G Model
MOLCAA-9613; No. of Pages13
ARTICLE IN PRESS
T.A. Minard et al. / Journal of Molecular Catalysis A: Chemical xxx (2015) xxx–xxx
1
2
All hydrogenation experiments employed industrial grade H2
0.43 mmol, 1.0 equiv.) were refluxed in degassed H O (10 mL)
2
gas (99.995%) and were carried out in an Autoclave Engineers (AE)
mini-reactor with a 50 mL 316 stainless steel (316SS) reactor vessel
and impeller. At a total reaction solution volume of 25 mL the reac-
tor has a gas phase headspace of 50 mL (unused reactor body space
and enclosed and pressurized magnet-drive stirring assembly).
Unless otherwise specified (cf. control experiments), reactor ves-
sel and impeller were polished thoroughly after every run by lathe
at 600 rpm with 3 M abrasive pads or sand-blasting, respectively.
Regular control reactions without addition of catalyst showed only
marginal conversion (<3%) of substrate to hydrogenated products
under argon overnight forming a clear red–brown solution. Sodium
triflate (153 mg, 0.89 mmol, 2.1 equiv.) dissolved in degassed H O
2
(2 mL) was added to the solution, and refluxed for an additional
2 h. The solution was concentrated under vacuum (to ∼4 mL), dry
acetonitrile was added (∼10 mL), and the solution was again con-
centrated to azeotropically remove H O. After this was repeated 4
2
times, activated molecular sieves (dried under vacuum overnight;
◦
slowly heated to 215 C under vacuum) were added and the
solution was stirred for 4 h. The solid was filtered over celite on
a filter stick, and the resultant solution was red–purple in colour.
The product was crystallized by layering dry diethyl ether over
the concentrated acetonitrile solution to generate small amount
(
see also main text) [74].
5.1. 2,2’-Bipyridine-6,6’-dimethanethiol
of deep red crystals. 1H NMR (400 MHz, CD CN) ı 2.08 (s, 6H),
3
4
.27 (br. s, 4H), 4.56 (t, J = 6.0 Hz, 4H), 7.63 (dd, J = 0.8 Hz, 8.0 Hz,
13
The procedure reported by Newkome and Kohli [87]
2H), 7.92 (t, J = 8.1 Hz, 2H), 8.18 (dd, J = 0.8 Hz, 8.0 Hz, 2H) C NMR
ꢀ
was
followed
with
modification.
2,2 -Bipyridine-6,6’-
(100 MHz, CD CN) ı 4.3, 54.3, 122.4, 122.7, 126.6, 136.0, 159.0,
164.6. ESI–MS [Ru(bambipy)] − 2H fragment (m/z) = 314.01.
3
2+
dimethanethiouronium chloride (2.0086 g, 5.0 mmol) was
suspended in water (150 mL), cooled to 5 C and bubbled with
◦
Ar for 1 h. While maintaining the same Ar flow, NaOH (1.5750 g,
◦
3
9 mmol) was added and the mixture stirred at T < 10 C for 10 min.
The solution was then allowed to warm to room temperature and
stirred under Ar overnight. The resulting pale yellow solution was
washed with 2 × 20 mL TBME, the pH adjusted to 7 with conc.
HCl and then extracted with 3 × 50 mL DCM. The organic extracts
were dried over Na SO and evaporated in vacuo providing an
5.5. Representative procedure for the preparation of a reaction
solution for hydrogenation experiments
(Using the example of 2.5-dimethyl furan in a 5:1 azeotropic
mixture of 1,4-dioxane: water in the presence of added acid co-
catalyst). Immediately before use 2,5-dimethyl furan was passed
through a short plug of neutral alumina to remove impurities and
stabilizer present, then added to a 25-mL volumetric flask (2.4033 g,
25 mmol); methyl sulfone (0.2353 g, 2.5 mmol) was also added to
this flask as the internal GC standard. The aqueous catalyst solu-
tion (≤0.5 mL) was then added to the volumetric flask, along with
1,4-dioxane (10 mL, to maintain 5:1 ratio) and 1.0 mL of a 125 mM
triflic acid stock solution (0.125 mmol) (and 5 mL dioxane, to main-
tain 5:1 ratio). The reaction solution was diluted to 25 mL with
a 5:1 1,4-dioxane:water mixture stirred and sonicated to ensure
homogeneity.
2
4
◦
off-white solid that was sublimed at 95 C, 30 m Torr to yield the
pure product as a foul smelling white powder that was stored
under Ar. Yield: 0.5775 g; 47%. 1H NMR: (400 MHz, CDCl ): ı = 8.34
3
(
3
d, J = 7.8 Hz, 2H), 7.80 (t, J = 7.8 Hz, 2H), 7.37 (d, J = 7.5 Hz, 2H),
.94 (d, J = 7.9 Hz, 4H), 2.14 (t, J = 7.8 Hz, 2H). 13C NMR: (100 MHz,
CDCl ): ı = 159.59 (C), 159.58 (C), 138.05 (CH), 122.60 (CH), 119.73
3
(
CH), 31.01 (CH ).
2
5
.2. [Ru(OH ) (di(picolyl)amine)](OTf) (5)
2 3 2
0
.1105 g (0.112 mmol) of [Ru(DMF) ](OTf) was dissolved in
6 3
2
.0 mL of degassed (Ar sparge) water. 0.0229 g (0.115 mmol) of
di(picolyl)amine (dpa) was dissolved separately in 1.0 mL of H O.
2
The di(picolyl) amine solution was then added slowly to the
[
Ru(DMF) ](OTf) solution and the mixture stirred. A colour change
5.6. Representative procedure for hydrogenation experiments
using the AE mini-reactor
6
3
1
from yellow to deep red was observed after 5 min. H NMR
(
1
300 MHz, D O): ı = 4.369 (s, 2H), 7.383 (dt, J = 2.4 Hz, J = 6.3 Hz,
2
1
2
H), 7.416 (d, J = 7.8 Hz, 1H), 7.826 (t, J = 6.6 Hz, 1H), 8.488 (d,
A 1 mL sample of the reaction solution was taken for initial
GC analysis. (Initial GC analysis can only be performed for reac-
tions with the 2,5-hexanedione substrate as 2,5-dimethylfuran is
not miscible with water at ambient conditions and therefore the
initial reaction mixtures are biphasic in these cases.) The solution
was added to the 50-mL reactor body, which was screwed into the
reactor head. The reactor was pressurized with H2 gas to 5.5 MPa
(800 psi) and purged three times, and then held at that pressure to
ensure there was no leakage. The system was then heated to the
1
3
J = 4.2 Hz, 1H). C NMR (75 MHz, D O): ı = 50.74 (CH ), 124.29 (CH),
1
2
2
24.61 (CH), 138.91 (CH), 149.04 (CH), 150.10 (CH). ESI–MS for
2
+
[
Ru(dpa)] fragment m/z = 149.50.
5
.3. [Ru(bambipy)(OH ) ](OTf) (6)
2
2
2
ꢀ
6,6 -
[
Ru(DMF) ](OTf)3
(0.0245 g,
0.0248 mmol)
(bambipy)
and
(0.0059,
6
ꢀ
bis(aminomethyl)-2,2 -bipyridine
0
◦
.0278 mmol) were combined in a Schlenk tube, which was
desired temperature (125, 150, 175, 200 or 225 C) and stirred at
evacuated and backfilled with argon three times. Degassed (Ar
sparge) water (2 mL) was added to this Schlenk tube, which was
stirred overnight; solution colour changed from yellow to deep
800 rpm for 16 h. The reactor was cooled to ambient temperature,
a headspace gas sample was taken for micro-GC analysis, and the
reactor depressurized. A 1 mL sample of the final reaction solution
is taken for GC analysis.
1
red/orange over the course of a few minutes. H NMR (600 MHz,
D O): ı (ppm) = 4.44 (s, 4H), 7.53 (d, J = 7.74 Hz, 2H), 8.04 (t,
2
13
J = 7.86 Hz, 2H), 8.37 (d, J = 7.86, 2H). C NMR (100 MHz, D O): ı
2
(
(
ppm) = 42.80 (CH ), 121.09 (CH), 122.80 (CH), 138.94 (CH), 151.57
C), 154.78 (C). ESI–MS [Ru(bambipy)] fragment (m/z) = 157.88.
2
2+
Acknowledgements
The authors thank the Natural Science and Engineering Coun-
porting this research.
5
.4. [trans-Ru(CH CN) (bambipy)](OTf) (6a)
3 2 2
ꢀ
ꢀ
6
,6 -bis(aminomethyl)-2,2 -bipyridine (bambipy) (100 mg,
0
.47 mmol, 1.1 equiv.) and trans-[RuCl (CH CN) ] (144 mg,
2
3
4