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H. Sawada et al. / Journal of Fluorine Chemistry 107 (2001) 59±62
Scheme 1.
Scheme 2.
RF CF(CF3)OCF2CF(CF3)OC3F7) were prepared by the
reactions of 5-amino-8-hydroxyquinoline (AQui±OH) with
the corresponding isocyanate co-oligomers (RF±(IMBO)x±
(Co±M)y±RF) in which the reactive isocyanate moieties
were protected as 2-butanone oxime adducts according to
our recently reported method [19]1 as shown in the following
Scheme 1.
The ¯uorinated co-oligomers thus obtained were slightly
soluble in water; however, they were easily soluble in
MeOH, EtOH, THF, chloroform and DMSO. Therefore,
these ¯uorinated co-oligomers are applicable to new ¯uori-
nated surfactant catalysts.
A typical solvolysis study was performed as follows.
Solvolysis reactions were followed from the absorbance
of the p-nitrophenoxide anion at 400 nm in aqueous metha-
nol buffer as shown in Scheme 2.
The sample cuvette was ®lled with 3.0 ml of a fresh
solution containing ¯uoroalkylated co-oligomers in a 3:1
(v/v) aqueous methanol buffer solution (0.05 M phosphate,
pH 9.2), and the solution was equilibrated for 2 h at 308C. A
solution (12 ml) of p-nitrophenyl propanoate (PNP) in
dioxane was added by microsyringe. The reaction mixture
was mixed quickly by shaking, and absorbance at 400 nm
was recorded as a function of time.
1 A typical experiment for the synthesis of RF±(Qui±OH)x±(DMAA)y±
RF [RF CF(CF3)OCF2CF(CF3)OC3F7] is as follows: perfluoro-2,5-
dimethyl-3,6-dioxanonanoyl peroxide (2.5 mmol) in 1:1 mixed solvents
(AK-225) of 1,1-dichloro-2,2,3,3,3-pentafluoropropane-1,3-dichloro-
1,2,2,3,3-pentafluoropropane (30 g) was added to a mixture of isocyana-
toethyl methacrylate 2-butanone oxime adduct (2.5 mmol), N,N-dimethy-
lacrylamide (DMAA: 25 mmol) and AK-225 (100 g). The solutions was
stirred at 458C for 5 h under nitrogen. After evaporating the solvent, the
crude products were reprecipiated from methanol±hexane to give RF±
(IMBO)x±(DMAA)y±RF [RF CF(CF3)OCF2CF(CF3)OC3F7] (3.64 g,
Mn 1640). A solution of the obtained co-oligomer [0.6 mmol (1.01 g)]
and 5-amino-8-hydroxyquinoline (AQui±OH: 1.2 mmol) in DMF (10 g)
was stirred at 1208C for 1 h. After evaporating the solvent under reduced
pressure, the crude products were reprecipitated from chloroform±hexane
to give RF±(Qui±OH)x±(DMAA)y±RF [RF CF(CF3)OCF2CF(C-
2CF(CF3)OC3F7; 0.84 g]. This cooligomer showed the following spectral
data: IR n (cm 1) 3450 (OH), 1720, 1631 (C=O), 1320 (CF3), 1248 (CF2);
1H NMR (CDCl3) d 0.78±3.20 (CH2, CH, CH3), 3.31±4.29 (CH2), 6.78±
9.03 (5H); 19F NMR (CDCl3, ext. CF3CO2H) d 4.21 to 7.95 (26F),
54.00 (6F), 69.95 (2F); average molar mass ꢀMn 4920 (Mw/
Mn 1:20; x:y 12:88). Molecular weight and co-oligomerization ratio
were determined by gel permeation chromatography (GPC: calibrated with
standard polystyrenes by using tetrahydrofuran as the eluent) and 1H
NMR, respectively.
Fig. 1 shows the appearance of the p-nitrophenoxide ion
in the solvolysis of PNP with RF±(Qui±OH)x±(DMAA)y±RF
(see Scheme 1) and the corresponding non-¯uorinated co-
oligomer: ±(Qui±OH)x±(DMAA)y± as a function of time. An
unmeasurably rapid increase (``burst'') is followed by slow
linear increase, which can be derived into the apparent ®rst-
order solvolysis of PNP. In the absence of co-oligomers, the
solvolysis of PNP catalyzed by aqueous methanol buffer
solution shows no burst of p-nitrophenoxide, and followed
an apparent ®rst order equation. Interestingly, a more rapid
increase was observed in the case of RF±(Qui±OH)x±
(DMAA)y±RF compared to the corresponding non-¯uori-
nated co-oligomer. The magnitude of the initial burst was
proportional to the concentration of the co-oligomer as
shown in Fig. 2.
The rate constant (ksp 1:98 Â 10 4 s 1) of PNP solvo-
lysis in the absence of co-oligomers was found to be
similar to the values for ksp(PNP) (data not shown) of