Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-04-08
2003-09-16
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06620979
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel high purity 9,9-bis (4-hydroxyphenyl) fluorene and to methods of preparation and purification thereof.
2. Background of the Art
In the modern polymeric manufacturing industry, bisphenols are used on a large scale in polycondensation reactions, particularly as monomers in the preparation of epoxy resins, polyurethanes, polycarbonates, polyethers and polyesters with especially high thermal resistance and good optical properties.
The compound 9,9-Bis-(4-HydroxyPhenyl) Fluorene and its substituted derivatives, generically known as BHPF, or Bisphenol F, is a useful monomer for the synthesis of the above mentioned polymers, particularly for the synthesis of polyesters, and especially for the preparation of polyarylates, i.e., polymers obtained from the copolymerization of BHPF with diacylic halides. These diacylic halide compounds show very high thermal resistance and exceptional optical properties (“High Performance Polyesters”).
High performance polyesters, and particularly, aromatic polyesters, known as “polyarylates”, have several important applications, such as:
1. polymeric films with mechanical properties higher than typical for a class of polymers, to be used in mechanical components where the resistance to a high number of stress-strain cycles (e.g., automotive components) is required;
2. replacement of glass, using films with very good optical properties, with good transparency to all the visible wavelength, low Yellow Index (e.g., as a components in liquid crystal—displays, ophthalmic lenses, goggle lenses, etc.);
3. thin films (under 10 &mgr;m) with good electrical insulation properties, especially at high temperatures (above 100° C.), e.g., for use with high performance electrical capacitors;
4. films suitable for the deposition of metal layers (e.g., copper, for the production of printed flexible circuits) or transparent conductive layers (e.g., ITO, Indium Tin Oxide).
These applications require polymeric materials with a very high glass transition temperature (Tg), for example above 300° C., a very high softening temperature and a very high melting temperature. A very high average molecular weight (AMW) (for example, above 500,000 Dalton), a narrow molecular weight distribution (MWD) and a low content of unreacted monomers or low molecular weight oligomers are other fundamental requirements desirable in high performance polyesters. These parameters are very important for the thermal and optical properties of these materials.
These results could be achieved previously only with the use of high purity reactants in the polymerization process, due to a well-known problem of polycondensation reactions (also known as a “step polymerization”). A description of this problem can be found in G. Odian,
Principles of Polymerization,
Chapter 2, “Step Polymerization”, page 41, 3
rd
Ed., John Wiley & Sons, Inc. New York, 1991.
The successful synthesis of high molecular weight polycondensation polymers can be achieved only at very high conversion rates (generally higher than 99%, better higher than 99.5%), and this places several stringent requirements on the reaction conditions, such as a favorable equilibrium and the absence of side reactions.
This last requirement is strictly related to the above mentioned high purity of the reactants involved in the polymerization reaction, and the purity of the bisphenol(s) used in this reaction is one of the main issues in controlling the direction and existence of side reactions, because the presence, even in traces, of reactants or catalysts used in their synthesis, or the presence of reaction by-products can have a strong impact on the final result of the polymerization, often decreasing the molecular weight of the polymer. The separation of these by-products from the main product is of fondamental importance, because the different reactivities or functionalities of these by-products can have a heavy negative impact on the polymerization reactions, lowering the conversion degree of the reactants into the polymer and giving lower average molecular weight or introducing chain branching inside the structure of the final polymer. The separation process must be able to eliminate also the traces of reactants that can be present in the reaction product, because the most of them (phenols, acid catalysts) could react with e.g., the diacylic halides, breaking the polymerization reaction because of their monofunctionality or their different reactivity.
Several methods for the purification of BHPF are described in the art. The known methods are rather complex or involve large amounts of water or mixtures such as of water/organic solvents (e.g., alcohols, acetone or other carbonilic compounds), to eliminate from the product the residual catalysts (acids) or the excess of phenol used in the synthesis reaction. A great number of examples in literature also describe the use of halogenated solvents in the purification steps, such as methylene chloride, 1,2 dichloroethane, trichloroethylene and tetrachloroethane, which raise severe problems from the environmental and safety points of view.
U.S. Pat. No. 3,546,165 describes the synthesis of soluble, high melting, thermally stable linear polyesters. Example II describes the preparation of the 9,9-bis (4-hydroxyphenyl) fluorene by reaction of the reactants in molten phenol, precipitation with water and purification with toluene. The final product has a melting point of 224° C.
U.S. Pat. No. 4,024,194 describes a method for the purification of BHPF where the by-products, identified as 9-(4-hydroxyphenyl)-9-(2-hydroxyphenyl) fluorene (ortho-, para-isomer of BHPF) are eliminated using nitromethane (CH
3
NO
2
) as a solvent of crystallization. The final product has a melting point range of 224.8-225.4° C. and less than 0.5% of the aforesaid impurity.
U.S. Pat. No. 4,049,721 describes a method for purifying BHPF containing phenol as an impurity by using methanol and water and/or mixtures thereof.
U.S. Pat. Nos. 4,387,209, 4,401,803, 4,430,493, 4,446,195 and WO 92/03493 describe a process for the preparation of aromatic polyesters by using BHPF having a melting range of from 228° to 230° C. All patents make reference to U.S. Pat. No. 4,467,122 for the preparation of such BHPF by reaction of fluorenone in melted phenols in the presence of gaseous hydrogen halide and catalytic amounts of divalent, trivalent or tetravalent metal halides (where metal is selected from Ca, Fe, Ti, Sn and Al). The purification method includes washing with water and 1,2-dichloroethane to obtain a purity of 99.8% (determined by HPLC).
U.S. Pat. No. 4,675,458 describes a preparation method of BHPF by reacting fluorenone and phenol in presence of sulfuric acid having a concentration greater than 75% and mercaptans, as condensing agent. Methanol and isopropanol are used for purification, and the isolated product showed a melting point of 223° C.
U.S. Pat. No. 4,931,594 describes the synthesis of BHPF by reacting phenol and fluorenone in presence of an insoluble, strong acidic ion cationic exchange resin as a condensation catalyst, in a range of temperature between 20° C. to 150° C. The product was washed with acetone, water and isopropanol to give a final product showing a melting point between 221° C.-224° C.
U.S. Pat. No. 5,110,994 describes a method for the preparation of BHPF where the fluorenone is reacted in presence of an excess of phenol, hydrochloric acid and aluminum trichloride as catalyst, and the catalyst is dissolved in an anhydrous organic solvent. The raw product is treated with boiling water, acetone, and 1,2-dichloroethane. The final product has a DSC onset melting temperature of 225.5° C.
U.S. Pat. No. 5,149,886 describes a process for the synthesis of BHPF by condensing fluorenone and phenol in a molar ratio of 1:4 to 1:8 at 30 to 90° C. in the presence of gaseous hydrogen chloride and &bgr;-mercaptopropionic acid catalyst, where the improvement comprises distilling water of reaction and dissolved hydrochloridric acid from the co
Angiolini Simone
Avidano Mauro
Ferrania S.p.A.
Mark A. Litman & Assoc. P.A.
Shippen Michael L.
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