Synthesis of hyperbranched organometallic polymers and their...

Details Synthesis of hyperbranched organometallic polymers and their... Synthesis of hyperbranched organometallic polymers and their...

2002-03-26

2004-07-06

Moore, Margaret G. (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From heavy metal or aluminum reactant having at least one...

C556S011000, C501S154000

Reexamination Certificate

active

06759502

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to certain hyperbranched organometallic polymers which are useful as precursors to certain ceramic materials, processes for the preparation of such polymers and the preparation of ceramic materials from such polymers, ceramic materials and their use as ferromagnetic materials and electrically conductive materials.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a process for the preparation of a hyperbranched organometallic polymer which comprises reacting dilithioferrocene or a complex thereof with a compound of the general formula RSiX
3
in which R represents a hydrogen atom or an optionally substituted alkyl, alkenyl or aromatic group and each X independently represents a halogen atom, optionally in the presence of an anionic initiator.
Preferably, the compound of general formula RSiX
3
is added as a solution in an ether solvent such as tetrahydrofuran. The reaction is conveniently carried out at a temperature from −80° C. to room temperature (20 to 30° C.).
In this specification, any alkyl group, unless otherwise specified, may be linear or branched and may contain up to 24, preferably up to 20, and especially up to 18, carbon atoms. Preferred alkyl groups are n-alkyl groups, that is, linear alkyl groups, with methyl, octyl, dodecyl, hexadecyl and ociadecyl groups being especially preferred.
Any alkenyl group, unless otherwise specified, may be linear or branched and may contain up to 12, preferably up to 6, and especially up to 4, carbon atoms. Linear alkenyl groups are preferred and ethenyl (vinyl), propenyl and butenyl groups are especially preferred. Ethenyl groups are particularly preferred.
An aromatic group may be any aryl or heteroaryl group, with aryl groups being particularly preferred. An aryl group may be any monocyclic or polycyclic aromatic hydrocarbon group and may contain from 6 to 14, especially 6 to 10, carbon atoms. Preferred aryl groups include phenyl, naphthyl, anthryl and phenanthryl groups, especially a phenyl or naphthyl, and particularly a phenyl, group. A heteroaryl group may be any aromatic monocyclic or polycyclic ring system which contains at least one heteroatom. Preferably, a heteroaryl group is a 5- to 14-membered, and especially a 5- to 10-membered, aromatic ring system containing at least one heteroatom selected from oxygen, sulphur and nitrogen atoms. Preferred heteroaryl groups include pyridyl, pyrrolyl, furyl, thienyl, indolinyl, imidazolyl, pyrimidinyl, pyrazinyl, oxazolyl, thiazolyl, purinyl, quinolinyl, quinoxalinyl, pyridazinyl, benzofuranyl, benzoxazolyl and acridinyl groups.
A halogen atom may be a fluorine, chlorine, bromine or iodine atom. Chlorine atoms are particularly preferred.
When any of the foregoing substituents are designated as being optionally substituted, the substituent groups which are optionally present may be any one or more of those customarily employed in the development of polymers and ceramic materials and/or the modification of such compounds to influence their structure/activity, stability or other property. Specific examples of such substituents include, for example, halogen atoms, nitro, cyano, hydroxyl, alkyl, haloalkyl, alkoxy, haloalkoxy, amino, alkylamino, dialkylamino, formyl, alkoxycarbonyl, carboxyl, alkanoyl, alkylthio, alkylsulphinyl, alkylsulphonyl, carbamoyl and alkylamido groups. When any of the foregoing substituents represents or contains an alkyl substituent group, this may be linear or branched and may contain up to 12, preferably up to 6, and especially up to 4, carbon atoms. A halogen atom may be a fluorine, chlorine, bromine or iodine atom and any group which contains a halo moiety, such as a haloalkyl group, may thus contain any one or more of these halogen atoms.
It is preferred that a complex of dilithioferrocene with tetramethylethylene diamine (TMEDA) is used. This complex of dilithioferrocene with TMEDA, that is, dilithioferrocene. TMEDA, may be prepared by reacting ferrocene with TMEDA in the presence of a solvent and a lithiating agent. Preferably, the solvent is a hydrocarbon solvent, such as anhydrous hexane. It is also preferred that the lithiating agent is n-butyl lithium. This reaction may be conveniently carried out at a temperature from −8° C. to room temperature (20 to 30° C.).
The process steps described above may also be carried out in a one-pot reaction. According to a second aspect of the invention there is therefore provided a one-pot process for the preparation of a hyperbranched organometallic polymer which comprises reacting ferrocene with TMEDA in the presence of a solvent and a lithiating agent, optionally adding an anionic initiator, and reacting the resultant mixture with a compound of the general formula RSiX
3
in which R represents a hydrogen atom or an optionally substituted alkyl, alkenyl or aromatic group and each X independently represents a halogen atom.
The lithiating agent in the above processes may be any compound which is capable of attaching lithium atoms to the ferrocene. One such lithiating agent is n-butyl lithium.
In some instances, it may be necessary or desirable to add an agent to facilitate the reaction between the dilithioferrocene or complex thereof and the compound of general formula RSiX
3
. For instance, it may be preferable to add an anionic initiator to get the ring moieties possibly existing in the system open. N-Butyl lithium may act as an anionic initiator in this respect. Preferably, this is added to the reaction mixture under an inert atmosphere, such as nitrogen.
As n-butyl lithium can function both as a lithiating agent and an anionic initiator, it is particularly advantageous to use this compound in the processes of the present invention.
In both processes, it is preferred that R represents an optionally substituted C
1-24
alkyl or C
2-12
alkenyl group. Preferably, R represents an optionally substituted C
1-20
, especially C
1-18
, alkyl group or an optionally substituted C
2-6
, especially C
2-4
, alkenyl group. Preferably, such alkyl and alkenyl groups arc linear. It is especially preferred that R represents an n-alkyl or linear alkenyl group, with methyl, n-octyl, n-dodecyl, n-hexadecyl, n-octadecyl and ethenyl (vinyl) groups being especially preferred. The optional substituents may be any of those listed previously with halogen atoms being particularly preferred.
Although each X may represent a different halogen atom, it is preferred that all three X atoms represent the same halogen atom. Preferably, each X represents a chlorine atom.
In a third aspect, the invention provides a hyperbranched organometallic polymer produced by any of the processes described above.
Such hyperbranched organometallic polymers are believed to be novel compounds. According to a fourth aspect of the invention there is therefore provided a hyperbranched organometallic polymer selected from the group consisting of poly [1,1′-ferrocenylenesilynes], poly [1.1′-ferrocenylene-(alkyl)silynes], poly [1.1′-ferrocenylene(alkenyl)silynes] and poly [1,1′-ferrocenylene(aromatic)silynes]. In these polymers, every silicon atom is surrounded on average by 3/2 (1.5) ferrocenylene moieties and one R moiety.
Preferably, the hyperbranched organometallic polymer has a general formula
in which Fc represents a 1,1′-ferrocenylene group, R represents a hydrogen atom or an optionally substituted alkyl, alkenyl or aromatic group and n represents an integer greater than 1.
It is preferred that the polymer described above contains at least one moiety of the general formula
in which Fc and R are as defined above.
The polymer may have a structure of the general formula:
in which Fc and R are as defined above.
It is believed that such structures form when the silicon atom is in a sterically accessible environment thereby promoting a three-directional propagating reaction. This situation tends to arise when R is relatively small. Thus, polymers of the invention in which R represents a methyl or

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