Abstract: A process for the production of diaryl ethers which comprises heating, to a temperature of 80.degree. C. to 220.degree. C., a compound of the formula ##STR1## wherein X and Y are selected from the group consisting of H, CN, CO.sub.2 H, CHO, NO.sub.2, and CF.sub.3, provided that both X and Y may not simultaneously be H, in a solvent, in the presence of an inorganic base selected from the group consisting of the alkali metal carbonates, bicarbonates, and hydroxides, and in the presence of a catalyst selected from the group consisting of benzoic acid, substituted benzoic acids, C2-C4 aliphatic carboxylic acids, and alkali metal salts of said acids.

Abstract: Novel halogenated polyimides and co-polyimides comprise recurring imide structural units of the formula ##STR1## where X is F, Cl, Br or I; Y is H, F, Cl, Br or I; and R is a divalent organic radical.

Abstract: Dioxydiphthalic anhydride is prepared by the reaction of dihalophthalic anhydride with an alkali metal compound, such as potassium carbonate. The compound is particularly useful as a monomer in the preparation of polyimides.

Abstract: Novel polyimides and co-polyimides are prepared by the condensation polymerization of an aryl diamine with dioxydiphthalic anhydride or a mixture thereof with oxydiphthalic anhydride. The polyimides and co-polyimides prepared exhibit a low moisture absorption and improved dielectric properties and can be tailored to provide a composition having desirable mechanical properties, specifically, rigidity.

Abstract: Dioxydiphthalic anhydride is prepared by the reaction of dihalophthalic anhydride with an alkali metal compound, such as potassium carbonate. The compound is particularly useful as a monomer in the preparation of polyimides.

Abstract: Disclosed is a method of making 1,1'-oxybis (3-nitro-5-trifluoromethyl)-benzene by heating a nitro benzofluoride compound having the formula ##STR1## where "X" is selected from the group consisting of NO.sub.2, Cl, and F, with an alkali metal fluoride selected from the group consisting of potassium fluoride, cesium fluoride, and mixtures thereof, in an organic solvent in the presence of water. The corresponding diamine, 5,5'-oxybis (3-trifluoromethyl)-benzamine, can be prepared by reducing the benzene compound.

Abstract: Disclosed is a method of making a bisphenyl dihalomethane by reacting a trihalomethylbenzene with a halobenzene and a Lewis acid. The bisphenyl dihalomethane can than be reacted with water to form a halobenzophenone. In an optical third step ring chlorines that are present can be replaced with fluorines and, in a final step, any remaining chlorines can be removed to leave a fluorobenzophenone. The process is particularly useful in making 4,4'-difluorobenzophenone, which is in turn useful in making polyetheretherketones.

Abstract: Oxydiphthalic anhydride is prepared by reacting an hydroxyphthalic anhydride with a bromophthalic or fluorophthalic anhydride and potassium fluoride in the presence of a solvent and a copper catalyst.

Abstract: Oxydiphthalic anhydrides are prepared by reacting a halophthalic anhydride with water and an alkali metal compound such as KF, CsF, or K.sub.2 CO.sub.3 in the presence of a copper catalyst.

Abstract: Novel halo-oxydiphthalic anhydrides are of the formula ##STR1## where X is F, Cl, Br, or I; X' is H, F, Cl, Br, or I.