Communications
Table 1: Copolymerization of ethylene with polar olefins.[a]
Table 2: Copolymerization of ethylene with polar olefins without protec-
tion with iBu3Al.[a]
Entry
1
Precatalyst
FG
Act.[b] Inc.[c]
Mw(104) PDI[d]
[mol%] [gmolÀ1
]
Entry
FG (mmol)
Al/Ti Act.[b] Inc.[c]
[mol%] [gmolÀ1 [d]
Mw(104)
PDI[e]
]
1
2
3
4
(CH2)8OH (2)
(CH2)8COOH (2) 3000 1.0
(CH2)3OH (2) 3000 0.74
(CH2)8OTBS (4) 2000 2.9
(CH2)8OTBS (8) 2000 2.0
(CH2)8OTBS (8) 2000 1.0
3000 1.2
3.7
1.5
0.6
3.9
4.2
5.1
8.2
29.8
8.4
1.8
2.0
2.0
2.4
2.5[g]
2.0
(CH2)8OH
0.6
0.7
3.5
3.4
94.0
11.5
2.9
2.2
19.5
64.0
96.0
5[f]
6[f,h]
2
(CH2)8OH
[a] Polymerization conditions: catalyst 2 (3.5 mmol), ethylene (0.1 MPa),
toluene (50 mL), 258C, 10 min. [b] Activity, 106 gpolymer
(molTi)À1 hÀ1 atmÀ1. [c] Incorporation ratio, gmolÀ1 and determined by
1H NMR spectroscopy. [d] Determined by high-temperature GPC.
[e] Polydispersity index: Mw/Mn. [f] Toluene (80 mL). [g] Under the
same conditions using ethylenebis(indenyl)zirconium dichloride as
3[e]
4[f]
(CH2)8OH 10.1 11.2
(CH2)8COOH 11.2 1.6
17.8
8.6
2.2
2.8
[a] Polymerization conditions:[8] catalyst (3.5 mmol), polar olefin (1.0m
solution in toluene pretreated with 1.2 equiv iBu3Al, 20 mmol), ethylene
(0.1 MPa), toluene (50 mL), 258C, MMAO/Ti=1000, 10 min; the incorpo-
catalyst instead of 2: activity: 0.6ꢀ106 gpolymer(molZr)À1 hÀ1 atmÀ1
,
incorporation ratio: 4.6 mol%; Mw: 6.9ꢀ104 gmolÀ1
[h] 30 min. TBS=tert-butyldimethylsilyl.
, Mw/Mn: 2.7.
1
ration ratio was determined by H NMR spectroscopy; Mw and Mw/Mn were
determined by high-temperature gel-permeation chromatography (GPC).
[b] Activity, 106 gpolymer(molTi)À1 hÀ1 atmÀ1. [c] Incorporation ratio gmolÀ1
and determined by 1H NMR spectroscopy. [d] Polydispersity index: Mw/Mn.
[e] 1.0 min. [f] 1.5 min and 10-undecenoic acid (1.0m solution in toluene
pretreated with 2.2 equiv iBu3Al, 2 mmol). MMAO=modified methylalumi-
noxane; Mw =weight-average molecular weight; Mn =number-average molec-
ular weight.
for the copolymerization of ethylene with w-alkenol and w-
alkenoic acids.
Stimulated by the aforementioned results, we envisioned
that it would be possible to zipper a catalyst on PE by
copolymerization of ethylene with catalyst-containing olefin,
thus providing a facile and simple method for the synthesis of
PE-supported catalyst with tunable loading. This polymer
might serve as a temperature-controlled, soluble, recoverable,
and reusable catalyst because the solubility of the PE-
supported catalyst is dependent on the temperature and
comonomer content. Since phosphines have been applied as
powerful organocatalysts in organic synthesis, we then tried to
attach a phosphine unit to the PE backbone by employing this
strategy.[9] It was found that diphenyl(undec-10-enyl)phos-
phine (3) was readily incorporated into PE in the presence of
1a/MMAO (Scheme 3).
ratio 1000) was employed. The activity was 16 times higher
than that when complex 1a was used under the same
conditions (Table 1). It is reported that w-alkenoic acids,
such as 10-undecenoic acid, are very poor comonomers for
copolymerization and only very low incorporation ratios were
observed.[3c,5b] Upon activation with MMAO, 2 is noticeably
highly active in the copolymerization of ethylene with 10-
undecenoic acid with an activity of 1.1 ꢀ 107 gcopolymer
(molTi)À1 hÀ1 atmÀ1 and 1.6 mol% incorporation ratio. The
molecular weight distribution is in the range of 2.2–2.9, similar
to those of PE produced by a single-site catalyst. Note that for
all the copolymers obtained, the comonomers were well
distributed as measured by 13C NMR analyses.[8]
Noticeably, even without pretreating the comonomer with
iBu3Al, the copolymerization still proceeds very well upon
activation with MMAO in an Al/Ti ratio of 3000:1. As shown
in Table 2, catalyst 2 promoted the efficient copolymerization
of ethylene with 10-undecenoic acid or 9-decen-1-ol, which
afforded functional PE with high activity (up to 1.2 ꢀ
106 gcopolymer(molTi)À1 hÀ1 atmÀ1) and good incorporation
ratio (up to 3.7 mol%; Table 2, entries 1 and 2), although both
alcohol and acid consumed at least one equivalent of MMAO
during the polymerization. 4-Penten-1-ol is also a suitable
comonomer giving good activity (Table 2, entry 3). tert-
Butyl(dec-9-enyloxy)dimethylsilane proved to be an excellent
comonomer. In this case, the activity is very high with
4.2 mol% comonomer content even in the presence of an
excess amount of the comonomer relative to MMAO
(Table 2, entries 5 and 6). To the best of our knowledge,
complex 2 offers one of the most efficient titanium catalysts
Scheme 3. Zippering phosphine on PE. Activity: 3.7ꢀ105 gpolymer
(molTi)À1 hÀ1 atmÀ1 with 3.9 mol% incorporation.
As expected, PE-supported phosphine (PE-P) 4 proved to
be an excellent recoverable and reusable organocatalyst. It
can catalyze a formal [3+2] cycloaddition[10] (Table 3) with a
much higher selectivity than the corresponding parent
phosphine 3. When 20 mol% diphenyl(undec-10-enyl)phos-
phine 3 was used as catalyst, the product was obtained with a
molar ratio of 6/7 = 1.6:1 since the regenerated catalyst 3 will
result in isomerization.[11] To inhibit the isomerization, 20%
aqueous H2O2 was added during the workup to remove the
phosphine. Under the same reaction conditions, however,
almost no isomerization product 6 was observed when the
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2009, 48, 8099 –8102