Silver-containing microemulsion as a high-efficient and recyclable catalytic system for hydration of alkynes

Article abstract of DOI:10.1016/j.jorganchem.2015.09.014

A silver-catalyzed highly efficient and regioselective synthesis of ketones from a wide range of alkynes is described. The reaction is dramatically accelerated by its performance in aqueous emulsion, which is self-assembled by the addition of silver perfluorooctanesulfonate (1) and perfluorooctanesulfonic acid (PFOS) to water. The reaction is conducted under convenient conditions with broad substrate scope, including a variety of aromatic and aliphatic terminal alkynes and internal alkynes. Furthermore, the air- and light-stable silver catalytic microemulsion can be reused for 4 times with minimal change in catalytic efficiency.

Full text of DOI:10.1016/j.jorganchem.2015.09.014

Journal of Organometallic Chemistry 799-800 (2015) 122e127
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Silver-containing microemulsion as a high-efficient and recyclable
catalytic system for hydration of alkynes
Qizhi Dong 1, Ningbo Li 1, Renhua Qiu**, Jinying Wang, Cancheng Guo***, Xinhua Xu*
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering Hunan University, Changsha 410082,
PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 June 2015
Accepted 18 September 2015
Available online 25 September 2015
A silver-catalyzed highly efficient and regioselective synthesis of ketones from a wide range of alkynes is
described. The reaction is dramatically accelerated by its performance in aqueous emulsion, which is self-
assembled by the addition of silver perfluorooctanesulfonate (1) and perfluorooctanesulfonic acid (PFOS)
to water. The reaction is conducted under convenient conditions with broad substrate scope, including a
variety of aromatic and aliphatic terminal alkynes and internal alkynes. Furthermore, the air- and light-
stable silver catalytic microemulsion can be reused for 4 times with minimal change in catalytic
efficiency.
Keywords:
Microemulsion
Silver perfluorooctanesulfonate
PFOS
© 2015 Elsevier B.V. All rights reserved.
Alkynes
Hydration
1. Introduction
ketone) [8]. Several strong brønated acids, such as TfOH, Tf2NH,
could catalyze hydration of alkynes efficiently [9]. And the efficient
Microemulsion as micro-heterogeneous systems [1] can solu-
bilize both polar and nonpolar substances, and have been exten-
sively applied in many fields, such as in organic synthesis, material
science, separation science [2]. Since water is a clean, safe, readily
available and almost free of charge solvent, thus utilizing water in
microemulsions for the synthesis of a broad spectrum of organic
compounds has been comprehensively realized and proven [3]. For
example, Sheng et al. have developed a high efficient silver-
catalyzed decarboxylative trifluoromethylthiolation of alkyl car-
boxylic acid in an aqueous emulsion [4]. Kobayshi et al. reported
another high efficient dehydration reactions in water assisted with
a surfactant-type catalyst [5]. Wass et al. found the noble metal
complex platinum (II) diphosphinamine can be also used as the
efficient catalyst for the hydration of alkynes in micellar media [6].
However, performing stereoselective organic synthesis in the
microemulsion with water is still very rare [7].
hydration of alkynes through acid-assisted brønsted acid catalysis
was also described [10]. Besides, a variety of metal based catalysts
such as Hg, Au, Pt, Pd, Ir, Co and Ru have been employed [11]. Silver
salts for the hydration of alkynes were also explored with limited
examples, such as AgSbF6, AgBF4, AgOTf and AgBArF [12]. But, these
catalysts were moisture-sensitive, light-sensitive and limited for
narrow substrates, e.g., lower yield was obtained or no reaction was
proceed for internal alkynes, and they can't be recycled. Another
silver exchanged silicotungstic acid as heterogeneous catalyst for
the hydration of alkynes was developed by Marsella et al. [13].
However, extremely longer reaction time (70 h) was needed. Thus,
the development of an highly efficient silver-catalyzed system that
free of hydrolysis as well as light-sensitive and can be conveniently
applied in hydration of alkynes is highly demanded.
In contrast to AgOTf, we found silver perfluorooctanesulfonate
(AgOSO2C8F17$H2O, 1) is air-stable and water-tolerant and suffered
no color change in air for at least half a year. Generally, per-
fluorooctanesulfonic acid (PFOS) is used as a surfactant in industrial
production [14]. Herein, we disclose our progress in direct hydra-
tion of alkynes in microemulsions self-assembled by adding silver
perfluorooctanesulfonate (1) and perfluorooctanesulfonic acid to
water. Moreover, the high catalytic efficiency for the hydration of
alkynes catalyzed by the above microemulsion is successfully
achieved (Fig. 1).
Hydration of alkynes is a simple and efficient method for the
preparation of valuable carbonyl compounds (aldehyde and
* Corresponding author. Fax: þ86 731 88821546.
** Corresponding author. Fax: þ86 731 88821546.
*** Corresponding author. Fax: þ86 731 88821546.
E-mail addresses: renhuaqiu@hnu.edu.cn (R. Qiu), ccguo@hnu.edu.cn (C. Guo),
xhx1581@hnu.edu.cn (X. Xu).
1
These authors contributed equally to this work.
http://dx.doi.org/10.1016/j.jorganchem.2015.09.014
0022-328X/© 2015 Elsevier B.V. All rights reserved.

Q. Dong et al. / Journal of Organometallic Chemistry 799-800 (2015) 122e127
123
Fig. 1. Hydration of alkynes catalyzed by 1 in the microemulsion.
2. Results and discussion
can stabilize the silver salt against hydrolysis in air.
TG-DSC analysis shows the complex 1 is thermal stable up to
400 ꢁC (Fig. 3). The endothermic step below 150 ꢁC can be assigned
to the removal of H2O molecules. The weight loss of an exothermic
nature at 400 ꢁC is plausibly due to the oxidation of counter anion
OSO2C8F17₋. The loss of weight is attributed to the fragments of
C8F17.
2.1. Characterization of AgOSO2C8F17·H2O
In previous works [15], C8F17SOꢀ3 was mainly used as counter
anion to overcome the hydrolytic instability of the cationic organ-
ometallic species and enhance the Lewis acidity. In order to further
reveal its air-stability and hydrophobility, the crystal structure of 1
and thermal behavior were studied. Single crystals of 1 could be
obtained by diffusion of hexane into a saturated solution of the
product 1 in THF. An ORTEP representation of 1, and the crystal
structure and unit cell are shown in Fig. 2.
The silver ion is coordinated by four O atoms in a distorted
tetrahedral coordination environment with the AgeO distance,
from 2.316 to 2.473 Å (Fig. 2a). Corner-sharing connectivity of AgO4
tetrahedron generated a double-chain coordination polymer, along
the b direction with the perfluorocarbon chain, regularly extending
outside on both sides (Fig. 2b). Double-chains are linked by two
OeH(water)/O(sulfonate) hydrogen bonds(H/O ¼ 1.98, 2.10, and
2.49 Å; O/O ¼ 2.781, 2.787, and 2.924 Å; OeH/O ¼ 157.2, 137.8,
and 112.3ꢁ), as two-dimensional symmetric “head-to-head” bilayer
structure with alternating R12(8) and R23(8) motifs (Fig. 2c). Because
of the hydrophobic and electron-withdrawing properties of long-
chain perfluorooctanesulfonate anion [16], the bilayer structure
2.2. Optimization of the reaction conditions for silver-catalyzed
hydration of alkynes
Since the high air-stability and thermal stability of the silver
complex 1, we hence estimate its catalytic performance in hydra-
tion of phenylacetylene at 100 ꢁC for 8 h in the dark. As shown in
Table 1, in the absence of the additive, the reaction is almost not
effective (entry 1). The reaction is performed in the presence of
PFOS and 35% yield of ketone is obtained (entry 2). When the 2 mol
% of PFOS and 5 mol% of 1 are added together, the yield is up to 95%
(entry 4). To further demonstrate the advantage of 1 over other
silver salts, the different silver catalysts were tested. AgNO2,
Ag2CO3, Ag2O, and AgOAc give about 10% yield (entries 6e9), which
may be the role of PFOS. AgBF4 and AgOTf give the yields of 53%,
57%, respectively (entries 10e11), while AgSbF6 affords 71% yield
(entry 12). We also put the reaction under natural light to reveal the
Fig. 2. (a) A perspective view of a single repeating unit of AgOSO2C8F17$H2O (1) with
the atomic numbering scheme; (b) the coordination environment in the silver salt, and
the one-dimensional infinite chain structure along the b axis linked by corner-sharing
connectivity of AgO4 tetrahedron; (c) two-dimensional symmetric “head-to-head”
bilayer structure in Ag complex guided by hydrogen bond between coordination water
and sulfonate. Nonbonded contacts are indicated by dashed lines.
Fig. 3. TG-DSC curves of AgOSO2C8F17$H2O (1).

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Q. Dong et al. / Journal of Organometallic Chemistry 799-800 (2015) 122e127
Table 1
Table 2
Optimization of the reaction conditions for silver-catalyzed hydration of alkynes.a
The hydration of alkynes catalyzed by 1 (5 mol%)/PFOS (2 mol%) in water.a
Entry
AgX
Additive
Solvent
Yield (%)
1
2
3
4
5
6
7
8
1
e
e
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
<5
35
78
PFOS (0.05 mmol)
PFOS (0.01 mmol)
PFOS (0.02 mmol)
PFOS (0.03 mmol)
PFOS (0.02 mmol)
PFOS (0.02 mmol)
PFOS (0.02 mmol)
PFOS (0.02 mmol)
PFOS (0.02 mmol)
PFOS (0.02 mmol)
PFOS (0.02 mmol)
1
1
1
95 (94)b
94
AgNO2
Ag2CO3
Ag2O
AgOAc
AgBF4
AgOTf
AgSbF6
11
13
12
15
9
10
11
12
53 (16)b
57 (28)b
71 (34)b
a
Reaction condition: phenylacetylene (1 mmol), AgX (0.05 mmol), additive:
PFOS; solvent: 1 mL; 8 h, 100 ꢁC, dark, isolated yield.
b
Under natural light.
light-stability of the complex 1 over AgBF4, AgOTf and AgSbF6, the
yields are shown in parentheses (entries 4, 10e12). The result im-
plies that the counter anion of C8F17SOꢀ3 in 1 has a significant
protection for the silver core. Finally, the optimum catalytic
microemulsion system is 1 (5 mol%)/PFOS (2 mol%)/water (1 mL)
mixture.
2.3. The scope with different alkynes
With an efficient protocol for the hydration of alkynes in hand,
we next investigate its scope with different alkynes. As shown in
Table 2, both electron-donating and electron-withdrawing alkynes
afford the corresponding products in good to excellent yields.
Clearly, the electronic effect plays an important role, the electron-
donating groups attached in the phenyl ring of alkynes exhibit in
higher yields than that of the electron-withdrawing groups (en-
tries 2e7). Substitution at the 2-position of the aromatic ring is
slightly lowered the yields (entries 3, 4). It should be noted that the
carbon-halogen bonds are well tolerated (entry 4), which could be
easily further functionalized. Gratifyingly, other acid-sensitive
functionalities such as eCN, eCHO, eC(O)CH3 and alkene are
also unaffected under the present reaction conditions (entries
5e8). For heterocycle alkyne, it still gives the corresponding het-
erocycle ketone in 80% yield (entry 9). The catalytic system can be
easily extending to the aliphatic alkyne, in 78% yield (entry 10). The
internal alkynes, such as 5-decyne and diphenylacetylene, can
afford the corresponding products in good yields (entries 11e12).
Interestingly, asymmetric internal alkynes also show good reac-
tivity in this catalytic system with 74% and 58%, respectively (entry
13e14).
a Reaction conditions: alkynes (1 mmol), 1 (0.05 mmol), PFOS (0.02 mmol),
H2O: 1 ml, 100 oC, 8 hours, isolated yield. b 15 hours, c 20 hours
2.5. The possible mechanism
2.4. Cycles of catalyst 1
The possible mechanism was proposed in Scheme 1 on the basis
of the previous reports [12b]. First, the silver center coordinates
with the triple bond of the terminal alkyne and forms a p-complex
A. the nucleophile C8F17SO3₋ anion attacks the complex to provide
intermediate B, and then protonation to form enol per-
fluorooctanesulfonate C, which subsequently undergoes successive
hydrolysis and ketoeenol tautomerism to generate methyl ketone.
The possible catalytic performance in the microemulsion is pro-
posed as shown in Fig. S1.
To test the reusability and reproducibility, the catalytic micro-
emulsion is subject to cycles of hydration of phenylacetylene as the
model reaction. After completion of reaction, n-hexane is added to
the reaction mixture, which is automatic layering. After separating,
the lower microemulsion is used for next cycle of the reaction. The
decline in product yield is minimal in a run of 4 cycles (95%e92%),
indicating that the microemulsion is stable and suitable for reuse
(Table 3).

Q. Dong et al. / Journal of Organometallic Chemistry 799-800 (2015) 122e127
125
Table 3
The rest of the solution was used for the next cycle of reaction. The
extraction solvent was removed and the crude product was sepa-
rated by column chromatography to give the pure sample.
Yields of Hydration of alkynes by recover
catalyst.a
Yield (%)b
Acetophenone (3a): 1H NMR (400 MHz, CDCl3):
d
7.96e7.94 (m,
Cycle
2H, ArH), 7.57e7.52 (m, 1H, ArH), 7.47e7.43 (m, 2H, ArH), 2.60 (s,
1
2
3
4
5
95
94
94
92
81
3H, CH3); 13C NMR (100 MHz, CDCl3):
d 198.15, 137.10, 133.10,
128.56, 128.29, 26.60; MS(70 ev): m/z ¼ 120.1 [Mþ].
1-(4-methphenyl)ethanone(3b): 1H NMR (400 MHz, CDCl3):
d
7.86 (d, J ¼ 8.4 Hz, 2H, ArH), 7.27 (t, J ¼ 4.0 Hz, 2H, ArH), 2.58 (s, 3H,
a
CH3), 2.41 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d 197.84, 143.84,
Reaction
conditions:
phenylacetylene
(1.0 mmol), solvent: water (1.0 mL), and 1
(5.0 mmol%), PFOS (2.0 mmol%), at 100 ꢁC for
8 h.
134.66, 129.19, 128.40, 26.50, 21.60; MS(70 ev): m/z ¼ 134.1 [Mþ].
1-(4-ethylphenyl)ethanone(3c): 1H NMR (400 MHz, CDCl3):
b
Isolated yield.
d
7.90 (d, J ¼ 4.0 Hz, 2H, ArH), 7.28 (d, J ¼ 7.6 Hz, 2H, ArH), 2.72e2.70
(m, 2H, CH2), 2.59 (s, 3H, CH3), 1.29e1.24 (m, 2H, CH3); 13C NMR
(100 MHz, CDCl3):
d 197.90, 150.05, 134.92, 128.54, 128.05, 28.93,
26.55, 15.20; MS(70 ev): m/z ¼ 148.1 [Mþ].
3. Experimental
3.1. General
All chemicals were purchased from Aldrich. Co. Ltd and used as
received unless otherwise indicated. The NMR spectra were
recorded at 25 ꢁC on INOVA-400M (USA) calibrated with tetrame-
thylsilane (TMS) as an internal reference. TG-DSC analysis was
performed on a HCT-1 (HENVEN, Beijing, China) instrument. X-ray
single crystal diffraction analysis was performed with SMART-APEX
and RASA-7A by Shanghai Institute Organic Chemistry, China
Academy of Science.
1-(4-n-propylphenyl)ethanone(3d): 1H NMR (400 MHz, CDCl3):
d
7.88 (d, J ¼ 8.0 Hz, 2H, ArH), 7.28 (d, J ¼ 7.6 Hz, 2H, ArH), 2.66e2.63
(m, 2H, CH2), 2.58 (s, 3H, CH3), 1.69e1.62 (m, 2H, CH3), 0.95 (t,
J ¼ 7.4 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d
197.96, 148.58,
134.94, 128.67, 128.46, 38.03, 26.57, 24.24, 13.77; MS(70 ev): m/
z ¼ 162.1 [Mþ].
1-(4-n-butylphenyl)ethanone(3e): 1H NMR (400 MHz, CDCl3):
d
7.89 (d, J ¼ 8.0 Hz, 2H, ArH), 7.27 (d, J ¼ 8.0 Hz, 2H, ArH), 2.70e2.66
(m, 2H, CH2), 2.59 (s, 3H, CH3),1.65e1.59 (m, 2H, CH3),1.37e1.33 (m,
2H, CH3), 0.97e0.93 (m, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d
197.89, 148.80, 134.88, 128.60, 128.46, 35.68, 35.25, 26.53, 22.32,
13.91; MS(70 ev): m/z ¼ 176.1 [Mþ].
1-(4-n-amylphenyl)ethanone(3f): 1H NMR (400 MHz, d6-DMSO):
3.2. Synthesis of AgOSO2C8F17 (1) [16].
d
7.87 (d, J ¼ 8.4 Hz, 2H, ArH), 7.31 (d, J ¼ 8.4 Hz, 2H, ArH), 2.65e2.62
To a solution of C8F17SO3H (5 g, 10 mmol) which was prepared
according to literature in 15 ml of H2O was added Ag2CO3 (1.656 g,
6 mmol) in ice water and stirred for an hour then was rise the
temperature to 100 ꢁC for 1 h, and then at RT for 1 h. After filtration,
the solids obtained were washed with ice-water till the filtrate
turned neutral. The solids were dissolved in acetone and filtered.
After the filtrate had been evaporated, the crude solids were sub-
jected to recrystallization from THF/Et2O to afford C8F17SO3Ag in a
pure form (2.42 g, 40%). 19F NMR (376 M, [d6] acetone):
(m, 2H, CH2), 2.55 (s, 3H, CH3), 1.62e1.54 (m, 2H, CH3), 1.32e1.23
(m, 4H, CH3), 0.87e0.83 (m, 3H, CH3); 13C NMR (100 MHz, d6-
DMSO): d 197.91, 148.66, 135.08, 129.00, 128.76, 35.48, 31.26, 30.72,
27.05, 22.36, 14.33; MS(70 ev): m/z ¼ 190.1 [Mþ].
1-(4-methoxyphenyl)ethanone(3g): 1H NMR (400 MHz, CDCl3):
d
7.94 (d, J ¼ 8.8 Hz, 2H, ArH), 6.93 (d, J ¼ 9.2 Hz, 2H, ArH), 3.87 (s,
3H, OCH3), 2.56 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d
196.75,
163.42, 130.53, 130.27, 113.62, 55.43, 26.30; MS(70 ev): m/
z ¼ 150.1 [Mþ].
1-(3-methoxyphenyl)ethanone(3h): 1H NMR (400 MHz, CDCl3):
d
¼ ꢀ78.95eꢀ79.00 (t, 3F, CF3₋), ꢀ112.91eꢀ112.99 (m, 2F,
eCF2₋), ꢀ118.72 (s, 2F, eCF2₋), ꢀ119.61eꢀ119.80 (m, 6F,
e(CF2)3₋), ꢀ120.65(s, 2F, eCF2₋), ꢀ124.03eꢀ124.11 (m, 2F, eCF2₋).
Crystal data for 1: C8H2F17AgO4S; Mr ¼ 625.03, Monoclinic,
d
7.54 (d, J ¼ 7.2 Hz, 1H, ArH), 7.49 (s, 1H, ArH), 7.37 (t, J ¼ 7.8 Hz, 1H,
ArH), 7.11 (d, J ¼ 8.0 Hz, 1H, ArH), 3.85 (s, 3H, OCH3), 2.60 (s, 3H,
CH3); 13C NMR (100 MHz, CDCl3):
d 198.07, 159.78, 138.43, 129.59,
121.16, 119.65, 112.29, 55.43, 26.77; MS(70 ev): m/z ¼ 150.1 [Mþ].
space group P21/c,
a
¼
26.001(7) Å,
b
¼
5.6450(14) Å,
c ¼ 11.469(3) Å; V ¼ 1678.5(7) Å3; T ¼ 298(2) K; Z ¼ 4; Reflections
1-(2-methoxyphenyl)ethanone(3i): 1H NMR (400 MHz, CDCl3):
collected/unique, 9858/3104, Rint ¼ 0.0415, Final R indices [I > 2
s(I)]
d
7.73 (d, J ¼ 7.6 Hz, 1H, ArH), 7.46 (t, J ¼ 7.6 Hz, 1H, ArH), 7.00e6.95
(m, 1H, ArH), 3.90 (s, 3H, OCH3), 2.61 (s, 3H, CH3); 13C NMR
R1 ¼ 0.0734, wR2 ¼ 0.2167; R indices (all data), R1 ¼ 0.0848,
wR2 ¼ 0.2282. GOF ¼ 1.071; CCDC No. 895177.
(100 MHz, CDCl3):
d 199.94, 158.93, 133.74, 130.34, 128.14, 120.52,
111.57, 55.47, 31.90; MS(70 ev): m/z ¼ 150.1 [Mþ].
3.3. Typical procedure for synthesis of ketones
1-(3,4-dimethoxyphenyl)ethanone(3j): 1H NMR (400 MHz,
CDCl3):
d
7.58 (d, J ¼ 8.4 Hz, 1H, ArH), 7.53 (s, 1H, ArH), 6.89 (d,
To the mixture of phenylacetylene (1 mmol), water (3.0 mL),
silver perfluorooctanesulfonate (5 mol%) and perfluorooctane sul-
fonate acid (2 mol%) was added. The mixture was stirred at 100 ꢁC
for 8 h. The solution was extracted with n-hexane (diethyl ether)
(3 ꢂ 5 mL), the combined extract was dried with anhydrous MgSO4.
J ¼ 8.0 Hz, 1H, ArH), 3.95 (s, 6H, OCH3), 2.57 (s, 3H, CH3); 13C NMR
(100 MHz, CDCl3):
d 196.84, 153.22, 148.91, 130.40, 123.31, 109.92,
109.88, 56.05, 55.94, 26.23; MS(70 ev): m/z ¼ 180.1 [Mþ].
1-(2-chlorophenyl)ethanone(3k): 1H NMR (400 MHz, CDCl3):
d
7.55 (d, J ¼ 7.6 Hz, 1H, ArH), 7.43e7.37 (m, 2H, ArH), 7.34e7.28 (m,
Scheme 1. The possible reaction mechanism.

126
Q. Dong et al. / Journal of Organometallic Chemistry 799-800 (2015) 122e127
1H, ArH), 2.65 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d
200.57,
d
8.05e8.02 (m, 2H), 7.56e7.51 (m, 1H), 7.49e7.45 (m, 2H),
7.37e7.30 (m, 2H), 7.29e7.25 (m, 3H), 4.31 (s, 2H). 13C NMR
(100 MHz, CDCl3): 197.95, 136.82, 134.77, 133.93, 133.42, 130.41,
139.08, 132.05, 131.30, 130.66, 129.43, 126.96, 30.75; MS(70 ev): m/
z ¼ 154.0 [Mþ].
d
1-(3-chlorophenyl)ethanone(3l): 1H NMR (400 MHz, CDCl3):
129.71, 128.91, 128.88, 128.86, 128.71, 127.13, 45.74; MS(70 ev): m/
d
7.94 (s, 1H, ArH), 7.85e7.83 (m, 1H, ArH), 7.56e7.54 (m, 1H, ArH),
z ¼ 196.1 [Mþ].
7.44e7.40 (m, 1H, ArH), 2.61 (s, 3H, CH3); 13C NMR (100 MHz,
Propiophenone (3z): 1H NMR (400 MHz, CDCl3):
d 7.95 (d,
CDCl3):
d
198.76, 134.51, 133.08, 129.96, 128.45, 126.43, 125.30,
J ¼ 7.6 Hz, 2H), 7.56e7.52 (m, 1H), 7.42 (t, J ¼ 7.6 Hz, 2H), 3.02e2.96
26.70; MS(70 ev): m/z ¼ 154.0 [Mþ].
(m, 2H), 1.22 (t, J ¼ 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3):
d 201.05,
1-(4-bromophenyl)ethanone(3m): 1H NMR (400 MHz, CDCl3):
137.11, 133.09, 128.75, 128.17, 31.98, 8.44; MS(70 ev): m/
d
7.82 (d, J ¼ 8.0 Hz, 2H, ArH), 7.61 (d, J ¼ 7.6 Hz, 2H, ArH), 2.59 (s,
z ¼ 134.1 [Mþ].
3H, CH3); 13C NMR (100 MHz, CDCl3):
d
197.08, 135.82, 131.92,
1-(4-methoxyphenyl)-2-(4-propylphenyl)ethanone(3aa′):
White solid, Mp. 59e60 ꢁC; [Lit. [17], Mp. 59e61 ꢁC]; 1H NMR
129.86, 128.34, 26.58; MS(70 ev): m/z ¼ 198.0 [Mþ].
1-(2-bromophenyl)ethanone(3n): 1H NMR (400 MHz, CDCl3):
(400 MHz, CDCl3):
d
7.99 (d, J ¼ 7.6 Hz, 2H, ArH), 7.17 (d, J ¼ 7.2 Hz,
d
7.61 (d, J ¼ 8.0 Hz, 1H, ArH), 7.47 (d, J ¼ 7.2 Hz, 1H, ArH), 7.37 (t,
2H, ArH), 7.12 (d, J ¼ 7.2 Hz, 2H, ArH), 6.91 (d, J ¼ 7.6 Hz, 2H, ArH),
4.19 (s, 2H, CH2), 3.84 (s, 3H, CH3), 2.54 (t, J ¼ 7.4 Hz, 2H, CH2),
1.68e1.56 (m, 2H, CH2), 0.92 (t, J ¼ 7.2 Hz, 3H, CH3); 13C NMR
J ¼ 7.2 Hz, 1H, ArH), 7.30 (t, J ¼ 6.8 Hz, 1H, ArH), 2.6 (s, 3H, CH3); 13
C
NMR (100 MHz, CDCl3):
d 201.44, 141.38, 133.85, 131.86, 128.95,
127.49, 118.90, 30.37; MS(70 ev): m/z ¼ 198.0 [Mþ].
(100 MHz, CDCl3): d 196.53, 163.49, 141.19, 132.12, 131.00, 129.68,
1-(4-cyanphenyl)ethanone(3o): 1H NMR (400 MHz, CDCl3):
8.05 (d, J ¼ 8.0 Hz, 2H, ArH), 7.79 (d, J ¼ 8.0 Hz, 2H, ArH), 2.66 (s,
129.23, 128.79, 113.78, 55.49, 44.92, 37.71, 24.56, 13.93; MS(70 ev):
d
m/z ¼ 268.1 [Mþ].
3H, CH3); 13C NMR (100 MHz, CDCl3):
d 196.64, 139.89, 132.55,
128.733, 117.98, 116.39, 26.84; MS(70 ev): m/z ¼ 145.1 [Mþ].
4. Conclusions
1-(4-(trifluoromethyl)phenyl)ethanone(3p): 1H NMR (400 MHz,
CDCl3):
d
8.07 (d, J ¼ 7.6 Hz, 2H, ArH), 7.74 (d, J ¼ 7.6 Hz, 2H, ArH),
197.07, 139.62,
In summary, we have developed a simple and efficient method
for the selective hydration of alkynes in the microemulsion con-
taining Ag catalyst. Both of the terminal alkynes and internal al-
kynes can proceed smoothly and afford good to excellent yields,
and a variety of functional groups are well tolerated. Furthermore,
the catalytic microemulsion system [AgOSO2C8F17$H2O (5 mol
%)/HOSO2C8F17 (2 mol%)/H2O] can be reused for four times. On
account of the stability and high catalytic efficiency, the silver-
containing microemulsion should find a broad range of utility in
organic synthesis.
2.66 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d
134.25, 128.64, 125.74, 125.71, 125.67, 124.95, 122.24, 26.83; 19F
NMR (376 MHz, CDCl3):
d
ppm 63.11; MS(70 ev): m/z ¼ 188.0 [Mþ].
1-(3-nitrophenyl)ethanone(3q): 1H NMR (400 MHz, CDCl3):
d
8.78 (s, 1H, ArH), 8.44 (s, 1H, ArH), 8.31 (s, 1H, ArH), 7.72 (s, 1H,
ArH), 2.72 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d 195.77, 148.40,
138.19, 133.85, 129.97, 127.44, 123.22, 26.79; MS(70 ev): m/
z ¼ 165.0 [Mþ].
1-(4-acetylphenyl)ethanone(3r): 1H NMR (400 MHz, CDCl3):
d
8.06 (d, J ¼ 8.0 Hz, 2H, ArH), 7.79 (d, J ¼ 8.0 Hz, 2H, ArH), 2.66 (s,
3H, CH3); 13C NMR (100 MHz, CDCl3):
d 196.64, 139.89, 132.55,
Acknowledgments
128.73, 117.98, 116.39, 26.84; MS(70 ev): m/z ¼ 162.1 [Mþ].
1-(4-nitrophenoxy)propan-2-one(3s): 1H NMR (400 MHz,
The authors thank the NSFC (Nos. 21273068, 21373003,
J1210040), the NSF of Hunan Province (14JJ7027), and the Funda-
mental Research Funds for the Central Universities, Hunan Uni-
versity, for financial support. The authors thank the Prof. A. Orita
(Okayama University of Science) and Prof. N. Kambe (Osaka Uni-
versity) for helpful discussion.
CDCl3):
d
8.22 (d, J ¼ 8.0 Hz, 2H, ArH), 6.96 (d, J ¼ 8.0 Hz, 2H, ArH),
4.69 (s, 2H, CH2), 2.32 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3):
d
203.19, 162.50, 142.25, 126.06, 114.64, 72.97, 26.58; MS(70 ev): m/
z ¼ 195.1 [Mþ].
4-(2-oxopropoxy)benzaldehyde(3t): 1H NMR (400 MHz, CDCl3):
d
9.84 (s, 1H, CHO), 7.79 (d, J ¼ 8.0 Hz, 1H, ArH), 7.20 (s, 1H, ArH),
6.93 (d, J ¼ 8.4 Hz, 2H, ArH), 4.59 (s, 2H, CH2), 2.24 (s, 3H, CH3); 13
C
Appendix A. Supplementary data
NMR (100 MHz, CDCl3):
d 197.78, 190.77, 132.09, 114.86, 72.82,
26.67; MS(70 ev): m/z ¼ 178.1 [Mþ].
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.09.014.
1-(cyclohex-2-en-1-yl)ethanone(3u): 1H NMR (400 MHz, CDCl3):
6.92 (s, 1H,CH¼), 2.28 (s, 3H, CH3), 2.24 (d, J ¼ 14.0 Hz, 4H, CH2),
d
1.62 (s, 4H,CH2); 13C NMR (100 MHz, CDCl3):
d 199.52, 141.10,
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