Table 3 Highly promising iron pre-catalysts in ethylene oligomerization
Pre-catalyst
a
Co-catalyst
Al/Fe
T (
C)
Time (min)
Pressure (atm)
Oligomers
Waxes
References
Type
R
R
1
R
2
A o
b
K
c
α-O
d
(%)
A w
e
6A
H
iPr
H
MAO
1,000
40
60
10
9.0
0.48
>97
Trace
[66]
6A
H
Me
Me
MMAO
500
20
30
1
0.95
0.65
>93
–
[67]
6A
H
Me
Me
MMAO
1,000
20
30
10
25.7
0.69
>95
40.7
[67]
6A
Me
Et
H
MAO
1,000
40
60
10
49.1
0.62
>94
14.6
[66]
6A
Me
Et
H
MMAO
500
0
30
1
1.34
0.52
>93
–
[67]
6A
Me
iPr
H
MMAO
1,000
20
30
10
24.1
0.26
>93
–
[67]
6A
Et
Me
H
MAO
1,500
50
60
10
13.9
0.70
>95
12.1
[68]
6A
Ph
Et
H
MAO
1,000
40
30
10
23.0
0.52
>95
3.25
[66]
6A
Ph
Me
H
MMAO
500
20
30
10
0.80
0.62
>95
0.747
[67]
6B
H
–
–
MMAO
1,000
20
20
30
3.51
–
>92
–
[69]
6B
Me
–
–
MMAO
1,000
20
20
30
1.07
–
>82
–
[69]
6B
Et
–
–
MMAO
1,000
20
20
30
0.92
–
>81
–
[69]
6C
H
–
–
MMAO
800
20
20
10
1.89
–
80
–
[70]
6C
Me
–
–
MMAO
800
20
20
10
1.01
–
81.5
–
[70]
6C
tBu
–
–
MMAO
800
20
20
10
0.91
–
83
–
[70]
MAO methylaluminoxane,
MMAO modified methylaluminoxane
a
See Scheme 6
b
Activity for oligomers, in10
6
g mol
À1
(Fe) h
À1
c
Dissociation constant
d
α-Olefin content (%), as determined by GC and GC–MS
e
Activity for low-molecular-weight waxes, in 10
5
g mol
À1
(Fe) h
À1
172
W.-H. Sun