Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles: A rapid and green procedure for Sonogashira coupling

Article abstract of DOI:10.1016/j.ultsonch.2014.05.016

A simple and green method was performed to the preparation of copper iodide nanoparticles by ultrasound approach. Consequently the synthesis of aryl ethynyl linked triarylamines was carried out through the Sonogashira coupling between iodo-substituted triarylamine and aryl acetylenes in the presence of CuI nanoparticles/Pd(PPh₃)₂Cl₂ as an efficient catalytic system and triethylamine as the base under ultrasonic irradiation. Good to excellent yields of products and short reaction times are some of the important advantages of this solvent free protocol which were attained by both nano CuI and ultrasound conditions.

Full text of DOI:10.1016/j.ultsonch.2014.05.016

Ultrasonics Sonochemistry xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Ultrasonics Sonochemistry
journal homepage: www.elsevier.com/locate/ultson
Sonochemically synthesis of arylethynyl linked triarylamines catalyzed
by CuI nanoparticles: A rapid and green procedure for Sonogashira
coupling
⇑
Javad Safaei-Ghomi , Zeinab Akbarzadeh
Department of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan 51167, Islamic Republic of Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
A simple and green method was performed to the preparation of copper iodide nanoparticles by ultra-
sound approach. Consequently the synthesis of aryl ethynyl linked triarylamines was carried out through
the Sonogashira coupling between iodo-substituted triarylamine and aryl acetylenes in the presence of
Received 11 April 2014
Received in revised form 19 May 2014
Accepted 20 May 2014
Available online xxxx
3 2 2
CuI nanoparticles/Pd(PPh ) Cl as an efficient catalytic system and triethylamine as the base under
ultrasonic irradiation. Good to excellent yields of products and short reaction times are some of the
important advantages of this solvent free protocol which were attained by both nano CuI and ultrasound
conditions.
Keywords:
Ultrasonic irradiation
Aryl ethynyl linked triarylamines
Sonogashira coupling
CuI nanoparticles
Ó 2014 Elsevier B.V. All rights reserved.
Green chemistry
1
. Introduction
Aryl ethynyl linked triarylamines (Ar-ethynyl-TAA) have
late palladium(II) complexes [22] and copper-free reaction in ionic
liquid [23]. These methods need high temperature and long reac-
tion time to terminate the reaction. Also there are some expensive
methods were reported to prepare the catalyst.
attracted widespread interest owing to their promising potential
in a variety of applications. These compounds are frequently
applied as a significant part in electrophotography [1–4] and
light-emitting devices [5–7] such as organic solar cell [8,9]. The
ethynyl group has importance as a conjugating group which might
facilitate intra-molecular charge transfer and lowering the overall
oxidation potential [10]. Also Ar-ethynyl-TAA are used in synthesis
of natural products [11,12], polymers [13,14] and in molecular
wires [15]. Synthesis of Ar-ethynyl-TAA has been performed by
Sonogashira coupling [16–18] which is a palladium-copper cata-
lyzed reaction of aryl halides and acetylene derivatives. In the
recent years, different catalytic systems have been applied for the
Sonogashira C–C coupling reaction of aryl halides and acetylene
compounds at various methods. For example, Kawanami et al. rep-
resented a copper-free Sonogashira coupling in good yields at high-
pressure and high-temperature water in a microfluidic system [19].
Furthermore Sonogashira coupling was performed in good to excel-
lent yields of products using various catalytic systems such as car-
bon-supported palladium/gold nanoparticles [20], Pd/Cu bimetallic
nanoparticles embedded in macroporous ion-exchange resins [21],
copper-phosphine free system by dimethylaminoalkyl chalcogeno-
Several pathways were reported for the synthesis of arylethynyl
linked triarylamines by Sonogashira coupling using CuI and
Pd(PPh ) Cl [10,13,24–26] which were applied in low yields of
3 2 2
products at long reaction times.
In this research we combined the advantages of ultrasonic irra-
diation and nanotechnology to find the more convenient and effi-
cient Sonogashira reaction of iodo-substituted triarylamine and
aryl acetylenes to produce aryl ethynyl linked triarylamines.
During the last 30 years, sonochemistry has been indicated as a
simple, clean and convenient technique in chemical synthesis
[27]. Ultrasound irradiation improved the synthesis of organic
and nano crystalline compounds [28,29] by cavitation effects lead-
ing to mass transfer development. Recently, nanoparticles com-
pounds were applied as an appropriate catalyst in many organic
reactions because of their high surface-to-volume ratio which cre-
ate a larger number of active sites per unit area in comparison to
their bulk counterparts [30]. Copper iodide nanoparticles showed
an important level of application as a catalyst in terms of selectiv-
ity, reactivity and improvement of reaction yields [31–35].
We applied a mild, simple and efficient method for the synthe-
3 2 2
sis of various derivatives of Ar-ethynyl-TAA using Pd(PPh ) Cl /CuI
⇑
Corresponding author. Tel.: +98 361 5912385; fax: +98 361 5912397.
E-mail address: safaei@kashanu.ac.ir (J. Safaei-Ghomi).
nanoparticles as the convenience and heterogeneous catalytic sys-
tem under ultrasonic irradiation.
http://dx.doi.org/10.1016/j.ultsonch.2014.05.016
350-4177/Ó 2014 Elsevier B.V. All rights reserved.
1
Please cite this article in press as: J. Safaei-Ghomi, Z. Akbarzadeh, Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles:
A rapid and green procedure for Sonogashira coupling, Ultrason. Sonochem. (2014), http://dx.doi.org/10.1016/j.ultsonch.2014.05.016

2
J. Safaei-Ghomi, Z. Akbarzadeh / Ultrasonics Sonochemistry xxx (2014) xxx–xxx
+
2
. Experimental
244 (M ), Anal. Calcd for C18
H
15N: C, 88.16; H, 6.12; N, 5.72%.
Found: C, 87.95; H, 6.01; N, 5.62%.
2.1. Materials and apparatus
2
.4.2. N,N-Bis (4-bromophenyl) aniline (3b)
Colorless viscous liquid. H NMR (400 MHz, CDCl
1
All solvents and reagents were purchased from Merck Company
3
) d ppm = 6.95
(
Germany) and Sigma–Aldrich and used without more purification.
The ultrasonic irradiation was used in reactions by a multiwave
(d, 4H, J = 8.8 Hz, ArH), 7.06 (m, 3H, ArH), 7.27 (d, 2H, J = 8.4 Hz,
1
3
ArH), 7.35 (d, 4H, J = 8.8 Hz, ArH). C NMR (100 MHz, CDCl
3
) d
ultrasonic generator (Sonicator 3200; Bandelin, MS 73, Germany),
equipped with a converter/transducer and titanium oscillator
ppm = 115.53, 123.82, 124.66, 125.46, 129.62, 132.22, 146.57,
ꢁ1
146.96. FT-IR (KBr): 3071, 3056, 1579, 1484, 1274, 1070 cm
.
+
(
horn), 12.5 mm in diameter, operating at 20 kHz with a maximum
2
MS (EI, 70 eV): m/z 400 (M ), Anal. Calcd for C18H13NBr : C,
power output of 200 W. The ultrasonic generator automatically
adjusted the power level.
53.87; H, 3.24; N, 3.50%. Found: C, 53.61; H, 3.03; N, 3.35%.
Melting points of products were determined on Electro thermal
2.4.3. N,N-Bis (4-methoxyphenyl) aniline (3c)
1
13
1
9
200. H NMR and C NMR spectra were recorded by a Bruker
Avance-400 MHz. NMR spectrums were obtained in CDCl and
DMSO-d solution and are reported as parts per million (ppm)
Pale yellow oil. H NMR(400 MHz,CDCl
3
) d ppm = 3.93 (s, 6H,
OMe), 6.83 (m, 5H, ArH), 6.90 (d,2H, J = 7.9 Hz, ArH), 7.13(t, 2H,
3
1
3
J = 7.9 Hz, ArH), 7.00 (d, 4H, J = 8.9 Hz, ArH). C NMR (100 MHz,
CDCl ) d ppm = 65.78, 115.37, 120.16, 122.04, 125.98, 133.51,
143.25, 151.71, 156.14. FT-IR (KBr): 3065, 1598, 1454, 1269 cm
6
downfield from tetramethylsilane as internal standard. The IR
spectra were recorded on FT-IR Magna 550 apparatus using with
KBr plates. EIMS (70 eV) was performed by Finnigan-MAT-8430
mass spectrometer in m/z. The elemental analyses (CꢀHꢀN) of the
samples were performed using a LECO CHNS 923 analyser. Powder
X-ray diffraction (XRD) of CuI nanoparticles was carried out on a
Philips diffractometer of X’pert Company with monochromatized
3
ꢁ1
.
+
MS (EI, 70 eV): m/z 305 (M ), Anal. Calcd for C20
2
H19NO : C, 78.69;
H, 4.59; N, 6.23%. Found: C, 78.58; H, 4.43; N, 6.25%.
2.5. General procedure for the preparation of iodophenyldiarylamine
derivatives
Cu K
alized by SEM (LEO 1455VP). Transmission electron microscopy
TEM) image of nano copper iodide was obtained on a Philips
EM208 transmission electron microscope with an accelerating
voltage of 100 kV.
a radiation (k = 1.5406 Å). Microscopic morphology was visu-
A 5 mL acetic acid solution of triarylamine (3a–c) (2.0 mmol),
potassium iodide (0.34 g, 2.1 mmol) and potassium iodate
(0.62 g, 3.08 mmol) in a two-necked round bottom flask was stir-
red in 3–5 h under nitrogen atmosphere at reflux. After the com-
pletion of the reaction (followed by TLC), the mixture was cooled
to room temperature and poured into 50 mL of distilled water.
The precipitate was filtered and dissolved in dichloromethane,
(
2.2. Preparation of CuI nanoparticle
then washed with aqueous Na
Na SO . The residue after evaporation of the solvent, was recrystal-
lized in acetone and obtained pure iodo phenyl diarylamine (4a–c).
2 2 3
S O and dried over anhydrous
The copper iodide nanoparticle was prepared by ultrasonic irra-
2
4
diation using copper sulfate (CuSO
4
) as the Cu source. At first
1
mmol of CuSO was cleaned for 20 s in acetone under ultrasonic
4
irradiation followed by repeated rinsing with distilled water. Then
the dried substrate dipped slowly into a solution of potassium
iodide (1 mmol) in 40 mL of distilled water and the mixture was
sonicated for 30 min. When the reaction was completed, the
obtained grey precipitate was filtered and washed by distilled
water and dried to provide pure nano CuI. The produced CuI nano-
particles were fully characterized by SEM, TEM and XRD analysis.
2
.6. Representative spectral data for iodo phenyl diarylamine
derivatives
2.6.1. N-(4-Iodophenyl) diphenylamine (4a)
1
White solid. mp = 107 °C. H NMR (400 MHz, CDCl
3
) d ppm = 6.93
(
d, 2H, J = 8.5 Hz, ArH), 7.01 (d, 4H, J = 8.8 Hz, ArH), 7.22 (m, 6H, ArH),
13
7
.37 (d, 2H, J = 8.5 Hz, ArH).
3
C NMR (100 MHz, CDCl ) d
ppm = 86.40 (C–I), 122.64, 124.78, 126.18, 133.48, 138.97, 146.13,
ꢁ
1
1
7
47.46. FT-IR (KBr): 3067, 1594, 1453, 1270, 1175 cm . MS (EI,
2.3. General procedure for the synthesis of triarylamines derivatives
+
0 eV): m/z 371 (M ). Anal. Calcd for C18H14NI: C, 58.22; H, 3.77;
N, 3.77%. Found: C, 58.13; H, 3.58; N, 3.63%.
In a two-necked flask a mixture of aniline (3 mmol), iodoben-
zene (7.5 mmol), CuI nanoparticles (3% mol), 1,10-phenanthroline
3% mol), potassium hydroxide (1.29 g, 0.024 mmol) and 20 mL of
toluene was stirred under nitrogen atmosphere at reflux for a suit-
able time. The completion of the reaction was monitored by TLC
with hexane as the eluent. At the end of reaction, the mixture
was then cooled to room temperature and poured into distilled
0
2
.6.2. N,N-Bis(4-bromophenyl)-4 -iodophenylamine (4b)
(
1
White solid. mp = 129 °C.
ppm = 6.83 (d, 2H, J = 8.4 Hz, ArH), 6.95 (d, 4H, J = 8.8 Hz, ArH),
.38 (d, 4H, J = 8.8 Hz, ArH), 7.55 (d, 2H, J = 8.4 Hz, ArH). 13C NMR
100 MHz, CDCl ) d ppm = 86.35 (C–I), 116.21, 125.77, 125.81,
32.57, 138.46, 145.97, 146.79. FT-IR (KBr): 3053, 1573, 1485,
3
H NMR (400 MHz, CDCl ) d
7
(
1
1
3
water. The products were extracted by CH
layer was dried over anhydrous sodium sulfate (Na
2
Cl
2
and the organic
SO ). Then
ꢁ1
+
312, 1282, 1270, 1173, 1071 cm . MS (EI, 70 eV): m/z 527 (M ).
2
4
Anal. Calcd for C18
4
H12NBr
2
I: C, 40.98; H, 2.28; N, 2.66%. Found: C,
the solvent was evaporated in vacuo, the products were purified
by silica column chromatography using normal hexane as an
eluent.
0.86; H, 2.21; N, 2.53%.
0
2
.6.3. N,N-Bis(4-methoxyphenyl)-4 -iodophenylamine (4c)
Pale yellow solid. mp = 111 °C. H NMR (400 MHz, CDCl
1
3
) d
2
2
.4. Representative spectral data for triarylamine derivatives
ppm = 3.32 (s, 6H, OMe), 6.69 (d, 2H, J = 7.8 Hz, ArH), 7.09 (d, 4H,
J = 8.2 Hz, ArH), 7.22 (d, 4H, J = 8.2 Hz, ArH), 7.36 (d, 2H,
J = 7.8 Hz, ArH). C NMR (100 MHz, CDCl ) d ppm = 57.45, 85.97
3
1
3
.4.1. Triphenylamine (3a)
White solid. mp = 126–127 °C. H NMR (400 MHz, CDCl
1
3
) d
(C–I), 118.22, 122.94, 127.13, 138.24, 140.86, 149.67, 156.71. FT-
ppm = 7.08 (m, 9H, ArH), 7.26 (d, 6H, J = 7.8 Hz, ArH), 1 C NMR
3
IR (KBr): 3078, 1545, 1422, 1312, 1285, 1273, 1170, 1072 cm
MS (EI, 70 eV): m/z 431 (M ). Anal. Calcd for C20
ꢁ1
.
+
(
100 MHz, CDCl
3
) d ppm = 124.82, 125.46, 135.62, 147.65. FT-IR
2
H18NO I: C,
ꢁ1
(
KBr): 3031, 3016, 1590, 1454, 1276 cm . MS (EI, 70 eV): m/z
55.68; H, 4.18; N, 3.25%. Found: C, 55.54; H, 4.03; N, 3.16%.
Please cite this article in press as: J. Safaei-Ghomi, Z. Akbarzadeh, Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles:
A rapid and green procedure for Sonogashira coupling, Ultrason. Sonochem. (2014), http://dx.doi.org/10.1016/j.ultsonch.2014.05.016

J. Safaei-Ghomi, Z. Akbarzadeh / Ultrasonics Sonochemistry xxx (2014) xxx–xxx
3
2.7. General procedure for the preparation of arylethynyl linked
13C NMR (100 MHz, DMSO-d
6
)
d ppm = 85.98 (C„C), 89.22
triarylamines
(C„C), 117.13, 122.78, 124.53, 128.81, 131.09, 132.51, 133.21,
45.59, 147.31, 167.95. FT-IR (KBr): 3091, 2198 (C„C), 1584,
1
+
2.7.1. Typical heating method (method A)
1421, 1332, 1272(C–N), 1069, 1020. MS (EI, 70 eV): m/z 389 (M ).
Anal. Calcd for C27 : C, 83.29; H, 4.88; N, 3.60%. Found: C,
83.15; H, 4.75; N, 3.67%.
A mixture of iodo phenyl diarylamine (4a–c) (1 mmol), aryl-
acetylene (5d–e) (1 mmol), Pd(PPh
H19NO
2
3 2 2
) Cl (2.5 mol%), CuI nanoparti-
cles (2.5 mol%) and Et N (5 mL) was being stirred at 50 °C. At the
3
end of reaction (monitored by TLC) the mixture was cooled to room
temperature, then filtered and the solvent was removed in vacuo.
The crude products were obtained by silica gel column chromatog-
raphy using n-hexane as an eluentin 39–58% yields.
3
. Results and discussion
3.1. Synthesis and structural analysis of CuI nanoparticles
In this research, ultrasound irradiation assisted the preparation
2
.7.2. Ultrasound irradiation method (method B)
mixture of (4a–c) (1 mmol), arylacetylene (1 mmol),
Pd(PPh Cl (2.5 mol%), CuI nanoparticles (2.5 mol%) in Et
5 mL) was sonicated at 20 KHz frequency and 50 W power, for
of copper iodide nanoparticles. The size of prepared CuI nanoparti-
cles was obtained until 20 nm, and specific surface area was about
A
3
)
2
2
3
N
2
ꢁ1
2
.96 m g . For comparison, in previously method for synthesis of
(
nano CuI such as pulse laser deposition, surface-etching, hydro-
thermal and coprecipitation techniques [36–39], particle sizes of
desired times (checked by TLC). After completed the reaction the
mixture was filtered and the solvent was evaporated in vacuo.
The products were purified by silica gel column chromatography
using n-hexane as an eluent in 65–88% yield.
nano Copper iodide were ranging from 70 nm to 1
lm (more than
ultrasound method) and specific surface area was less than
2
ꢁ1
ultrasound approach (2.08 m g ). This result is described by the
influence of sonication method in controlling size of nanoparticles
2
.8. Representative spectral data for Ar-ethynyl-TAA derivatives
[
33,40,41].
In the XRD pattern of CuI nanoparticles as illustrated in Fig. 1,
2
.8.1. 4-(Phenylethynyl) triphenylamine (6a)
White solid. mp = 96 °C. H NMR (400 MHz, CDCl
all reflection peaks should be readily indexed to pure cubic crystal
phase of nano crystalline CuI. In addition, no specific peaks because
of any impurities were observed. This pattern is in well agreement
with the reported pattern for copper iodide (JCPDS No. 75-0832).
The crystalline size diameter (D) of the copper iodide nanoparticles
1
3
) d ppm = 7.25
) d
ppm = 88.57 (C„C), 89.64 (C„C), 116.27, 120.45, 121.87, 124.53,
28.18, 129.24, 131.09, 132.15, 133.21, 135.74, 144.99, 146.22.
FT-IR (KBr): 3084, 3023, 2214 (C„C), 1574, 1463, 1332, 1268
(
m, 12H, ArH), 7.38 (m, 7H, ArH). 13C NMR (100 MHz, CDCl
3
1
+
(
C–N), 1070, 1025. MS (EI, 70 eV): m/z 345 (M ). Anal. Calcd for
C
26
H19N: C, 90.43; H, 5.51; N, 4.06%. Found: C, 90.36; H, 5.42; N,
3
.97%.
0
2
.8.2. N,N-Bis(4-bromophenyl)-4 -(phenylethynyl) aniline (6b)
1
White solid. mp = 68 °C. H NMR (400 MHz, CDCl
m, 10H, ArH), 7.54 (m, 7H, ArH). 13C NMR (100 MHz, CDCl
ppm = 89.21 (C„C), 89.45 (C„C), 115.72, 119.36, 122.71, 125.34,
29.13, 130.75, 130.39, 131.55, 132.97, 136.72, 145.22, 146.89.
FT-IR (KBr): 3059, 3021, 2147 (C„C), 1589, 1483, 1312, 1278
3
) d ppm = 7.36
(
3
) d
1
+
(
C–N), 1067, 1022. MS (EI, 70 eV): m/z 501 (M ). Anal. Calcd for
C
26
2
H17NBr : C, 62.28; H, 3.39; N, 2.79%. Found: C, 62.23; H, 3.31;
N, 2.81%.
0
2
.8.3. N,N-Bis(4-methoxyphenyl)-4 -(phenylethynyl) aniline (6c)
1
Yellow solid. mp = 85 °C. H NMR (400 MHz, CDCl
3
) d ppm = 3.46
(
s, 6H, OMe), 7.18 (m, 3H, ArH), 7.22 (m, 8H, ArH), 7.38 (m, 6H, ArH).
1
3
C NMR (100 MHz, CDCl
3
) d ppm = 58.34, 89.47 (C„C), 89.88
Fig. 1. XRD pattern of the CuI nanoparticles.
(
C„C), 119.26, 120.09, 123.87, 125.49, 128.30, 131.07, 132.76,
1
2
7
35.18, 138.52, 144.80, 147.65, 154.98. FT-IR (KBr): 3094, 3011,
189 (C„C), 1556, 1421, 1311, 1272(C–N), 1069, 1025. MS (EI,
+
0 eV): m/z 405 (M ). Anal. Calcd for C28
2
H23NO : C, 82.96; H, 5.68;
N, 3.46%. Found: C, 82.83; H, 5.57; N, 3.39%.
2
.8.4. 4-(4-Methoxyphenylethynyl) triphenylamine (6d)
Pale yellow solid. mp = 92 °C. H NMR (400 MHz, CDCl
1
3
) d
C
1
3
ppm = 3.57 (s, 3H, OMe) 7.09 (m, 10, ArH), 7.32 (m, 8H, ArH).
NMR (100 MHz, CDCl ) d ppm = 58.92, 88.58 (C„C), 90.22 (C„C),
16.31, 121.05, 121.97, 125.35, 128.81, 130.42, 135.21, 136.47,
3
1
1
1
43.65, 145.22, 157.42. FT-IR (KBr): 3032, 2210 (C„C), 1574,
485, 1333, 1270 (C–N), 1075, 1021. MS (EI, 70 eV): m/z 375
+
(
M ). Anal. Calcd for C27
H21NO: C, 86.40; H, 5.61; N, 3.73%. Found:
C, 86.31; H, 5.52; N, 3.66%.
2
.8.5. 4-(4-Carboxyphenylethynyl) triphenylamine (6e)
Orange solid. mp = 102 °C. H NMR (400 MHz, DMSO-d
1
6
) d
ppm = 6.94 (m, 6H, ArH), 7.39 (m, 12H, ArH), 10.22 (s, 1H, COOH).
Fig. 2. SEM image of the CuI nanoparticles.
Please cite this article in press as: J. Safaei-Ghomi, Z. Akbarzadeh, Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles:
A rapid and green procedure for Sonogashira coupling, Ultrason. Sonochem. (2014), http://dx.doi.org/10.1016/j.ultsonch.2014.05.016

4
J. Safaei-Ghomi, Z. Akbarzadeh / Ultrasonics Sonochemistry xxx (2014) xxx–xxx
Table 1
Optimization of the model reaction for the synthesis of arylethynyl linked triaryl-
amines under ultrasound irradiation.
Entry Solvent
Catalytic system (mol%)
Time (min) Yielda (%)
1
2
3
4
5
6
7
8
9
1
1
CH
Toluene
THF
3
CN
CuI/Pd(PPh
CuI/Pd(PPh
CuI/Pd(PPh
CuI/Pd(PPh
3
3
3
3
3
)
)
)
)
)
2
2
2
2
2
Cl
Cl
Cl
Cl
Cl
2
2
2
2
2
(12%)
(12%)
(12%)
(12%)
(12%)
80
80
70
70
50
60
60
60
43
39
46
32
56
42
45
29
71
78
78
EtOH
Solvent-free CuI/Pd(PPh
Solvent-free CuCl/Pd(PPh
Solvent-free CuBr/Pd(PPh
3
)
2
Cl
Cl
(12%)
2
(12%)
3
)
2
2
(12%)
3 2 2
Solvent-free Pd(PPh ) Cl
Solvent-free Nano CuI/Pd(PPh
Solvent-free Nano CuI/Pd(PPh
Solvent-free Nano CuI/Pd(PPh
)
3 2
)
3 2
)
3 2
Cl
2
Cl
2
Cl
2
(1%) 30
(2%) 30
(3%) 30
0
1
a
Isolated yield.
of copper iodide nanoparticles were achieved in the scale of nano-
meters (20 nm) under ultrasound irradiation.
Particle size of the nano CuI was also found to be small size until
0 nm according to TEM image of CuI nanoparticle as shown in
Fig. 3. TEM image of the CuI nanoparticles.
2
Fig. 3.
was calculated by Debye–Scherrer equation (D = Kk/bcosh) [42],
where FWHM (full-width at half-maximum or half-width) is in
radians and h is the position of the maximum of diffraction peak
3.2. Synthesis of organic compounds
(b = 0.4723 [°2h]), K is the shape factor which commonly is a value
about 0.9, and k is the X-ray wavelength. The average diameter of
nano CuI was obtained to be 20 nm.
The synthetic procedures used to prepare the arylethynyl linked
triarylamines are outlined in Scheme 1.
The scanning electron microscopy (SEM) image of CuI nanopar-
ticles was represented in Fig. 2. As shown in this figure, diameters
Triarylamine was prepared via Ullman coupling started from
the reaction between aryl amine and aryl iodide (molar ratio 1:2)
R1
R1
NH2
I
N
CuI (Nano Particle)
+
1
,10-Phenanthroline
KOH
toluene, Reflux
R1
1
2a : R
1
= H
3a : R
3b : R
3c : R
1
1
1
= H
2
2
b : R
1
= Br
= Br
c : R
1
= OCH
3
= OCH
3
R1
R1
R
1
R
1
N
R
2
N
KI, KIO3
5d: R =OCH
2
3
5
2
e: R = COOH
CuI Nanoparticles, Pd(PPh ) Cl
2
Acetic acid, Reflux
3
2
Et N
3
I
4
4
4
a : R
b : R
c : R
1
1
1
= H
= Br
= OCH
3
R2
6
6
6
6
6
a : R
1
= H
,
,
R
2
=H
b : R
1
= Br
R =H
2
c : R
d : R
1
= OCH
= H
= H
3
, R
R
2
=H
1
,
2
=OCH
3
e : R
1
2
, R =COOH
Scheme 1. Synthesis route of arylethynyl linked triarylamine.
Please cite this article in press as: J. Safaei-Ghomi, Z. Akbarzadeh, Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles:
A rapid and green procedure for Sonogashira coupling, Ultrason. Sonochem. (2014), http://dx.doi.org/10.1016/j.ultsonch.2014.05.016

J. Safaei-Ghomi, Z. Akbarzadeh / Ultrasonics Sonochemistry xxx (2014) xxx–xxx
5
Table 2
presence of CuI nanoparticles and Pd(PPh
)
Cl
as a catalytic sys-
3
2
2
Synthesis of Ar-ethynyl-TAA under heating conditions (method A) and sonication
irradiation (method B).
3
tem and trietylamine (Et N) as the base under conventional and
ultrasound conditions.
Entry
R
1
R
2
Product
Method A
Time
Yielda
min)
Method B
The improved reaction conditions were found by performing
this reaction using various experimental factors such as solvent
and catalytic system. The effect of different solvents have been
screened using varying polarity and protic solvents such as tolu-
ene, acetonitrile, THF and ethanol. It was shown that solvent free
condition is the best choice for the aforementioned reaction
Time
Yieldb
(
(%)
(min)
(%)
1
2
3
4
5
H
H
H
H
6a
6b
6c
6d
6e
360
400
300
300
360
47
39
51
58
49
30
45
30
30
45
75
65
79
88
76
4-Br
4-OCH
H
3
4-OCH
4-COOH
3
(
Table 1, entry 5). In order to find the suitable catalyst, behaviors
of some types of catalytic system were examined (Table 1, entries
–9). Obviously, Pd(PPh Cl /CuI nanoparticle is the most effec-
H
a
Isolated yields.
Isolated yields.
5
3
)
2
2
b
tive catalytic system for this reaction (Table 1, entry 9). It was
shown that the higher yields were obtained by 2% mol of nano
CuI/Pd(PPh
3 2 2
) Cl (Table 1, entry 10). For comparison, we tested a
by the catalytic system containing CuI nanoparticles/1,10-phenan-
trolineatthe presence of potassium hydroxide as the base in tolu-
ene at reflux condition under nitrogen atmosphere. This step has
reported in our previous work [43]. Then, iodination reaction was
performed at the para-position of the triarylamine group using
potassium iodide and potassium iodate in acetic acid at reflux con-
dition under nitrogen atmosphere to afford compounds 4a–c.
Ar-ethynyl-TAAs (compounds 6a–e) were synthesized from the
Sonogashira coupling of compounds 4a–c with arylacetylene in the
similar reaction without CuI, but the results were less satisfactory
(Table 1, entry 8).
This synthesis is also based on the more reactivity of the iodide
than the bromide as a leaving group. Consequently, the iodo-
substituted site was exclusively alkynylated by controlling the
suitable ratio of reactant.
The study was also extended to synthesis of various Ar-ethynyl-
TAAs using nano CuI/Pd(PPh
3
)
2
Cl
2
under the same conditions. In
Ph3P
PPh3
Pd
Cl
I
NAr
2
Cl
)
)
)
)
)
)
)
)
)
NAr
2
)
)
)
Oxidative addition
Reductive elimination
I
PPh3
Ph
3
P
PPh3
Cl
Cl
Pd
3
Ph P
Cl
Pd
Cl
NAr
2
NAr
2
Transmetallation
))))))
)
H
)
)
)
3
Et NHI
)
)
)
)
)
)
)
)
H
Et
3
N
=CuI nanoparticles
)))))) = Ultrasound irradiation
Scheme 2. Proposed reaction mechanism for the formation of arylethynyl linked triarylamine catalyzed by CuI nanoparticles and Pd(PPh ) Cl .
3 2 2
Please cite this article in press as: J. Safaei-Ghomi, Z. Akbarzadeh, Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles:
A rapid and green procedure for Sonogashira coupling, Ultrason. Sonochem. (2014), http://dx.doi.org/10.1016/j.ultsonch.2014.05.016

6
J. Safaei-Ghomi, Z. Akbarzadeh / Ultrasonics Sonochemistry xxx (2014) xxx–xxx
order to demonstrate the influence of ultrasound approach, reac-
tions were compared at heating conditions (method A) and ultra-
sonic irradiation (method B). The results were listed in Table 2.
When the reactions were carried out under conventional condi-
tion it produced relatively low yields of Ar-ethynyl-TAAs in longer
reaction times, but the same reaction under ultrasound irradiation
provided high yields of products in short reaction times. In com-
parison with conventional approach, sonication method is more
environmentally friendly due to the basic green chemistry con-
cepts of ultrasonic irradiation.
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The possible mechanism for the synthesis of Ar-ethynyl-TAAs
catalyzed by CuI nanoparticles and Pd(PPh
ited in Scheme 2. As shown in this scheme Pd(PPh
oxidative addition by iodo-substituted triarylamine. Aryl acetylene
is subsequently deprotonated by Et N and then metallated by CuI
3
)
2
Cl
2
has been exhib-
[
[
3
)
2
Cl undergoes
2
[
[
[
3
nanoparticles to give a nano copper aryl acetylide, which is trans-
metallated to palladium. Reductive elimination ultimately yields
the arylethynyl linked triarylamine and regenerates Pd(PPh ) Cl .
3 2 2
According this mechanism, adsorption of aryl acetylene is
improved on the nanoCuI surface by the effects of nano scale of
catalyst surface and also ultrasonic irradiation. Furthermore, ultra-
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3
)
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Cl
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by the cavitation effect.
[
(
4
. Conclusion
[
[
In this work a simple and effective approach has been devel-
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CuI nanoparticles and Pd(PPh Cl as a highly efficient heteroge-
[
[
3
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produced the wide range of Ar-ethynyl-TAAs in good to excellent
yields. This ultrasonically method indicates several advantages
such as green procedure, mild reaction conditions, short reaction
times, high yields.
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Acknowledgments
The authors are grateful to University of Kashan for supporting
this work by Grant no: 363010/VI.
Please cite this article in press as: J. Safaei-Ghomi, Z. Akbarzadeh, Sonochemically synthesis of arylethynyl linked triarylamines catalyzed by CuI nanoparticles:
A rapid and green procedure for Sonogashira coupling, Ultrason. Sonochem. (2014), http://dx.doi.org/10.1016/j.ultsonch.2014.05.016