Stainless-Steel Ball-Milling Method for Hydro-/Deutero-genation using H2O/D2O as a Hydrogen/Deuterium Source

Article abstract of DOI:10.1002/cssc.201501019

A one-pot continuous-flow method for hydrogen (deuterium) generation and subsequent hydrogenation (deuterogenation) was developed using a stainless-steel (SUS304)-mediated ball-milling approach. SUS304, especially zero-valent Cr and Ni as constituents of the SUS304, and mechanochemical processing played crucial roles in the development of the reactions.

Full text of DOI:10.1002/cssc.201501019

DOI: 10.1002/cssc.201501019
Communications
Stainless-Steel Ball-Milling Method for Hydro-/Deutero-
genation using H2O/D2O as a Hydrogen/Deuterium Source
Yoshinari Sawama,*[a] Takahiro Kawajiri,[a] Miki Niikawa,[a] Ryota Goto,[a] Yuki Yabe,[a]
Tohru Takahashi,[a] Takahisa Marumoto,[a] Miki Itoh,[b] Yuuichi Kimura,[b] Yasunari Monguchi,[a]
Shin-ichi Kondo,[c] and Hironao Sajiki*[a]
A one-pot continuous-flow method for hydrogen (deuterium)
generation and subsequent hydrogenation (deuterogenation)
was developed using a stainless-steel (SUS304)-mediated ball-
milling approach. SUS304, especially zero-valent Cr and Ni as
constituents of the SUS304, and mechanochemical processing
played crucial roles in the development of the reactions.
the SUS304. During the course of the study, we discovered
that the hydrogenation of reducible functionalities could
smoothly proceed under the ball-milling conditions in the
presence of H2O as a hydrogen source. Although numerous
protocols are published that use ball milling for organic
chemistry,[8] an uninterrupted one-pot reaction of the SUS304-
mediated quantitative production of H2 from H2O and subse-
quent hydrogenation of organic compounds is not reported in
the literature. This is regarded as a convenient and direct H2
transfer approach from H2O to organic compounds.
Minimizing the dependence on fossil fuels is currently under
the spotlight to avoid global warming[1] through the reduction
of greenhouse gases emitted from the combustion these ma-
terials. Additionally, the depletion of fossil fuels is of pending
concern and alternatives are required. Although hydrogen gas
is a sustainable and very promising next-generation energy
carrier, many improvements are needed in the distribution,
storage, generation and consumption of hydrogen to build
a hydrogen economy.[2] While significant research was conduct-
ed on the topic over the past decade,[3] there are still many
problems to be solved, such as energy efficiency, sustainability,
safety, and operability. Therefore, the creation of an innovative,
pioneering, and fundamental study with the potential for
growth is extremely important.
Diphenylacetylene (1) and H2O (30 equiv.) were added to
a tightly-closed 12 mL SUS304 vessel without gas replacement
(under air). The mixture was rotated at 800 rpm using a Fritsch
Pulverisette 7 Classic Line Ball Mill (P-7) with SUS304 balls (ca.
5 mm diameter, 50 pieces). The rotation was paused for 1 min
every 30 min after which the rotation was reversed; this
method was used over the 3 h reaction time to prevent failure
of the planetary ball mill. The organic products were deter-
1
mined by H NMR analysis after filtration.
Hydrogenation of the alkyne moiety showed significant
progress resulting in the formation of a mixture of cis and
trans-stilbenes (2 and 3) and diphenylethane (4) in the ratio of
36:8:56 (Table 1, entry 1). The hydrogenation continued for
12 h to give diphenylethane (4) as the sole product in 98% iso-
lated yield (entries 2 and 3). The reaction was dramatically ac-
celerated by the addition of 5 mol% of Pd foil (entry 4), where-
as 0.1 equivalents of 7,7,8,8-tetracyanoquinodimethane (TCNQ)
completely inhibited the hydrogenation (entry 5). It was con-
cluded that the series of reactions involved a single electron-
transfer process and a hydrogenation step. Furthermore, the
hydrogenation became less efficient with a decrease in the
number of SUS304 balls (mechanochemical efficiency, entries 6
and 7), rotation speed (mechanochemical efficiency, entries 8–
10), and usage of H2O (hydrogen source, entries 11 and 12).
In our early study, it was demonstrated that the presence of
zero-valent Cr within the constituents of SUS304 is essential to
promote H2 gas generation.[7] We subsequently investigated
the metal efficiencies of zero-valent Ni, Fe, and Cr to clarify hy-
drogenation using H2O (5 equiv.) as a hydrogen source under
ball-milling conditions [ca. 5 mm diameter zirconia (ZrO2) balls
(50 pieces), 80 mL ZrO2 vessel specially made for the Fritsch
Pulverisette Premium Line 7 Ball Mill (PLP-7), 1100 rpm for
30 min]; we previously reported the chemical inactivity of ZrO2
for the hydrogenation (Table 2, entry 1).[7] No significant effect
was observed by the addition of 1 equivalent of zero-valent Fe,
Cr, Ni, Mn, or Cr and Ni mixed powders as components of
Recently, we reported a quantitative stainless-steel (SUS304)-
mediated gaseous H2 generation method derived from H2O
that could be achieved using a simple ball-milling setup con-
sisting of a planetary ball-mill machine with a stainless-steel
vessel and balls.[7] Full conversion of H2O in the reaction vessel
was achieved by the rotation frequency dependent ball-milling
reaction (see the Supporting Information for details) that was
especially enabled by Cr metal as a structural component of
[a] Dr. Y. Sawama, T. Kawajiri, Dr. M. Niikawa, R. Goto, Dr. Y. Yabe,
Dr. T. Takahashi, T. Marumoto, Dr. Y. Monguchi, Dr. H. Sajiki
Laboratory of Organic Chemistry
Gifu Pharmaceutical University
1-25-4 Daigaku-nishi, Gifu 501-1196 (Japan)
E-mail: sawama@gifu-pu.ac.jp
sajiki@gifu-pu.ac.jp
[b] M. Itoh, Y. Kimura
Frontier Research Center
Canon Inc.
3-30-2 Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan)
[c] Dr. S.-i. Kondo
Laboratory of Pharmaceutical Physical Chemistry
Gifu Pharmaceutical University
1-25-4 Daigaku-nishi, Gifu 501-1196 (Japan)
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cssc.201501019.
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Communications
ceeded in the presence of Ni powder under the H2 gas condi-
tions (entry 11), while Cr or Mn powder did not act as an effi-
cient catalyst (entries 10 and 12). Therefore, the Ni-catalyzed
hydrogenation proceeded with the consumption of H2 gas
generated by the Cr-mediated H2 generation under the ball-
milling conditions.
Table 1. Stainless-steel-mediated hydrogenation using H2O as a reductant
under ball-milling conditions.
The scope of the reactions under the ball-milling conditions
at 800 rpm is summarized in Table 3. Alkyne, alkene, aromatic
bromide and iodide, nitro, and azide functionalities were all ef-
ficiently reduced under the reaction conditions (entries 1-10),
although the phenolic benzyl ether could not be hydrogenat-
ed (entry 4). Aromatic ketones were hydrogenated to the cor-
responding sec-benzyl alcohol derivatives (entries 11–13). Con-
sequently, the zero-valent Ni, as a constituent of SUS304,
smoothly catalyzed the H2 fixation reaction under the ball mill-
ing conditions.[9]
Entry
H2O
[equiv.]
Number
of balls
Rotation
[rpm]
t
[h]
Ratio [%][a]
1
2
3
4
1
2
3
4[c]
5[d]
6
7
8
9
30
30
30
30
30
30
30
30
30
30
20
10
50
50
50
50
50
25
10
25
25
25
50
50
800
800
800
800
800
800
800
650
500
250
800
800
3
6
0
0
0
0
36
5
0
8
5
0
0
0
6
14
1
0
0
56
90
100[b]
100
0
94
75
4
12
3
0
6
100
0
0
0
12
12
12
12
12
12
12
0
11
16
0
0
9
79
100
100
0
0
0
10
11
12
Deuterium labeled compounds are extremely useful in wide
variety of scientific fields including analysis of metabolism, re-
action mechanisms, kinetics, heavy drugs, and material scien-
ces.[10] Although gaseous D2 is useful as a convenient deuteri-
4
8
87
76
0
16
[a] The ratio was determined by 1H NMR spectroscopy. [b] 98% of 4 was
isolated. [c] The reaction was performed in the presence of Pd foil
(5.0 mol%). [d] The reaction was performed in the presence of TCNQ
(0.1 equiv.).
Table 3. Scope of substrates used in the hydrogenation.[a]
SUS304 (entries 2, 3, 5, 7, and 8) in a 80 mL ZrO2 vessel. A sub-
stantial amount of hydrogenation could proceed by the coexis-
tence of Cr and Ni powders together with 5 equivalents of H2O
in a 20 mL ZrO2 vessel (entry 9, ca. 35% of 1 was consumed),
whereas the single application of zero-valent Cr or Ni in
a 20 mL ZrO2 vessel only achieved 5% hydrogenation (entries 4
and 6). As H2 gas should be generated in the presence of zero-
valent Cr powder (entry 3),[7] the hydrogenation may in this
case be catalyzed by Ni powder. Furthermore, a certain level of
hydrogen partial pressure may be necessary for hydrogenation
(compare entries 8 and 9). As expected, hydrogenation pro-
Entry
1
Substrate
Product
t [h]
Yield [%]
69
12
2
3
6
6
100
95
4
12
91[b]
5
6
7
6
70
85
78
Table 2. Effect of metals and H2 on the hydrogenation.
6
12
8
12
62
Entry
Hydrogen
source
Additive
(1 equiv.)
Ratio [%]
1
2
3
4
9
6
6
76
70
1
2
3
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2O (5 equiv.)
H2 (7.2 equiv.)
H2 (7.2 equiv.)
H2 (7.2 equiv.)
none
Fe
Cr
Cr
100
99
91
95
96
95
95
95
65
81
0
0
0
3
1
2
2
1
2
8
0
1
5
3
2
1
2
1
16
5
0
0
1
1
0
1
2
2
10
4[a]
5
11
12
13
6
6
6
88
80
70
Ni
Ni
Mn
6[a]
7
8
Cr and Ni[b]
9[a]
10
11
12
Cr and Ni[b]
10
1
100[c]
1
Cr
Ni
Mn
11
0
3
0
3
93
[a] 0.5 mmol of the substrate was reacted with 30 equiv. of H2O using 50
SUS304 balls in a 12 mL SUS304 vessel. [b] A mixture of the unchanged
substrate and the product (9:91) was obtained.
[a] A 20 mL ZrO2 vessel was used instead of a 80 mL ZrO2 vessel. [b] Cr
and Ni powders were used (1 equiv. each). [c] 63% of 4 was isolated.
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um source, the use of D2 as a deuterium source is still prob-
lematic owing to the cost, flammability, and designation as
a strategic material. Therefore, the development of in situ gen-
eration methods that retain small amounts of D2 within the re-
action vessel is of interest. Over the course of the present
study, we have also discovered that the D2 gas generated from
D2O could proceed with nearly the same efficiency as the H2
generation from H2O using a planetary ball mill in an 80 mL
SUS304 vessel equipped with a wireless manometer terminal
to observe the real-time internal pressure and temperature
(compare Figure S1–S2 in the Supporting Information). The
complete conversion (disappearance) of D2O (271 mL, 15 mmol)
into D2 gas was achieved at 800 rpm in approximately 70 min.
Therefore, we further investigated the deuterium labeling (fixa-
tion) reactions of substrates possessing reducible functionali-
ties within the molecule. As expected, the deuterogenation ef-
ficiently occurred on alkyne, diyne, alkene, aromatic halide,
and aromatic carbonyl functionalities with nearly quantitative
deuterium efficiencies (Table 4, entries 1–9). Furthermore, the
deuteration based upon the H–D exchange reaction also pro-
ceeded on the relatively active methylene and methyl groups.
Consequently, more than 50% deuterium efficiencies were ob-
served on the both methylenes of 3-phenyl ethyl propionate
(entry 5) and the methyl group of 1-phenylethanol even
though the deuterium efficiencies were not very high (entry 9).
In conclusion, we have demonstrated a SUS304 ball-milling-
mediated continuous H2 (D2) generation reaction from H2O
(D2O) along with the hydrogenation (deuterogenation and H–
D exchange) reaction. The SUS304 and mechanochemical proc-
essing play crucial roles in the development of the reactions. It
was especially revealed that zero-valent Cr as a constituent of
SUS304 served for the H2 (D2) generation and Ni acted as a cat-
alyst for the hydrogenation (deuterogenation). In all cases of
the in situ hydrogenation and deuterogenation, the pure prod-
ucts could be isolated in good to excellent yields after simple
workup procedures, which reduces the environmental impact.
The present reactions are attractive as an environmentally-
benign hydrogenation (deuterogenation) using H2O (D2O) as
a hydrogen (deuterium) source. The feature of the present re-
action is an innovative and widely applicable method. Further
applications as a clean energy process for the next generation
and research contributions towards a hydrogen economy are
ongoing in our group.
Table 4. Deuteration using D2O[a]
Entry
1
Substrate
Product
t [h]
Yield [%]
12
93
83
2
6
3
4
6
48
87
12
5
6
6
9
98
66
7
8
12
9
91
84
9
6
75
[a] 0.5 mmol of the substrate was reacted with 30 equiv. of D2O using 50
SUS304 balls in a 12 mL SUS304 vessel.
to a 12 mL SUS304 vessel. The vessel was closed using a SUS304
cover. The vessel was placed in a planetary ball mill (P-7) and rotat-
ed at 250, 500, 650, or 800 rpm for the adequate time, the rotation
was stopped once for 1 min after the first 30 min-rotation, then
the vessel was rotated again for another 30 min (inverse rotation).
After the rotation, MeOH (20 mL) was added to the reaction mix-
ture, and the suspension was filtered through a Celite pad and
washed with MeOH (20 mL). The filtrate was concentrated in vacuo
to yield the reduced products (2, 3, and 4). The ratio of products
1
was determined by H NMR spectroscopy.
Effect of metals and H2 on the hydrogenation
Entries 1–4: Diphenylacetylene (89.1 mg, 0.5 mmol), selected metal
powder (0.5 mmol), ZrO2 balls (ca. 5 mm diameter, 50 pieces), and
H2O (270 mL, 15 mmol) were added to a 80 mL ZrO2 vessel. The
vessel was tightly sealed using a ZrO2 cover. The vessel was placed
in a planetary ball mill (PLP-7) and rotated at 1100 rpm for 30 min.
After the rotation, MeOH (20 mL) was added to the reaction mix-
ture, and the suspension was filtered through a Celite pad and
washed with MeOH (20 mL). The filtrate was concentrated in vacuo
to yield the reduced products (2, 3, and 4). The ratio of products
Experimental Section
Equipment
All experiments were performed using a commercially available
Pulverisette 7 Classic Line Ball Mill (P-7) or Pulverisette Premium
Line 7 Ball Mill (PLP-7) with a SUS304 or ZrO2 vessel (20 mL or
80 mL) and cover manufactured by Fritsch.
1
was determined by H NMR spectroscopy.
Entries 5 and 6: Diphenylacetylene (89.1 mg, 0.5 mmol), selected
metal powder (0.5 mmol), and ZrO2 balls (ca. 5 mm diameter,
50 pieces) were added to a 80 mL ZrO2 vessel. The vessel was
tightly sealed using a ZrO2 cover. The inside gas was replaced by
H2 through the valve attached to cover. The vessel was placed in
a planetary ball mill (PLP-7) and rotated at 1100 rpm for 30 min.
After the rotation, MeOH (20 mL) was added to the reaction mix-
Stainless-steel-mediated hydrogenation using H2O as a re-
ductant
Diphenylacetylene (89.1 mg, 0.5 mmol), SUS304 balls (ca. 5 mm di-
ameter, adequate pieces), and H2O (adequate amount) were added
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was determined by H NMR spectroscopy.
Scope of substrates used in the hydrogenation
The selected substrate (0.5 mmol), SUS304 balls (ca. 5 mm diame-
ter, 50 pieces), and H2O (270 mL, 15 mmol) were added to a 12 mL
SUS304 vessel. The vessel was closed using a SUS304 cover. The
vessel was placed in a planetary ball mill (P-7) and rotated at
800 rpm for the adequate time. After the rotation, MeOH (20 mL)
was added to the reaction mixture, and the suspension was filtered
through a Celite pad and washed with MeOH (20 mL). The filtrate
was concentrated in vacuo to yield the reduced product. The resi-
due was purified by silica-gel column chromatography, if necessary.
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Deuteration using D2O
The selected substrate (0.5 mmol), SUS304 balls (ca. 5 mm diame-
ter, 50 pieces), and H2O (270 mL, 15 mmol) were added to a 12 mL
SUS304 vessel. The vessel was closed using a SUS304 cover. The
vessel was placed in a planetary ball mill (P-7) and rotated at
800 rpm for the adequate time. After the rotation, MeOH (20 mL)
was added to the reaction mixture, and the suspension was filtered
through a Celite pad and washed with MeOH (20 mL). The filtrate
was concentrated in vacuo to yield the reduced product. The resi-
due was purified by silica-gel column chromatography, if necessary.
Acknowledgements
This work was partially supported by the Canon Foundation. Y.S.
expresses his deep and sincere gratitude for the Grant-in-Aid for
Challenging Exploratory Research (26670005) and the Koshiyama
Research Grant. We sincerely thank Shiono Chemical Co., Ltd.,
for the partial financial support and Mr. Masatoshi Yamada, Mr.
Yoshiyuki Mori, and Dr. Eiji Imai of Shiono Chemical Co., Ltd., for
the intellectual discussions. We are grateful for the kind assis-
tance provided by Fritsch Japan Co, Ltd., relevant to the Fritsch
Pulverisette 7 Classic Line Ball Mill (P-7) and Fritsch Pulverisette
Premium Line 7 Ball Mill (PLP-7).
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Keywords: (heavy) water · ball milling · deuterogenation ·
hydrogenation · stainless-steel
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Received: July 28, 2015
Revised: September 9, 2015
Published online on October 23, 2015
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ChemSusChem 2015, 8, 3773 – 3776
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