Biocatalytic green alternative to existing hazardous reaction media: Synthesis of chalcone and flavone derivatives via the Claisen-Schmidt reaction at room temperature

Article abstract of DOI:10.1039/d0nj03839c

Owing to the increasing amount of waste materials around the globe, the conversion of waste or secondary by-products to value-added products for various applications has gained significant interest. Herein, two novel agro-food waste products, Musa sp. 'Malbhog' peel ash (MMPA) and Musa Champa Hort. ex Hook. F. peel ash (MCPA) are used as catalysts to promote an inexpensive, efficient and eco-friendly carbon-carbon bond forming crossed aldol reaction at room temperature in solvent free conditions. Furthermore, the resulting products were subjected to reactions with these promoters in an oxygen atmosphere and led to the formation of novel flavone derivatives. Moreover, the used catalysts were properly characterized using different sophisticated analytical techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), Brunauer-Emmett-Teller analysis (BET), Raman spectroscopy, scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS), transition electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) along with element detection using atomic absorption spectroscopy and ion chromatographic methods. These two approaches are metal free, as well as being devoid of any extra additives, co-catalysts, harsh conditions, the use of column chromatography for purification and result in a higher yield of the product within a short space of time. The catalytic abilities of the promoter were also examined to synthesize important bioactive molecules such as butein and apigenin at room temperature. With gram scale synthesis of the chalcone derivatives, the used catalysts (MMPA and MCPA) were further reused for five cycles and did not demonstrate any loss in catalytic activity.

Full text of DOI:10.1039/d0nj03839c

View Article Online
View Journal
NJC
New Journal of Chemistry
Accepted Manuscript
A journal for new directions in chemistry
This article can be cited before page numbers have been issued, to do this please use: K. J. Tamuli, R. K.
Sahoo and M. Bordoloi, New J. Chem., 2020, DOI: 10.1039/D0NJ03839C.
Volume 42
This is an Accepted Manuscript, which has been through the
Number
6
21 March 2018
Pages 3963-4776
Royal Society of Chemistry peer review process and has been
accepted for publication.
NJC
New Journal of Chemistry
rsc.li/njc
A journal for new directions in chemistry
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1144-2546
PAPER
Chechia Hu, Tzu-Jen Lin et al.
Yellowish and blue luminescent graphene oxide quantum dots
prepared via a microwave-assisted hydrothermal route using
H2O2 and KMnO4 as oxidizing agents
rsc.li/njc

Please do not adjust margins
Page 1 of 10
New Journal of Chemistry
1
2
3
4
5
6
7
View Article Online
DOI: 10.1039/D0NJ03839C
ARTICLE
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
A Biocatalytic Green Alternative to Existing Hazardous Reaction
Medium: Synthesis of Chalcone and Flavone Derivatives via
Claisen-Schmidt Reaction at Room Temperature
Received 00th January 20xx,
Accepted 00th January 20xx
Kashyap J. Tamuli,a,b Ranjan K. Sahooa and Manobjyoti Bordoloi*a,b
DOI: 10.1039/x0xx00000x
With increasing amount of waste materials around the globe, the conversion of wastes or secondary by‐products to
value‐added products for various applications has gained lot of interest. Herein, two novel agro‐food wastes of Musa sp.
‘Malbhog’ peel ash (MMPA) and Musa Champa Hort. ex Hook. F. peel ash (MCPA) used as catalysts to promote an
inexpensive, efficient and eco-friendly carbon-carbon bond forming crossed aldol reaction at room temperature in solvent
free conditions. Further, these resulted products were subjected to reacts with these promoters in oxygen atmosphere led
to formation of noval flavone derivatives. Moreover, the used catalysts were properly characterized by using different
sophisticated analytical techniques like FT-IR, XRD, BET, Raman, SEM-EDS, TEM, XPS and TGA along with element detection
by atomic absorption spectroscopy and ion chromatographic methods. These two approaches are metal free as well as
devoid of any extra additives, co-catalyst, harsh conditions, column chromatography for purification with higher yield
production within short span of time. Catalytic abilities of the promoter were also examined to synthesize important
bioactive molecules like, butein and apigenin at room temperature. With gram scale synthesis of chalcone derivatives, the
used catalysts (MMPA and MCPA) were further reused for five cycles without loss of catalytic activity.
or base in solvent or solvent free systems,1 but it was typically
proceeded in the presence of various catalysts and solvents
afterwards. The products formed by this reaction are known as
1. Introduction
To reduce environment pollution around the world, using of waste
materials will create a sustainable environment for living creatures.
Hence, to improve long-term negative effects on environment,
researcher proposed numerous methodologies for the benefit of all
living organisms of our planet by searching ingenious and inventive
approach to diminish waste materials and come upon with
replacements for hazardous materials. In organic chemistry domain,
in search of green syntheses, researcher have developed some
unique and environment friendly protocols for the existing ones. So,
improvement of new greener and mild synthetic methodology for
constructing biologically active organic molecules has received
tremendous attention in the recent years. Usually, the main aspect
of such pathways is to ensure that our next generation of materials,
chemicals and energy is more feasible than the current generation,
which inspire the future researchers to generate some great
scientific innovations to preserve our planet green in a blue sky.
To design such materials, compounds or pathways, one of the most
important products formed from crossed aldol condensation via
Claisen-Schmidt reaction originally performed by using a strong acid
chalcones which are the parent skeleton for various natural
products as biogenetic precursors and have diverse array of
biological activities associated with them such as antidiabetic,2
antimalarial,3 antiinflammatory,4 anticancer,5 antituberculosis,6
antileishmanicidal,7 antioxidant8 etc. In addition to their diverse
biological activities, chalcones are found to have pronounced
applications in synthetic organic chemistry as they are the
important building blocks of many heterocycles9 and are also used
as intermediates in various syntheses of
a wide range of
pharmaceuticals.10 Therefore, by developing the core chalcone
moieties along with their structural modifications, a number of
efficient methods for the synthesis of this very important bunch of
molecules were developed. Moreover, this organic reaction
provides carbon-carbon bond forming products which are the most
important aspects of an organic reaction. Therefore, numerous
methodologies have been reported so far to synthesize chalcones
by employing mainly acids or bases,11 or in combination with
various transition metals,12 nano particles,13 but most of it
proceeded through very harsh conditions, addition of extra bases,
long reaction time, conventional heating, using toxic organic
reagents etc.
a. Chemical Sciences and Technology Division, CSIR-North East Institute of Science &
Technology, Jorhat, 785006, Assam, India.
So, due to the growing and demanding environmental
regulations, the researchers and chemical industries are in need of
the improvement of more eco-compatible synthetic methodologies,
which are highly recommendable in this instance. Hence, in the
synthesis of chalcone derivatives, encouraging results have been
b. Academy of Scientific and Innovative Research, CSIR-NEIST campus, 785006, India.
*E-mail: m.j.bordoloi.pub@gmail.com, mjb_rrljt@yahoo.co.in
†Electronic Supplementary Information (ESI) available: General experimental
methods, general synthetic procedures, AAS and IC data of fresh catalysts, XRD,
SEM, EDX, XPS spectra of recovered catalysts, physical and spectroscopic data of all
the compounds, 1H NMR and 13C NMR spectra of isolated compounds. See
DOI: 10.1039/x0xx00000x
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 10
ARTICLE
Journal Name
1
2
3
4
5
achieved by using naturally occurring resources or materials, like knowledge, there are no earlier scientific ViedweAtratiicllse Onflioner
high-temperature water,14 KF/natural phosphate,15 Clay- characterization of these catalysts usinDgOI:d1i0ff.1e0r3e9n/tD0NanJ0a3ly8t3ic9aCl
catalysed,16 but, even with these existing procedures we have methods.
found that Musa sp. ‘Malbhog’ peel ash (MMPA) and Musa Champa
Before the catalyst preparation, we calculated the moisture
6
Hort. ex Hook. F. peel ash (MCPA) are effective promoters for the content of both the banana peel samples. The fresh peels were
Claisen-Schmidt reaction. Since, such agro-food waste as catalysts placed in a hot air oven at 110oC for 24 hours. After complete
has received significant attention in the field of chemistry evaporation of the moisture, the samples got their constant weight.
research.17 Exhilarating Saikia et al.18 and Rokhum et al.19 work by Then, the dried samples were cooled and weighed. The results
using natural feedstock as greener context in organic showed that both the banana peels containeds almost more than
transformation to achieve more exploration of the natural catalyst, 80% of moisture (Table S1 in ESI).
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
we wish to report herein a facile green synthesis of chalcone and
Literature survey revealed that, banana peel is rich in high
flavones derivatives by using banana peel ash as a promoter in amount of different types of ions as major ingredients along with
solvent free condition.
other trace elements like aluminum, vanadium, chromium, iron,
magnesium, manganese, lead etc.21 However, the main
constituents of the MMPA and MCPA were determined by atomic
absorption spectroscopy (AAS) and ion chromatographic (IC)
techniques. It was observed that, both the sample contained high
amount of potassium (1.60 and 1.48 %), sodium (0.58 and 0.42 %),
calcium (0.42 and 0.38 %), magnesium (0.36 and 0.32 %) in MMPA
and MCPA respectively from AAS study (Table S2 in ESI). Moreover,
the catalysts were found to contain ammonium (1.401 and 1.238
ppm), chloride (3.620 and 4.304 ppm) as the major component for
catalytic activation in MMPA and MCPA respectively from the ion
chromatographic study (Fig. S1 in ESI). Besides these major
elements, some other trace elements like manganese, bromide,
phosphate, sulphate etc. were also found to in the catalysts. Hence,
for this nature of the ash, it acts as a basic promoter for our
proposed reactions (Table S3 in ESI).
2. Results and discussions
At first, we have initiated our study by preparing our catalyst from
natural feedstocks. In this pathway, these two banana peel ashes of
Musa sp. ‘Malbhog’ and Musa champa (Family: Musaceae) were
chosen as basic promoter by alternating the hazardous reaction
environments. These two varieties of banana species were collected
in the month of April, 2018 from Jorhat, Assam, India by Prof. M.
Bordoloi and sample identity was confirmed at CSIR-NEIST, Jorhat,
Assam, India.20 Afterwards, banana peels were washed with
deionized water carefully followed by sun dried. The dried peels
were further cut into small pieces and burnt completely, then
grinded to produce the ash catalysts. Furthermore, the prepared
catalysts were well characterized by various sophisticated analytical
techniques prior to study in catalytic applications. To the best of our
Fig. 1 (a) FT-IR spectra of MMPA (red) and MCPA (blue); (b) XRD spectra of MMPA; (c) XRD spectra of MCPA; (d) BET isotherm of MMPA
(red) and MCPA (blue); (e) TGA thermogram of MMPA (red) and MCPA (blue); (f) Raman spectra of MMPA (red) and MCPA (blue)
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 10
New Journal of Chemistry
Please do not adjust margins
Journal Name
ARTICLE
1
2
3
4
5
6
7
8
9
FT-IR analysis was performed to identify the functional groups 33.70 indicated the presence of CaCO3 and CaO in the catalyst
present in MMPA and MCPA (Fig. 1a). The absorption bands at 3405 (JCPDS No. 87-1863). The existence of SiO2 was confirmed by
View Article Online
DOI: 10.1039/D0NJ03839C
and 693 cm-1 in MMPA as well as 3420 and 701 cm-1 in MCPA are appearance of peaks at 2θ= 24.10, 34.88, 56.30 (JCPDS No. 89-
corresponded to –OH stretching with Ca–O and K–O stretching 3609). Besides, the peaks at 2θ= 24.10, 44.54, 50.12, 66.42 due to
vibrations respectively. The peak at 2372 and 2358 cm-1 may be the presence of P2O5, MgO and C molecule in the catalyst (JCPDS
ascribed to stretching vibration of Mg/Si–O–K bonds of MMPA and No. 72-1664, 23-1301, 65-0470 and 82-0619). These result were
MCPA respectively. The appearance of peaks at 1595, 1630, 1118 similar to the results that are found in the literature.22
and 1127 cm-1 are assigned to the C–O stretching and bending
From Brunauer–Emmett–Teller (BET) analysis, the surface area
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
vibrations of carbonate ions which is indicative of the presence of of MMPA and MCPA were found to be 25.221 and 12.561 m²/g
Ca, K and other metal carbonates in our prepared catalysts. The respectively. It was observed that, the surface area of MCPA was
characteristic peak at 1394 and 1408 cm-1 is specific to K2CO3 and is less than MMPA, may be due to the more open combustion of the
supported by the presence of K2CO3 in the XRD spectral of of MMPA catalyst, the burnt carbon content, i.e, chars were produced by
and MCPA respectively (Fig. 1 (b-c)). In addition to that, two open combustion resulting smaller surface area.23 In addition to
absorption peaks at 998 and 833 cm-1 in MMPA along with 1006 that, we have calculated the pore volume and pore size of the
and 835 cm-1 in MCPA were assigned to stretching and bending prepared catalysts by BET-N2 adsorption-desorption measurements.
vibrations of Si-O-Si bond.
The pore volume of the MMPA and MCPA were found to have
Wide-angle powder X-ray diffraction (PXRD) analyses were used 0.077 cm3/g and 0.067 cm3/g respectively. Moreover, the pore size
to detect the presence of crystalline compounds in the catalysts and distribution obtained as 17.731 Å and 17.704 Å for MMPA and
it was found that both banana peel ashes were rich in metal oxides MCPA respectively. This isotherm showed type-I isotherm that are
and carbonate as shown in Fig. 1(b-c). In MMPA, some intense allied with enhanced adsorbent-adsorptive interactions with
prominent peaks were observed at 2θ= 24.24, 28.46, 31.46, 40.68, supermicropores characteristic (Fig. 1d).24
50.30 revealed the presence of K2O and K2CO3 in the catalyst (JCPDS
The evaluation of higher thermal stability of both the catalysts
No. 77-2176 and 87-0730) (Fig. 1b). The presence of CaO and CaCO3 (MMPA and MCPA) was confirmed by thermogravimetric analysis
was confirmed by occurrence of characteristic peaks at 2θ= 30.18, (TGA). In MMPA, initial 15% weight loss was observed at around
39.32 (JCPDS No. 87-1863 and 82-1691). The strong distinctive peak 100oC because of the moisture present in the sample (Fig. 1e).25
of SiO2 was observed at 2θ= 34.14, 58.72 (JCPDS No. 89-3609). Then, one more mass loss was noticed due to decomposition of
Several other peaks at 2θ= 21.00, 44.54, 50.84, 66.48 also indicated hemicelluloses, cellulose etc.26 But, in MCPA a sharp 25% of weight
the presence of C, MgO, SO3 and P2O5 molecules in the ash catalyst loss was visible due to water loss (Fig. 1e). Although, up to 700oC,
respectively (JCPDS No. 72-1664, 23-1301, 65-0470 and 82-0619). both the catalysts exhibited moderate thermogravimetric
Likewise, to identify crystalline constituents present in MCPA, XRD properties. Further, at around 800oC small mass loss was associated
diffraction pattern was analyzed (Fig. 1c). A number of strong with decomposition of lignins or oxidation of carbonaceous
characteristic peaks were found at 2θ= 27.20, 28.36, 31.48, 40.56 materials.27 Finally at 1000oC, the residual mass loss was observed
attributed to the presence of K2O and K2CO3 in the catalyst (JCPDS for MMPA and MCPA as 65% and 51% respectively.
No. 77-2176 and 87-0730). The prominent peaks at 2θ= 29.80,
Fig. 2 (a-b) SEM images of MMPA; (c-d) SEM images of MCPA; (e-f) TEM images of MMPA; (g-h) TEM images of MCPA
For carbon-based material, Raman spectroscopy analysis is one catalysts (Fig. 1f). From the Raman spectra of both the catalysts, the
of the most essential techniques to examine the composition of the bands near at 500 cm-1 was ascribed to the Si-O-Si or metal-O
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 10
ARTICLE
Journal Name
View ATrtihclee Ownildinee
1
2
3
4
5
6
7
8
vibrations.28a Moreover, sharp bands were observed at 822 and C=C/C–C and C=O of metal carbonates group (Fig. 3b).29a
815 cm−1 for the vibrations of C-O-C, C-Cl and O-O groups of MMPA scan of O 1s was fitted with two peaks at bDinOdIi:n1g0.e10n3e9r/gDie0sNoJ0f 3583309.C3
and MCPA respectively.28b Two strong ‘D band’ were noticed at and 532.5 eV, indicated C=O and C–OH bonds respectively (Fig.
1344 and 1329 cm-1 represents with the effect of experience to the 3c).29b Fig. 3d showed a high resolution K 2p was obtained with two
laser and ascribed to C–O vibrations of or metal oxidized products binding energy peaks at 292.0 and 294.7 eV, attributed to the
or surface carboxylates of MMPA and MCPA respectively.28c existence of potassium in its different ionic forms.29c A typical Si 2p
Similarly, in MMPA and MCPA two ‘G band’ were identified at 1460 broad XPS spectrum exhibited with three prominent peaks at 101.4,
and 1589 cm-1 respectively. Furthermore, apart from these peaks 102.8 and 103.9 eV binding energies belonging to the Si-C, Si-O and
we have not found any other distinguishable Raman bands, but Si-O2 groups respectively (Fig. 3e).29c,22a Similarly, with the survey
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
with intense fluorescence background.
scan of Musa Champa peel ash particles in XPS spectrum (Fig. 4a), it
The surface morphology of the catalysts were studied by field displayed that, the major components that were attached with
emission scanning electron microscopy (FE-SEM) and transmission surface regions were carbon (51.13%), oxygen (31.72%), potassium
electron microscopy (TEM) analysis. The SEM images of the both (10.81%), calcium (1.66%) and silicon (1.13%). Additionally, some
catalysts revealed innumerable aggregates with both microporous minor compounds chlorine (1.80%), phosphorus (0.76%),
and mesoporous arrangements. From the SEM images, it was magnesium (0.64%), sulfur (0.18%), iron (0.16%) etc. were also
observed that the catalysts displayed various spongy and porous found. Through deconvolution of MCPA we observed that, almost
structures at 20 μm and 1 μm resolution (Fig. 2(a‐d)). The TEM similar types of characteristic binding energies were present for
images also showed lamellar type of morphology of the ash each elements. The high resolution XPS spectrum of C 1s consists of
particles (Fig. 2(e‐h)). The results of SEM and TEM analysis two peaks with binding energies of 288.7 eV and 284.7 eV, which
correlated with the literature information.19a
can be attributed to the presence of C=O and C=C/C-C respectively
X-ray photoelectron spectroscopy (XPS) analyses were (Fig. 4b). The high resolution O 1s spectrum fitted with only one
performed to identify the surface chemical composition and peak at 530.3 eV binding-energy refer to the presence of C=O group
properties of the both prepared ash particles (Fig. 3 and 4). From of metal oxides (Fig. 4c). For K 2p, the major peaks at 292.1 and
the survey scan of Musa sp. ‘Malbhog’ peel ash XPS spectrum, it can 294.6 eV are assigned to the spin–orbit splitting of K 2p3/2 and K
be seen that the major components of the surface area were 2p1/2 of the MCPA catalyst, which are assigned as potassium oxide
carbon (45.98%), oxygen (32.55%), potassium (10.92%) and silicon or carbonates (Fig. 4d). The deconvoluted peak of Si 2p of MMPA is
(3.83%). Moreover, other constituents like chlorine (2.69%), calcium similar to the MCPA catalyst with three peaks at binding energies of
(1.74%), phosphorus (1.03%), magnesium (0.70%), sulfur (0.25%), 101.4, 102.6 and 104.2 eV corresponding to the Si-C, Si-O and Si-O2
iron (0.31%) etc. were also present in minor amount (Fig. 3a). bonds respectively (Fig. 4e). In addition to that, from the detail
Further with wide scan and via deconvolution it was seen that, from investigation by EDS analysis, both the catalysts also supported the
C 1s spectrum of MMPA fitted with two peaks with different results of XPS study and revealed the presence of C, O, K, and Si in
binding energies 284.8 eV and 288.9 eV corresponding to the the catalysts (Fig. 3f and 4f).
Fig. 3 (a) XPS survey spectrum of fresh MMPA and high-resolution spectra of (b) C 1s; (c) O 1s; (d) K 2p; (e) Si 2p; (f) EDX of fresh MMPA
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 10
New Journal of Chemistry
Please do not adjust margins
Journal Name
ARTICLE
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ03839C
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 4 (a) XPS survey spectrum of fresh MCPA and high-resolution spectra of (b) C 1s; (c) O 1s; (d) K 2p; (e) Si 2p; (f) EDX of fresh MCPA
Table 1
: Optimizing table for effect of the amount of the promoter synthetic pathway for the preparation of chalcone and flavone
in preparation of chalcone at room temperaturea
derivatives at room temperature. In this pathway, these two
banana peel ashes (MMPA and MCPA) were selected as green
promoters without employing an external base, toxic organic
solvents, transition metals, harsh medium etc. It is very notable to
see that, MMPA and MCPA has great potential towards the
conversion of diverse kinds of functional moieties and substrates to
targeted products. To the best of our knowledge, there are no
earlier reports, where MMPA and MCPA have been used as basic
promoter for the aforesaid syntheses. So, we believe that, this
greener approach can exhibit easy conversion and can also provide
an alternative way to the existing processes. Additionally, one
unique characteristic is that, after completion of the desired
reaction, the reaction mixture is filtered and the precipitate can be
recrystallized with ethanol to get pure chalcone and flavone
derivatives.
Entry Catalysts amount
(mg)
Solvent
(ml)
Time
(min)
Yieldb
(%)
MMPA
MCPA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
5
-
-
-
-
-
Water
Water
Water
60
60
45
20
20
15
15
10
10
10
10
10
10
60
trace
trace
32, (39)c
47, (56)c
61
10
15
15
15
15
20
15
20
25
15
-
Isopropanol
Methanol
Ethanol
-
68
Firstly, to optimize the reaction condition, we have studied a
model reaction between acetophenone 1a and benzaldehyde 2a in
equimolar amount with both the prepared catalysts (Table 1,
entries 1-13). Some initial experiments were accomplished by using
5 mg of MMPA with water (Table 1, entry 1) as a basic catalytic
system in this domino reaction which led to trace amount of yield
within 1 hour. After that, ranging from 5 mg to 20 mg of promoter
MMPA used in a series of reactions were performed in the
aforesaid reaction, but could not improved even after prolonging
the reaction time as well as adding solvents like water, isopropanol
and methanol (Table 1, entries 1-7). Ethanol was preferred over
methanol as a solvent system because of its availability from the
renewable resources. To our delight, extraordinary result has been
found when we performed the reaction under solvent free
condition with 15 mg of MMPA in 10 minutes (Table 1, entry 8).
-
-
-
-
Ethanol
78, (83)c
95
95
93
89d
92
90
NRe
-
-
-
-
-
-
-
-
15
20
-
-
-
aReaction conditions: acetophenone (1 mmol), benzaldehyde (1
mmol) with banana peel ash as promoter at room temperature.
c
bIsolated yields. The reaction time in 60 minutes. dThe reaction
temperature at 70oC. eNR: No reaction proceeds.
In continuation of our study towards greener protocol,30 we
have explored highly cost efficient, environmentally benign
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 10
ARTICLE
After further increase in the amount of the promoter to 20-25 mg,
Journal Name
1
2
3
4
5
6
7
8
With the best optimized and favourable reaction condition in
View Article Online
DOI: 10.1039/D0NJ03839C
it was observed that there was not much alteration in the yield hand, a series of chalcone derivatives were synthesized (Table 2,
(Table 1, entries 9-10). Moreover, to improve the yield percentage, 3aa-3ay). Various kinds of structurally and electronically diverse
we have also screened this model reaction under 70oC (Table 1, acetophenones 1 with different aldehydes 2 were easily converted
entry 11). But no significant deviation in reaction yields was to this domino type coupled products under this favorable mild
observed with 15 mg of MMPA. With the promising results amid green condition in 10-24 minutes of time. For obtaining good to
MMPA, the other prepared promoter MCPA (15 mg) was also excellent yield of chalcone derivatives, acetophenone substrates
screened further for synthesis of chalcone 3aa under solvent free consisting of electron rich and electron poor groups, such as, –CH3,
conditions. Out of these, both of the promoters gave outstanding –OCH3, –F, –Cl, –OH, –NO2 etc. were used with aldehydes at room
results to afford desired products at room temperature. It was also temperature in solvent free medium. It is remarkable to see that
observed that, in absence of the catalysts the reaction did not with substituted acetophenones and aldehydes containing halogens
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
afford desired product (Table 1, entry 14).
as functional groups on the aromatic ring were well tolerated and
showed smooth conversion to the desired products by giving
satisfactory yields (Table 2, 3af-3aj, 3ar, 3at). Similar trends were
observed for heterocyclic aldehydes, where reactions with
substituted acetophenones consisting electron withdrawing as well
as electron donating groups also offered corresponding products
with moderate yields, without any difficulties (Table 2, 3ag, 3ah,
3ao). Noticeably, some sterically demanding multi-substituted
functionality effectively reacts with other aldehyde coupling
partners to obtain corresponding cross aldol products. Moreover,
an interesting chalconoid, butein generally derived from
Toxicodendron vernicifluum, Butea, Dahlia by exhaustive extraction
methods.31 Butein is extensively used in the treatment of breast
cancer as aldose reductase inhibitor and antioxidative drug.32 To
check the applicability of the optimized catalytic condition, we
attempted the straightforward synthesis of butein using readily
available starting materials. Pleasingly, we established an
alternative green protocol for the synthesis butein 3ay in excellent
yield of 80% using inexpensive two banana peel ash as catalysts in
20 minutes. For both the catalysts, reactivity was not affected by
the nature of the substrates on both aromatic rings by the catalytic
system in Claisen-Schmidt reaction. Hence, the difference between
the resulted yield percentages of the products for two different
catalysts is very negligible. On the basis of the above findings, the
main advantages of the current green synthetic protocol are mild
reaction condition, high yield, short reaction time and very easy
purification procedure.
Table 2: Substrate scope for preparation of chalcone derivatives via
Claisen-Schmidt reaction at room temperaturea,b
To check the potentiality of the catalyst towards the milder
reaction conditions, we next employed our synthesized 2-
hydroxylchalcone derivatives with a new green catalytic system.
Excellent results were found for the preparation of flavones
4,
when 1 mmol of 2-hydroxylchalcones were placed with MMPA and
MCPA with oxygen balloon (1 atm) at room temperature in 35-60
minutes of reaction time. It is noteworthy that, flavones were
obtained with this new banana peel ash-O2 catalytic system
proceeded to different range of functional groups, such as –H, –CH3,
–OCH3, –OH effortlessly. The reaction smoothly led to the formation
of corresponding flavones products by giving good to excellent
isolated yields (Table 3, 4aa-4af). Furthermore, a most imperative
naturally occurring glycoside belonging to the flavone class,
apigenin is usually found in various vegetables, fruits, flowers etc.33
Additionally, this plant-derived flavonoid exhibited anti-
inflammatory, antiproliferative, antimetastatic activities and
promises as a skin cancer chemopreventive agent.34 Gratifyingly, as
an application from the synthesized substituted 2-
aReaction conditions: acetophenone (1 mmol), aldehyde (1 mmol),
MMPA and MCPA (15 mg) at room temperature bIsolated yields.
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 10
New Journal of Chemistry
Please do not adjust margins
Journal Name
ARTICLE
1
2
3
4
5
6
7
8
9
hydroxylchalcones, we presented another green alternative aldol addition product. Since ketones are less reaVciteiwveArtticolewOanrlidnes
pathway to synthesize apigenin 4af with 72% of yield in 1 hour at nucleophilic addition, the enolate formed frDoOmI:k1e0t.1o0n3e9/wDh0NicJh0r3e8a3c9tCs
room temperature. Synthesis of such bioactive drugs, butein and with an aldehyde where reactive hydrogen and a hydroxide
apigenin highlighted the potential applications of our established molecule formed to an adjacent aromatic ring. The reaction will
green protocol.
undergo dehydration leading to the formation of the desired
chalcone products.
Table 3
:
Substrate scope of flavone derivativesa,b
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Scheme 2: Probable mechanistic pathway for synthesis of chalcones
aReaction conditions: Substituted 2-hydroxylchalcone (1 mmol),
MMPA and MCPA (15 mg), O2 (1 atm) at room temperature
bIsolated yields.
In the perspective of “green chemistry”, the recyclability of the
used catalyst after completion of the reaction is the key feature for
environmental concern. In this regard, we have evaluated the
recyclability test for both the catalysts (MMPA and MCPA) in
standard reaction conditions. The catalysts can be reused up to five
cycles with 61% and 57% of conversion rate for MMPA and MCPA
respectively (Fig. 5). Then the recovered catalysts were again
characterized with XRD, SEM and XPS analyses. From the XRD
analysis, it indicated that the huge loss of potassium ions as well as
other elements of the recovered catalysts which may be caused by
the leaching process of major elements which reduce the active
sites (see ESI, S2). Same way, from the EDS study of recycled
One of the key fields where synthetic chemist has been working
is to concoct and design large-scale synthesis of biologically active
scaffolds. Therefore, further exploration of our proposed catalytic
system, we have demonstrated large scale synthesis of chalcone
derivatives by our model coupled reaction between acetophenone
1a, benzaldehyde 2b, promoter (30 mg) and we have found that
1.86 g of chalcone products within 20 minutes of reaction time. The
resulted products (89% of yield) were futher purified by simple
filtration technique and washed with double distilled water
(Scheme 1).
catalysts, it was observed that there was major loss of
K
concentration from 21.81% and 7.77% to 2.35% and 1.72% for
MMPA and MCPA respectively (see ESI, S4(f) and S5(f)).
Additionally, the concentration of Ca was also decreased in the
recycled catalysts. Moreover, no obvious changes were observed in
the SEM images of both the catalysts before and after five catalytic
cycles, indicating the stability of the catalysts after the catalytic
reactions (see ESI, S3). In addition to that, the XPS analyses of
reused catalysts were also studied and it revealed that, with
decreasing the amount of potassium (2.59% and 2.20%) with
calcium (0.74% and 0.24%) for MMPA and MCPA respectively (see
ESI, S4(a-e) and S5(a-e)). The atomic weight percentage of carbon
was increased in high number to 56.38% and 53.87% for MMPA and
MCPA respectively. Hence it was confirmed that potassium source
played a key role in the Claisen-Schmidt reaction due to its high
basic nature.
Scheme 1: Gram-scale synthesis of Chalcone.
On the basis of previous reports and above controlled
experiments, we proposed a plausible mechanism of formation of
chalcone derivatives (Scheme 2).1,18,19 The first part of this reaction
is proceeded via aldol reaction then second part through a
dehydration-an elimination reaction which involves removal of a
water or an alcohol molecule. As shown in mechanism, here the
prepared catalysts (MMPA and MCPA) acts as base to form an
enolate ion with carbonyl group of acetophenone derivatives. Then
the enolate will generally react with unreacted aldehydes to form
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 8 of 10
ARTICLE
Journal Name
1
2
3
4
pharmaceutical industries for the preparation of synthetically as
well as biologically useful derivatives like, buDtOeiIn: 1a0n.1d03a9p/iDg0eNniJn0.3839C
View Article Online
5
6
7
8
Conflicts of interest
There are no conflicts to declare
.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Acknowledgements
We thank CSIR New Delhi, India for providing financial support for
conducting this research work under the grants of
BT/PR25189/NER/95/1067/2017 (DBT, India) and CSC-0130, OLP-
2020 (CSIR, India) projects. We also thank the Director, CSIR-NEIST,
Jorhat, Assam for providing all the needed facilities.
Fig. 5 Reusability of the catalysts (MMPA and MCPA) on synthesis of
References
chalcone derivatives
1
2
3
(a) L. Claisen and A. Claparede, Ber. Dtsch. Chem. Ges., 1881,
14, 2460-2468; (b) J. Gustav Schimdt, Ber. Dtsch. Chem. Ges.,
1881, 14, 1459-1461.
T. Enoki, H. Ohnogi, K. Nagamine, Y. Kudo, K. Sugiyama, M.
Tanabe, E. Kobayashi, H. Sagawa and I. Kato, J. Agric. Food
Chem., 2007, 55, 6013-6017.
(a) A. Agarwal, K. Srivastava, S. K. Puri and P. M. S. Chauhan,
Bioorg. Med. Chem. Lett., 2005, 15, 3133-3136; (b) V. J. Ram,
A. S. Saxena, S. Srivastava and S. Chandra, Bioorg. Med.
Chem. Lett., 2000, 10, 2159-2161.
In view of the importance of our catalytic environment, we
further studied towards our catalytic ability of the catalysts by
comparing with other reported methodologies (Table 4). Amid
some of the prepared catalysts like, WEB (Musa balbisiana Colla
water extract) by Saikia et al.18a,b and MAPA (Musa acuminata peel
ash) by Rokhum et al.19a we have attempted to study our model
reaction with these catalysts. From the results, it can be seen that
our prepared banana peel extracts afforded exceptional conversion
for both the reactions in our optimized conditions. This variation of
the resulted yield percentage of the products and the reaction time
may be due to the presence of different metals, elements, active
constituents that are responsible for the catalysis.
4
5
(a) P. Rani, V. K. Srivastava and A. Kumar, Eur. J. Med. Chem.
2004, 39, 449-452; (b) Z. Nowakowska, J. Med. Chem. 2007,
42, 125-137. (c) M. Feldman, S. Tanabe, F. Epifano, S.
Genovese, M. Curini and D. Grenier, J. Nat. Prod. 2011, 74
,
26-31; (c) H. K. Hsieh, L. T. Tsao, J. P. Wang and C. N. Lin, J.
Pharm. Pharmacol., 2000, 52, 163-171.
(a) A. Shah, A. M. Khan, R. Qureshi, F. L. Ansari, F. M. Nazar,
and S. S. Shah, Int. J. Mol. Sci., 2008, 9, 1424-1434; (b) X. Liu,
Table 4. Comparison between our protocol with other prepared
banana catalysts for the synthesis of chalcones and flavones
C. N. Kim, J. Yang, R. Jemmerson, and X. Wang, Cell, 1996, 86
147-157; (c) T. Takahashi, N. Takasuka, M. Ligo, M. Baba, H.
Nishino, H. Tsuda and T. Okuyama, Cancer Sci., 2004, 95
,
Catalysts
(15 mg)
WEB
MAPA
MMPA
WEB
Time
(min)
30
45
10
60
Yield
(%)
91
87
95
88
Ref.
Procedure
17a
18a
Our report
17a
Products Entry
1
,
448-453; (d) X. -Y. Xiao, M. Hao, X. -Y Yang, Q. Ba, M. Li, S. -J
Ni, L. -S Wang and X. Du, Cancer Lett., 2011, 302, 69-75; (e)
G. Yoon, Y. D. Jung and S. H. Cheon, Chem. Pharm. Bull.,
2005, 53, 694-695.
Y. Lin, Y. Zhou, M. Flavin, L. Zhou, W. Niea and F. Chen,
Bioorg. Med. Chem. Lett., 2002, 10, 2795-2802.
O. Kayser and A. F. Kiderlen, Phytother. Res., 2001, 15, 148-
152.
Chalcone
2
3
4
6
7
8
Flavone
5
6
60
35
80
89
18a
Our report
MAPA
MMPA
(a) A. Ghosh, S. Mandal, A. Banerji, M. Kar and J. Banerji, Nat.
Prod. Commun., 2009, 4, 209-210; (b) Y. -W. Chin, H. -A.
3. Conclusions
Jung, Y. Liu, B. -N. Su, J. A. Castoro, W. J. Keller, M. A. Pereira
and A. D Kinghorn, J. Agric. Food Chem., 2007, 55, 4691-
4697; (c) E. H. Lee, D. -G. Song, J. Y. Lee, C. -H. Pan, B. H. Um
and S. H. Jung, Biol. Pharm. Bull., 2008, 31, 1626-1630.
D. G. Powers, D. S. Casebier, D. Fokas, W. J. Ryan, J. R. Troth
and D. L. Coffen, Tetrahedron, 1998, 54, 4085-4096.
In conclusion, we have developed a synthetic greener route for the
syntheses of chalcone and flavone derivatives by using two novel
agro‐food wastes of Musa sp. ‘Malbhog’ peel ash (MMPA) and
Musa Champa Hort. ex Hook. F. peel ash (MCPA) which were
biodegradable, highly efficient, cheap and environmentally benign.
From the overall discussion, we can see that our new approach
gives an excellent yield of the desired condensation products as
9
10 E. P. Rondon, R. M. M. Aranda, B. Casal, C. J. Duran-Valle, W.
N. Lau, X. F. Zhang and K. L. Yeung, Catal. today, 2006, 114
183-187.
,
well as large scale synthesis at room temperature under metal and 11 (a) M. Azad and M. Munawar Ali, J. Appl. Sci., 2007, 7, 2485-
2489; (b) N. O. Calloway and L.D Green. J. Am. Chem. Soc.,
1937, 59, 809-811; (c) R. Prasad, P. Kumar and P. R. Kumar,
E-Journal of Chem., 2008, 5, 144-148; (d) M. Iglesias. J. M.
Marinas and J. V. Sinisterra, Tetrahedron., 1987, 43, 2335-
2342; (e) T. Narender and K. P. Reddy, Tetrahedron Lett.,
2007, 48, 3177-3180; (f) M. Chitra, T. V. Rajendran and V.
toxic organic solvent free conditions. These two methods are very
much compatible to various ranges of substrates for presenting
Claisen-Schmidt reaction with offer an easy access to flavones as
product. With these advantages, our new catalytic system is
commercially beneficial for the sake of academia along with
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 9 of 10
New Journal of Chemistry
Please do not adjust margins
Journal Name
ARTICLE
1
2
3
4
5
6
7
8
9
Duraipandiyan, Indian J. Sci. Technol., 2010,
3
, 890-893; (g) 20 (a) S. K. Sinha and A. C. Deka, Afr. J. Biotechnol. 2016, 15
,
View Article Online
M. D. Savanth and K. Chakraborti, J. Mol. Catal., 2006, 244
,
465-471; (b) P. K. Bordoloi, P. D. Bhuyan, P. Boruah, M
DOI: 10.1039/D0NJ03839C
20-24.
Bordoloi and P. G. Rao, Phytochem. Lett., 2009, 2, 22-24; (c)
12 (a) L. Mazza and A. Guaram, Synthesis., 1980,
1
, 41-43; (b) S.
A. C. Dutta, Dictionary of Economic and Medicinal Plants,
K. Akuskar, T. K. Chondhekar and D. G. Dhuley, Asian. J. of
1985, Khelmati, Jorhat, Assam, SL No. 122, p. 21.
Chem., 1997,
9, 336-340; (c) N. Iranpoor and F. Kazemi, 21 (a) D. C. Deka and N. N. Talukdar, Indian J. Tradit. Know.
Tetrahedron., 1998, 54, 9475-9480.
2007,
6, 72-78; (b) I. O. Olabanji, E. A. Oluyemi and O. S.
13 (a) M. R. Sazegar, S. Mahmoudian, A. Mahmoudi, S.
Ajayi, Afr. J. Biotechnol., 2012, 11, 16512-16518.
Triwahyono, A. A. Jalil, R. R. Mukti, N. H. N. Kamarudin and 22 (a) J. H. Park, J. H. Eom, S. L. Lee, S. W. Hwang, S. H. Kim, S.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
M. K. Ghoreishi, RSC Adv., 2016,
6
, 11023-11031; (b) C.
W. Kang, J. J. Yun, J. S. Cho, Y. H. Lee and D. C. Seo, Sci. Total
Environ., 2020, 740, 140205; (b) Z. Xu, X. Xu, , D. C. W. Tsang
and X. Cao, Environ. Pollut. 2018, 242, 1362-1370.
Tamuly, I. Saikia, M. Hazarika, M. Bordoloi, N. Hussain, M.
R. Das and K. Deka, RSC Adv., 2015,
5, 8604-8608.
14 C. M. Comisar and P. E. Savage, Green Chem., 2004,
6
, 227- 23 N. S. Trivedi, R. A. Kharkar and S. A. Mandavgane, Resour.-
231.
Effic. Technol., 2016, 2, S39-S46.
15 D. J. Macquarrie, R. Nazihand and S. Sebti, Green Chem., 24 F. J. Sotomayor, K. A. Cychosz and M. Thommes, Acc. Mater.
2002,
4
, 56–59.
Surf. Res. 2018, 3, 34-50.
16 R. Ballini, G. Bosica, R. Maggi, M. Ricciutelli, P. Righi, G. 25 R. P. Santos, J. Martins, C. Gadelha, B. Cavada, A. V. Albertini,
Sartori and R. Sartorio, Green Chem., 2001,
17 (a) T. N. Nguyen, P. A. Le and V. B. T. Phung, Biomass
3
, 178-180.
F. Arruda, M. Vasconcelos, E. Teixeira, F. Alves, J. L. Filho, and
V. Freire, Sci. World J., 2014, 154651.
Convers. Biorefin., 2020, doi: 10.1007/s13399-020-00839-2; 26 B. G. de O. Maia, A. P. N. de Oliveira, T. M. N. de Oliveira, C.
(b)
J.
Jitjamnong,
C.
Thunyaratchatanon,
A.
Marangoni, O. Souza, and N. Sellin, Environ. Prog.
Sustainable Energy, 2018, 37, 1266-1273.
Luengnaruemitchai, N. Kongrit, N. Kasetsomboon, N.
Chuaykarn and N. Khantikulanon, Chiang Mai J. Sci., 2019, 27 A. P. S. Chouhan and A. K. Sarma, Biomass Bioenergy, 2013,
47, 484-498; (c) X. Rong, M. Xie, L. Kong, V. Natarajan, L. Ma 55, 386–389.
and J. Zhan, Chem. Eng. J., 2019, 372, 294-303; (d) N. Ozbay, 28 (a) A. K. Yadav and P. Singh, RSC Adv., 2015,
5
, 67583-67609;
A. S. Yargic, R. Z. Y. Sahin and E. Yaman, Renewable Energy,
2019, 140, 633-646; (e) D. S. Rosa, B. P. Vargas, M. V.
Silveira, C. H. Rosa, M. L. Martins and G. R. Rosa, Waste
Biomass Valor., 2019, 10, 2285–2296; (f) M. Fan, H. Wu, M.
(b) I. H. Boyaci, H. T. Temiz, H. E. Genis, E. A. Soykut, N. N.
Yazga, B. Guven, R. S. Uysal, A. G. Bozkurt, K. Ilaslan, O.
Torum and F. C. D. Seker, RSC Adv., 2015, 5, 56606-56624; (c)
A. Guedes, B. Valentim, A. C. Prieto, A. Sanz, D. Flores and F.
Noronha, Int. J. Coal Geol., 2008, 73, 359–370; (d) N. P.
Ivleva, S. Huckele, B. Weinzierl, R. Niessner, C. Haisch and T.
Baumann, Anal. Bioanal. Chem., 2013, 405, 9071–9084.
Shi, P. Zhang and P. Jiang, Green Energy Environ., 2019, 4,
322-327; (g) M. Balajii and S. Niju, Energy Convers. Manage.,
2019, 189, 118-131; (h) V. O. Odude, A. J. Adesina, O. O.
Oyetunde, O. O. Adeyemi, N. B. Ishola, A. O. Etim and E. 29 (a) Y. J. Heo and S. J. Park, Sci. Rep., 2017,
7
, 5653; (b) J. C.
Dupin, D. Gonbeau, P. Vinatier and A. Lavasseur, Phys. Chem.
Chem. Phys., 2000, , 1319-1324; (c) R. Sawyer, H. W. Nesbitt
and R. A. Secco, J. Non-Cryst. Solids, 2012, 358, 290-302.
797-806; (k) R. L. Liu, X. Y. Gao, L. An, J. Ma, J. F. Zhang and Z. 30 (a) K. J. Tamuli, D. Dutta, S. Nath and M. Bordoloi,
Q. Zhang, RSC Adv., 2015, , 93858-93866; (l) J. Ma, W. ChemistrySelect, 2017, , 7787-7791; (b) K. J. Tamuli and M.
Huang, K. Chen, D. Xue and S. Komarneni, Nanosci. Bordoloi, ChemistrySelect, 2020,
Nanotechnol. Lett., 2014, , 997-1000.
18 (a) P. R. Boruah, A. A. Ali, B. Saikia and D. Sarma, Green
Betiku, Waste Biomass Valor., 2019, 10, 877-888; (i) S. N. Sari
and A. Melati, Mater. Today: Proc., 2019, 13, 165-168; (j) E.
2
Betiku, A. M. Akintunde and T. V. Ojumu, Energy, 2016, 103
,
5
2
5
, 1353–1358.
6
31 R. B. Semwal, D. K. Semwal, S. Combrinck and A. Viljoen,
Phytochem. Lett., 2015, 11, 188-201.
Chem., 2015, 17, 1442-1445; (b) B. Saikia, P. Borah and N. C. 32 (a) E. H. Lee, D. G. Song, J. Y. Lee, C. H. Pan, B. H. Um and S.
Barua, Green Chem., 2015, 17, 4533-4536 (c) N. Surneni, N.
C. Barua and B. Saikia, Tetrahedron Lett., 2016, 25, 2814-
2817.
H. Jung, Biol. Pharm. Bull. 2008, 31, 1626–1630; (b) Y. Wang,
Life Sci. 2005, 77, 39-51.
33 (a) B. Salehi, A. Venditti, M. Sharifi-Rad, D. Kręgiel, J. Sharifi-
Rad, A. Durazzo, M. Lucarini, A. Santini, E. B. Souto, E.
Novellino, H. Antolak, E. Azzini, W. N. Setzer and N. Martins,
Int. J. Mol. Sci. 2019, 20, 1305; (b) M. Venigalla, E. Gyengesi
and G. Münch, Neural Regener. Res., 2015, 10, 1181-1185.
34 F. Ali, Rahul, F. Naz, S. Jyoti and Y. H. Siddique, Int. J. Food
Prop., 2017, 20, 1197-1238.
19 (a) G. Pathak, D. Das, K. Rajkumari and L. Rokhum, Green
Chem., 2018, 20, 2365-2373; (b) G. Pathak, K. Rajkumari and
L. Rokhum, Nanoscale Adv., 2019,
1, 1013-1020; (c) K.
Rajkumari, D. Das, G. Pathak and L. Rokhum, New J. Chem.,
2019, 43, 2134-2140.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
Please do not adjust margins

New Journal of Chemistry
Page 10 of 10
View Article Online
DOI: 10.1039/D0NJ03839C
1
2
3
4
Table of contents entry
5
6
7
8
9
A Biocatalytic Green Alternative to Existing Hazardous Reaction Medium: Synthesis of
Chalcone and Flavone Derivatives via Claisen-Schmidt Reaction at Room Temperature
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Kashyap J. Tamuli,a,b Ranjan K. Sahooa and Manobjyoti Bordoloi*a,b
Herein, two novel agro‐food wastes of banana peels were used to synthesize chalcone and
flavone derivatives at room temperature in solvent free conditions.