Organic compounds -- part of the class 532-570 series – Organic compounds – Boron containing
Reexamination Certificate
2000-11-28
2002-05-14
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Boron containing
C564S008000
Reexamination Certificate
active
06388138
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for making a magnesium di[tetrakis(
F
aryl)borate], which can be further reacted with an organic cation salt to produce the corresponding organic cation tetrakis(
F
aryl)borate. When the organic cation is a protic ammonium cation or a triarylmethyl cation, the tetrakis(
F
aryl)borate salt is useful as a cocatalyst for metallocene-catalyzed polymerization. When the organic cation is an onium cation, the tetrakis(
F
aryl)borate salt is useful as an initiator in the crosslinking of polyorganosiloxanes.
BACKGROUND
It is known that when a halomagnesium salt of a tetrakis(aryl)borate anion is obtained, other magnesium salts are usually also present. Often, the removal of these other magnesium salts is necessary because they interfere with the intended use of the halomagnesium salt of the tetrakis(aryl)borate anion. Reaction of the halomagnesium tetrakis(aryl)borate with an alkali metal salt to form an alkali metal tetrakis(aryl)borate is a separation method that has been used. For various descriptions of this method, see Nishida et al.,
Bull. Chem. Soc. Jpn.,
1984, 57, 2600; Goldberg et al.,
Zhurnal Organicheskoi Khimii,
1989, 25, 1099; Fujiki et al.,
J. Fluorine Chemistry,
1992, 57, 307; and EP 913,400. A method which cleanly separates other magnesium salts from the halomagnesium salt of the tetrakis(aryl)borate without the introduction of a reagent such an alkali metal salt would be desirable.
Once a suitably pure tetrakis(aryl)borate salt is obtained, it can be reacted with an appropriate compound to yield an organic cation salt of the tetrakis(aryl)borate. It is often desirable to purify these organic cation tetrakis(aryl)borates. It is known that phenyl(dimethyl)ammonium tetrakis(pentafluorophenyl)borate can be purified via the formation of a liquid clathrate. The liquid clathrate is formed in toluene at temperatures typically above 55° C.; at temperatures less than about 55° C., the compound precipitates. While the liquid clathrate provides relatively pure phenyl(dimethyl)ammonium-tetrakis(pentafluorophenyl)borate, it is inconvenient to keep the clathrate-containing solution and apparatus at elevated temperatures while performing necessary manipulations. A more convenient purification method is desirable.
SUMMARY OF THE INVENTION
This invention provides for the formation of a magnesium di[tetrakis(
F
aryl)borate], which can be, but need not be, isolated. The magnesium di[tetrakis(
F
aryl)borate] can be reacted, in isolated or unisolated form, with a salt of a desired cation to form the desired cation tetrakis(
F
aryl)borate. Certain of these tetrakis(
F
aryl)borates can be conveniently purified via the formation of a liquid clathrate at ambient temperatures.
A first embodiment of this invention is a process which comprises contacting i) a solution comprising a liquid organic medium, which is substantially immiscible with water, and a halomagnesium tetrakis(
F
aryl)borate, and ii) water, in such proportions that a two-phase mixture is obtained. A solution of a magnesium di[tetrakis(
F
aryl)borate] in the organic phase of a two-phase water/liquid organic medium is produced. Each aryl group of the tetrakis(
F
aryl)borate has bonded directly to an aromatic ring at least two fluorine atoms, or at least two perfluorohydrocarbyl groups, or at least one fluorine atom and at least one perfluorohydrocarbyl group. The liquid organic medium is comprised of one or more liquid dihydrocarbyl ethers, one or more liquid hydrocarbons, one or more liquid halogenated hydrocarbons, or mixtures thereof.
The borate anion has four fluorine-containing aryl groups, each of which has bonded directly to an aromatic ring at least two fluorine atoms, or at least two perfluorohydrocarbyl groups, or at least one fluorine atom and at least one perfluorohydrocarbyl group. It is preferred that at least two fluorine atoms, or at least two perfluorohydrocarbyl groups are bonded directly to an aromatic ring. Each position on the aromatic ring(s) of the
F
aryl group that is not a fluorine atom or a perfluorohydrocarbyl group is substituted by a hydrogen atom, a hydrocarbyl group, an alkoxy group, or a silyl group. The
F
aryl groups may be the same or different from each other; it is preferred that all four
F
aryl groups are the same.
Another embodiment of this invention is a process which comprises mixing at least a portion of the magnesium di[tetrakis(
F
aryl)borate] produced in the first embodiment in a liquid medium with a salt selected from a) a protic ammonium salt, b) an onium salt, and c) a triarylmethyl salt, wherein the triarylmethyl cation has three aryl groups bound to a central carbon atom, to produce a protic ammonium tetrakis(
F
aryl)borate, an onium tetrakis(
F
aryl)borate, or a triarylmethyl tetrakis(
F
aryl)borate. The protic ammonium cation has the formula [R
3
NH]
⊕
, in which each R is independently a hydrocarbyl group containing up to about thirty carbon atoms, and the onium cation has the formula [ER
n
]
⊕
, wherein E is an element of any of Groups 15-17 of the Periodic Table, wherein each R is independently a hydrocarbyl group containing up to about thirty carbon atoms, and wherein n is equal to the valence of E plus one. For labeling of the groups of the Periodic Table, see for example, the Periodic Table appearing in
Chemical
&
Engineering News,
1985, 69, 26.
Still another embodiment of this invention is a process which comprises mixing, in a liquid medium, at least a portion of the magnesium di[tetrakis(
F
aryl)borate] produced in the first embodiment and at least one metal salt. An inorganic metal tetrakis(
F
aryl)borate is produced.
Yet another embodiment of this invention is a process which comprises mixing, in a liquid medium, at least a portion of the metal tetrakis(
F
aryl)borate produced in the preceding embodiment with a salt selected from a) a protic ammonium salt, b) an onium salt, and c) a triarylmethyl salt, to produce a protic ammonium tetrakis(
F
aryl)borate, an onium tetrakis(
F
aryl)borate, or a triarylmethyl tetrakis(
F
aryl)borate. The protic ammonium cations, onium cations, and triarylmethyl cations are as described above.
Further embodiments of this invention will be apparent from the ensuing description and appended claims.
FURTHER DETAILED DESCRIPTION OF THE INVENTION
The liquid organic medium of the solution that also comprises a halomagnesium tetrakis(
F
aryl)borate is comprised of one or more liquid dihydrocarbyl ethers, one or more liquid hydrocarbons, one or more halogenated hydrocarbons, or mixtures thereof. Those ethers, hydrocarbons, and halogenated hydrocarbons that are substantially immiscible with water, such that a two-phase mixture will be formed, are preferred. Ethers that may be used include, for example, diethyl ether, di-n-propyl ether, diisopropyl ether, tert-butyl ethyl ether, diheptyl ether, and similar compounds. Preferred ethers are diethyl ether and diisopropyl ether, especially diethyl ether. Suitable hydrocarbons include pentane, hexane, methylcyclohexane, heptane, octane, cyclooctane, nonane, benzene, toluene, and xylenes. Halogenated hydrocarbons that may be used include dichloromethane, trichloromethane, 1,2-dichloroethane, 1-bromo-2-chloroethane, 1-bromopropane, (chloromethyl)cyclopropane, 1-bromobutane, 1-bromo-2-ethylbutane, 1,1-dichloro-3,3-dimethylbutane, cyclobutyl chloride, neopentyl chloride, 1-bromo-5-chloropentane, cyclopentyl bromide, 1,6-dibromohexane, trans-1,2-dichlorocyclohexane, 1-chloroheptane, and 1,8-dichlorooctane.
The proportions of water and liquid organic medium are such that either component can be present in a larger amount than the other; however, a large excess of either is unnecessary. Preferred ratios of water to liquid organic medium are in the range of from about 0.2 parts to about three parts by volume of water per part by volume of liquid organic medium.
The halogen atom of the halomagnesium moiety of the halomagnesium tetrakis(
F
aryl)borate may be a ch
Albemarle Corporation
Pippenger Philip M.
Vollano Jean F.
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