Oligomeric anilines and their synthesis

Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing

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564434, C07C24900

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active

061601772

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention generally describes novel oligomeric anilines and novel methods of synthesizing oligomeric anilines.


BACKGROUND OF THE INVENTION

Polyaniline has been known for over 100 years and has been recently studied due to its properties as a conductive polymer after being doped with an appropriate species. Polyaniline is the name given to the polymer having the structure, in a completely reduced leucoemeraldine oxidation state, of the general formula: ##STR2## where n is greater than about 25. Oligomers of aniline, having the above structure where n is far less than 25, have attracted less attention in the scientific community.
Polyanilines can, in principle, exist in other oxidation states. Masters et al, Syn. Met., 41-43, 715 (1991). For example, polyanilines can exist in the completely oxidized pernigraniline oxidation sate of the general formula: ##STR3## where n is about 25 or more.
Polyanilines can also exist in the partially oxidized emeraldine oxidation state of the general formula: ##STR4## where n is about 25 or more.
The emeraldine oxidation state can be protonated by protonic acids, e.g., HA, to give polymers of the general formula: ##STR5## where n is about 25 or more, which exhibit a significant increase in electrical conductivity.
The synthesis of several oligomeric anilines including, for example, dianiline, N,N'-(4'-aminophenyl)phenylenediamine (e.g., trimer), N,N'-(4,4'-aminophenyl)phenylenediamine (e.g., amino-capped trimer), tetramer, phenyl-capped tetramer, phenyl-capped hexamer and phenyl-capped octamer, is described in the literature by U.S. Pat. No. 2,041,782, Willstatter et al, Ber., 40, 2665 (1907); Honzl et al, J. Polym. Sci., 22, 451 (1968); Liu et al, J. Am. Chem. Soc., 108, 8311 (1986); Wei et al, Tetrahedron Letters, 37, 731 (1996); and Green and Woodhead, J. Chem. Soc., 97, 2388 (1910).
The synthesis of some oligomers of aniline by the oxidative reaction of dianiline in an acidic aqueous solution is described by Willstatter et al, Ber., 40, 2665 (1907). However, attempts to prepare higher oligomers through the oxidative coupling of a tetraaniline in the emeraldine oxidation state, as described by Wei et al, J. Polym. Sci. Pt. A., 27, 2385 (1989), have been unsuccessful.
It is now universally recognized, as described by MacDiarmid and Epstein, Faraday Discuss Chem. Soc., 88, 317 (1989), that the so-called "octamer" of aniline allegedly produced by the oxidative polymerization of aniline, as described by Green and Woodhead, supra, and Green and Woodhead, J Chem. Soc., 101, 1117 (1912), is actually a polymer of aniline having a molecular weight of about 325,000.
The present invention describes, among other things, novel oligomeric anilines and novel methods of synthesizing oligomeric anilines. The oligomeric anilines have utility as conductive materials in similar applications as polyanilines.


SUMMARY OF THE INVENTION

The present invention describes novel compounds of the formula (I): ##STR6## where n is 2 or 4.
The present invention describes novel methods of producing compounds of the formula (I), where n is 2 or 4. Tetraaniline in the emeraldine oxidation state is prepared and converted to tetraaniline in the leucoemeraldine oxidation state. The tetraaniline in the leucoemeraldine oxidation state is then contacted with an oxidative coupling agent to produce compounds of the formula (I) where n is 2 or 4.
These, as well as other, aspects of the present invention will become apparent from the following detailed description.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of a gel permeation chromatography (GPC), taken in a tetrahydrofuran solvent, showing the molecular weights of known polystyrenes, phenyl-capped dimers, dianiline and phenylenediamine, as well as the experimentally determined molecular weights of tetraaniline (tetramer), a novel octaaniline (8-mer) and a novel hexadecaaniline (16-mer), all of which are in their emeraldine oxidation states, synthesized by the novel methods of the present invention.
FIG. 2 is a graph sho

REFERENCES:
Green et al., Aniline-black and allied compounds Part I, J. Chem. Soc., vol. 97, (1910), pp. 2388-2403.
Green et al., Aniline-black and allied compounds Part II, J. Chem. Soc., vol. 101, (1912), pp. 1117-1123.
Honzl et al., Polyaniline Compounds. II. The linear oligoaniline derivatives tri-, tetra-, and hexaanilinobezene and their conductive complexes, J. Polymer Sci., No. 22, (1968), pp. 451-462.
Lu et al., Phenyl-capped octaaniline (COA): An excellent model for polyaniline, J. Am. Chem. Soc., vol. 108, (1986), pp. 8311-8313.
MacDiarmid et al., Polyanilines: A novel class of conducting polymers, Faraday Discuss. Chem. Soc., vol. 88, (1989), pp. 317-332.
Masters et al., Polyaniline: Allowed oxidations states, Synthetic Metals, vol. 41-43, (1991), pp. 715-718.
Wei et al., A one-step method to synthesize N,N'-BIS (4'-aminophenyl)-1,4-quinoenediimine and its derivatives, Tetraedron Letters, vol. 37, No. 6, (1996), pp. 731-734.
Wei et al., A study of the mechanism of aniline polymerization, J. Polym. Sci. Pt. A., vol. 27, (1989), pp. 2385-2396.
Willstatter et al., Ber., vol. 40, (1907), p. 2665-3689.

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