Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-06-09
2001-02-20
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S615000, C562S586000, C562S587000, C562S588000
Reexamination Certificate
active
06191314
ABSTRACT:
The present invention relates to a process for obtaining (per)fluoropolyethers (Z-PFPE) substitued at one or both end groups with a halogen atom selected between bromine or iodine. The obtained (per)fluoropolyethers have the structure
A—CF
2
—O—(CF
2
CF
2
O)
p
—(CF
2
O)
q
—CF
2
—B (III)
wherein
A=B=halogen; or A=halogen and B=COOH or F, and halogen=I, Br;
p and q are integers such as to give number average molecular weight (MW) in the range 350-5000 and p/q=0.5-2.0.
These compounds are obtained through an industrial process using mild reaction conditions, inexpensive reactants and having improved halogenated product yields.
More specifically the present invention relates to a process to obtain di-iodinated alpha, omega (per)fluoropolyethers (Z-PFPE) having the structure
I—CF
2
—O—(CF
2
CF
2
O)
p
—(CF
2
O)
q
—CF
2
—I (I)
wherein
p and q are integers to give molecular weight (MW) by number in the range 350-5000 and p/q=0.5-2.0.
Reactions allowing for the introduction of a halogen atom in the perfluoropolyether end groups starting from the corresponding carboxylic acids or derivatives thereof are known in the art.
EP 348,948 describes a process for obtaining perfluoropolyether mixtures having at one or at both chain ends an iodine atom, wherein a perfluoropolyether mono- or diacylfluoride is reacted with iodine in the presence of at least a salt selected from the alkaline and earth-alkaline metal carbonates, in a perhalogenated solvent having a boiling point in the range 180°-260° C. The reaction occurs at high temperatures and is triggered by carbonate decomposition. By operating at these high temperatures iodine tends to sublimate and its concentration in the solvent decreases. Moreover the sublimated iodine which solidifies can obstruct the reactor. In order to overcome these drawbacks with the above solvents which at the reaction temperatures are in reflux conditions and maintain the iodine in solution as described in the cited '948 reference are used. The yields are high using the acid halide. Tests carried out by the Applicant have shown that the process is not applicable to Z-PFPE: the main reaction is of decomposition (“zipping”) of the perfluoropolyether chain with COF
2
release. The iodinated Z-PFPE yields are very low, lower than 5%, the product is essentially monoiodinated. Moreover the molecular weight is much lower than the precursor. The separation of the mixture is extremely difficult and in any case the '948 does not give any indication about the Z-PFPE separation method. The separation method indicated in the examples is not applicable to the iodinated Z-PFPEs.
U.S. Pat. No. 5,455,373 relates to a method to obtain mono- and dibromo perfluoroalkane derivatives by treating the corresponding mono- and bicarboxylic acids with bromine in the presence of fluorine. Monoiodides are likewise synthetized with very low yields.
In EP 803,526 in the name of the Applicant a method to obtain Z-PFPE type perfluoropolyethers with brominated or iodinated end groups is described. The method consists of subjecting a peroxidic perfluoropolyether to thermal treatment in absence of UV radiations at temperatures in the range 120°-280° C. in the presence of brominated or iodinated compounds such as CBr
4
, CHBr
3
, CHI
3
, CH
2
I
2
. The iodinated or brominated end groups starting from Z-PFPE peroxides are of the type: —CF
2
—CF
2
I, —CF
2
I, —CF
2
—CF
2
Br, —CF
2
Br. No separation method of these kinds of di-iodinated derivatives is indicated. In this patent a thermal treatment at high temperatures and expensive iodinated/brominated reactants are used.
The need was felt to have available a process for preparing di-iodinated derivatives having a Z-PFPE structure with an industrial process using less severe conditions and less expensive reactants and having improved di-iodinated product yields.
An object of the invention is therefore a process to obtain (per)floropolyethers (Z-PFPE) substituted at one or both end groups with a halogen atom selected between bromine or iodine, having the formula:
A—CF
2
—O—(CF
2
CF
2
O)
p
—(CF
2
O)
q
—CF
2
—B (III)
wherein
A=B=halogen; or A=halogen and B=COOH or F, and halogen=I or Br;
p and q are integers such as to give number average molecular weight (mw) in the range 350-5000 and p/q=0.5-2.0,
consisting in treating, with a halogen selected between iodine or bromine, in a polyhalaogenated organic solvent, at temperatures in the range 20°-80° C., preferably 30°-50° C., di- or poly-acylperoxides having average equivalent weight in the range 350-5000, of formula:
T—CF
2
—O—[(CF
2
CF
2
O)
p
—(CF
2
O)
q
—CF
2
—CO—O—O—CO—CF
2
—(OCF
2
)
q
—(OCF
2
CF
2
)
p
]
y
—OCF
2
—COOH (II)
wherein:
y is an integer in the range 1-5;
p and q are integers such as to give the indicated EW of formula (II) and p/q=0.5-2.0;
T=COOH or F with the proviso that when T=COOH y=1-5, and when T=F then y=1.
The diacyl peroxides of formula (II) are obtained by starting from perfluoroether acylhalides having average molecular weights (MW) by number in the range 350-5000, and having the formula:
Y′″—CF
2
—O—(CF
2
CF
2
O)
p
—(CF
2
O)
q
—CF
2
—CO—Y″ (II′)
wherein
Y″=Cl, F;
Y′″=CO—Y″, F;
by reacting them with H
2
O
2
in a basic environment. A preferred process for obtaining the diacylperoxides of formula (II) is carried out at a temperature in the range −5° C.-+5° C. in a mixture formed by two immiscible liquid phases having a total volume equal to at most ⅔ of that of the reactor, kept under stirring so that no emulsions are formed, said liquid phases being the following:
an organic phase formed by a polyhalogenated solvent having very low ODP, in an higher amount,
an aqueous alkaline solution containing an excess of hydrogen peroxide with respect to the added halide;
said process comprising the following steps:
a) addition of the (per)fluoropolyether acyl-halide of formula (II′) by cooling so that the &Dgr;T thermal increase, with reference to a reactor having an internal volume in the range 50-250 ml cooled by a 2 l volume cryogenic bath having a temperature comprised between −40° C. and −80° C., is in the range 6° C.-20° C. and when the addition is over, the temperature decreases to the initial one in a time in the range 0.1-5 minutes;
b) reacting, at the initial temperature, for the necessary time (t
max
) to obtain the 75% conversion of the acyl-halide (II′), determined by quantitative FTIR analysis;
c) reaction interruption, by stopping stirring and allowing the phases to be separated by maintaining the system at the initial temperature, and recovery of the organic phase containing the perfluoropolyether acyl-peroxides of formula (II).
The polyhalogenated solvents can be the same as those of the present invention.
Preferably in step a) the ratio between the alkali moles with respect to the —CO—Y″ functional group equivalents is in the range 1.2-1.8 and the ratio between the aqueous phase ml volume and the base grams is in the range 5-10; preferably the organic phase volume is half than that of the reactor.
This process to obtain peroxides has been described in a Patent Application in the name of the Applicant filed on the same day as the present invention and herein incorporated by reference (Italian Patent Application MI98A001328); corresponding U.S. application Ser. No. 09/328,399, having the title: perfluoropolyether acylperoxides and process for their preparation.
The reaction time to prepare the halogenated compounds of formula (III) of the present invention is generally comprised from 1 minute to 24 hours, preferably from 1 to 3 hours. Specifically the temperatures and the reaction time are related to the equivalent weight of the starting peroxide.
In particular, when the peroxides of formula (II) have equivalent weights in the range 350-4000, the temperature is in t
Tortelli Vito
Wlassics Ivan
Arent Fox Kintner Plotkin & Kahn
Ausimont S.p.A.
Keys Rosalynd
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