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R.K. Bly et al. / Journal of Organometallic Chemistry 690 (2005) 825–829
Table 2
The polymerization of 2,5-didodecyl-1,4-dipropynylbenzene 1
Catalyst
Wt Monomer Conc. Monomer Conc. Cocat. (mmol/mL) Mol% Cat. Time (h) Temp. (°C)
P
n
Solvent
(
mg)
(mmol/mL)
a
a
a
c
3
5
4
245
245
245
490
490
245
470
0.125
0.125
0.125
0.2
0.137
0.137
0.137
0.22
10
10
10
10
10
10
5
20
20
20
15
15
6
135
135
135
132
132
110
140
120
120
120
o-C
o-C
o-C
6
6
6
H
H
H
4
4
4
Cl
Cl
Cl
2
2
2
c
4
Mo(CO)
130
140
C
o-C
6
H
5
Cl
Cl
CH
Cl
b
6
c
0.2
0.22
6
H
4
2
MoO
7
2
(acac)
2
7AlEt
3
0.125
0.12
0.274
0.125
420 C
33 o-C
6
H
5
3
20
6
H
4
2
a
These values were read off the combined plots in Fig. 1.
b
c
2
These runs were carried out at reflux without N being passed over the solution.
These values were read off the plots in Fig. 3.
4
. Experimental section
dium hydroxide for 7 h, washed with water and stirred
with 10 mL of 25% HCl. Precipitation into methanol, fil-
tration and drying furnished 2 [2b].
4
.1. Catalysts
Catalysts 3–5 and 7 were prepared as reported [3,4,8].
MoO (acac) /7Al(Et) (6) [3] was prepared by adding a
4.3. Polymerization of 1 with 4 and 5 in chlorobenzene
solution
2
2
3
1
to a stirred solution of MoO (acac) (Acros Organics)
in freshly distilled toluene. All operations were carried
out under a nitrogen atmosphere; 6 deteriorates at ambi-
ent temperature but remains active for ꢀ3–4 h at 0 °C.
.9 M toluene solution of triethylaluminum (Aldrich)
Stirred solutions of 490 mg (0.998 mmol) of 1, 140
mg (1.09 mmol) of p-chlorophenol and 28 mg (0.104
mmol) of 4 or 26 mg (0.0828 mmol) of 5 in 5 mL
of chlorobenzene (50-mL side-arm flasks) were flushed
with nitrogen and heated to reflux. Samples of 2 were
2
2
1
4.2. Polymerization of 1 with catalysts 3–5 in
o-dichlorobenzene solution
withdrawn, analyzed by H NMR and 2 was isolated
(see Section 4.2).
Stirred solutions of 245 mg (0.500 mmol) 1, 70 mg
0.544 mmol) of 4-chlorophenol and 15 mg of 3, 4 or
and 4 mL of o-dichlorobenzene were heated under a
slow stream of nitrogen at 135 °C in 50-mL side-arm
flasks. Small samples (ꢀ0.1 mL) were periodically with-
drawn by syringe, under a back flush of nitrogen, com-
4.4. Polymerization of 1 with catalyst 6 in toluene solution
(
5
To stirred solutions of 245 mg (0.500 mmol) of 1 and
ꢀ0.55 mmol of co-catalyst (phenol, p-chlorophenol or o-
fluorophenol) in 4.5 mL of toluene (freshly distilled from
calcium hydride) was added to 0.5 mL of a toluene solu-
tion containing 0.005 mmol of 6. The mixtures were kept
overnight at 30 °C under a steady stream of nitrogen.
Small samples (ꢀ0.1 mL) were withdrawn from each,
combined with ꢀ2 mL of methanol and the product
was extracted with chloroform and dried under vacuum.
The reaction temperature was next increased to reflux.
Samples were removed after 1 h and worked up (see Sec-
tion 4.2). Freshly prepared catalyst (0.5 mL, 0.005
mmol) was added to each solution and samples were
withdrawn after three additional one-hour periods
(Table 1). In a second experiment, a mixture of 245
mg (0.499 mmol) of 1, 140 mg (1.09 mmol) of o-fluoro-
phenol and 1 mL of toluene was combined with 3 mL of
6 (0.05 mmol) and heated to reflux under nitrogen.
Intermittently samples were withdrawn and 2 was iso-
lated and analyzed.
bined with 0.5 mL of CDCl in a 5-mm tube and
3
1
analyzed by H NMR on a Bruker AM 300 MHz or a
Varian Mercury 400 MHz spectrometer. The number
of monomeric units incorporated in the polymer chain
was calculated as the ratio of the integrated areas of
the methyl protons of the dodecyl substituents to the
methyl protons of the terminal propynyl groups. In
the later stages of the reactions, special care had to be
taken to measure the area of the methyl end groups with
any degree of accuracy. Spectra were recorded after 64
scans, with a one-second pulse delay. The area of the ter-
minal methyl signals was taken as one tenth of the meas-
ured (not printed) value of the integral step with the
amplitude set to 10 times higher than was used to meas-
ure the area of the dodecyl methyls. The values recorded
in Table 2 are accurate within ꢀ10%.
Reactions were discontinued when 2 began to sepa-
rate from the solution. A 5–10 mL portion of solvent
was added to the reaction mixture, heated to dissolve
4.5. Polymerization of 1 with 7 in o-dichlorobenzene
2 and filtered through a plug of cotton. The filtrate
was stirred consecutively with 5 mL of 10% aqueous so-
This reaction was carried out at 140 °C, under a
stream of nitrogen, using 470 mg (0.957 mmol) of 1,