ02
Figure 4. TEM images of (a) S-MWCNT and (b) S-MC catalysts.
J. Nanosci. Nanotechnol. 18, 426–433, 2018
(m, 1H), 6ꢃ96–6ꢃ92 (m, 1H), 4.25 (s, 2H), 3.55 (s, 2H).
429

Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
Minchitha et al.
Table II. Catalytic performance of S-MWCNT and S-MC in the amidation of acetamide derivatives from aromatic acids and substituted aromatic
amines using 0.05 g of catalysts.
Entry
1
Aromatic acids
Aromatic amines
Aniline
Acetamide derivatives
% yield S-MWCNT/MC
91/96
2
3
Phenyl acetic acid
Benzyl amine
88/94
68/73
Para-chloro aniline
4
5
Para-methoxy aniline
Aniline
85/90
89/93
Phenylthio acetic acid
6
7
Benzyl amine
82/88
63/69
Para-chloro aniline
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8
9
Para-methoxy aniline
80/86
88/92
Indole 3-acetic acid
Aniline
10
11
12
Benzyl amine
Para-chloro aniline
Para-methoxy aniline
87/91
65/70
83/91
430
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Minchitha et al.
Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
100
1
1. N-(4-chlorophenyl)-2-(1H-indol-3-yl)acetamide: (Table II,
1
entry 11): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 10.85
6
S-MC
(
(
6
1
s, 1H), 8.40 (s, 1H), 7.52 (dꢀJ = 8ꢃ0 Hz, 1H), 7ꢃ33–7ꢃ29
80
S-MWCNT
m, 3H), 7ꢃ23–7ꢃ16 (m, 3H), 7.06 (tꢀJ = 1ꢃ2 Hz, 1H),
.96 (tꢀJ = 1ꢃ2 Hz, 1H), 3.55 (s, 2H).
2. 2-(1H-indol-3-yl)-N-(4-methoxyphenyl) acetamide: (Table II,
60
1
entry 1): HNMR (400 MHz, DMSO-d ꢅ: ꢆ: 12.1
6
(
(
(
s, 1H), 10.86 (s, 1H), 7.33 (2ꢀJ = 8ꢃ4 Hz, 2H), 7.21
dꢀJ = 2ꢃ4 Hz, 2H), 7ꢃ06–7ꢃ04 (m, 2H), 6ꢃ97–6ꢃ93
m, 2H), 6. 83 (dꢀJ = 2ꢃ4 Hz, 1H), 3.67 (s, 2H),
4
2
0
0
0
3
.60 (s, 3H).
In general, the % yield of the acetamide derivatives
obtained was very less when the reactions were carried
out in the absence of the catalysts. Table II indicates
amidation reactions carried out using different aromatic
acids (phenyl acetic acid, phenylthio acetic acid and Indole
Toluene
THF
EtOAc
Ethanol
Different Solvents
Figure 5. Catalytic performance of S-MWCNT and S-MC catalysts
using 3(a) different solvents.
3
-acetic acid) with substituted aromatic amines (1:1 molar
ratio) and their % yield of the products using S-MWCNT
and S-MC catalysts supports. It was noteworthy that S-MC
gave higher % yield of acetamide derivatives irrespective
of the different acids and amines used. Further aniline,
benzyl amine and para methoxy aniline (electron donat-
ꢀ
1
30 C. The reactions were carried out using S-MWCNT
and S-MC catalysts at different intervals of time such as
, 4, 6, 8, 10 and 24 h and found highest % yield of
product when the reaction was refluxed for 10 h. Further
increase in the duration of the reaction from 10 to 24 h,
there was no significant difference found in the % yield of
the product.
2
ing group –OCH ꢅ with phenyl acetic acid gave highest %
3
yield of respective products. On the other hand presence
of electron-withdrawing substituent (i.e., Cl) on the aro-
matic ring of aniline gave low % yield of product (Table II,
entry 3, 7 and 11).
The study on the effect of solvents and amount of
the catalysts in the synthesis of N ,-diphenyl acetamide
IP: 109.236.53.131 On: Sat, 22 Dec 2018 08:37:37
Further experiments were carried out to evaluate the cat-
Copyright: American Scientific Publishers
was performed using S-MWCNT and S-MC catalysts. The
alytic activity of the S-MWCNT and S-MC for th De ea ml ivi ed ra e- d by Ingenta
reaction was conducted in the presence of different sol-
tion of phenyl acetic acid and aniline in the synthesis of
N ,-diphenyl acetamide by changing the temperature, dura-
tion, amount of the catalysts and with different solvents.
The effect of temperature and duration of the reaction with
respect to % yield of N ꢀ-diphenyl acetamide was studied
using S-MWCNT and S-MC catalysts (50 mg) and the
results are given in Table III. The reaction did not proceed
at room temperature. But it was observed that, the % yield
of the product was increased with increase in the temper-
vents such as toluene, THF, ethyl acetate, and ethanol.
Figure 5 indicates the % yield of N ,-diphenyl acetamide
using S-MWCNT and S-MC catalysts in the presence of
different solvents. It is important to note that toluene gave
highest % yield of N -diphenyl acetamide compare to other
solvents using both the catalysts. This may be due to
1
00
ꢀ
ature from 70 to 110 C and further remained same at
S-MC
S-MWCNT
8
6
4
2
0
0
0
0
0
Table III. Catalytic performance of S-MWCNT and S-MC catalysts at
different temperature and duration of the reaction.
Reaction
duration (h)
% Yield at % Yield at % Yield at % Yield at
ꢀ
ꢀ
ꢀ
ꢀ
130 C
Catalysts
S-MC
70
C
90
C
110
C
2
4
6
8
0
0
0
0
26
44
49
54
57
32
47
62
76
76
39
59
73
96
97
43
62
76
96
10
24
97.7
S-MWCNT
2
0
0
0
0
4
6
8
22
38
44
50
53
28
42
56
70
74
36
57
69
91
38
60
71
91
92
0.01
0.02
0.03
0.04
0.05
Amount of the catalysts (g)
10
Figure 6. Catalytic performance of S-MWCNT and S-MC catalysts
using different amount of catalysts.
24
91.8
J. Nanosci. Nanotechnol. 18, 426–433, 2018
431

Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
Minchitha et al.
S-MC
from 0.05 to 0.1 g, a less (∼2%) increase in the % yield
of the product was observed. Thus 0.05 g of catalyst was
found to be optimum amount of catalyst for the reaction.
Reusability studies: Reusability of S-MWCNT and
S-MC catalysts were investigated in the synthesis of
N ,-diphenyl acetamide at optimum reaction condition
S-MWCNT
1
00
8
6
4
2
0
0
0
0
0
ꢀ
using 0.05 g catalysts at 110 C for 10 (Fig. 7). Both S-
MWCNT and S-MC were found to be reusable catalysts;
however S-MWCNT was efficiently reused up to 5 times
without losing its catalytic activity. During the catalysts
reusability S-MWCNT was recovered easily and more effi-
ciently than S-MC catalyst. Hence S-MWCNT catalyst
was found to be a better reusable catalyst for the synthesis
of N ,-diphenyl acetamide via amidation reaction.
1
2
3
4
5
No of Cycles
3
.4. Mechanism of Amidation Reaction
Figure 7. Reusability of S-MWCNT and S-MC catalysts in the amida-
tion of N,-diphenyl acetamide from phenyl acetic acid and aniline.
A possible mechanism for the synthesis of N -diphenyl
acetamide from phenyl acetic acid and aniline using
S-MWCNT or S-MC are explained as follows (Fig. 8).
Initially, acidic site of the catalyst reacts with oxygen of
carbonyl group of phenyl acetic acids forming intermedi-
ate A. Protonation of the carbonyl oxygen by acidic cata-
lyst makes the carbonyl carbon a much better electrophile,
which reacts with aniline forming intermediate B. As the
reaction precedes N -diphenyl acetamide (C) is obtained
along with elimination of water molecule and the catalyst
the higher boiling point of toluene as compare to other
solvents and also presence or absence of hydrogen bond-
ing interactions between the amino groups and the solvents
3
2
in the reaction mixture.
The effect of amount of the catalyst was studied by
varying the amount of the catalysts from 0.01 g to 0.05 g
(
Fig. 6). The results confirmed that the catalytic activity
increases, when the amount of catalysts increases from
0
.01 g to 0.05 g. Further increase in the amount of catalyst
is regenerated.
IP: 109.236.53.131 On: Sat, 22 Dec 2018 08:37:37
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Figure 8. A plausible reaction mechanism for amidation of N-diphenyl acetamide from phenyl acetic acid and aniline.
J. Nanosci. Nanotechnol. 18, 426–433, 2018
432

Minchitha et al.
Synthesis of Acetamide Derivatives using S-MWCNT and S-MC as an Efficient Heterogeneous Catalysts
4
. CONCLUSION
8. Z. Zhao, S. Yanjuan, and F. Dong, Nanoscale 7, 15 (2015).
9. V. Malgras, Q. Ji, Y. Kamachi, T. Mori, F.-K. Shieh, K. C.-W.
Sulphuric acid modified MWCNT and MC have been
investigated as solid acid heterogeneous catalysts for the
synthesis of acetamide derivatives via amidation reaction.
S-MWCNT and S-MC was found to be an efficient catalyst
for the synthesis of acetamide derivatives with 100% selec-
tivity and good yield. However, the catalytic activity of
S-MC on the % yield of acetamide derivatives was found
to be high as compare to S-MWCNT, this increase in activ-
ity due to surface acidity of S-MC (1.75 mmol/g) is more
than the surface acidity of the S-MWCNT (0.82 mmol/g).
Notably, the S-MWCNT catalyst was found to be recy-
clable up to five times without any loss in its catalytic
activity, but in case of S-MC catalyst reusability was very
poor. The results of amidation reaction from both the cat-
alysts revealed that an electron donating group on the aro-
matic ring of aniline led to increase % yield of product,
whereas yield decreases with electron withdrawing group
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Acknowledgment: Authors thank the funding agency
Department of Science and Technology—(SERB), Project
number: SERB/F/3690/2013–14 for financial support for
this research work. Authors thank Dr. Krishna Venkatesh,
Director, Centre for Incubation, Innovation Research and
Consultancy, Jyothy Institute of Technology, Bengaluru for
giving constant support and encouragement to carry out
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2
IP: 109.236.53.131 On: Sat, 22(2 D0 1 e1 c) . 2018 08:37:37
this research work.
Copyright: American S 2c 5i .e nX t.i fYi c. L Pi u u, bM l .i sHh u ea nr gs , H. L. Ma, Z. Q. Zhang, J. M. Gao, Y. L. Zhu,
X. J. Han, and X. Y. Guo, Molecules 15, 7188 (2010).
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Delivered by Ingenta
2
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J. Nanosci. Nanotechnol. 18, 426–433, 2018
433