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S.M. Rountree et al. / Applied Catalysis A: General 408 (2011) 54–62
4:[H2IMesH][OTf] ratio is 2:1]: 18.43 (s, 1H, Ru = CH)4, 7.06 (s, 4H,
Mes-mH)4, 7.00 (s, 4H, Mes-mH)*, 4.52 (s, 4H, (CH2)2 bridge in
H2IMesH)*, 4.11 (s, 4H, (CH2)2 bridge in H2IMes)4, 2.41 (s, 12H,
Mes-oCH3)4, 2.39 (s, 6H, Mes-pCH3)4, 2.37 (s, 12H, Mes-oCH3)*,
2.32 (s, 6H, Mes-pCH3)*, 1.94 (broad m, P(C6H11)3)4+other, 1.77
thickness, 0.25 m; IDO, 0.32 mm). Decane was used as internal
standard for GC analysis.
2.2. Ionic liquids
(broad m, P(C6H11)3)4+other, 1.36 (broad m, P(C6H11)3)4+other
.
The ionic liquids [A][NTf2] (A = 1-butyl-3-methylimidazolium
= N(CF3SO2)2) and
2.4. ICP analyses
[C4mim][X] (X = PF6, CF3SO3 (OTf)) were prepared in-house
from the corresponding bromide salts and LiNTf2 or NaX
(X = PF6, OTf) following methods similar to those previously
described [19]. Analogous procedures were also used to prepare
[A][NTf2] (A = methyl(trioctyl)ammonium (N8,8,8,1), tetrade-
cyl(trihexyl)phosphonium (P6,6,6,14)), using the chloride salts
[N8,8,8,1]Cl and [P6,6,6,14]Cl, which were obtained from Aldrich
and Cytec, respectively. The ILs were dried for 24–48 h under
high vacuum at 60–70 ◦C prior to use, the resulting ILs typically
containing a residual water content of <0.02 wt% as determined by
Karl Fischer titration. They were stored and handled in a glove box
attempts were made to determine the residual content of halide
or 1-methylimidazole in the ILs. The presence of such impurities,
however, have been shown to have an effect in the self-metathesis
of 1-octene in ILs [12c].
ICP analyses were performed at the ASEP unit in Queen’s Univer-
sity, Belfast. Samples to determine the amount of catalyst dissolved
in various solvents were prepared by adding 5.4 mg (0.007 mmol)
of 1 and 10 mL of solvent (dichloromethane, methanol, hex-
ane, benzene, ethyl acetate, tetrahydrofuran, 2-propanol or
1,2-dichloroethane) into a Schlenk flask, under nitrogen. The mix-
tures were stirred for 10 min and then passed through a sintered
glass funnel. Any undissolved catalyst remaining on the funnel
was washed with dichloromethane (5 mL) into a crucible. The
dichloromethane was allowed to evaporate and the remaining
residue in the crucible was submitted for ICP-MS analysis. A
sample was also analysed where the catalyst was dissolved in
dichloromethane and no filtration was undertaken, giving a value
of 268 ppm. Compared to this standard the % of undissolved Ru in
each solvent was: dichloromethane (4%), 1,2-dichloroethane (13%),
ethyl acetate (15%), methanol (18%), benzene (27%), tetrahydro-
furan (48%), 2-propanol (49%) and pentane (84%). ICP analyses
to determine the loss of Ru in reactions using catalyst 3 or
4 in IL/dichloromethane or IL/pentane were carried out on the
IL/catalyst phase after three recycles, and the results compared to
the standard. Prior to analysis, the organic solvent was removed, as
described in Section 2.8, and the samples dried under high vacuum
for ca. 24 h.
2.3. Catalysts
Catalysts 1, 2 and 3 were obtained from Aldrich, stored and
handled in a glove box, and used without further purification. Cata-
lyst 4 and its precursor [(Ru C)(PCy3)(H2IMes)Cl2] were prepared
following literature procedures [10], as summarised below. Feist’s
Ester was also synthesised as previously reported [20].
[(Ru C)(PCy3)(H2IMes)Cl2]: Grubbs’ 2nd generation catalyst [2]
(1.0 g, 1.178 mmol) was weighed in a glove box and dissolved in dry
dichloromethane (10 cm3). To this, a solution of Feist’s Ester (0.2 g,
1.178 m mol) in dichloromethane (5 cm3) was added. The resulting
solution was stirred under nitrogen for 15 h, after which the solvent
was removed under vacuum. The resulting brown residue was dis-
solved in pentane (15 cm3) and sonicated for 10 min. The solid was
then filtered and repeatedly washed with cold pentane, forming a
2.5. Dimerisation of COE in organic solvents
To 0.066 mmol of catalyst [1 (54 mg), 2 (56 mg), 3 (41 mg) or
4 (60 mg)] into a Schlenk flask, under nitrogen, 100 mL of sol-
vent (dichloromethane, methanol, hexane, benzene, ethyl acetate,
tetrahydrofuran, 2-propanol or 1,2-dichloroethane) were added,
followed by degassed cyclooctene (0.1 mL, 0.77 mmol) and decane
(0.1 mL, 0.51 mmol). The reaction mixtures were stirred at r.t., for
24 h, under nitrogen. Samples (1 mL) for GC analysis were taken
every 10 min for the first hour and subsequently every hour for 8 h.
Finally, a 24 h sample was taken. Each sample was quenched with
tert-butylhydroperoxide (TBHP, 2 drops), diluted with diethyl ether
(1 mL) and filtered through a silica plug prior to being submitted
for GC analysis.
light brown solid which was dried under vacuum (0.69 g, 75%). 1
H
NMR (300 MHz, CDCl3, ı): 6.96 (s, 2H, Mes-mH), 6.89 (s, 2H, Mes-
mH), 4.07 (m, 4H, (CH2)2 bridge in H2IMes), 2.54 (s, 6H, Mes-oCH3),
2.49 (s, 6H, Mes-oCH3), 2.29 (s, 3H, Mes-pCH3), 2.24 (s, 3H, Mes-
pCH3), 1.88 (m, P(C6H11)3), 1.65 (m, P(C6H11)3), 1.17 (m, P(C6H11)3).
31P NMR (300 MHz, CDCl3, ı): 35.4 (s).
[{Ru CH(PCy3)}(H2IMes)Cl2][OTf] (4): A solution of triflic acid
(0.039 g, 0.259 mmol) in dichloromethane (5 cm3) was added to
a solution of [(Ru C)(PCy3)(H2IMes)Cl2] (0.2 g, 0.259 mmol) in
dichloromethane (5 cm3), and the mixture stirred for 30 min.
The solvent was removed under vacuum, and the resulting solid
suspended in pentane (15 cm3) and stirred for 10 min. The pentane
was then decanted, leaving a brown solid which was dried under
vacuum (0.18 g, 90%). The product obtained was used without
further purification. However, fast degradation of 4 was observed
in CDCl3 by 1H NMR, most likely producing [H2IMesH][OTf] [21]
and other unidentified product(s). Attempts to obtain a better 1H
detail were not made. The major product in the 1H NMR spectrum
after dissolution of the catalyst in CDCl3 corresponded well with
the spectroscopic data previously reported for 4 [10]. After 72 h
in solution, the signals for 4 had disappeared leaving only those
attributed to [H2IMesH][OTf] [21] plus other PCy3-containing
impurities. 1H NMR (300 MHz, CDCl3, ı): [fresh solution; signals
attributed to [H2IMesH][OTf] are indicated with *; the approximate
For experiments at different catalyst loadings, the reactions
were carried out as above, in dichloromethane, using 14, 27, 54 and
108 mg (2.2, 4.3, 8.5 and 17.1 mol%, respectively) of catalyst 1. The
same procedure was also used for reactions at different substrate
1.54 and 7.7 mmol, respectively) of COE and 0.01, 0.05, 0.1, 0.2 and
1 mL, respectively, of decane.
2.6. Reactions involving 1,9-cyclohexadecadiene
For the reaction of COE and 1,9-cyclohexadecadiene, Grubbs’
1st generation catalyst 1 (54 mg, 0.066 mmol) was weighed into a
Schlenk flask, under nitrogen. Distilled dichloromethane (100 mL)
was added, followed by degassed cyclooctene (0.1 mL, 0.77 mmol),
1,9-cyclohexadecadiene (0.2 mL, 0.77 mmol) and decane (0.1 mL,
0.51 mmol). The reaction mixture was stirred, at r.t., for 24 h, under
nitrogen. Samples for GC analysis were obtained as described
above for the dimerisation of COE. The reaction using only