Synthesis and characterization of nano?zinc wire using a self designed unit galvanic cell in aqueous medium and its reactivity in propargylation of aldehydes

Article abstract of DOI:10.1016/j.tet.2019.07.012

Electrochemistry is used for propargylation of carbonyls in aqueous ZnCl₂ medium. For electrochemical process we designed a unit galvanic cell. ZnCl₂ is used as stoichiometric reagent and causes electrochemical deposition of zinc in

Full text of DOI:10.1016/j.tet.2019.07.012

Tetrahedron xxx (xxxx) xxx
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis and characterization of nanoꢀzinc wire using a self
designed unit galvanic cell in aqueous medium and its reactivity in
propargylation of aldehydes
,
Bibhas Mondal a b, Siba Prasad Mandal c, Mousumi Kundu d, Utpal Adhikari b,
,
*
Ujjal Kanti Roy a
a Department of Chemistry, Kazi Nazrul University, Asansol 713340, India
b Department of Chemistry, National Institute of Technology Durgapur, Durgapur 713209, India
c Department of Physics, Deshabandhu Mahavidyalaya, Chittaranjan 713331, India
d Department of Chemistry, Deshabandhu Mahavidyalaya, Chittaranjan 713331, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Electrochemistry is used for propargylation of carbonyls in aqueous ZnCl2 medium. For electrochemical
process we designed a unit galvanic cell. ZnCl2 is used as stoichiometric reagent and causes electro-
chemical deposition of zinc in cathode. Wire shaped nano zinc architecture has been formed in cathode
during electrochemical process which is the active reagent. Homopropergylic alcohols are synthesized in
good yields. After the organic reaction is over aqueous solution containing zinc salts can be reused up to
5th cycle without significant loss of reactivity.
Received 7 May 2019
Received in revised form
5 July 2019
Accepted 6 July 2019
Available online xxx
© 2019 Published by Elsevier Ltd.
Keywords:
Electrochemistry
Aqueous
Propargylation
Zinc
Nano wire
1. Introduction
electronic displays, touch screens, and solar cells [4,5]. To the best
of our knowledge, electrochemical synthesis of wire like nano ar-
Electrochemical methods can eliminate or dispose the waste
materials and recycle the metal reagents [1]. For that reason elec-
trochemical methods are excellent approach to green synthesis. On
the other hand, aqueous reactions have been widely studied in
order to reduce the use of flammable, toxic, or carcinogenic organic
solvents [2]. A combination of aqueous and electrochemical con-
version will be an excellent green synthetic approach [1,3].
During the electrochemical process new metal nano architec-
ture is formed that can create interest as the new material. Due to
higher surface area of the deposited nano-material reactivity on
electrode will also be increased. Nano architecture with particular
size and shape can be synthesized by electrodeposition. Because of
their applications in nanotechnology material chemists will be
interested with these newly synthesized nano architecture.
Metallic nano-wires also have huge technological applications like
chitecture of metallic zinc from aqueous ZnCl2 solution was first
reported from our laboratory [6]. Here we wish to report prop-
argylation of carbonyls using electrochemical process when nano
wire architecture of pure metallic zinc is formed on cathode.
Aqueous ZnCl2 solution is used as starting material for the elec-
trochemical process. In situ formed zinc nano wire is the active
reagent for propargylation. Synthesis of homopropargylic alcohols
by propargylation of carbonyls is synthetically very important in
organic chemistry because of their use as building blocks in natural
product synthesis. Metal-mediated propargylation reactions are
well-known examples of green aqueous reactions [7,8]. But in most
of the cases over stoichiometric amount of metal is used and the
corresponding metal salt is generated as waste material. Lots of
research has been done on developing metal mediated prop-
argylation reactions in aqueous media. But direct use of ZnCl2 is
new and reported for the first time from this laboratory for Barbier
type propargylation [6]. Among the successful metals zinc is very
cheap and low toxic to mediate the Barbier-type reactions [9]. In
most of the cases, physical or chemical activation is necessary.
* Corresponding author.
E-mail address: uroccu@gmail.com (U.K. Roy).
https://doi.org/10.1016/j.tet.2019.07.012
0040-4020/© 2019 Published by Elsevier Ltd.
Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
medium and its reactivity in propargylation of aldehydes, Tetrahedron, https://doi.org/10.1016/j.tet.2019.07.012

2
B. Mondal et al. / Tetrahedron xxx (xxxx) xxx
Among the various activation methods, the addition of an acidic co-
reagent is very common. Here, we wish to report aqueous ZnCl2
mediated electrochemical propargylation reactions of carbonyls
(pH 2e2.5). Process is efficient and a range of functional groups are
tolerated in these mild electrochemical reaction conditions.
The addition of allyl, propargyl or allenylstannanes to organic
electrophiles like aldehydes, imines, and epoxides is a well-known
tool for carbon-carbon bond formation in organic chemistry
[7e10]. Carbonyls are one of the most useful and versatile sub-
strates in organic synthesis due to their high reactivity. A number of
methods have been reported for the activation of carbonyls with
various nucleophiles. On the other hand, only a few methods are
known for the propargylation of carbonyls. [8] Most of them suffer
from a lack of efficiency and simplicity. Therefore, the development
of simple and novel methods, which are more efficient and provide
convenient procedures with improved yields still remains a chal-
lenge for synthetic organic chemists.
We are trying to explore noble strategies to generate propargyl
organometallic reagents [6,7d]. The strategy involves oxidative
addition of an organic halide (RX) across reactive metal [M], to form
R-[M]-X. The reactive metals can be in situ generated via electro-
chemical reduction of corresponding metal salts. The reactive nu-
cleophiles thus generated react with electrophile to give the
corresponding coupling products. Successful delineation of the
strategy for zinc nano-wire mediated carbonyl allylation prompted
us to investigate the nucleophilic addition of organometallic
propargylic reagents to an electrophile in aqueous electrochemical
conditions [6].
mediated propargylation of aldehydes for carbon-carbon bond
formation. Our idea was to use the in situ generated metallic nano
zinc for propargylation reactions. We found, that an efficient
propargylation can take place in an undivided galvanic cell with or
without using external bias. We concluded that these organic re-
actions in an undivided cell mainly take place at the cathode where
metallic zinc was deposited.
2.2. Synthesis of nano zinc wire
The deposition of Zn(0) from solutions of Zn(II) both in the
presence and absence of organic reactants was studied. It was
found that from the 0.02 M ZnCl2 solutions (pH 2e2.5), ~20 mg of
powder was deposited on the cathode within 2 min as a thick film
(F1) when no organic reaction was performed in an unit galvanic
cell without the presence of an external bias. Zinc deposition was
determined by the XRD analysis (Fig. 2). EDX, EDX mapping (sup-
porting information, Figs. 1 and 2) and XRD analysis showed that
the Zn was deposited from ZnCl2 solutions consisted of pure Zn(0)
with a good crystalline structure (FI). HRTEM micrograph of the NPs
highlights the well-defined NPs of cylindrical shape (Fig. 3). An
ultrathin oxide layer (ZnO) may have been grown on the zinc wire
2. Results and discussion
2.1. Designing of unit galvanic cell
In our laboratory we designed a unit galvanic cell using a beaker
containing aqueous zinc chloride solution, zinc rod, ITO (Indium Tin
Oxide) glass plate (3 ꢁ 1 Cm2) and connecting copper wire (Fig. 1A).
Zinc rod and ITO glass substrate were clamped and short-circuited
externally through a copper wire. Instead of connecting by copper
wire we can also use an external bias for applying voltage (Fig. 1B).
The Zinc rod was used as a self-decaying anode and the ITO glass
plate as the cathode (Fig. 1). The optimum pH of the solution for
zinc film deposition was found to be within 2e2.5. Regeneration of
metallic zinc is based on reduction of zinc salt at cathode. Here
cathode is used as the reducing agent. We performed the zinc-
Fig. 2. PXRD pattern of the as synthesized Zn-NPs (F1).
Fig. 1. Electrochemical set up for the synthesis of thick Zn films.
Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
medium and its reactivity in propargylation of aldehydes, Tetrahedron, https://doi.org/10.1016/j.tet.2019.07.012

B. Mondal et al. / Tetrahedron xxx (xxxx) xxx
3
Fig. 3. HRTEM: HRTEM micrograph of the NPs, highlights the well-defined NPs of cylindrical shape.
due to aerial oxidation, but no signature is found for the oxide in
the XRD spectrum (Fig. 2). So our synthesized Zn nano wire is phase
pure [11].
may be formed because of the aerial oxidation of deposited nano
zinc at room temperature condition (supporting information,
Fig. 3).
Primarily, the as-synthesized Zn-NPs are characterized by PXRD
pattern. The PXRD pattern was indexed with DICVOL06 and
TREOR90 of Fullprof2k package [11b,c].The miller indices and peak
positions match well with those of the characteristic PXRD pattern
of Zn-NPs with the JCPDS number 00-004-0831 and there is no
further peak regarding to any impurity can be detected in PXRD
pattern of the sample. The Zn-NPs are crystallized in hexagonal
crystal system with cell dimension: a ¼ b ¼ 2.6573, c ¼ 4.9526,
However, the SEM images show that the thick deposits are in
wire like nano architecture (supporting information, Figs. 4 and
5)..The nano structure of Zn(0) is probably responsible for its
reactivity in the propargylation reactions. The wire like nano ar-
chitecture may be formed by head to tail, tail to head polar depo-
sition of charged nano zinc particles in charged ITO cathode plate.
Here the charge on ITO plate directs the 1D growth and slowly the
whole surface is covered with the Zn nano wires [6,12].
a
¼ 90ꢂ and
g
¼ 120ꢂ. XRD analysis showed that the Zn was
deposited from ZnCl2 solutions consisted of pure Zn(0) with a good
crystalline structure. Identified crystal planes of metallic zinc
include (002), (100), (101), (102), (103), (110) and (004) and
perfectly match with that of pure metallic Zn. Our synthesized Zn
nano wire is phase pure [11]. The average crystallite size of the
sample is calculated from the broadening of well defined peaks
(mention the peaks) of the sample in the (XRD) pattern by using the
Debye - Scherrer equation.
2.3. Reactivity of nano zinc wire: propargylation
The reactivity of metallic zinc in the aqueous medium is worth
mentioning. Here we want to explore the reactivity of the deposited
nano zinc material. The heterogeneous reactions can occur on the
surface. Nanoparticles have a large surface area than the bulk one. It
enhances the number of reaction site for the reaction to occur.
Keeping it in mind and triggered by our initial success [6], we
applied the standard condition of allylation for propergylation re-
actions also.
A variety of aldehydes and propargyl bromides can be used for
the propargylation reactions. Table 1 summarizes the details of the
carbonyl propargylation results. Both the aromatic and aliphatic
aldehydes can be utilized in this methodology. For the aromatic
aldehydes, homopropargylic alcohols can be prepared smoothly in
good to excellent yields, and the functionalities including bromo,
chloro, methoxy etc. groups (entries 5e9) on aldehydes are toler-
ated in these mild conditions. Aliphatic aldehydes are also prop-
argylated (entries 1e3). Study using 3,3-dimethylpropargyl
bromide showed that substituted propargyl bromide efficiently
form homopropargylic alcohols (entry 3) with moderate yield.
However, ketones did not undergo propargylation in this reaction
conditions, and negligible conversion of ketone was observed even
.
ꢀ
< D > ¼ 0:9
l
ð
b1=2 cosq
where <D> is the average crystallite size, ‘
l
’ is the wavelength of
1/2’ is
the incident X-ray radiation and ‘ ’ is the Bragg angle. Here, ‘
q
b
the full-width at half-maximum (FWHM) of the XRD peak
(2
q
¼ 36.228ꢂ, FWHM ¼ 0.45). The average estimated crystallite
size of the sample is ~19 nm which indicates the nanocrystalline
nature of the sample.
HRTEM micrograph of the NPs highlights the well-defined NPs
of cylindrical shape (Fig. 3). To study the morphology of nano-
crystalline sample, TEM observations were carried out. Some low
magnification micrographs and lattice fringe pattern of the sample
recorded during high resolution TEM (HRTEM) observations are
shown in Fig. 3(aec). From the micrographs it is seen that the
particles have a strong tendency of agglomeration. Due to high
agglomeration of the nanoparticles we could not measure the
average particle size of the particles from TEM micrograph. The
zoomed view of the micrograph (Fig. 3b) shows that the particles
have nanofibre morphology of length ~93 nm. The lattice fringe
pattern of the sample is displayed in Fig. 3c.
after 24 h, but a-keto ester such as methyl pyruvate gave only 40%
of the desire homopropargyl alcohol (entry 10). Nonterminal
alkyne like ethyl propargyl bromide gave homopropargyl alcohol as
a major product (35%) with only 17% of alenyl alcohol (entry 11).
The depositions of zinc on ITO plate were reproduced in the reac-
tion mixture i.e. in the presence of aldehyde, propargyl bromide,
water and THF. The Zn(0) film obtained after the completion of the
organic reaction are very much similar in absence (F3) and pres-
ence (F4) of external bias (supporting information, Fig. 5). By
The phase purity of the as synthesized nano-wires was further
analyzed by XPS which shows the electrodeposited thin film exists
as a metallic Zn layer. On top of the layer a very thin layer of ZnO
Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
medium and its reactivity in propargylation of aldehydes, Tetrahedron, https://doi.org/10.1016/j.tet.2019.07.012

4
B. Mondal et al. / Tetrahedron xxx (xxxx) xxx
Table 1
comparing F1 with F3 and F2 with F4 it can also be told that the
Propargylation of Carbonyls.a
nano structure of deposited zinc is very much similar before and
after the organic reaction. During the electrochemical process, we
observed that the zinc deposited on the cathode was of a metallic
luster. Scanning electron microscopy (FESEM; supporting infor-
mation, Figs. 4 and 5) showed that Zn had a three-dimensional (3D)
wire-like architecture. The effects of organic reactants and co-
solvent (THF) on controlling the morphology were investigated
by FESEM and found to be negligible. It was also found that with all
cases F1 to F4 nano-architectures could be obtained with similar
FESEM picture.
Recycling of the reagent (ZnCl2 solution) can be easily achieved
for this electrochemical process. Aqueous layer can be reused for
the next cycle without further purification after extraction (thrice)
of the reaction mixture with ethyl acetate. Up to the 5th cycle
decrease of the yield is not very significant (Supporting informa-
tion, Table 2).
The scope of the reaction was successfully extended to prop-
argylation of various aldehydes. 10 ml H2O-THF (8:2) mixture con-
taining 0.02 M ZnCl2 solution (pH 2e2.5) was stirred at room
temperature in a one-compartment galvanic cell (Fig. 1B, ITO glass
foil 3 ꢁ 1 cm2) using external bias (2 V, 20 mA). In the model re-
action of 3-bromo-prop-1-yne 2A and benzaldehyde 1C yielded
67% of 1-phenyl-but-3-yn-1-ol 3D (Table 1, entry 4). Complete
absence of isomeric allenyl alcohol for terminal propargyl bromides
suggests that under the reaction conditions, metallotropic rear-
rangement between the propargylzinc and allenylzinc is
completely arrested [13]. The generality of the method was further
tested for the propargylation by varying the propargyl bromides
(2A-2C) and Carbonyls (1A-1J) affording moderate to good yields of
the corresponding homopropargyl alcohols (3A-3K) (Table 1).
The high activity of deposited Zn towards the propargylation of
simple aldehydes might be attributed to its special wire like 3D
nano-architectures. A preliminary comparative reactivity study of
different types of zinc depending up on surface morphology was
carried out using Rieke zinc, commercial zinc powders, granules,
foils etc. under non electrochemical conditions (Table 2). F1 showed
the highest reactivity (Yield ¼ 67%) towards the propargylation of
p-chloro benzalaldehyde in water-THF (4:1). Under non-
electrochemical conditions, the propargylation reaction mediated
by F1 was less effective compared to that in electrochemical process
(yield 72%). However, in the non-electrochemical process, pH value
during the reaction was not acidic (pH 6.5e7).
#
1
Carbonyl
1A
Halide
2A
Product
Time (h)
18
Yield (%)
61
2
3
1B
1A
2A
2B
15
16
92
48
4
5
1C
1D
2A
2A
16
16
67
72
6
1E
2A
16
72
7
8
9
1F
2A
2A
2A
17
14
14
85
74
90
1G
1H
Table 2
Comparative reactivity study of different types of zinc depending up on surface
Morphology.a
10
11
1I
1J
2A
2C
17
17
40
Sl. No
1
Zinc reagents
Time (h)
17
Propargylationb Yield (%)
59
35
17
Rieke zinc
synthesized
Zinc powder
325 mesh (SRL)
Zinc powder
200 mesh (Merck)
Zinc granules
30 mesh (Sigma Aldrich)
Zinc foil
0.38 mm (commercial)
Zinc (F1, this work)
2
3
4
5
17
17
17
17
17
50
37
15
trace
67
a
Conditions: Aldehyde 2 mmol, propargyl bromide 4 mmol, solvent 10 ml H2O-
THF (8:2) 0.02 M ZnCl2 solution, 2 V, 20 mA, pH 2.5, 70 ꢂC.
6
a
Condition: aldehyde 1 mmol, propargyl bromide 2 mmol, zinc 2 mmol and H2O-
THF(4:1) 3 ml.
Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
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B. Mondal et al. / Tetrahedron xxx (xxxx) xxx
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Field emission scanning electron microscopy (FESEM) was used for
size and shape of the Zn nano-wire with a supra 40, Carl Zeiss Pvt.
Ltd. Instrument and an EDS machine (Oxford link and ISIS 300)
attached to the instrument is used to obtain the elemental
composition. The chemical states of Zn nanowire was studied by X-
ray photoelectron spectroscopy (XPS) using PHI 5000 Versa Probe II
(ULVAC ꢀ PHI, INC, Japan) system equipped with microfocused
(100
(h
¼ 1486.6 eV). The phase of Zn nanowire was studied by X-ray
diffraction (XRD) (Philips XPert MRD) at a grazing incidence mode
using Cu K radiation (45 kV, 40 mA).
mm, 25 W, 15 KV) monochromatic Al-Ka XRay source
n
Scheme 1. Plausible mechanism for propargylation of carbonyl.
a
2.4. Comments on plausible mechanism
4.2. General procedure
The mechanism of the reaction is very simple. Plausible reaction
mechanism has been demonstrated schematically in Scheme 1.
Zinc(II) salt(s) generated from the hydrolysis of alkoxyzinc(II)
halide along with zinc(II) of zinc chloride are reduced in cathode to
generate metallic zinc. Metallic zinc thus generated deposits in
cathode as nano-wires which are more reactive compared to
commercial zinc and supposed to be active reagent for
propargylation.
Whilst a detailed mechanism of the present reaction must await
further studies, some of the plausible bond forming steps are
enumerated below (Scheme 1, where R ¼ propargyl). The sugges-
tions are based on previous studies [6,14] and observations
described in previous sections. In early stages of the reaction for-
mation of organozinc R-Zn-Br (I) is postulated by a well-known
oxidative addition pathway of organic halide R-X across nano
zinc. The final step of the reaction would involve a carbonyl addi-
tion via SE2’ attack of organozinc intermediate (I) to aldehyde (II) to
furnish the end-organic product.
The procedures given below for carbonyl propargylation were
followed in similar cases. All products showed satisfactory spectral
and analytical data.
4.3. Propargylation of aldehyde
Aldehyde (2 mmol) and Propargyl bromide (4 mmol) were
added in 10 ml H2O-THF (8:2) containing 0.02 M ZnCl2 (pH 2.5). The
stirring mixture was then electrolyzed in a unit cell at a current of
2 V and 20 mA in a beaker equipped with a zinc electrode (1.5 cm2)
and ITO electrode (1 ꢁ 3 cm2) at 70 ꢂC with slow stirring. The
electrolysis was stopped when the aldehyde had been completely
consumed (TLC monitoring). After the electrolysis, zinc film (F4)
was collected and THF was removed by evaporation. The aqueous
reaction mixture was extracted twice with diethyl ether (2 ꢁ 10
ml). The combined organic layer was washed with brine (10 ml),
dried over Na2SO4, filtered, and concentrated under vacuum. The
crude product was purified by column chromatography on silica gel
(petroleum ether/ethyl acetate 9:1).
3. Conclusions
4.4. 1-Phenyl-pent-4-yn-2-ol (3A) [15,16]
An efficient aqueous electro-synthesis of homopropargyl alco-
hols using simple aldehydes and propargylic bromides has been
developed. The deposited zinc(0) powder with nano-wire archi-
tectures played an key role in the reaction. Green nature rendered
this methodology as an attractive synthetic route to homo-
propargyl alcohols as well as zinc nano-wires. Further investigation
to know the nature and properties of nano-wires as well as
organometallic intermediates is underway in our laboratory. We
are also trying to expand its scope for other organic reactions.
Using the general procedure but with 3-bromo-propyne 2A
(476 mg, 4.0 mmol) and Phenyl-acetaldehyde 1A (240 mg,
2.0 mmol) afforded the title compound 3a (196 mg, 61%) as a light
yellow oily liquid.
1H NMR (400 MHz, CDCl3):
d
1.95 (d, 1H, J ¼ 4.4 Hz), 2.09 (t, 1H,
J ¼ 2.7 Hz), 2.30e2.49 (m, 2H), 2.78e2.95 (m, 2H), 3.88e4.06 (m,
1H), 7.13e7.38 (m, 5H); 13C NMR (100.6 MHz, CDCl3)
26.64, 42.70,
d
71.03, 71.33, 80.82,126.90, 128.83, 129.61, 137.87; Anal (C11H12O)
calcd, C: 82.46, H: 7.55; found, C: 82.66, H: 7.47.
4. Experimental
4.5. 1-Anthryl-pent-4-yn-2-ol (3B) [17]
4.1. General comments
Using the general procedure but with 3-bromo-propyne 2A
(476 mg, 4.0 mmol) and Anthracen-9-yl-acetaldehyde1B (440 mg,
2.0 mmol) gave the title compound 3B (480 mg, 92%) as a yellow
solid, mp 84e87 ꢂC (dec.).
1H (200 MHz) and 13C NMR (54.6 MHz) spectra were recorded
on Brucker-AC 200 MHz spectrometer,1H (400 MHz) and 13C NMR
(100.6 MHz) spectra were recorded on Brucker-Avance II 400 MHz
spectrometer at 300 K and 1H (500 MHz) and 13C NMR (126 MHz)
spectra were recorded on Variant 500 MHz spectrometer. Chemical
shifts are reported in ppm from tetramethylsilane with the solvent
resonance as the internal standard (for CDCl3 in 1H NMR spectra
H ¼ 7.26 ppm and in 13C NMR spectra C ¼ 77.0 ppm). Data are re-
ported as follows: chemical shifts, multiplicity (s ¼ singlet,
d ¼ doublet, t ¼ triplet, q ¼ quartet, br ¼ broad, m ¼ multiplet).
Coupling constants (J) are reported in Hz. ESI mass spectra were
recorded on a Waters LCT mass spectrometer. Elemental analyses
were carried out using a CHNS/O Analyzer Perkin Elmer 2400 Series
II instrument. IR spectra were taken on a Thermo Nicolet FTIR
Spectrometer (NEXUS-870). Melting points were determined on an
Electrothermal 9100 melting point apparatus and are uncorrected.
IR (KBr) 3442, 3295, 2925, 1670, 1653, 1600, 1457, 1317, 1261,
1074, 1025, 734, 700, 668 cmꢀ1. 1H NMR (200 MHz, CDCl3):
d 1.85
(br s, 1H), 2.22 (t, 1H, J ¼ 2.6 Hz), 2.54e2.58 (m, 2H), 3.91e3.99 (m,
2H), 4.28e4.31 (m, 1H), 7.44e7.59 (m, 4H), 8.00e8.05 (m, 2H),
8.34e8.41 (m, 3H); 13C NMR (54.6 MHz, CDCl3):
d 27.06, 34.16,
71.25, 71.30, 80.81, 124.47, 124.96, 125.91, 127.28, 129.23, 129.86,
130.57, 131.54; Anal (C19H16O) calcd, C: 87.66, H: 6.19; found, C:
87.75, H: 6.21.
4.6. 3,3-Dimethyl-1-phenyl-pent-4-yn-2-ol (3C) [18,19]
Using the general procedure but with 3-bromo-3-methyl-but-1-
yne 2B (588 mg, 4.0 mmol) Phenyl-acetaldehyde 1A (240 mg,
Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
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B. Mondal et al. / Tetrahedron xxx (xxxx) xxx
2.0 mmol) afforded the title compound 3C (181 mg, 48%) as a light
yellow oily liquid.
122.03, 127.71, 131.78, 141.59; Anal. C10H9BrO calcd, C: 53.36, H:
4.03; found, C: 53.37, H: 4.04.
1H NMR (200 MHz, CDCl3):
d 1.25 (s, 6H), 1.63 (br s, 1H), 2.15 (s,
1H), 2.56 (dd, 1H, J ¼ 13.8 Hz, J ¼ 10.5 Hz), 3.02 (dd, 1H, J ¼ 13.8 Hz,
4.12. 1-(3-Methoxy-phenyl)-but-3-yn-1-ol (3I) [24]
J ¼ 2.1 Hz), 3.51 (dd, 1H, J ¼ 10.5 Hz, J ¼ 2.1 Hz), 7.13e7.27 (m, 5H);
.
13C NMR (54.6 MHz, CDCl3):
d 24.64, 25.57, 36.70, 38.80, 70.10,
Using the general procedure but with 3-bromo-propyne 2A
(478 mg, 4.0 mmol) and 3-Methoxy benzaldehyde 1H (272 mg,
2.0 mmol) afforded the title compound 3I (317 mg, 90%) as a light
yellow oily liquid.
78.76, 89.44, 126.38, 128.50, 129.29, 139.21 Anal. (C13H16O) calcd. C:
82.94, H: 8.57; found, C: 82.84, H: 8.62.
4.7. 1-Phenyl-but-3-yn-1-ol (3D) [20]
1H NMR (400 MHz, CDCl3)
d
2.06 (t, 1H, J ¼ 2.6 Hz), 2.38 (d, 1H,
J ¼ 3.5 Hz), 2.64e2.59 (m, 2H), 3.80 (s, 3H), 4.83 (m, 1H), 6.82 (m,
Using the general procedure but with 3-bromo-propyne 2A
(476 mg, 4.0 mmol) and benzaldehyde 1C (212 mg, 2.0 mmol)
afforded the title compound 3D (196 mg, 67%) as a light yellow oily
liquid.
1H), 6.90e6.97 (m, 2H), 7.21e7.29 (m, 1H); 13C NMR (100.6 MHz,
CDCl3)
d 29.65. 55.45, 71.21, 72.46, 80.86, 111.49, 113.68, 118.22,
129.74, 144.35, 159.95, Anal. C11H12O2 calcd, C: 74.98, H: 6.86;
found, C: 74.99, H: 6.87.
1H NMR (400 MHz, CDCl3)
d
2.06 (t, 1H, J ¼ 2.8 Hz), 2.36 (s, 1H),
2.69e2.55 (m, 2H), 4.86 (td, 1H, J ¼ 6.5, 2.6 Hz), 7.44e7.21 (m, 5H),
13C NMR (100.6 MHz, CDCl3)
29.42, 70.94, 72.30, 80.62, 125.70,
d
4.13. 2-Hydroxy-2-phenyl-pent-4-ynoic acid methyl ester (3J)
127.96, 128.45, 142.39, Anal. (C10H10O) calcd, C: 82.16, H: 8.20, O:
10.94; found, C: 82.17, H: 8.21.
Using the general procedure but with 3-bromo-propyne 2A
(478 mg, 4.0 mmol) and Oxo-phenyl-acetic acid methyl ester1I
(328 mg, 2.0 mmol) afforded the title compound 3J (163 mg, 40%) as
a colorless oily liquid.
4.8. 1-(4-Chloro-phenyl)-but-3-yn-1-ol (3E) [21,22]
Using the general procedure but with 3-bromo-propyne 2A
(476 mg, 4.0 mmol) and 4-Chloro benzaldehyde 1D (281 mg,
2.0 mmol) afforded the title compound 3E (260 mg, 72%) as a light
yellow oily liquid.
1H NMR (400 MHz, CDCl3)
d
: 2.06 (t, 1H, J ¼ 2.4), 3.02 (ddd, 2H,
J ¼ 2.4, 16.6, 133.0),3.82 (s, 3H), 3.94 (s, 1H), 7.42e7.31 (m, 3H), 7.59
(d, 2H, J ¼ 8.2), 13C NMR (101 MHz, CDCl3)
d: 30.89, 53.55, 71.23,
79.00, 125.39, 128.44, 139.83, 173.93, Anal. C12H12O3 calcd, C: 70.57,
H: 5.92; found, C: 70.59, H: 5.93.
1H NMR (400 MHz, CDCl3):
d
2.06e2.07 (m, 1H), 2.58e2.61 (m,
2H) 4.82e4.85 (m, 1H), 7.25e7.36 (m, 4H); 13C NMR (100.6 MHz,
CDCl3): 29.59, 71.54, 71.62, 80.14, 127.15, 128.62, 133.69, 140.83;
d
4.14. 1-(3-Chloro-phenyl)-hex-3-yn-1-ol (3K)
Anal. (C10H9ClO) calcd, C: 66.49, H: 5.02; found, C: 66.50, H: 5.03.
Using the general procedure but with 1-Bromo-pent-2-yne 2C
(588 mg, 4.0 mmol) and 3-Chloro benzaldehyde 1J (281 mg,
2.0 mmol) afforded the title compound 3I (146 mg, 35%) as a
4.9. 1-(2-Chloro-phenyl)-but-3-yn-1-ol (3F)
Using the general procedure but with 3-bromo-propyne 2A
(478 mg, 4.0 mmol) and 2-Chloro benzaldehyde 1E (281 mg,
2.0 mmol) afforded the title compound 3F (260 mg, 72%) as a light
yellow oily liquid.
colorless oily liquid with (72 mg, 17%)
a
-Hydroxy-allene (3L). as a
¼ 1.14 (t,
colorless oily liquid; 1H NMR (500 MHz, CDCl3):
d
J ¼ 7.5 Hz, 3H), 2.18 (dt, J ¼ 7.5, 2.4 Hz, 1H), 2.21 (dt, J ¼ 7.5, 2.4 Hz,
1H), 2.55 (ddt, J ¼ 16.5, 7.7, 2.4 Hz, 1H), 2.62 (ddt, J ¼ 16.5, 4.8,
2.4 Hz, 1H), 4.81e4.78 (m, 1H), 7.29e7.24 (m, 3H), 7.42e7.40 (m,
1H NMR (200 MHz, CDCl3):
d 2.09 (s, 1H), 2.78e2.79 (m, 2H),
2.79e2.83 (m, 1H) 5.27e5.30 (m, 1H), 7.21e7.35 (m, 3H), 7.62e7.64
(m, 1H); 13C NMR (54.6 MHz, CDCl3): 29.84, 68.85, 71.33, 80.16,
127.19,127.22,129.06,129.55,131.83,139.84; Anal. (C10H9ClO) calcd,
C: 66.49, H: 5.02; found, C: 66.50, H: 5.03.
1H), 13C NMR (126 MHz, CDCl3):
d
¼ 12.1, 13.8, 29.8, 71.6, 74.5, 85.2,
123.6, 125.8, 127.6, 129.3, 134.0, 144.6, Anal. C12H13ClO calcd, C:
69.07, H: 6.28; found, C: 69.09, H: 6.29.
4.10. 1-(4-Methoxy-phenyl)-but-3-yn-1-ol (3G) [22,23]
4.15.
a-Hydroxy-allene (3L)
Using the general procedure but with 3-bromo-propyne 2A
(478 mg, 4.0 mmol) and 4-Methoxy benzaldehyde 1F (272 mg,
2.0 mmol) afforded the title compound 3G (300 mg, 85%) as a light
yellow oily liquid.
1HNMR (500 MHz, CDCl3):
d
¼ 0.99 (t, 3H, J ¼ 7.4 Hz), 1.92e1.76
(m, 2H), 5.07e5.01 (m, 2H), 5.11 (br s, 1H), 7.28e7.24 (m, 3H), 7.38
(ddd, 1H, J ¼ 2.1, 1.5, 0.7 Hz).
13C NMR (126 MHz, CDCl3):
d
¼ 11.7,20.5, 73.4, 80.2, 109.3, 124.6,
1H NMR (400 MHz, CDCl3)
d
2.07 (t, 1H, J ¼ 2.6 Hz), 2.30 (br s,
126.5, 127.6, 129.3, 134.0, 144.0, 203.8.
1H), 2.66e2.60 (m, 2H), 3.81 (s, 3H), 4.84 (t, 1H, J ¼ 6.4 Hz),
Anal. C12H13ClO calcd, C: 67.18, H: 6.66; found, C: 67.19, H: 6.68.
6.92e6.86 (m, 2H), 7.35e7.29 (m, 2H); 13C NMR (100.6 MHz, CDCl3)
d
29.61, 55.51, 71.08, 72.21, 81.03, 114.08, 127.23, 134.87, 159.56;
Acknowledgement
Anal. C11H12O2 calcd, C: 74.98, H: 6.86; found, C: 74.99, H: 6.87.
Financial support of this work by SERB-New Delhi, SR/FT/CS-
4.11. 1-(4-Bromo-phenyl)-but-3-yn-1-ol (3H) [23]
137/2011 dated 12.07.2012, and Science
Biotechnology-WB, 50(Sanc.)/ST/P/S&T/15G-10/2018
&
Technology and
dated
Using the general procedure but with 3-bromo-propyne 2A
(478 mg, 4.0 mmol) and 4-Bromo benzaldehyde 1G (370 mg,
2.0 mmol) afforded the title compound 3H (333 mg, 74%) as a light
yellow oily liquid.
30.01.2019 to UKR is gratefully acknowledged.
Appendix A. Supplementary data
1H NMR (400 MHz, CDCl3)
d
2.07e1.97 (m, 1H), 2.37 (br s, 1H),
2.66e2.50 (m, 2H), 4.85e4.72 (m, 1H), 7.29e7.15 (m, 2H), 7.51e7.36
(m, 2H); 13C NMR (100.6 MHz, CDCl3)
29.64, 71.58, 71.87, 80.34,
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.tet.2019.07.012.
d
Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
medium and its reactivity in propargylation of aldehydes, Tetrahedron, https://doi.org/10.1016/j.tet.2019.07.012

B. Mondal et al. / Tetrahedron xxx (xxxx) xxx
7
(d) D.R. Fandrick, K.R. Fandrick, J.T. Reeves, Z. Tan, C.S. Johnson, H. Lee,
J.J. Song, N.K. Yee, C.H. Senanayake, Org. Lett. 12 (2010) 88, https://doi.org/
10.1021/ol902457m;
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Please cite this article as: B. Mondal et al., Synthesis and characterization of nanoꢀzinc wire using a self designed unit galvanic cell in aqueous
medium and its reactivity in propargylation of aldehydes, Tetrahedron, https://doi.org/10.1016/j.tet.2019.07.012