CuI nanoparticles as recyclable heterogeneous catalysts for C-N bond formation reactions

Article abstract of DOI:10.1039/c7cy00832e

Herein, copper iodide nanoparticles (NPs) are reported for the reductive amination of carbonyl compounds for the first time. The generated NPs were characterized by TEM, EDX, XRD and XPS analyses. The XRD patterns, XPS, and EDX analysis confirmed that the resulting NPs were CuI instead of Cu. The TEM images of CuI exhibited the size of monodispersed spherical NPs in the range of 4 ± 2 nm. These generated NPs can be used as versatile heterogeneous catalysts for important organic transformations. As a proof of concept, CuI NPs were successfully applied as heterogeneous catalysts for the synthesis of secondary amines, amides and triazoles. CuI NPs can be easily recovered and recycled up to six times.

Full text of DOI:10.1039/c7cy00832e

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Technol., 2017, DOI: 10.1039/C7CY00832E.
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DOI: 10.1039/C7CY00832E
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CuI nanoparticles as a recyclable heterogeneous catalyst for C-N
bond formation reactions
Received 00th January 20xx,
Accepted 00th January 20xx
Manoranjan Kumar,a,b,¥ Vinod Bhatt,a,b,¥ Onkar S. Nayal,
Sushila Sharma,a,b Vishal Kumar,c
a,b
Maheshwar S. Thakur,a,b Neeraj Kumar,† Rajaram Bal,*d Bikram Singh*a,b and Upendra Sharma*a,b
DOI: 10.1039/x0xx00000x
Herein, copper iodide nanoparticles (NPs) are first time reported for the reductive amination of carbonyl compounds. The
generated NPs were characterized by TEM, EDX, XRD and XPS analysis. The XRD pattern, XPS, and EDX analysis confirmed
that the resulted NPs were of CuI instead of Cu. The TEM image of CuI exhibited the monodispersed spherical NPs size in
the range of 4±2 nm. These generated NPs can be used as versatile heterogenous catalysts for important organic
transformations. As a proof of concept, CuI NPs were successfully applied as a heterogeneous catalyst for the synthesis of
secondary amines, amide and triazole. CuI NPs can be easily recovered and recycled up to six times.
www.rsc.org/
direct reductive amination of carbonyl compound is one of the
most convenient and efficient method to facilitate the
synthesis of complex amines. Previous approaches have been
Introduction
Nowadays nanocatalysts are very popular in chemical
industries, energy related applications and environmental
remediation’s. The catalytic systems based on nanoparticles
(NPs), are most promising candidates due to their broad
spectrum of characteristics which forms the bridge over the
heterogeneous and homogeneous catalysts.1 The recyclability
and recovery offers heterogeneous characteristics whereas
low catalytic loading and selectivity offers homogeneous
characteristics of NPs.1 In addition, small dimension and large
surface area of NPs, revealed high catalytic activity under mild
conditions.
Amino compounds are ubiquitous in natural products,
synthetic intermediates and pharmaceutical agents.2
Therefore, efficient and economic synthesis of amines is a very
active field in medicinal chemistry and modern organic
synthesis. The introduction of amine functionality into organic
framework is generally achieved by C-N bond formation
strategies. Although, various methods for the synthesis of
substituted amines viz. alkylation of amines, reduction of
nitriles and Buchwald-Hartwig amination are known,3 the
focused on the use of precious metal based catalysts such as
Au, Pd, Pt, Rh, Ir and Ru for this transformation.4 However,
limited availability, high cost and toxicity of these metal based
catalyst, turned researchers towards the environment friendly
and easily available bio-relevant metal based catalysts such as
Zn,5 Fe,6 and Co7. However, high catalyst loading, longer
reaction time and non-ecofriendly solvent limits the scope of
these methods. Hence a simple approach with minimum
catalyst loading to control the quantity of heavy metal waste
at the end of reactions is highly desired. In this context, the
catalytic system based on NPs, played a vital role. Previously,
nanocatalyst viz Pd8 and Ni9 were reported for the synthesis of
amines via C-N bond formation strategies. The separate step
for nanometal preparation, high cost of palladium salts and
toxicity of nickel limit their scope. These limitations can be
overcome by the use of less expensive and bio-relevant CuI
nanoparticles (NPs). Herein, we disclose a new and simple
method for the synthesis of CuI NPs and successfully applied
these NPs as heterogeneous catalyst for various C-N bond
formation reactions to synthesize secondary amines, amide
and substituted triazole. This is first report on CuI catalyzed
direct reductive amination of carbonyl compounds.
a.Natural Product Chemistry and Process Development Department, CSIR-Institute
of Himalayan Bioresource Technology Palampur, Himachal Pradesh 176 061,
India.
b.Academy of Scientific and Innovative Research, Anusandhan Bhawan, 2 Rafi
Marg, New Delhi-110001, India.
Result and discussions
c. State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Weijin
Road 300 071, Tianjin, China.
In continuation of our interest on reductive amination,10
herein we disclosed a new method to prepare CuI NPs using
phenylsilane in ethanol without the use of additional
stabilizing agents. Furthermore, CuI NPs have been utilized as
heterogeneous catalyst for reductive amination of carbonyl
compound to synthesize secondary amine. Recently, Beller and
co-workers reported the first successful copper(II) catalyzed
d.Refining Technology Division, CSIR-Indian Institute of Petrolium, Dehradun,
248005.
¥ These authors contributed equally
†Author deceased.
*E-mail: upendra@ihbt.res.in, upendraihbt@gmail.com (US);
raja@iip.res.in (RRB); bikramsingh@ihbt.res.in (BS)
Electronic
Supplementary
Information
(ESI)
available:
See
DOI: 10.1039/x0xx00000x
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reductive amination of ketone using molecular hydrogen as
Journal Name
Among all the tested Cu catalysts, CuI was found to be the
View Article Online
o
reducing agent but non recyclability of the catalyst limit the most active at 80 C, while ZnI affordeDdOoI:n1l0y.1063%9/Co7fCdY0e0s8ir3e2dE
scope of this method.11
product (Table 1, entries 1-9). Further, investigation of
To identify the best reaction conditions, the direct different organosilanes as reducing agent revealed
reductive amination of benzaldehyde with aniline was chosen phenylsilane as most efficient reducing agent with 92%
as model reaction and subjected to a series of different copper isolated yield of the desired product (Table 1, entry 1).
catalysts, reducing agents and solvents under varying Diphenylsilane afforded the desired product in lower yield of
temperature conditions (Table 1).
31% (Table 1, entry 10) whereas no product or poor yield of
products were observed with other organosilanes (Table 1,
entries 11‒14).
Table 1 Optimization of reaction conditions for reductive amination.a
Next, we examined the influence of different solvent on
the yield of desired product. In protic solvent, comparable
yields were found with ethanol, methanol, PEG-400, t-butanol,
and n-butanol whereas lower yield was observed in ethylene
glycol, isopropanol and water (Table 1, entries 1, 15‒21). In
aprotic solvents, low yield was obtained with THF and DMF
whereas no product was observed in toluene (Table 1, entries
22‒24). Effect of co-solvent was also tested, however,
comparatively lower yield (77%) of desired product was
observed (Table 1, entries 25).
CHO
NH2
Catalyst (3 mol%)
Reducing agents (1.5 equiv.)
o
N
H
+
solvent, 80
4h
C
Yield
[%]b
92c
<5
8
Entry
Catalyst
Reductant
Solvent
1
CuI
CuSO4
Cu2O
CuPc
Cu(OAc)2
CuCl2
CuCl
Cu
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
Ph2SiH2
Ph3SiH
PMHS
TMDS
EtOH
EtOH
2
3
EtOH
4
EtOH
<5
38
27
48
37
6
After optimization of metal salt and solvent, the amount of
reducing agent was determined. In presence of one equivalent
of phenylsilane 49% of product was observed while increasing
its amount upto two equivalents gave 80% of the desired
product (Table 1, entries 26 & 27). After that effect of
temperature was also observed, at room temperature 62% of
product was observed while increasing the temperature upto
5
EtOH
6
EtOH
7
EtOH
8
EtOH
9
ZnI
EtOH
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
CuI
EtOH
31
‒
o
120 C resulted in 83% of product yield (Table 1, entries 28 &
CuI
EtOH
29). Notably, in case of other aldehydes and amines very low
yields of products were observed at room temperature.
CuI
EtOH
<5
<5
‒
CuI
EtOH
Under best optimized reaction conditions, deposition of a
brown red mass was observed at the bottom of reaction tube.
This deposited brown red mass at the end of reaction was
filtered and washed multiple times with ethyl acetate and
ethanol. After analysis with transmission electron microscopy
(TEM), X-ray diffraction (XRD) and X-ray photoelectron
spectroscopy (XPS), this brown red mass was found to be of
CuI NPs. Previously it was reported that, amines and
aminosilanes play a very important role in controlling shape,
size, growth and aggregation of metal NPs.12-14 The importance
of amines and silanes were similarly observed in our case. In
the absence of amine, or silane, the expected NPs were not
formed, however, aniline alone in the presence of phenylsilane
resulted in the growth of larger size of CuI NPs.
The TEM image of CuI exhibited the spherical NPs size in
the range of 4±2 nm (Fig 1. (A), (B)). Further probing of the
sample using high resolution TEM (HRTEM) showed the
presence of crystalline particles with a lattice spacing of 0.2136
nm, corresponding to the 220 plane of CuI (JCPDS no. 06-0246)
[Fig 1. (D)]. The XRD diffraction patterns of the fresh catalyst
having no ghost peak confirms the purity and crystalline
nature of CuI NPs, which were also well matched with
standard γ phase (fcc structure) of CuI (JCPDS no. 06-0246)
[(Fig 2. (a)].15 EDX analysis showed copper and iodine signals
which supported the formation of CuI NPs [(Fig 3. (a)]. Further,
investigation was carried out to find the exact oxidation state
CuI
Et3SiH
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
PhSiH3
EtOH
CuI
MeOH
PEG-400
Ethylene glycol
Isopropanol
t-Butanol
n-Butanol
H2O
88
89
57
33
77
88
30
50
23
‒
CuI
CuI
CuI
CuI
CuI
CuI
CuI
THF
CuI
DMF
CuI
Toluene
EtOH:H2O
EtOH
CuI
77
49d
80e
62f
83g
CuI
CuI
EtOH
CuI
EtOH
CuI
EtOH
aReaction condition: benzaldehyde (1 mmol), aniline (1 mmol), catalyst (3
mol%), silane (1.5 mmol), solvent (3 mL) at 80oC for h. byield was
determined by GC analysis using anisole as an internal standard. cIsolated
yield. dThe reaction was carried out with 1 equivent of reducing agents. eThe
reaction was carried out with 2 equivent of reducing agents. fThe reaction
was carried out at room temperature. gThe reaction was carried out at 120
oC.
4
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of constituent elements by XPS analysis. The bindViniegw eArnticelergOynlionef
Cu 2p3/2 and 2p1/2 at 932.1 eV and 952.D3OeI:V10r.e10s3p9e/cCt7iCveY0ly08a3n2dE
weak satellite peak in XPS supported that copper(I) is present
in the active catalyst [(Fig 4. (a)].16 Additionally, the XPS peaks
Figure 4 (a) XPS spectra of Cu 2p3/2 and 2p1/2, (b) XPS spectra of I¯ 3d5/2 and 3d3/2
.
at 619 eV and 630.5 eV corresponds to the I 3d5/2 and 3d3/2
,
which clearly indicates the presence of Iˉ [(Fig 4. (b)]. These
XPS results confirms the presence of only one oxidation state
for both Cu and I.17 Further, the recyclability of catalyst was
investigated for the model reaction and found to be active up
to six cycles with milder decrease in catalytic activity (Fig. 5).
Figure 1 (A) & (B) TEM images, (C) Particle size distribution histogram as calculated
from B, (D) HRTEM image showing lattice fringes.
92
89
86
100
80
60
40
20
0
84
82
79
1
2
3
4
5
6
Cycle
Figure 5 Recyclability of catalyst.
To study the fate of spent catalyst (after sixth cycle) the
XRD and EDX analysis was carried out. The XRD pattern of the
spent catalyst showed the presence of metallic Cu with the
Figure 2 (A) XRD pattern of CuI NPs (B) XRD pattern of CuI NPs after sixth cycle of
reaction.
peaks at 2 values of 43.83 and 74.14 in addition to the CuI
peaks [(Fig 2. (b)]. Hence, from XRD patterns of spent catalyst,
it appears that Cu (I) tends to reduce into Cu (0) which might
be resulted in decrease of product yield. However, EDX
analysis of spent catalyst showed copper and iodine signals
[(Fig 3. (b)], the presence of metallic copper could not be
denied.
To find out the heterogeneity/leaching of catalyst, the
atomic absorption spectroscopy (AAS) analysis of filtered
solution at the end of model reaction was carried out and only
<4 ppm of Cu was found in the solution. Hot filteration test
was also performed by filtering the hot reaction mixture
through celite at 40% conversion. After filtration, reaction was
kept continued for standard 4 hour of reaction time. GC
analysis of the filtrate even after 4 hour did not show any
change in the yield. These analyses proved that developed
Figure 3 (a) EDX spectra of CuI NPs before reaction, (b) EDX spectra of CuI NPs after
sixth cycle of reaction.
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catalyst is heterogeneous in nature. Further CHN combustion (Table 3, entries 6a-6c). Various heteroaromaticVaiemw Ainrteicsle Osunlcinhe
analysis of catalyst was also done to find out the presence of as aminopyridine derivatives and 6-amiDnOoIb: e10n.z10o3t9h/iCa7zCoYle00w83i2thE
any residual amine with catalyst. Only < 0.005% of nitrogen benzaldehyde and cinnamaldehyde gave the reductive
was found. This experiment confirmed that there is no role of amination products in good to excellent yields (Table 3, entries
any ligand or residual amine for the stabilization of generated 6d
CuI NPs.
After characterization, CuI NPs were screened for various chosen as heteroaromatics (Table 3, 6k
C-N bond formation reactions. First we checked its utility for
-
6j). The developed method also afforded good yields of
desired products, when both aldehyde and amines were
6l).
Further, the synthesized catalyst was applied for other
&
the synthesis of amines via reductive amination of carbonyl important C-N bond formation reactions viz for amide and
compounds. Various aldehydes and amines bearing electron triazole synthesis, since both moieties play a very important
donating as well as electron withdrawing functional groups role in pharmaceutical industry.18,19 We selected two sterically
such as alkene, hydroxy, halides, alkyl, alkoxy, acetyl, nitrile hindered substrates for both triazole and amide bond
and esters afforded the desired products selectively in good to formation reactions (Scheme 1).
excellent yields (Table 2, entries 3a-3s). Ketones were also
tested under developed reaction conditions affording the
CHO
expected products in good yields (Table 2, entries 3t-3x).
CuI NPs (5 mol%), TBHP (1.1 equiv)
O
NH2 .HCl
HN
(a)
Cl
+
o
CaCO (1.1 equiv), CH CN, 60 C, 6h
Cl
3
3
Table 2 CuI catalyzed reductive amination of various carbonyls and amine.a
1.2 equiv
7a, 80%
1 equiv
R
O
N
N
Cl
CuI NPs (5 mol%)
R
C
NH2
PhC CH
NaN3
(b)
+
+
Ph
o
N
EtOH, 80 C, 24h
NO2
0.30 mmol
CuI (3 mol%), PhSiH (1.5 equiv.)
3
N
H
R2
+
NO2
o
1 equiv
1 equiv
7b, 90%
EtOH, 80 C, 4h
R2
R1
R1
Scheme 1 CuI NPs for other C-N bond formation reactions.
3, isolated yields
1
2
Ph
Ph
Ph
MeO
Ph
Ph
O
N
H
N
N
H
H
Earlier, CuSO4.5H2O20 and silica supported Cu(I)21 catalyst
were reported for amide and triazole synthesis respectively
under the given reaction conditions. The synthesized CuI NPs
were found to be more effective and resulted in higher
product yields.
Ph
N
R2
O
MeO
OMe
R1
H
3n, 82%
2
3m, 82%
1
3f, 92% R = 4-F
3a, 92% R = H
2
1
3g, 91% R = 4-I
3b, 92% R = 4-OMe
2
1
N
H
N
H
3h, 82% R = 4-Me
3c, 77% R = 4-Me
2
1
3i, 88% R = 4-OMe
3d, 86% R = 4-Br
MeO
OH
2
1
3j, 65% R = 4-COMe
3e, 83% R = 4-Cl
OMe
3p, 78%
3o, 79%
2
3k, 85% R = 3-CN
To get insight of mechanism for CuI NPs catalyzed
reductive amination, first the fate of phenylsilane was studied.
Upon addition of phenylsilane to the reaction mixture,
effervescence was observed which may be due to evolution of
H2 gas. Further to investigate the origin of effervescence, the
reaction of phenylsilane and CuI in ethanol was studied at
different time intervals with IR spectroscopy (for details see
SI). From the analysis of IR spectra, it was found that the Si-H
band at 2154 cm-1 of phenylsilane shifted to 2169.9 cm-1
alongwith a new band at 1066 cm-1 and 1043 cm-1 which can
be attributed to long chain Si-O-Si stretching frequencies.22
This suggested that copper iodide promoted the long chain
polymerization of phenylsilane leading to H2 generation during
this process. Further, over a period of 4h, new bands appeared
at 2922 and 2852 cm-1 corresponding to Si-OC2H5 which
confirms the formation of PhSiOEt (Scheme 2).
2
Ph
3l, 80% R = 4-COOEt
NH
Ph
N
Ph
N
Ph
O
Me
Ph
N
H
H
H
O
3r, 81%
3s, 85%
3t, 81%
MeO
3q, 85%
H
H
N
H
N
H
N
N
Ph
Ph
Ph
Ph
3x, 88%
3u, 92%
3v, 86%
3w, 82%
Me
Me
aReaction conditions: aldehyde (1 mmol), amine (1 mmol), CuI (3 mol%), PhSiH3 (1.5
mmol), EtOH (3 mL) at 80 oC for 4 h.
Further, the scope of reductive amination for
heteroaromatic aldehydes as well as amines were explored
(Table 3).
Table 3 CuI catalyzed reductive amination of heteroaromatic aldehydes and amines.a
CuI (3 mol%), PhSiH (1.5 equiv.)
3
H
R1
R2NH2
R1
N
+
O
o
EtOH, 80 C, 4h
4
R3 6, isolated yields
5
H
H
H
HN Ph
N
N
N
Ph
Ph
PhSiH3
H2O
CuI + Ethanol
Ph
6a, 79%
AcO
H
H
Ph Si OH
H
H
H
H
Ph Si
H
O
O
O
6b, 75%
6c, 61%
6d, 72%
H
Ph Si OC2H5
H
H
Si O Si
Ph Ph
H
N
N
Br
Cl
H
H
H
N
H
N
Ph
N
Ph
N
Br
Ph
Ph
H2
CuI NPs
C2H5OH
N
Cl
N
N
Br
6f, 72%
6h, 78%
6g, 95%
6e, 45%
Scheme 2 Generation of CuI NPs with phenyl silane in ethanol.
H
N
N
H
N
N
S
O
O
S
To determine the possible role of polysiloxane during the
reduction of imine, polysiloxane was prepared by treating
phenylsilane with catalytic quantity of CuI in ethanol at 80 C
for 2 h. Subsequently, starting material/reactants were added
in the reaction mixture and the desired product was observed
in 28% yield after 4 h. The result indicated that polysiloxane
may also be involved in the reduction of imine.
Ph
N
H
Ph
N
H
N
Cl
N
6i, 86%
6j, 80%
6k, 75%
6l, 72%
S
o
aReaction conditions: aldehyde (1 mmol), amine (1 mmol), CuI (3 mol%) , PhSiH3 (1.5
mmol), EtOH (3 mL) at 80 oC for 4 h.
Notably, the reaction of heteroaromatic aldehydes such as 2-
furaldehyde,
benzofurancarboxaldehyde with anilines afforded the
reductive amination products in good yields respectively
5-acetoxymethyl-2-furaldehyde
and
2-
4 | J. Name., 2012, 00, 1-3
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A tentative reaction mechanism for synthesis of secondary Prestige-21 FT-IR spetrophotometer. AtomicViewAbArstioclrepOtniloinne
amines catalyzed by CuI NPs under heterogeneous conditions Spectroscopy (AAS) were performed oDnOSI:h1i0m.10a3d9z/uC7CAYA0-06833020E
is proposed on the basis of experimental results and reported spectrophotometer. The CHN analysis experiment of catalyst
literature (Scheme 3).6(b),22 It is proposed that initially the were recorded on Elementar, vario Macro cube using
active CuI NPs coordinates to imine generated in situ from the sulphanilamide as reference compound.
reaction of aldehyde and amine, which activated imine. The
activated imine undergoes reduction with phenylsilane or its General procedure for the synthesis of CuI nanoparticles
polymer, followed by solvolysis with ethanol or trace amount To a 15 mL reaction tube with magnetic stirrer bar, added
of water, to give desired product along with regeneration of benzaldehyde (1 mmol), aniline (1.0 mmol), phenysilane (1.5
active species.
mmol), CuI (5 mol%), and ethanol (3 mL). The reaction mixture
was stirred at 80 oC for 4h. After completion of reaction,
catalyst settled down at the bottom was filtered, and washed
5-6 times with ethyl acetate and ethanol. Dried catalyst was
kept under nitrogen atmosphere.
PhSiH + CuI +
EtOH
3
H
H
H
2
Ph-Si-O-Si-Ph+ CuI NPs
Ph
H
H
Ph
O +
H N
2
General procedure for reductive amination of carbonyl
compounds using CuI NPs/PhSiH3
CuI
EtOH
Ph
Ph
Ph
N
H
Ph
N
Ph
Ph
N
CuI NPs
SiPhHR
To a 15 mL reaction tube with magnetic stirrer bar, added CuI
(0.03 mmol), carbonyl compound (1 mmol), amines (1.0
mmol), phenysilane (1.5 mmol) and ethanol (3 mL). The
H
H
or
Ph-Si-O-Si-Ph
PhSiH
3
Ph
o
reaction mixture was stirred at 80 C and monitored by TLC.
Ph
N
H
H
After completion of reaction, the reaction mixture was filtered,
dried under reduced pressure and purified by column
chromatography using n-hexane/ethyl acetate as eluent.
Purified products were characterized by NMR (1H and 13C) and
mass spectrometry.
CuI
CuI NPs
Scheme 3 Plausible mechanism.
Conclusions
In conclusion, we disclosed the in situ generation/synthesis
and characterization of CuI NPs, its application in reductive
amination for the first time. This method avoids complicated
processes for the synthesis of metal NPs. In situ
generated/synthesized CuI NPs were successfully applied as
highly active and selective catalyst for various C-N bond
formation reactions for the synthesis of amines, amide and
triazole. The advantages of developed method are the short
reaction time, easy workup (by filtration), recyclability of
catalyst, uses ethanol as a green solvent and minimum waste
generation. Overall, the developed method is green, safer and
environment friendly.
General procedure for the synthesis of sterically hindered
amide using CuI NPs/TBHP/CaCO3
To a 15 mL reaction tube with magnetic stirrer bar, added CuI
(5 mol %), aldehyde (0.3 mmol), amine (1.2 mmol), TBHP (1.1
mmol), CaCO3 (1.1 mmol), and acetonitrile (3 mL). The reaction
mixture was stirred at 60 oC for 6 h. After completion of
reaction, the reaction mixture was filtered, dried under
reduced pressure and purified by column chromatography
using n-hexane/ethyl acetate as eluent. Purified products were
characterized by NMR (1H and 13C) and mass spectrometry.
General procedure for the synthesis of triazole using CuI NPs
To a 15 mL reaction tube with magnetic stirrer bar, added CuI
NPs (5 mol %), 2-nitrobenzylchloride (0.3 mmol), NaN3 (1.0
mmol), phenylacetylene (1.0 mmol), and ethanol (3 mL). The
reaction mixture was stirred at 80 oC for 24 h. After completion
of reaction, the reaction mixture was filtered, dried under
reduced pressure and purified by column chromatography
using n-hexane/ethyl acetate as eluent. Purified products were
characterized by NMR (1H and 13C) and mass spectrometry.
Experimental
General
Cuprous iodide was purchased from Loba Chemie Pvt. Ltd,
India. Silica gel (60-120 mesh) was used for column
chromatography and all other chemicals were purchased from
Merck, Sigma Aldrich and Spectrochem, used without further
purification. NMR spectra were measured on a Bruker Avance-
300 and Avance-600 spetrometer. Mass spectra were recorded
on a QTOF Micromassof Waters. The GC analysis was
performed on
a
Shimadzu (QP 2010) series Gas
Chromatogram-Mass Spectrometer (Tokyo, Japan), an AOC-20i
auto-sampler coupled, and a DB-5MS capillary column (30 m ×
0.25 mm i.d., 0.25 μm). The initial temperature of the column
was held at 70 °C for 4 min and was programmed to 230 °C at
4 °C min-1, then held for 15 min at 230 °C; the sample injection
volume was 1 μL in GC grade dichloromethane. Nitrogen was
used as the carrier gas at a flow rate of 1.1 mL min-1 on split
mode (1:50). The IR spectra were recorded on Shimadzu IR
Acknowledgements
Authors are grateful to Director of the CSIR-IHBT for
encouragement and financial support (BSC-0213). V.B., M.K.,
S.S. and M.S.T. also thanks UGC for granting research
fellowships. The authors thanks IIT, Kanpur for XPS analysis
and Dr. S. C. Yadav for TEM analysis and insightful discussions.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
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Catalysis Science & Technology
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ARTICLE
Journal Name
14 A. Frattini, N. Pellegri, D. Nicastro, and O. de. Sanctis, Mater.
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Page 7 of 7
Catalysis Science & Technology
View Article Online
DOI: 10.1039/C7CY00832E
CuI nanoparticles as a recyclable heterogeneous catalyst for C-N bond
formation reactions
Manoranjan Kumar, Vinod Bhatt, Onkar S. Nayal, Sushila Sharma, Vishal Kumar, Maheshwar S. Thakur,
Neeraj Kumar, Rajaram Bal,* Bikram Singh* and Upendra Sharma*
O
.HCl
H2N
HN
CHO
Cl
+
+
Cl
CuI NPs
R2
R2
R4
CuI
CuI
R4
R1
N
R3
HN
R3
R1
O
CuI
CuI
36 examples
N
N
Cl
Hetrogenous catalyst
recylable upto 6 times
NaN3
+
Ph
N
NO2
PhC CH
20 nm
NO2