Magnetic nanoparticle supported second generation Hoveyda Grubbs catalyst for metathesis of unsaturated fatty acid esters

Article abstract of DOI:10.1002/adsc.200900370

The Hoveyda-Grubbs catalyst has been successfully immobilized on surface-modified magnetic nanoparticles with a loading amount of 0.28 mmol ruthenium/g (magnetic support). The supported catalysts were active for the self-metathesis of methyl oleate and ma

Full text of DOI:10.1002/adsc.200900370

FULL PAPERS
DOI: 10.1002/adsc.200900370
Magnetic Nanoparticle Supported Second Generation Hoveyda–
Grubbs Catalyst for Metathesis of Unsaturated Fatty Acid Esters
Zhu Yinghuai,a,* Loo Kuijin,a Ng Huimin,a Li Chuanzhao,a Ludger Paul Stubbs,a
Chia Fu Siong,b Tan Muihua,a,c and Ship Chee Pengc
a
Institute of Chemical and Engineering Sciences (ICES), 1 Pesek Road, Jurong Island, Singapore 627833
Fax : (+65)-6316-6182; e-mail: zhu_yinghuai@ices.a-star.edu.sg
Singapore Polytechnic, 500 Dover Road, Singapore 139651
Department of Chemistry, National University of Singapore, 3 Science Drive, Singapore 117543
b
c
Received: May 28, 2009; Revised: September 14, 2009; Published online: October 28, 2009
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.200900370.
Abstract: The Hoveyda–Grubbs catalyst has been conversion, respectively. In addition, the catalyst can
successfully immobilized on surface-modified mag- be easily separated by using a magnet and reused
netic nanoparticles with
a loading amount of several times with sustained activity.
0.28 mmol ruthenium/g (magnetic support). The sup-
ported catalysts were active for the self-metathesis of Keywords: fatty acids; immobilization; metathesis;
methyl oleate and macro-monomer in a quantitative nanoparticles; ruthenium; supported catalysts
Introduction
nature of the support, however, they all demonstrate
improvements in catalyst recovery.[5–7]
The olefin metathesis reaction has been well recog-
On the other hand, several reports have been pub-
nized as a powerful tool to form new C=C bonds in lished on metathesis of fatty acid esters.[2,8] However,
organic compounds.[1] The reaction is playing a key the catalyst recovery issue has not been well ad-
role in the new emerging oleochemical industry, dressed till now. To make the processes greener, in
which is concerned with producing chemicals from re- general, neat reactions are preferred in fatty acid
newable resources such as natural oils and fats. By ester transformations. Consequently, that makes it
olefin metathesis, unsaturated fatty acid esters and more difficult to recover the catalyst from a reaction
oils are converted into new products.[2] However, mixture with a high boiling point and high viscosity
before extending the application, it is necessary to re- caused by starting material or products. The conven-
cover the metathesis catalysts from the view of both tional purification techniques such as distillation, fil-
economy and environmental benefit. To date, only a tration and chromatography may not be suitable in
few methods for recovering or separating metathesis large-scale operation to separate catalysts and prod-
catalysts have been investigated, these include chro- ucts in the reactions. There is a need to discover a
matographic purification of homogeneous catalysts,[3] viable process to recover catalysts from these high vis-
and aqueous extraction of water-soluble catalysts.[4] cosity product mixtures. Magnetic nanocomposites as
Despite the great progress achieved so far, the separa- catalyst supports have been attracting more and more
tion and recovery of highly active ruthenium-based attention because they can be easily recovered from
homogeneous metathesis catalysts from the product the reaction mixture simply by using an external
remains a big challenge because these techniques are magnet.[9] In our lab, we are using magnetic nanopar-
either difficult to be scaled up or toxic materials are ticles as a catalyst support, which can be easily dis-
used. Thus, heterogenizing metathesis catalysts has at- persed into a solution homogeneously, to facilitate
tracted more and more interest, and ruthenium-based catalyst recovery of, e.g., a supported palladium cata-
[10]
À
metathesis catalysts have been immobilized on vari- lyst for C C coupling reactions. Herein, we report
ous organic and inorganic supports.[5–7] The activity of our preliminary results regarding supported Hovey-
the supported catalyst is highly dependent on the da–Grubbs catalyst on magnetic nanoparticles and
used in transformation reactions of methyl oleate.
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Magnetic Nanoparticle Supported Second Generation Hoveyda–Grubbs Catalyst
FULL PAPERS
The catalyst composite can be easily recovered from
the reaction mixture by magnet with sustained activi-
ty.
Results and Discussion
Carbene-coordinated ruthenium catalysts such as the
second generations of Grubbs and Hoveyda–Grubbs
catalysts, have demonstrated high activities for olefin
metathesis reactions with functional group toler-
ance.[1] Immobilization and activity examinations of
these catalysts are necessary for catalyst recovery in
green and economically viable industry processes. In
our lab, commercially available magnetic nanoparti-
cles with a mean diameter of 100 nm were successful-
ly enriched with ortho-isopropoxystyrene ligands by
covalent bonds as shown in Scheme 1. Reaction of the
immobilized ligand with second generation Grubbs
catalyst produced the supported second generation
Hoveyda–Grubbs catalyst. To characterize the sup-
ported catalyst 4, we examined it with NMR, IR,
XPS, ICP, TGA and TEM technologies. In the
1H NMR spectra, a broad peak was obtained with a
shifted d as compared with normal NMR absorptions.
The poor NMR signals may be caused by the magnet-
ic properties of the support material.[11] In the near
IR spectra [Figure 1 (top)], obvious changes have
been found for supported catalyst 4 when compared
with free and anchored ortho-isopropoxystyrene
Figure 1. Near (top), and far (bottom) IR spectra of related
compounds.
ligand 2 and 3, respectively in the range of 2700–
3200 cmÀ1. However, in the far IR [Figure 1
(bottom)], 4 and the 2nd generation Grubbs catalyst
showed identical peaks in the range of 200–310 cmÀ1 also showed obvious absorptions at the frequencies of
for nRu absorptions.[12] The results suggest that Ru
108 (broad), 48 and 41 cmÀ1, respectively [Figure 1
À
À
Cl
Cl bonds in 4 and the 2nd generation Grubbs catalyst (bottom)], when compared with the far IR spectrum
have similar chemical environments. In addition, 4 of the 2nd generation Grubbs catalyst. These absorp-
Scheme 1. Synthesis of magnetic nanoparticle supported Hoveyda–Grubbs catalyst.
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À
tions may be caused by Ru=C and Ru O (p-bond) to calculate the Ru concentrations. Samples for ICP
resonances. However, no obvious absorption was analysis were obtained by decomposing the supported
found for supported ligand 3 in the far IR spectrum. catalyst 4 with concentrated HNO3. ICP analysis
In ICP-OES analysis, diluted solutions of the pur- showed that a loading amount of 0.28 mmol Ru/g
chased ruthenium atomic absorption standard solu- (magnetic support) was achieved. The modification
tion (1000 mg/mL) were used to construct the calibra- was also confirmed by TGA results which showed a
tion lines. The analytical determinations were per- reduced amount of residues for 3 and 4 compared
formed at the wavelength numbers of 245.657, with the residue from the purchased magnetic support
267.876 and 349.894 nm, respectively. At these fre- (see Supporting Information Figure S-1). The modifi-
quencies, elements such as Zr and Cr that could po- cation did not cause aggregation of magnetic nanopar-
tentially influence our ICP analysis results were not ticles and the particle size was maintained as observed
used in our processes.[13] The data obtained from the in TEM after our process. After supporting the ruthe-
average of the three detection wavelengths were used nium catalyst, the amount of residue dropped to
53.8 wt% compared with the residues from ortho-iso-
propoxystyrene ligand enriched magnetic support 3
(62.7 wt%) and the purchased magnetic support
(70.3 wt%). These results were consistent with the
above ICP analysis. The magnetic nanoparticles
loaded with the ruthenium-based second generation
of Hoveyda–Grubbs catalyst have also been analyzed
with TEM (Figure 2). In the TEM image, only mag-
netic particle cores with an average of ca. 13 nm have
been seen, no other particles are found. Combining
all the information, it can be concluded that the
ruthenium catalysts have been successfully loaded
onto the magnetic support.
The prepared magnetic nanoparticle-supported
second generation of Hoveyda–Grubbs catalyst, 4, has
been tested as a catalyst for both self- and cross-meta-
thesis reactions. Self-metathesis of methyl oleate, as
shown in Scheme 2, was conducted neat at 508C with
commercially available sources. An isolated yield of
73% with a TOF of 489 hÀ1 has been reached after 3 h
reaction in a ratio of [methyl oleate]mol/[Ru]mol =2008.
Two products were separated as colorless oils by chro-
matography. H and 13C NMR spectra of the com-
pounds are consistent with literature values and con-
1
Figure 2. TEM image of catalyst 4.
Scheme 2. Metathesis reactions of methyl oleate and macro-monomer.
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Magnetic Nanoparticle Supported Second Generation Hoveyda–Grubbs Catalyst
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firmed them as 9-octadecene and the second product achieved in a ratio of [macro-monomer]mol/[2nd gener-
as dimethyl 9-octadecene-1,18-dioate, respectively.[8a] ation Grubbs catalyst]mol =156.
The activity is slightly lower than that of the second
Cross-metathesis of unsaturated fatty acid esters
generation of Grubbs catalyst which exhibited TOFs such as methyl oleate, with a normal olefin is an ele-
of 652 hÀ1 at 408C[8d] and 700 hÀ1 at 508C[2a], respec- gant method with great potential synthetic value for
tively. It should be pointed out that our catalyst could generating the desired unsaturated alkenes.[2] Howev-
be easily separated from the reaction mixture by at- er, more consideration should be taken for catalyst se-
traction of a magnet. The magnetic-supported cata- lection. A more desirable catalyst should be able to
lysts were attracted onto the inner surface of the reac- tolerate a wide range of functional groups such as
tor, a round-bottom flask by using an external magnet ester groups, and exhibit significant selectivity for
(1.14 T) when the reaction mixture was kept in a sta- cross-metathesis rather than self-metathesis of olefins.
tionary condition. The product mixture could be col- As a model reaction, we investigated the cross-meta-
lected easily by decantation, and the attracted cata- thesis of methyl oleate with methyl acrylate. A proce-
lysts were further reused after washing with dichloro- dure similar to the literature report was performed in
methane to remove any absorbed starting material or bulk with conditions of [methyl oleate]mol/[Ru]mol
=
product. The concentrations of leaching Ru in the 497, [methyl acrylate]mol/[methyl oleate]mol =10 in
product mixture combined with the wash solution ob- neat conditions.[8f] After purification with thin layer
tained from above reactions are less than 3.0 ppm chromatograph (TLC), 1-methylundec-2-enoate and
based on ICP results. In addition, after 3 runs, no sig- 1,11-dimethylundec-2-enedioate (based on NMR
nificant aggregation and size changes of the magnetic spectra compared with literature data[8f]) were ob-
nanoparticle support were observed as confirmed by tained as the major products. An isolated yield of
TEM images. It is very important to note that our cat- 60% with a TON of 300 (TOF=12 hÀ1) has been ach-
alyst 4 could be recycled easily and reused at least 5 ieved after 25 h at 458C. Similar to the self-metathesis
times under our conditions with TOFs of 488 hÀ1, reaction of methyl oleate, the catalyst could be recov-
484 hÀ1, 487 hÀ1, 485 hÀ1, 486 hÀ1, respectively. Since ered by magnetic attraction, and reused for at least 3
our reactions were performed neat, the approach times with slightly reduced TOFs of 11.8 hÀ1, 11.9 hÀ1,
avoids solvent waste, and thus is beneficial in terms of 11.8 hÀ1, respectively. These activities are much higher
green chemistry. These results demonstrate a signifi- than the 2nd generation Grubbs catalyst (TOF
cant improvement of the existing catalyst recycling <1 hÀ1), and comparable with unsupported 2nd gener-
procedures and the process is more viable for the use ation Hoveyda–Grubbs catalyst (TOF=11 hÀ1).[8f]
of renewable materials. To confirm that the high ac- The concentrations of leaching Ru in the product
tivity was contributed by the supported ruthenium mixture combined with the wash solution obtained
catalyst, contrast experiments have been investigated from above reactions are very small, less than
under the same conditions in a dichloromethane solu- 4.0 ppm (based on ICP analysis).
tion obtained from the wash solution of catalyst. No
isolable products were found after similar purifica-
tion. The results confirmed that the supported Hovey- Conclusions
da–Grubbs catalyst provides the high activity rather
than a leaching catalyst species. At present, although In conclusion, we have successfully immobilized the
the classic metathesis mechanism might be applicable second generation Hoveyda–Grubbs catalyst on mag-
to catalyst 4, a further confirmation study is undergo- netic nanoparticles by forming covalent bonds and
ing in our lab using on-line IR technology.
demonstrated that the magnetic nanocomposites are
To investigate the catalytic activity of 4 to a func- high effective for both self- and cross-metathesis reac-
tional polymer, macro-monomer, 9-decen-1-ol tailed tions of methyl oleate. The supported catalysts could
poly(d/l-lactide), was synthesized (Scheme 2). A col- be well dispersed in the organic reaction mixture to
orless polymer with an MW of 1.75ꢁ104 (PDI=1.73) produce a false homogeneous catalyst system. In addi-
was produced with SnOct2 as catalyst. As shown in tion, the unique catalyst could be easily separated by
Scheme 2, the macro-monomer underwent self-meta- magnetic attraction with sustained activity.
thesis in a mixed solvent of dichloromethane and
N,N-dimethylacetamide, with a ratio of [macro-mono-
mer]mol/[Ru]mol =98, a new product with double mo-
lecular weight (Mw=3.56ꢁ104, PDI=1.74) was
formed based on gel permeation chromatography
analysis as expected. In the self-metathesis reaction, 4
exhibited a TOF of 29 hÀ1. In contrast, under the
same conditions, the 2nd generation Grubbs catalyst
Experimental Section
General Remarks
All operations were conducted under an argon atmosphere
with in a glove box or standard Schlenk lines. Magnetic sup-
was more active than 4, a higher TOF of 43 hÀ1 was port (50 mgmLÀ1, 100 nm, matrix with starch) was provided
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by chemicell GmbH. Ruthenium atomic absorption standard
solution (1000 mg/mL, Ru in 5% HCl) and other reagents
were supplied from Sigma–Aldrich Pte. Ltd. Compound 1
was prepared according to the literature.[5a] 1H and
13C NMR were recorded on a Bruker Fourier-Transform
multinuclear spectrometer at 400 and 100.6 MHz, relative to
external Me4Si (TMS) standard. Near infrared (IR) spectra
were measured using a BIO-RAD spectrophotometer with
the KBr pellet technique. Far infrared spectra were mea-
sured using a Bruker FT-IR, Vertex 70 spectrophotometer
with neat sample pellets. ICP analysis was determined with
a VISTA-MPX, CCD Simultaneous ICP-OES analyzer. The
TGA analyses were carried out on an SDT 2960 Simultane-
ous DSC-TGA analyzer. Transmission electron microscopy
(TEM) measurements were carried out on a JEOL Tecnai-
G2, FEI analyzer at 200 kV. The MS was measured on a
Thermo Finnigan MAT XP95 analyzer using the EI mode.
Molecular weights and molecular weight distributions of the
polymers were determined by means of gel-permeation
chromatography (GPC: Agilent GPC), using dichlorome-
thane as eluent with a column set of 2xPLgel 5 mm MIXED-
C. The weight average molecular weight and polydispersity
index (Mw and Mw/Mn, respectively) were calculated on the
basis of polystyrene standards. Flow rate=1.0 mLminÀ1, in-
jected volume=50 mL.
1.1 mmol) and dicyclohexylcarbodiimide (DCC) (0.288 g,
1.40 mmol) were added to the above solution with vigorous
stirring at 08C. After addition, the resulting mixture was
stirred at room temperature for 6 h. An external magnet
was used to recover the magnetic nanocomposite from the
reaction mixture. The separated nanocomposite was washed
with dimethyl sulfoxide (2ꢁ50 mL), dichloromethane (2ꢁ
10 mL) followed by deionized water (2ꢁ10 mL) and dried
under vacuum at 508C for 3 days to produce the ligand-sup-
ported magnetic nanoparticles (yield: 0.178 g) with a ligand
loading of 0.33 mmolgÀ1(based on elemental analysis). The
obtained sample was also analyzed by IR, and TGA.
Synthesis of Compound 4
A literature method was used to immobilize the ruthenium
catalyst.[14] Grubbs second generation catalyst (0.43 g,
0.506 mmol) and CuCl (0.05 g, 0.505 mmol) were added to a
solution of 3 (0.1 g) in a mixed solvent of dichloromethane
(25 mL) and DMA (10 mL) and furthered reacted at 408C
for 3 h. External magnets were used to separate the magnet-
ic nanocomposite from the reaction mixture. The separated
nanocomposite was then washed with dichloromethane (2ꢁ
10 mL) dimethyl sulfoxide (2ꢁ10 mL) and acetone (2ꢁ
15 mL) followed by drying under vacuum to produce a
brown product with an Ru loading of 0.28 mmolgÀ1 (based
on ICP analysis). The product was also subjected to analysis
with TGA, TEM and IR, respectively.
Synthesis of Compound 2
NaH (0.288 g, 0.012 mol) was added carefully to a solution
of 1[5a] (1.780 g, 0.01 mol) in dry tetrahydrofuran (15 mL) in
a glove box. After stirring for 3 h at room temperature,
sodium bromoacetate (1.642 g, 0.01 mol) was added to the
reaction mixture and the mixture was refluxed overnight.
The solvent was removed under vacuum, and distilled water
(7 mL) was added to the residue. Extraction was carried out
with 10 mL of diethyl ether to remove unreacted starting
material. After acidification of the aqueous layer with 1N
HCl, the reaction mixture was extracted with diethyl ether
(3ꢁ100 mL), the combined organic phase was dried with an-
hydrous Na2SO4 and concentrated under vacuum followed
by purification with chromatography (SiO2, eluted with a
mixted solvent of hexane/diethyl, v/v=5/1) ether to give
pure product 2; yield: 2.056 g (87%). Elemental analysis for
calcd. 2 C13H16O4 (%): C 66.09, H 6.83; found: C 65.87, H
6.94; EI-MS: m/z=233.81 (M+À2H), 234.82 (M+ÀH);
1H NMR (CDCl3): d=1.32 (d, 6H, 2CH3), 4.42 (m, 1H,
CHO), 4.65 (s, 2H, OCH2CO2), 5.25 (d, 1H, =CH2), 5.72 (d,
1H, =CH2), 6.77–7.08 (m, 4H, C6H3, CH=CH2); 13C NMR
(CDCl3): d=21.94 (2C, 2CH3), 65.43 (1C, CHMe2), 72.16
(1C, OCH2CO2), 112.47, 114.45, 114.63, 116.34, 129.25,
131.25, 150.19, 151.44 (8C, C6H3, CH=CH2), 173.55 (1C,
CO2). IR (KBr, pellet): n=2976 (s, s), 2933 (s, s), 1735 (s, s),
1588 (m, m), 1491 (s, s), 1432 (m, s), 1374 (m, s), 1286 (m,
s), 1209 (s, br), 1137 (m, s), 1110 (s, s), 1078 (m, s), 956 (m,
s), 921 (m, s), 873 (m, s), 854 (m, s), 807 (m, s), 772 (w, s),
676 (w, s), 504 cmÀ1 (w, s).
Synthesis of Macro-monomer
Macro-monomer was prepared according to the literature
report.[15] d/l-Lactide (2.89 g, 20 mmol), 9-decen-1-ol
(0.016 g, 0.1 mmol) and SnOct2 (0.083 g, 0.2 mmol) were dis-
solved in 70 mL toluene. The resulting solution was refluxed
for 6 h before cooling to room temperature. All solvents
were removed under reduced pressured. The obtained resi-
due was then re-dissolved in a small amount of CH2Cl2 and
precipitated with cold methanol. The resulting solid was col-
lected by filtration and washed with 2ꢁ20 mL cold metha-
nol followed by drying at 508C under vacuum for 2 days to
give the solid product; yield: 2.30 g (MW=1.75ꢁ104, DPI=
1.73 based on GPC analysis). The product was also subject-
ed to analysis with IR.
Self-Metathesis of Methyl Oleate using 4 as Catalyst
A literature procedure was used to conduct the self-meta-
thesis of methyl oleate.[8c] Methyl oleate (4.50 g,
15.18 mmol) was added to
a dry round-bottom flask
equipped with magnetic stirring bar. Compound
a
4
(27.0 mg, 7.56 mmol [Ru]) ([methyl oleate]mol/[Ru]mol =2008)
was added with vigorous stirring. The resulting mixture was
heated to 508C for 3 h before cooling to room temperature
and the catalyst was recovered with an external magnet. The
recovered catalyst was washed with dry dichloromethane
and dried under vacuum for a subsequent run. The resulting
mixture was purified with flash chromatography (SiO2,
eluted with hexane/diethyl ether, v/v=10/1) to produce 9-
octadecene (yield: 2.76 g) and dimethyl 9-octadecene-1,18-
dioate (yield: 3.75 g) with an isolated yield of 73% (TOF=
489 hÀ1).
Synthesis of Compound 3
Commercially available magnetic support (0.100 g) was sus-
pended in a mixture of dichloromethane (20 mL) and N,N-
dimethylacetamide (DMA) (5 mL). Compound 2 (0.30 g,
1.27 mmol), 4-dimethylaminopyridine (DMAP) (0.134 g,
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1
9-Octadecene: H NMR (CDCl3): d=0.89 (t, 6H, 2CH3),
149.80 (2C, CH2CH=CHCO2), 167.16 (1C, CO2): EI-MS:
m/z=221.15 (M+ +Na+).
1.29–1.33 (br. m, 24H, 12CH2), 1.97–2.02 (m, 4H,
2
CH2CH=), 5.40–5.42 (m, 2H,CH=CH); 13C NMR (CDCl3):
d=14.12 (2C, 2CH3-), 22.69 (2C, 2CH2CH3), 29.17, 29.32,
29.50, 29.66, 31.91, 32.61 (12C, 12CH2), 130.36 (2C, 2CH=).
Dimethyl 9-octadecene-1,18-dioate: 1H NMR (CDCl3):
d=1.28–1.29 (br. m, 16H,8CH2), 1.59–1.63 (br. t, 4H,
2CH2), 1.95–1.96 (br. m, 4H, 2CH2), 2.30 (t, 4H, 2CH2),
3.67 (s, 6H, 2CO2CH3), 5.36–5.38 (m, 2H, CH=); 13C NMR
(CDCl3): d=24.95, 28.94, 29.11, 32.55, 34.11 (12C, 12CH2),
51.45 (2C, 2CH2CO2), 130.32 (2C, 2CH=), 174.36 (2C,
2CO2); EI-MS: m/z=363.25 (M+ +Na+).
Dimethyl undec-2-ene-1,11-dioate:1H NMR (CDCl3): d=
1.31 (br. s, 6H, 3CH2), 1.45 (br. s, 2H, CH2), 1.62 (br. s, 2H,
CH2), 2.17–2.22 (dt, 2H, CH2), 2.28–2.32 (t, 2H, CH2CO2),
3.67 (s, 3H, CO2CH3), 3.72 (s, 3H, CO2CH3), 5.80–5.83
(d,1H, =CHCO2), 6.93–6.70 (m, 1H, CH=CHCO2);
13C NMR (CDCl3): d=24.89, 27.95, 28.92, 29.01, 32.17, 34.04
(7C, 7CH2, one signal is overlapped), 51.37 (2C,
2CO2CH3), 120.91, 149.65 (2C, CH=CH), 167.15, 174.22
(2C, 2CO2); EI-MS: m/z=265.15 (M+ +Na+).
Acknowledgements
Self-Metathesis of Macro-monomer using 4 as
Catalyst
This work was supported by Institute of Chemical and Engi-
neering Sciences (ICES), Singapore. We are also grateful for
the contributions made by our colleague Dr. Ang Thiam
Peng at ICES.
A similar procedure to the self-metathesis of methyl oleate
was used to conduct the self-metathesis of macro-monomer.
From 1.2 g (68.6 mmol, based on MW) of the above prepared
macro-monomer, with 4 (2.5 mg, 0.70 mmol) ([macro-mono-
mer]mol/[Ru]mol =98) in a mixture of (DMA) (5 mL) and di-
chloromethane (10 mL) the polymer was obtained after pre-
cipitation with cold methanol from dichloromethane and
drying in vacuum at 508C for 2 days; isolated yield: 1.10 g
(90%, TOF=29 hÀ1).
The procedure above was also conducted with second
generation Grubbs catalyst. From 1.2 g (68.6 mmol, based on
MW) of the above prepared macro-monomer, with second
generation Grubbs catalyst (0.37 mg, 0.44 mmol) ([macro-
monomer]mol/[2nd generation Grubbs catalyst]mol =156), the
polymer was obtained after drying; isolated yield: 1.0 g
(82%; TOF=43 hÀ1). The product was subjected to analysis
with NMR, IR and GPC (MW=3.56ꢁ104, DPI=1.74).
1H NMR (CDCl3): d=1.58 (d, 3H, CH3), 5.17 (q, 1H, CH);
13C NMR (CDCl3): d=16.65 (1C, CH3), 69.01 (1C, CHO),
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169.62 (1C, CO2); IR (KBr pellet): n=3651ACTHUNRTGNEUNG(w, s), 3560 (w,
s), 3510 (w, s), 2998 (m, s), 2947 (m, s), 2087 (vw, br), 1760
(vs, s, nCO), 1457 (s, s), 1386 (s, s), 1361 (s, s), 1213 (vs, s),
1186 (vs, s), 1134 (vs, s), 1093 (vs, s), 1045 (s, s), 957 (w, s),
921 (w, s), 872 (m, s), 756 (m, s), 694 (m, s), 507 cmÀ1 (w, s).
Cross-Metathesis of Methyl Oleate with Methyl
Acrylate using 4 as Catalyst
A literature method was used to perform the reaction.[8f]
Catalyst 4 (115 mg, 32.2 mmol,) was added to a mixture of
methyl acrylate (14.0 g, 0.16 mol,) and methyl oleate (4.74 g,
16 mmol) ([methyl oleate]mol/[Ru]mol =497) with continuous
stirring for 10 min. The reaction mixture was stirred magnet-
ically at 458C for 25 h. The excess of methyl acrylate was
evaporated under vacuum and the residue was purified by
TLC developed with hexane/diethyl ether (v/v=4/1) to pro-
duce methyl undec-2-enoate (yield: 1.90 g) and dimethyl
undec-2-ene-1,11-dioate (yield: 2.32 g), respectively in an
isolated yield of 60% (TOF=12 hÀ1).
Methyl undec-2-enoate: 1H NMR (CDCl3): d=0.88 (t,
3H, CH3), 1.27–1.28 (br, 10H, 5CH2), 1.43–1.47 (m, 2H,
CH2), 2.17–2.22 (dt, 2H, CH2C=), 3.72 (s, 3H, OCH3), 5.80–
5.84 (d, 1H, =CHCO2), 6.94–7.01 (m, 1H, CH2CH=C);
13C NMR (CDCl3): d=14.05, 22.62, 27.99, 29.11, 29.17,
29.32, 31.81, 32.20 (7C, 7CH2), 51.31 (1C, CH3CO2), 120.77,
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