Tris[(1H,1H,2H,2H-perfluoroalkyl) aryl]phoshites...

Details Tris[(1H,1H,2H,2H-perfluoroalkyl) aryl]phoshites... Tris[(1H,1H,2H,2H-perfluoroalkyl) aryl]phoshites...

2001-12-07

2003-03-18

Chang, Ceila (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Phosphorus containing

Reexamination Certificate

active

06534684

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a process for preparing tris[(1H,1H,2H,2H-perfluroalkyl)aryl] phosphites, referred to hereinbelow as fluorine-containing aryl phosphites.
The present invention also relates to the said fluorine-containing aryl phosphites and to their uses in particular in two-phase catalysis with a fluorine-containing phase.
PRIOR ART
This two-phase catalysis with a fluorine-containing phase has been described by Istvan T. Horwath et al. in patent U.S. Pat. No. 5,463,082.
The general concept of this catalysis is based on the use of a fluorinated phase which is immiscible with an organic phase without heating and generally miscible when heated.
The fluorinated phase is a solvent rich in C-F bonds (fluorocarbons or hydrofluorocarbons).
When not heated, the system consists of two phases:
a fluorinated phase which is a solvent rich in C-F bonds and which contains a catalyst made soluble in said fluorine-containing solvent by means of fluorine-containing chains,
a hydrocarbon-based organic phase, which is immiscible with the fluorine-containing phase, and which contains the reagents.
The catalysis reaction is carried out with heating in a phase which is generally homogeneous, that is to say that above a certain temperature a single phase is generally obtained in which the catalysis takes place. Once the reaction is complete, the catalysis is readily recovered by cooling the reaction medium to a temperature below the temperature of miscibility of the two phases.
Thus, in order to make the catalyst preferentially soluble in the fluorine-containing phase, it has been recommended to functionalize it with one or more perfluoroalkyl groups.
The perfluoroalkyl groups of the fluorine-containing phosphites used as coordination ligands have electron-withdrawing properties which may influence the coordination characteristics of the phosphorus atom and thus adversely modify the catalytic activity of the catalysts made with such fluorine-containing ligands.
In order to reduce these adverse effects of the perfluoroalkyl chains on the phosphorus atom, it has been proposed to introduce non-fluorine-containing groups known as “spacers” between the phosphorus atom and said perfluoroalkyl chain.
Examples of such spacers which may be mentioned are polymethylene radicals (CH
2
)
n
with n ranging from 1 to 3 and the phenylene radical —C
6
H
4
—.
As illustrations of fluorine-containing phosphites containing such spacers, mention will be made of tris (1H,1H,1H,2H,2H-perfluoroalkyl) phosphite mentioned by I. T. Horwath et al. in patent U.S. Pat. No. 5,463,082; tris(4-tridecafluorohexylphenyl) phosphite mentioned by E. G. Hope et al. in J. Chem. Soc. Perkin Trans. 1. 1997, pages 3609-3612, and the tris(perfluoroalkylphenyl) phosphites mentioned by T. Mathivet et al. in Tetrahedron Letters 39, 1998, pages 9411-9414.
In general, these fluorine-containing phosphites are obtained with low yields, by processes using expensive reagents and with long reaction times (several days) in particular, for the aryl phosphites containing perfluoroalkyl chains.
Thus, for example, E. G. Hope et al. (J. Chem. Soc. Perkin Trans. 1, 1997, pages 3609-3612) obtain tris(4-tridecafluorohexylphenyl) phosphite by synthesizing, in a first step, 4-tridecafluorophenol by reacting C
6
F
13
I dissolved in hexafluorobenzene with para-iodophenol in the presence of copper in DMSO at 80° C., under nitrogen for 6 days. In a second step, the 4-tridecafluorophenol, obtained in a yield of 63%, is introduced slowly with triethylamine into a solution of PCl
3
in Et
2
O. The tris(4-tridecafluorohexylphenyl) phosphite is obtained in a yield of 55.7%, ie an overall yield of 35%.
Mathivet et al. (Tetrahedron Letters, 39, 1998, pages 9411-9414) also use the reaction of a perfluoroalkyl iodide with bromophenol or iodophenol to obtain the (perfluoroalkyl)phenols, but they perform the process in DMSO. They obtain the (perfluoroalkyl)phenols in yields ranging from 23% for 2-methyl-4-perfluorooctylphenol to 70% for 4-perfluorooctylphenol.
The use of the reaction between an iodophenol or bromophenol and an iodoqerfluoroalkyl in the presence of copper (Ullmann reaction) does not allow 1H,1H,2H,2H-perfluoroalkyl groups to be introduced onto the phenol nucleus.
Japanese patent application JP 7-179 384 describes the production of 4-(1H,1H,2H,2H-perfluoroalkyl)phenol by carrying but the following reactions:
reaction of an alcohol CF
3
(CH
2
)
p
CH
2
CH
2
OH with triflic acid to give an ester of formula: CF
3
(CH
2
)
p
CH
2
CH
2
OSO
2
CF
3
(with p=1 to 15),
followed by reaction of said ester with a Grignard reagent obtained from magnesium and a p-alkoxyhalobenzene to give the 4-(1H,1H,2H,2H-perfluoroalkyl)-alkoxybenzene and, after cleavage of the alkoxy function, to give the 4-(1H,1H,2H,2H-perfluoroalkyl)-phenol in yields in the region of 50%.
However, performing the process in this way has the drawback of using expensive reagents: the alcohols CF
3
(CF
2
)
p
CH
2
CH
2
OH and triflic acid, the latter also being difficult to handle.
DESCRIPTION OF THE INVENTION
A process has now been found for preparing tris[(1H,1H,2H,2H-perfluoroalkyl)phenyl] phosphites of formula (I):
in which the (5-x)R, which may be identical or different, represent a hydrogen atom, a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 10; a halogen atom such as bromine or chlorine; Rf represents a 1H,1H,2H,2H-perfluoroalkyl radical C
n
F
2n+1
C
2
H
4
— with n ranging from 4 to 20 and preferably ranging from 8 to 20, x is an integer ranging from 1 to 5 and preferably ranging from 1 to 3; characterized in that it comprises the steps consisting in:
a) preparing a Grignard reagent of formula (II)
 from an alkoxyhalobenzene of formula (III):
 in which formulae R
1
represents a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 6 and preferably ranging from 1 to 3, X represents a bromine, chlorine or iodine atom, R and x having the same meanings as in formula (I), followed by reacting said compound (II) with a 1-iodo-1H,1H,2H,2H-perfluoroalkane C
n
F
2n+1
C
2
H
4
I (IV), represented hereinbelow by RfI, to give a (1H,1H,2H,2H-perfluoroalkyl)alkoxybenzene (V):
c) converting the alkoxy function R
1
O— of (V) obtained in step a) into a hydroxyl function HO
−
to give a (1H,1H,2H,2H-perfluoroalkyl)hydroxybenzene of formula (VI):
d) reacting compound (VI) obtained in step b) with PCl
3
to give the tris[(1H,1H,2H,2H-perfluoroalkyl)phenyl] phosphite (I).
The Grignard reagent (II) is obtained according to methods known to those skilled in the art, which consist in reacting an alkoxyhalobenzene of formula (III) with magnesium in an ethereal solvent such as diethyl ether or THF at room temperature.
Preferably, X represents a bromine atom.
As illustrations of bromoalkoxybenzenes which may be used according to the present invention, mention will be made of 4-bromoanisole, 3-bromoanisole, 2,4-dibromoanisole, 2,4,6-tribromoanisole, 4-bromo-2,6-dimethylanisole and 4-bromophenetole.
The reaction between the Grignard reagent (II) and the iodofluoro compound RfI is carried out in the presence of copper iodide CuI used in weight amounts ranging from 0.1% to 10% relative to the compound RfI.
Preferably, the ethereal solution of the Grignard reagent is introduced slowly into an ethereal suspension of RfI plus CuI at a temperature in the region of 0° C. and, once the addition is complete, the reaction medium is then maintained at 20-30° C. with stirring for a period of not more than 6 hours and preferably between 1 and 3 hours.
Then, the medium is hydrolyzed and the compound (V) is isolated according to methods known to those skilled in the art (extraction, washing, drying and removal of the solvent under reduced pressure).
As illustrations of RfI which may be used according to the present invention, mention will be made of 1-iodo-1H,1H,2H,2H-perfluorodecane CF
3
(CH
2
)
7
CH
2
CH
2
I and 1-iodo-1H,1H,2H,2H-perfluorooctane CF
3
(CH
2
)
5
CH
2
CH
2
I

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