Rh(iii)-Catalysed solvent-free hydrodehalogenation of alkyl halides by tertiary silanes

Article abstract of DOI:10.1039/C8DT03703E

Efficient catalytic reduction of CDCl₃ and other alkyl halides, including persistent organic pollutants, by different tertiary silanes using the unsaturated silyl-hydrido-Rh(iii) complex {Rh(H)[SiMe₂(o-C₆H₄SMe)](PPh₃)₂}[BAr^F₄] as a pre-catalyst is accomplished. The reactions are performed in a solvent-free manner. On account of experimental evidence, a simplified catalytic cycle is suggested for the hydrodehalogenation of CDCl₃.

Full text of DOI:10.1039/C8DT03703E

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Rh(III)-Catalysed solvent-free hydrodehalogenation
of alkyl halides by tertiary silanes†
Cite this: Dalton Trans., 2018, 47,
16225
a
a
a
a,b
N. Almenara, S. Azpeitia, M. A. Garralda * and M. A. Huertos
*
3
Efficient catalytic reduction of CDCl and other alkyl halides, including persistent organic pollutants, by
Received 13th September 2018,
Accepted 19th October 2018
different tertiary silanes using the unsaturated silyl-hydrido-Rh(III) complex {Rh(H)[SiMe (o-C H SMe)]
2
6 4
F
(
PPh
On account of experimental evidence, a simplified catalytic cycle is suggested for the hydrodehalogena-
tion of CDCl
3 2 4
) }[BAr ] as a pre-catalyst is accomplished. The reactions are performed in a solvent-free manner.
DOI: 10.1039/c8dt03703e
rsc.li/dalton
3
.
common method to reduce alkyl halides involves organotin
hydrides and proceeds via a radical chain mechanism.
Introduction
1
,28
Organic halides are versatile compounds and have been widely Mechanisms involving radicals have also been proposed in
2
9
employed for many synthetic and industrial applications. redox-active polyoxometalate dehalogenations. Due to the
Using them as building blocks in organic chemistry may lead toxicity of hydrido-stannanes, alkylsilanes have been proposed
to the generation of deleterious wastes and some industrial as a more friendly alternative. (TMS) SiH is unique in promot-
3
products, as for example pesticides, are now included in the ing the activation of the Si–H bond via a radical chain mecha-
3
0–32
persistent organic pollutants catalogue. The hydrodehalogena- nism, but is not economically attractive.
The cheaper and
tion reactions of organic halides can be metal-mediated and more accessible triethylsilane has been used as a dehalogena-
1
–3
their study remains a subject of significant interest.
tion agent in combination with metallic catalysts such as Pd(II)
33
34
35
Substantial progress has been made for the intermolecular salts, AlCl , a Pt(II) compound, an unsaturated hydrido-Ir(III)
activation of the C–X bond in halogenated olefins or aromatics complex,
3
6,37
3
38,39
or a few rhodium compounds.
Moreover,
promoted by transition metals. Several noble metals have been nanoscopic aluminium chlorofluoride (ACF) can be used in a
4
–7
8,9
shown to degrade chlorinated ethylene or chloroaromatics
heterogeneous catalytic process for the activation of fluoro-
4
0
using H as the reductant or by hydrogen transfer in hetero- methanes in the presence of Et SiH. Apart from these metal-
geneous catalysed processes. Heterogeneous rhodium-based based catalysts, [Ph
2
3
+
− 41
42
3
C] [BAr
4
] ,
[B(C
6
F
5
)
3
],
pyridinium
4
3
44,45
catalysts have been used to dehalogenate chlorinated phosphonium dications, bissilylated onium salts
and
and rhodium nanoparticles promote the dehalo- silyl chalconium salts can be used as catalysts to reduce
genation of halobenzenes under coexistence of homogeneous alkylfluorides. In the dehalogenation reaction of alkyl halides
6
,10
46
alkenes,
1
1
47–49
and heterogeneous catalysis. Catalytic homogeneous reac- with tertiary silanes, halosilanes are formed.
tions are also known for the reduction of aryl halides, as for Our group has recently reported on the solvent-free hydro-
example in the hydrodechlorination of aryl chlorides in the silylation of remote alkenes catalysed by an unsaturated
1
2–14
15,16
17–19
20–23
presence of Pd(0),
Pd(II),
Ru(II)
or Rh(III)
com- hydrido-Rh(III) complex, {Rh(H)[SiMe (o-C H SMe)](PPh ) }
2 6 4 3 2
F
plexes. [RhCl(PPh ) ] has been employed as a homogeneous [BAr ] (1), and we have observed that when this reaction is
3
3
4
catalyst in the presence of Et
and fluorinated ethylenes,
3
3 3
SiH to dehalogenate chlorinated performed in CDCl , Et SiCl is formed as a side-product
2
4,25
26
50
or polychloroarenes.
(Scheme 1). We reasoned that the appearance of Et SiCl
3
Polymethylhydrosiloxane has also been reported to dehalogen-
2
7
ate the latter at room temperature under palladium catalysis.
The cleavage of the carbon–halogen bond is less favoured
1
in alkyl halides than in vinylic or aromatic halides. The most
a
Department of Applied Chemistry, University of Basque Country (UPV/EHU),
2
0080 San Sebastián, Spain. E-mail: miguelangel.huertos@ehu.es
b
IKERBASQUE. Basque Foundation for Science, 48013 Bilbao, Spain
†
Electronic supplementary information (ESI) available. See DOI: 10.1039/
Scheme 1 Hydrosilylation of 1-hexene in CDCl
dechlorination of CDCl catalysed by 1.
3
and the competitive
c8dt03703e
3
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a
could be a consequence of the hydrodechlorination of chloro- Table 1 Scope of tertiary silanes
form and thought that it would be interesting to further study
these rhodium-catalysed reactions in neat alkyl halides, which
avoids the otherwise required solvent elimination. We report
F
here studies on the {Rh(H)[SiMe (o-C H SMe)](PPh ) }[BAr ]
(
b
2
6
4
3 2
4
Entry
Silane
Et SiH
Conversion (%)
t1/2 (h)
1) catalysed solvent-free dehalogenation reaction of alkyl
halides, including persistent organic pollutants, with tertiary
hydrosilanes.
1
2
3
4
3
80
72
54
0
2
3
9
—
Me PhSiH
MePh SiH
Ph SiH
2
2
3
a
Reaction conditions:
R
3
SiH (0.25 mmol) with
1
mol% of 1
b
Results and discussion
(0.0025 mmol) in CDCl
by H NMR by the formation of R
3
(0.5 mL) at 50 °C. Conversions determined
SiCl after 10 h of reaction.
1
3
Hydrodechlorination of CDCl with tertiary hydrosilanes
3
Reaction of Et SiH in CDCl with a catalytic amount of unsatu-
3
3
rated hydrido-silyl-Rh(III) complex, 1, at 50 °C led to the acti- Hydrodechlorination of other alkyl halides
vation of the Si–H bond with chlorination of the silyl fragment
In order to test the possibility of extending this reactivity to
to form Et Si–Cl. The other product of this reaction was mono-
deuterated methylene chloride, CHDCl2.
3
other alkyl halides, benzyl chloride, benzyl bromide, trityl
chloride and tert-pentyl chloride were similarly reacted under
solvent-free conditions. Table 2 shows the reduction results
This reaction was performed in a sealed NMR tube and suc-
1
cessive H NMR spectra were collected. Et Si–H undergoes
3
3
obtained after a 12 hour reaction between Et SiH and an equi-
transformation to Et Si–Cl by a pseudo-first order process
3
molar amount of the alkyl halide with 1 mol% of 1 at 60 °C.
−
3
−1
−1
(
50 °C, k = (12.24 ± 0.02) × 10
s
M
, and t1/2 = 2 h) as
1
The conversions were determined by H NMR spectroscopy, in
measured by the absolute integrals of the Et Si–Cl and Et Si–H
3
3
all cases using dichloroethane as the internal standard.
Entries 1 and 2 show that the reactivity follows the order RBr >
RCl. On the other hand, the aryl-substituted tertiary chloride,
trityl chloride was reduced with 90% conversion, (entry 3,
Table 2) while the alkyl-substituted tertiary chloride, tert-
pentyl chloride showed low conversion. Benzyl chloride
reached 44% conversion.
signals (see Fig. 1 and the ESI† for more details). This reaction
was carried out with other tertiary silanes collected in Table 1.
In the presence of 1 mol% of 1, Me PhSiH was chlorinated by
2
CDCl3 to give Me PhSiCl via a pseudo-first order process
2
−3
−1
−1
(
50 °C, k = (9.46 ± 0.01) × 10
s
M , and t1/2 = 3 h). The
chlorination of Ph MeSiH, under the same reaction con-
2
ditions, was significantly slower (50 °C, 54% of conversion
3
after 10 h, and t1/2 = 9 h). Finally, the reaction of Ph SiH in
CDCl3 with 1 mol% of 1 failed to give any conversion into
Dehalogenation of potential contaminants: polychlorinated
compounds
Ph SiCl. We thus observe that the chlorination reaction is
3
faster for alkylsilanes compared to that of arylsilanes and In order to extend the scope of the dehalogenation reaction
follows the trend: Et SiH > Me PhSiH > MePh SiH ≫ Ph SiH. catalysed by 1, we decided to perform the reduction of poly-
3
2
2
3
The trend observed for the present reaction excludes a radical chlorocarbons. The study of the dechlorination of these alkyl
chain mechanism, for which the opposite trend has been chlorides is important due to the high number of potential
5
1,52
reported.
contaminants, which contain several C–Cl bonds and are
present in our environment. We have tested our catalytic
system on the dehalogenation of polychlorinated hexachlorocy-
clohexanes (HCH), dichlorodiphenyltrichloroethane (DDT),
a
Table 2 Reduction of alkyl halides
b
Entry
R–X
Conversion (%)
1
2
3
4
Benzyl bromide
Benzyl chloride
Trityl chloride
86
44
90
23
tert-Pentyl chloride
a
3
Reaction conditions: Et SiH (0.25 mmol) and R–X (0.25 mmol) with
b
1
mol% of 1 (0.0025 mmol) without solvent at 60 °C. Conversions
1
Fig. 1 Dechlorination of CDCl
by H NMR at 50 °C.
3
using Et
3
SiH. Reaction was monitored determined by H NMR by the formation of R SiX using dichloro-
3
1
ethane as the internal standard.
16226 | Dalton Trans., 2018, 47, 16225–16231
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dichlorodiphenyldichloroethane (DDD) and dimethoxydiphe- of HCH with Et
3
SiH catalysed by RhCl(PPh
3
)
3
in solution of
nyldichloroethane (methoxychlor) that are considered con- p-xylene, dehydrogenation occurs concomitant with dechlori-
3
8
taminants. As shown in Table 3 (entries 1–4) 2 mol% of the nation leading to the formation of benzene. Complete con-
precatalyst 1, at 70 °C catalyses the dechlorination of HCH version of γ-HCH (lindane) is accomplished after 48 h while
isomers by Et SiH under solvent-free conditions (1/C H Cl / α-HCH requires 72 h. Dechlorination of β-HCH and δ-HCH is
3
6
6
6
Et
3
SiH = 2/100/900). As in previously reported dechlorination slower. Conversion up to 43% and 19%, respectively, requires
2 h. 4,4′-DDT can be partially hydrodechlorinated by neat
Et SiH in the presence of 1 (1/C H Cl /Et SiH = 2/100/500)
7
3
14
9
5
3
(
Table 3, entry 5). At 80 °C complete conversion into the di-
a
Table 3 Reduction of polychlorocarbons
dechlorination product C14 is reached after 72 h. The
H
11Cl
3
aromatic chlorides remain intact and this fact gives us details
about the selectivity of this system to dechlorinate alkyl chlor-
ides in the presence of aromatic chlorides. Complete conver-
sion of 4,4′-DDT into the mono-dechlorination product
C H10Cl can be achieved after one hour at 60 °C, showing
14 4
that further reduction is much slower. In line with this, hydro-
b
R–X
T (°C)
Time (h)
72
Product conv. (%)
1
2
70
dechlorination of 4,4′-DDD C H Cl (1/C H Cl /Et SiH = 2/
1
4
10
4
14 10
4
3
100/500) requires 48 h at 80 °C to reach the di-dechlorination
product (Table 3, entry 6). Hydrodechlorination of 2,4′-DDD is
slower (Table 3, entry 7). Methoxychlor (1/C H Cl /Et SiH =
70
72
1
4
10
4
3
2
/100/500) undergoes step by step dechlorination similar to
that observed for DDT, with complete conversion after 72 h
Table 3, entry 8). In this case a mixture of di- (70%) and
(
3
4
70
70
72
48
mono-(30%) dechlorination products is obtained.
Kinetic measurements. KIE and control experiments
In order to obtain further insights into the hydrodehalogena-
tion of alkyl halides by tertiary silanes we have undertaken
kinetic studies. Measurement of the reaction of Et SiH in
3
CDCl with 1 mol% of 1 over the temperature range 40 °C to
3
5
6
7
8
80
80
80
80
72
48
72
72
5
5 °C allowed for Eyring analysis, from which the following
‡
activation barriers were determined: ΔH = 106.6 ± 5.6
kJ mol− , ΔS = +49.9 ± 17.6 J mol
1
‡
−1 −1
K
and ΔG(298) = 91.7 ±
‡
1
1
0.9 kJ mol− (Fig. 2). The positive entropy of activation could
be related to ligand dissociation, in this case
triphenylphosphine.
a
3
Reaction conditions: Et SiH (entries 1–4, 0.31 mmol; entries 5–6,
0
1
8
.16 mmol; entry 7, 0.17 mmol; entry 8, 0.12 mmol) and R–X (entries
–4, 0.035 mmol; entries 5–6, 0.031 mmol, entry 7, 0.028 mmol; entry
b
, 0.029 mmol) with 2 mol% of 1 without solvent. Major product
1
c
1
identified by H NMR. Conversions determined by H NMR by the
formation of Et SiCl using dichloroethane as the internal standard.
3
d
1
Conversion determined by H NMR with the starting polychloro-
carbon remaining using dichloroethane as the internal standard.
e
Fig. 2 Reaction of Et
SiCl vs. time at different temperatures, first order plots, Eyring analysis
and activation barriers.
3 3
SiH with CDCl catalysed by 1. Concentration of
Bi-dechlorinated compound is the major product formed in the
dechlorination of methoxychlor (70%). A mono-dechlorinated product Et
3
is also observed (30%).
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Chlorination of Et
0 °C was performed in a sealed NMR tube and successive H
NMR spectra were collected. Et Si–D undergoes transformation
to Et Si–Cl by a pseudo-first order process (40 °C, k = (1.59 ±
.04) × 10−
observed for Et
3 3
Si–D in CDCl with 1 mmol% of 1 at
1
4
3
3
5
−1
−1
0
s
M , and t1/2 = 9 h), at a rate similar to that
−
5
−1
−1
Scheme 2 Control experiment.
3
Si–H (40 °C, k = (1.69 ± 0.07) × 10
s
M ,
and t1/2 = 8 h), giving a KIE of 1.24 ± 0.05 (Fig. 3). These data
indicate that Si–H activation is not involved in the rate-deter-
1
mining step. In addition, the halogenation rate of Et
using CDBr instead of CDCl was measured. The bromination
reaction rate (40 °C, k = (5.81 ± 0.11) × 10
h) shows that the formation of Et Si–Br is five times faster
Fig. 4) than that of Et Si–Cl. This fact could be indicative of a
3
SiH
3
of 20% of Et Si–H as measured by H NMR spectroscopy after
only 15 minutes (25 °C) (Fig. 5 and Scheme 3, for more details
see in the ESI†). This deuteration experiment suggests rela-
tively rapid reversible Si–H activation being promoted by 1.
3
3
−5
−1
−1
s
M , and t1/2 =
1
3
(
3
C–X bond (X = Cl and Br) activation being involved in the rate- Proposed and simplified catalytic cycle
determining step of the catalytic cycle. To evaluate the impor-
Taken together, our observations (KIE ≈ 1; rate dependence on
the nature of the halogen, easier C–Br than C–Cl activation;
3 3
tance of PPh along the catalytic cycle, the reaction of Et SiH
in CDCl with 1 mol% of 1 at 50 °C was carried out in the pres-
‡
−1 −1
3
ΔS = +49.9 ± 17.6 J mol
sphere slowing down the reaction; 1 fails to react with CDCl
easy H/D exchange between 1 and Et Si–D) lead to an outline
3 2
K ; an excess of PPh or a H atmo-
3
ence of 1.5 mol% of PPh . A decrease in the reaction rate (72%
3
;
of conversion after 60 hours and t1/2 = 31 h) was observed, and
suggests triphenylphosphine dissociation occurring in the
catalytic cycle (see the ESI† for more details). Dehalogenation
3
+
3
catalytic cycle as shown in Scheme 4 with 1 -SiEt assigned to
a resting-state in the cycle. We propose that the dehalogena-
of CDCl
3
using Et
3
SiH was evaluated under a H
2
atmosphere
+
tion of CDCl3 catalyzed by 1 starts with the equilibrium
and a decrease in the reaction rate (48% of conversion after
+
+
between precatalyst 1 and 1 -SiEt
3
, which is an active species
1
6 hours) was also observed (ESI†).
+
in the catalytic cycle. 1 -SiEt
to the formation of another active species 1 -CDCl and
3
reacts with chloroform-d leading
A control experiment was carried out, stirring complex 1 in
+
2
CDCl3 for 12 hours, and after this time, no reaction was
observed (Scheme 2, for more details see in the ESI†). This fact
could suggest that the activation of the C–Cl bond, a well-
releases an equivalent of Et
3
Si–Cl. This step, which could
involve a concerted PPh
3
dissociation upon CDCl approach to
3
5
3–55
known process,
to occur and is not the first step in this process. The addition
of an equivalent of Et Si–D to 1 in CD Cl resulted in the
incorporation of D into the Rh–H position and the formation
requires in our case the presence of silane
3
2
2
Fig. 3 Chlorination of Et
time and first order plots. KIE = k
3
SiD vs. ET
3
SiH. Concentration of Et
D
= 1.24 ± 0.05.
3
SiCl vs.
H
/k
1
Fig. 5 H NMR spectrum (CD
1
2
Cl
2
and rt) of the mixture 1/Et
3
SiD,
) of
1
0 minutes after being prepared (top). The H NMR spectrum (CD
2
Cl
2
1
(bottom).
Fig. 4 Halogenation of Et
3
SiH with CDCl
3
or CDBr
3
. Concentration of
Scheme 3 H/D exchange in 1. The insertion shows the putative Si–H
3
Et SiX vs. time and first order plots.
activation.
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1
5
00 MHz spectrometer. H NMR spectra were referenced to the
residual solvent signals. The chemical shifts are quoted in
ppm and coupling constants in Hz.
Hydrodehalogenation of CDCl using tertiary silanes
3
To a solution of 1 (4.2 mg, 0.0025 mmol) in CDCl
charged in a J. Young NMR tube was added a hydrosilane
Et SiH 40 μL, 0.25 mmol; Me PhSiH, 40 μL, 0.25 mmol;
MePh SiH 51 μL, 0.25 mmol; Ph SiH, 65.1 mg, 0.25 mmol).
3
(0.5 mL)
(
3
2
2
3
1
The solution was monitored by H NMR at 50 °C, following the
disappearance of the hydrosilane resonance and the appear-
ance of a new chlorosilane and CHDCl .
2
Hydrodehalogenation of different alkyl halides using Et SiH
3
A Young’s flask charged with 1 (8.4 mg, 0.05 mmol), Et SiH
3
(
80 μL, 0.5 mmol) and the alkyl halide (benzylchloride, 57 μL,
0
1
.5 mmol; benzylbromide, 60 μL, 0.5 mmol; tritylchloride,
89 mg, 0.5 mmol; tert-pentylchloride, 61 μL, 0.5 mmol) was
Scheme 4 Proposed and simplified catalytic cycle for hydrodehalo-
genation of CDCl catalyzed by 1.
3
3
stirred for 12 h at 60 °C. After this time, CDCl and dichlor-
oethane (10 μL, 0.0126 mmol, Internal Standard) were added
1
and the H NMR spectra were recorded at room temperature to
calculate the conversion.
the metal centre could well be the rate determining step.
+
2
Finally, 1 -CDCl reacts with an equivalent of triethylsilane
Dehalogenation of polychlorinated pesticides using Et SiH
+
3
3
leading to the regeneration of the active species 1 -SiEt and
To a Young’s flask charged with 10 mg of the corresponding
POP [hexachlorocyclohexane isomers (α-, β-, δ-, and γ-HCH),
releasing CDHCl out of the cycle.
2
0.035 mmol; dichlorodiphenyldichloroethane isomers (2,4′-
and 4,4′-DDD), 0.031 mmol; 4,4′-dichlorodiphenyltrichloro-
ethane (4,4′-DDT), 0.028 mmol; and 4,4′-dimethoxydiphenyl-
Conclusions
In conclusion, we report here an easy method to perform dichloroethane (methoxychlor), 0.29 mmol] and 2 mol% of 1,
the reduction of alkyl halides using triethylsilane catalysed Et SiH (0.31 mmol, when POP = HCH; 0.16 mmol, when POP =
3
by the cationic and unsaturated rhodium(III) complex DDD; 0.17 mmol, when POP = DDT; 0.12 mmol, when POP =
F
{
Rh(H)[SiMe
2
(o-C
6
H
4
SMe)](PPh
3
)
2
}[BAr
4
]. The reactions are methoxychlor) was added. The resulting mixture was stirred up
performed in a solvent-free manner. This method can be used to to 48 or 72 h at temperatures between 70–80 °C. After this
dehalogenate persistent organic pollutants, such as dichlorodiphe- time, 0.5 mL of CDCl3 and 2 equivalents of dichloroethane
1
nyltrichloroethanes, dichlorodiphenyldichloroethanes, methoxy- (Internal Standard) were added and a H NMR spectrum was
chlor and hexachlorocyclohexanes. Furthermore, based on experi- recorded at room temperature to calculate the conversion.
F
4
mental evidence of {Rh(H)[SiMe
2
(o-C
6
H
4
SMe)](PPh
3
)
2
}[BAr
] cata-
lyzed hydrodehalogenation of CDCl
lytic cycle has been proposed.
3
by Et
3
SiH, a simplified cata- Hydrodehalogenation of CDCl using Et SiH at different
3
3
temperatures
To a solution of 1 (4.2 mg, 0.0025 mmol) in CDCl
charged in a J. Young NMR tube was added triethylsilane
3
(0.5 mL)
Experimental section
1
(
Et SiH 40 μL, 0.25 mmol). The solution was monitored by H
3
General considerations
NMR at 40 °C, following the disappearance of the hydrosilane
resonance and the appearance of new chlorosilane and
All manipulations, unless otherwise stated, were performed
under an atmosphere of nitrogen, using standard Schlenk
techniques. All glassware was oven dried at 110 °C overnight
and flamed under vacuum prior to use. Dry and oxygen free
CHDCl . This experiment was repeated at different tempera-
2
tures (45 °C, 50 °C and 55 °C).
Hydrodehalogenation of CDCl using Et SiD (KIE)
3
3
3 2 3
solvents were employed. CDCl was purified adding K CO ,
which is then distilled and degassed by successive freeze– To a solution of 1 (4.2 mg, 0.0025 mmol) in CDCl
3
(0.5 mL)
F
pump–thaw cycles. {Rh(H)[SiMe (o-C H SMe)](PPh ) }[BAr ] charged in a J. Young NMR tube was added Et SiD (40 μL,
2
6
4
3 2
4
3
5
0
1
(
1) was prepared as previously described. The other reagents 0.25 mmol). The solution was monitored by H NMR at 40 °C,
were commercial purchased and used without previous purifi- following the disappearance of the hydrosilane resonance and
cation. NMR spectra were recorded on a Bruker Ultrashift the appearance of new chlorosilane.
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Hydrodehalogenation of CDCl
3
using Et
3
SiH and PPh
3
5 G. V. Lowry and M. Reinhard, Environ. Sci. Technol., 2001,
3
5, 696–702.
J. W. Bozzeli and Y. M. Chen, Chem. Eng. Commun., 1992,
15, 1–11.
To a solution of 1 (4.2 mg, 0.0025 mmol) and PPh
3
(1 mg,
6
0
.0038 mmol) in CDCl (0.5 mL) charged in a J. Young NMR
3
1
tube was added Et SiH (40 μL, 0.25 mmol). The solution was
3
1
7 W. W. McNab Jr., R. Ruiz and M. Reinhard, Environ. Sci.
Technol., 2000, 34, 149–153.
monitored by H NMR at 50 °C, following the disappearance of
the hydrosilane resonance and the appearance of new
chlorosilane.
8
T. Hara, K. Mori, M. Oshiba, T. Mizugaki, K. Ebitani and
K. Kaneda, Green Chem., 2004, 6, 507–509.
9
A. Arcadi, G. Cerichelli, M. Chiarini, R. Vico and D. Zorzan,
Eur. J. Org. Chem., 2004, 3404–3407.
Hydrodehalogenation of CDCl
A J. Young NMR tube charged with 1 (4.2 mg, 0.0025 mmol),
CDCl (0.5 mL) and Et SiH (40 μL, 0.25 mmol) was placed
under 1 atm. of H . The solution was monitored by H NMR at
3 3 2
using Et SiH and H
1
1
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3
1
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5 minutes of the reaction the H NMR spectra shows the for-
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3
a 20% of Et SiH demonstrating the H/D
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Conflicts of interest
There are no conflicts of interest to declare.
2
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2 A. Sisak, O. B. Simon and K. Nyíri, J. Mol. Catal. A: Chem.,
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004, 213, 163–168.
3 K.-I. Fujita, M. Owaki and R. Yamaguchi, Chem. Commun.,
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Acknowledgements
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This research was supported by the Universidad del Pais Vasco 24 A. A. Peterson, K. A. Toreson and K. McNeill,
(
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UPV/EHU) and Ministerio de Economia y Competitividad
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CTQ2015-65268-C2-1-P and
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M. A. H. acknowledges support from IKERBASQUE. N. A. 26 M. A. Esteruelas, J. Herrero, F. M. Lopez, M. Martin and
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