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A. Mena-Cruz et al. / Journal of Molecular Catalysis A: Chemical 411 (2016) 27–33
The resulting mixture was placed into a water bath at 80 ◦C
controlled by a circulator; this was considered the starting time
of the reaction. After the required time, the solution was cooled
to room temperature in a water bath and extracted with CHCl3
(2 × 2 mL). The chloroform extracts were combined and passed
through MgSO4 and Silica, and analysed by GC. Two sets of reac-
tions were carried out for each catalyst either under nitrogen or an
air atmosphere.
Scheme 1. Metal catalyzed isomerization of allylic alcohol.
2.3. Isomerization of 1-octen-3-ol catalyzed by 1 in a mixture of
MeOH/phosphate buffer
Complex 1 (6 mg, 7.60 × 10−3 mmol) was dissolved in 1.5 mL
of
a mixture of phosphate buffer (0.1 M, pH 6.75) and
MeOH in variable proportions: 1.5/0, 1.2/0.3, 1.05/0.45, 0.9/1.1,
0.75/1.25 and 0/1.5 mL. In each experiment 1-octen-3-ol (80 L,
5.18 × 10−1 mmol) was added and the reaction kept at 70 ◦C for 3 h.
The final products were worked up and analyzed by the general
procedure described above.
Scheme 2. Water soluble piano–stool ruthenium complexes.
isomerization of 1-octen-3-ol in water urged us to study the
catalytic properties of the bimetallic complexes [RuClCp(PPh3)--
dmoPTA-1P:22N,N’-MCl2] (M = Ni (2), Co (3), Zn (4)) (Scheme 2)
[11], with the aim to distinguish the possible influence of the het-
erometal on the catalytic properties of the {CpRu} moiety.
Complex 1 (6 mg, 7.6 × 10−3 mmol) was introduced into a mix-
ture of 0.4 mL of MeOH and 1.6 mL of a phosphate buffer solution
(0.1 M) in the pH range 1.85–9.00. Then 105 L of 1-octen-3-ol
(6.80 × 10−1 mmol), or 95 L of 1-hepten-3-ol (6.96 × 10−1 mmol)
or 82 L of 1-hexen-3-ol (6.83 × 10−1 mmol), respectively, were
added and the reaction mixture was kept at 70 ◦C for 1 hour and
processed as indicated above
2. Experimental
2.1. Materials and methods
2.5. Isomerization of 1-octen-3-ol catalyzed by 1 as a function of
reaction time at pH 2.75 and 6.77
All chemicals were reagent grade and, unless otherwise stated,
were used as received from commercial suppliers. The reactions
were performed in a pure argon atmosphere by using standard
plexes [RuClCp(PTA)(PPh3)], [RuClCp(HdmoPTA)(PPh3)](OSO2CF3)
(1) and [RuClCp(PPh3)--dmoPTA-1P:22N,N’-MCl2] (M = Ni (2),
Co (3), Zn (4)) were prepared as described in the literature
[10,11]. Appropriate amounts of NaH2PO4·2H2O, Na2HPO4·7H2O
and Na3PO4·6H2O were used to prepare 0.1 M solutions, and phos-
phate buffer solutions of the desired pH were obtained by mixing
In a Schlenk tube, complex 1 (6 mg, 7.6 × 10−3 mmol) was dis-
solved in a mixture of 1.6 mL of phosphate buffer (0.1 M, pH
2.75 or pH 6.75) and 0.4 mL of MeOH. 1-Octen-3-ol (105 L,
6.80 × 10−1 mmol) was added and the reaction mixture was stirred
at 70 ◦C. After the desired reaction time the resulting solution was
cooled to room temperature and analysed as described above.
2.6. Conversion of isomerization as a function of 1-octen-3-ol / 1
molar ratio
1
corresponding volumes of these solutions. 1H and 13C{ H} NMR
Complex 1 (6 mg, 7.6 × 10–3 mmol) was dissolved in a mixture
of 1.6 mL of phosphate buffer solution (0.1 M, pH 2.75) and 0.4 mL
MeOH. Then at 70 ◦C 1-octen-3-ol was added (105, 210, 420 and
840 L; 0.68, 1.36, 2.72 and 5.44 mmol, respectively; ranging from
0.34 to 2.72 M) and the reaction mixture was strongly stirred. After
3 h the resulting solutions were worked up as described above.
spectra were recorded on Bruker AV300 and AV500 spectrometers
operating at 300.13 and 500.13 MHz (1H), respectively. Peak posi-
tions are relative to tetramethylsilane and were calibrated against
the residual solvent resonance (1H) or the deuterated solvent mul-
1
1
tiplet (13C{ H}). Chemical shifts for 31P{ H} NMR spectra were
measured relative to external 85% H3PO4. Gas chromatographic
measurements were made on a Hewlett-Packard HP 5890 Series
II equipment using a Varian CP-Wax 52CB, 30 m, 0.32 mm, 0.25 m
(CP884) column and FID, and on a Varian CP-3380 GC gas chro-
matograph equipped with a Factor Four VF23 capillary column and
flame ionization.
2.7. Study of the effect of chloride concentration on the
isomerization of 1-octen-3-ol and 1-hepten-3-ol catalysed by 1 at
pH 2.75
Isomerization of both allyl alcohols at three different NaCl con-
centrations were studied by the same procedure. Into a mixture of
1.6 mL of phosphate buffer (0.1 M, pH 2.75) and 0.4 mL of MeOH was
added 1 (6 mg, 7.6 × 10−3 mmol), 1-octen-3-ol (105 L, 6.80 × 10−1
mmol), or 1-hepten-3-ol (95 L, 6.96 × 10−1 mmol) together with
NaCl (0.0, 11.7 and 35.1 mg; 0.0, 2.0 × 10−1 and 6.0 × 10−1 mmol).
The resulting mixture was stirred at 70 ◦C for 3 h, worked up and
analysed by the procedure described above.
2.2. Catalytic reactivity of the complexes 1–4 in water for the
isomerization of 1-octen-3-ol
In a standard experiment, complex 1 (7.8 mg, 9.9 × 10−3 mmol)
and the bimetallic complexes 2–4 (9 mg, 9.9 × 10−3 mmol) were
dispersed in 4.5 mL of water with strong stirring before addition of
1-octen-3-ol (180 L, 1.17 mmol).