Abstract: A resin blend is provided including a blend of resorcinol diphthalonitrile ether resin and a bisphenol M diphthalonitrile ether resin. Another resin blend is provided including a blend of resorcinol diphthalonitrile ether resin and a bisphenol T diphthalonitrile ether resin. The resin blends prior to cure have more favorable processing and curing properties compared to the resorcinol diphthalonitrile resin alone, enabling greater ease in manufacturing.

Abstract: A method for producing a carboxylic acid anhydride includes heating a composition containing a specific compound in a solvent to yield the carboxylic acid anhydride. The solvent is an aprotic polar solvent having a boiling point of 50° C. or more.

Abstract: An object of the present invention is to provide a method for producing polyamide acid particles which is used as a raw material for polyimide particles with a small average particle diameter having high heat resistance. Other objects of the present invention are to provide a method for producing polyimide particles using the method for producing polyamide acid particles, and polyimide particles produced by the method for producing polyimide particles. Yet another object of the present invention is to provide a bonding material for an electronic component, which has a low linear expansion coefficient and a low elastic modulus after being cured in the temperature range equal to or less than the glass transition temperature, so that a joined body with high reliability can be produced.

Abstract: A dianhydride monomer having a large side chain R is provided. The large side chain would interrupt the symmetry and regularity of diamine monomer. The diamine monomer has the general formula shown as formula (I) below: The functional group R includes ?-substitution cycloalkene having at least a tertiary carbon atom, cycloalkene having at least a tertiary carbon atom, cycloalkane having at least a tertiary carbon atom, ?-substitution phenyl, phenyl, ?-substitution naphthalyl, naphthalyl, ?-substitution phenanthrenyl, phenanthrenyl, ?-substitution anthracenyl, anthracenyl, ?-substitution adamantyl, adamantyl, ?-substitution adamantyl and adamantyl.

Abstract: A process for obtaining (ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione) is disclosed. In the disclosed process chloro-, bromo-, or iodoisobenzofuran-1,3-dione is reacted with ethyne in a solvent in the presence of a dissolved homogenous palladium catalyst, optionally a copper salt, a base, and optionally a solvent distinct from said base. Subsequently the obtained (ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione) may be washed with a washing agent, such as a carboxylic acid, a polar aprotic solvent, or chloroform.

Abstract: A process for obtaining (ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione) is disclosed. In the disclosed process chloro-, bromo-, or iodoisobenzofuran-1,3-dione is reacted with ethyne in a solvent in the presence of a dissolved homogenous palladium catalyst, optionally a copper salt, a base, and optionally a solvent distinct from said base. Subsequently the obtained (ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione) may be washed with a washing agent, such as a carboxylic acid, a polar aprotic solvent, or chloroform.

Abstract: A dianhydride monomer having a large side chain R is provided. The large side chain would interrupt the symmetry and regularity of diamine monomer. The diamine monomer has the general formula shown as formula (I) below: The functional group R includes ?-substitution cycloalkene having at least a tertiary carbon atom, cycloalkene having at least a tertiary carbon atom, cycloalkane having at least a tertiary carbon atom, ?-substitution phenyl, phenyl, ?-substitution naphthalyl, naphthalyl, ?-substitution phenanthrenyl, phenanthrenyl, ?-substitution anthracenyl, anthracenyl, ?-substitution adamantyl, adamantyl, ?-substitution adamantyl and adamantyl.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: There are provided novel fluorescent agents, such as pyrazoline compounds represented by formula (I): (wherein R1, R2 and R3 are as defined in the specification), having an ethynyl group in the molecule, which have high absorptivity in the ultraviolet-visible short wavelength range (for example, 350 nm-420 nm).

Abstract: When phthalic acid is heated in heptane under azeotropic reflux conditions in the presence of a catalytic amount of an arylboronic acid compound (such as 2,6-(diisopropylaminomethyl)phenylboronic acid or 2,6-bis(diisopropylaminomethyl)phenylboronic acid), phthalic anhydride is obtained in high yield.

Abstract: A method for purifying an oxydiphthalic anhydride comprises diluting a first mixture comprising an oxydiphthalic anhydride, a solvent, a catalyst, and an inorganic salt with a solvent, to provide a second mixture having a solids content of 10 to 30 percent based on total weight of the second mixture; filtering and washing the solids of the second mixture at a temperature below the crystallization point temperature of the oxydiphthalic anhydride to provide a third mixture; hydrolyzing the third mixture by adding water and a water-soluble acid to form a fourth mixture; heating the fourth mixture; then cooling to provide a solid-liquid mixture, optionally decanting a portion of the liquid, rediluting the remaining solid-liquid mixture, then filtering to provide a solid component; washing the solid component with water to provide a fifth mixture of oxydiphthalic tetraacid and water; ring closing the oxydiphthalic tetraacid to provide oxydiphthalic anhydride, and filtering the oxydiphthalic anhydride.

Abstract: Disclosed herein is a method for purification of dianhydrides comprising a substantial amount (10000 ppm or more) of at least one metal salt. In one aspect the method is useful for the purification of dianhydrides prepared by the reaction of a halophthalic anhydride with a metal carbonate and may be optionally catalyzed by a phase transfer catalyst. The purification of the dianhydrides may be accomplished by hydrolyzing the dianhydride metal salt mixture directly to a tetraacid with an inorganic acid, followed by separating the impurities from an aqueous phase, and subsequently heating the tetraacid to effect ring closure to form a purified dianhydride having less than 50 parts per million metal halide and lower levels of other residual impurities. In one aspect the method is highly effective in removing phase transfer catalyst impurities such as hexalkylguanidinium halides initially present in the dianhydride undergoing purification.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: A method for preparing an oxydiphthalic anhydride comprises contacting, under reactive and substantially anhydrous conditions in a reactor, at least one halophthalic anhydride containing more than 250 ppm chlorophthalide impurity with a carbonate of the formula M2CO3, wherein M is an alkali metal, in the presence of a catalytic proportion of at least one phase transfer catalyst selected from the group consisting of hexaalkylguanidinium halides and alpha,omega-bis(pentaalkylguanidinium)alkane salts, phosphonium salts, phosphazenium salts, pyridinium salts, phosphazenium salts, ammonium salts, and combinations thereof. The phase transfer catalyst is present in a sufficient amount to prepare the oxydiphthalic anhydride when the chlorophthalide is present in an amount that is more than 250 ppm, and the oxydiphthalic anhydride is produced in a yield, based on the carbonate, of at least 70%.

Abstract: A method for purifying an oxydiphthalic anhydride comprises diluting a first mixture comprising an oxydiphthalic anhydride, a solvent, a catalyst, and an inorganic salt with a solvent, to provide a second mixture having a solids content of 10 to 30 percent based on total weight of the second mixture; filtering and washing the solids of the second mixture at a temperature below the crystallization point temperature of the oxydiphthalic anhydride to provide a third mixture; hydrolyzing the third mixture by adding water and a water-soluble acid to form a fourth mixture; heating the fourth mixture; then cooling to provide a solid-liquid mixture, optionally decanting a portion of the liquid, rediluting the remaining solid-liquid mixture, then filtering to provide a solid component; washing the solid component with water to provide a fifth mixture of oxydiphthalic tetraacid and water; ring closing the oxydiphthalic tetraacid to provide oxydiphthalic anhydride, and filtering the oxydiphthalic anhydride.

Abstract: The present invention relates to a deuterated polyimide, the backbone of which comprises an alternation between: at least one repeat unit corresponding to the following formula (I): in which: Y represents a single bond or a spacer group; and at least one repeat unit corresponding to the following formula (II): -A1-Z-??(II) in which: A1 represents a perdeuterated aromatic group comprising from 6 to 10 carbon atoms; Z represents a single bond or a group chosen from —O—C6D4—, —CO—C6D4— and —C6D4—. These polyimides are used in particular as materials which are transparent within the region from 2500 to 3500 cm?1, for example in laser devices.

Abstract: There is provided a continuous process for making 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane. The process has the following steps: a) continuously feeding 2,2-bis(3,4-dimethylphenyl)hexafluoropropane and aqueous nitric acid into a reactor cell and b) heating the mixture to a temperature sufficient to effect reaction between the 2,2-bis(3,4-dimethylphenyl)hexafluoropropane and the nitric acid.

Abstract: 2,3,3?,4?-biphenyltetracarboxylic acid is heat-dehydrated in a molten state at a temperature not lower than 200° C. in a flow of an inert gas in a reactor 10 having at least one reaction vessel 11 by stirring the molten material to produce 2,3,3?,4?-biphenyltetracarboxylic dianhydride. Thus obtained 2,3,3?,4?-biphenyltetracarboxylic dianhydride in the molten state is subsequently cooled and solidified in an inert gas or dry air, or cooled and solidified in the ambient air at a temperature of 40° C. or lower or 100° C. or higher.

Abstract: A method for purifying dianhydrides is provided. In one aspect, purified oxybisphthalic anhydrides, intermediates useful in the preparation of polyetherimides are provided. In one embodiment, a first solution containing a dianhydride compound, a solvent, and a phase transfer catalyst is contacted with a solid inorganic adsorbent material having a total pore volume of about 0.5 milliliters/gram or greater and a cumulative pore volume distribution of about 20 percent or greater of particles having a pore diameter in a range between about 3 nanometers and about 20 nanometers. The solution containing the dianhydride compound is then separated from the solid inorganic adsorbent material to provide a purified dianhydride compound which is substantially free of the phase transfer catalyst. The purification technique is especially valuable for preparing high purity oxybisphthalic anhydrides, such as 4,4?-oxybisphthalic anhydride (4,4?-ODPA), which are substantially free of residual phase transfer catalyst.

Abstract: There is provided biphenyltetracarboxylic dianhydride containing biphenyltetracarboxylic monoanhydride in an amount of not more than 0.4%. By using the biphenyltetracarboxylic dianhydride as a raw material, it is possible to produce polyimide or polyamic acid having an increased molecular weight.

Abstract: This invention is related to a method for making diether dianhydrides by the reaction of halophthalic anhydride and a metal salt of an aromatic dihydroxy compound in the presence of a solvent and a phase transfer catalyst. Typical phase transfer catalyst include guanidium salts, aminopyridinium salts, or phosphazenium salts.

Abstract: The present invention relates to halogen-containing aromatic compounds and methods thereof. The present invention relates a halogen-containing aromatic acid dianhydride, halogen-containing aromatic tetranitrile compound, halogen-containing m-phenylenediamine compound and fluorine compound, and a method thereof.

Abstract: A method for the synthesis of poly(etherimide)s comprises the reaction of 4-halotetrahydrophthalic anhydride with an activating primary amine to yield an activated 4-halotetrahydrophthalimide. Activated 4-halotetrahydrophthalimide may then be aromatized and treated with the disodium salt of a bis(phenol) to yield an activated bisimide. The activated bisimide may then be directly treated with a diamine to yield poly(etherimide)s.

Abstract: An acid anhydride of the formula (4), and a polyimide using the acid anhydride, 1

Abstract: Oxydiphthalic anhydrides such as 4-oxydiphthalic anhydride are prepared by the reaction of a halophthalic anhydride with an alkali metal carbonate such as potassium carbonate in the presence of a catalyst system comprising an alkali metal bicarbonate such as potassium bicarbonate and a phase transfer catalyst, preferably a tetraarylphosphonium halide.

Abstract: A process to isolate dianhydride from an exchange reaction comprises extracting a bisimide/anhydride exchange reaction aqueous phase with an organic solution comprising an exchange catalyst at a first temperature and pressure to form an extracted aqueous phase comprising water, exchange catalyst and a dianhydride precursor; removing water from the extracted aqueous phase at a second temperature and pressure to form a molten phase, wherein the second pressure is less than the first pressure; removing water and exchange catalyst from the molten phase at a third temperature and pressure to form an isolation mixture; and converting the dianhydride precursor in the isolation mixture to dianhydride at a fourth temperature and pressure, wherein the fourth temperature is greater than the second and third temperatures and the fourth pressure is less than the second and third pressures.

Abstract: Oxydiphthalic anhydrides such as 4-oxydiphthalic anhydride are prepared by the reaction of a halophthalic anhydride with an alkali metal carbonate such as potassium carbonate. The reaction proceeds in the presence of a hexaalkylguaninium halide or &agr;,&ohgr;-bis(pentaalkylguanidinium)alkane halide as a phase transfer catalyst.

Abstract: A process to isolate dianhydride from an exchange reaction comprises extracting a bisimide/anhydride exchange reaction aqueous phase with an organic solution comprising an exchange catalyst at a first temperature and pressure to form an extracted aqueous phase comprising water, exchange catalyst and a dianhydride precursor; removing water from the extracted aqueous phase at a second temperature and pressure to form a molten phase, wherein the second pressure is less than the first pressure; removing water and exchange catalyst from the molten phase at a third temperature and pressure to form an isolation mixture; and converting the dianhydride precursor in the isolation mixture to dianhydride at a fourth temperature and pressure, wherein the fourth temperature is greater than the second and third temperatures and the fourth pressure is less than the second and third pressures.

Abstract: A 6,6′-dialkyl-3,3′,4,4′-biphenyltetracarboxylic dianhydride is prepared by brominating a 4-alkylphthalic anhydride at its 5-position, and coupling the bromination product in the presence of a nickel catalyst; A photosensitive resin composition containing a polyimide precursor having repetitive units of general formula (7) is applied onto a substrate, exposed to i-line, developed and heated to form a polyimide relief pattern. wherein Y is a divalent organic group, R7 and R8 are OH or a monovalent organic group, R9 and R10 are a monovalent hydrocarbon group, R11, R12 and R13 are a monovalent hydrocarbon group, a and b are an integer of 0 to 2, c is an integer of 0 to 4, and m is an integer of 0 to 3.

Abstract: A method for the synthesis of a dianhydride comprises transimidation of bis (imide) (IV) in the presence of a substituted phthalic anhydride or 4-substituted tetrahydrophthalic anhydride to yield dianhydride (V)

Abstract: A 6,6′-dialkyl-3,3′,4,4′-biphenyltetracarboxylic dianhydride is prepared by brominating a 4-alkylphthalic anhydride at its 5-position, and coupling the bromination product in the presence of a nickel catalyst; A photosensitive resin composition containing a polyimide precursor having repetitive units of general formula (7) is applied onto a substrate, exposed to 1-line, developed and heated to form a polyimide relief pattern.

Abstract: Disclosed is a method for preparing oxy-diphthalic anhydrides, which comprises reacting a halo-phthalic anhydride represented by the formula (1): where Hal represents F, Cl, Br or I, with a carbonate salt selected from the group consisting of lithium carbonate, sodium carbonate, magnesium carbonate and calcium carbonate in a solvent to prepare oxy-diphthalic anhydrides represented by the formula (2):

Abstract: The present invention provides a series of easily processable poly(ether-imide)s that are organic-soluble and can afford colorless films, their organic solutions and their manufacturing process. The poly(ether-imide) is prepared from a dianhydride and a diamine, wherein the dianhydride is a bis(ether anhydride) having tert-butyl group, i. e. 1,4-bis(3,4-dicarboxyphenoxy)-2-tert-butylbenzene dianhydride.

Abstract: A bis(trisubstitutedtrimellitic anhydride) derivative and a polyesterimide for optical communications, the polyesterimide being formed therefrom. The polyesterimide has a high refractive index, so that when using such polyesterimide as a material for a core of an optical fiber, the range of materials that can be selected for the cladding becomes wide. Also, a coating property and adhesion to a substrate are improved, thereby providing a good film forming property and thermal stability. Also, because the polyesterimide can minimize optical loss at a near infrared wavelength range, the polyesterimide is very useful as an optical material in the optical communications field adopting the light of near infrared wavelength.

Abstract: Oxybisphthalic compounds such as 4,4'-oxybis(N-methylphthalimide) and 4,4'-oxybis(phthalic anhydride) are prepared from the corresponding nitro- or halo-substituted phthalic compounds by reaction with an alkanoate or carbonate salt in a non-polar solvent and in the presence of a hexaalkylguanidinium salt as phase transfer catalyst. A carboxylic acid such as 4-chlorobenzoic acid may be used as an additional catalyst. Reaction rates and yields are higher than with other phase transfer catalysts.

Abstract: A perfluorinated polyimide comprising a repeating unit represented by general formula (1): ##STR1## and a perfluorinated poly(amic acid) comprising a repeating unit represented by general formula (6): ##STR2## wherein R.sub.1 is a tetravalent organic group; and R.sub.2 is a divalent organic group, provided that chemical bonds between carbon atoms and monovalent elements contained in R.sub.1 and R.sub.2 are exclusively carbon-to-fluorine bonds; methods for preparing them; and optical material including the perfluorinated polyimide. 1,4-Bis(3,4-dicarboxytrifluorophenoxy)-tetrafluorobenzene dianhydride, 1,4-difluoropyromellitic anhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)-tetrafluorobenzene, 1,4-difluoropyromellitic acid, and 1,4-bis(3,4-dicyanotrifluorophenoxy)-tetrafluorobenzene as well as methods preparing them. The perfluorinated polyimide has a thermal stability and has a low optical loss in an optical communication wavelength region (0.8 to 1.7 .mu.m).

Abstract: A perfluorinated aromatic compound represented by general formula (7): ##STR1## wherein R.sub.3 is a tetravalent perfluorinated aromatic group represented by formula (8): ##STR2## wherein (R.sub.4)s are the same, each being a carboxyl group or a cyano group, or two adjacent (R.sub.4)s combine to form a divalent group represented by formula (10): ##STR3## provided that when R.sub.4 is a cyano group, R.sub.3 denotes said tetravalent perfluorinated aromatic group represented by formula (9).

Abstract: Disclosed herein are novel poly(imide-ethers) containing ortho substitution in the main chain of the polymer. These polymers are made from novel aromatic bis-carboxylic anhydrides which contain two ether groups attached to an aromatic ring in ortho positions to each other. The polymers are particularly useful for films, fibers and encapsulation, as well as thermoplastics.

Abstract: The invention provides a compound of general formula I ##STR1## in which X represents a direct bond or a ##STR2## group.

Abstract: A process for making relatively high purity eulfonylbis(phthalic anhydride) is provided. 3,3',4,4'-tetramethyl diphenyl sulfone is catalytically oxidized in a solvent under liquid phase elevated temperature and pressure conditions. The catalyst is constituted by cobalt, manganese, zirconium, and bromine. Sulfonylbis(phthalic) acid is recovered by crystallization and is then heated to produce the anhydride. Preferably, the acid is purified prior to dehydration.

Abstract: Disclosed is a method of making oxydiphthalic anhydride from oxydiphthalic acid. The oxydiphthalic acid is mixed with an organic liquid that codistills with water and the resulting slurry is heated to the boiling point of the slurry to remove any water. About 1 to about 4 moles of acetic anhydride per mole of oxydiphthalic acid are added to the slurry and the slurry is heated to a temperature between 50.degree. and 160.degree. C. until the oxydiphthalic acid content thereof is less than 0.1 weight percent. The slurry is filtered and the filter cake is heated to a temperature between about 180.degree. C. and below its melting point for about 12 to about 24 hours.

Abstract: A process of making poly(dianhydride) compounds having formulae (I) and (II): ##STR1## where m is 0 to 50. ##STR2## wherein n is 0 to 20 and X is bond junction, oxygen atom, sulfur atom, SO.sub.2, C(CF.sub.3), CO, C(CH.sub.3).sub.2, CF.sub.2 --O--CF.sub.2, CH.sub.2, and CHOH.

Abstract: A compound of the formula ##STR1## and the dianhydride thereof are prepared by air oxidation in the presence of a catalyst mixture composed of at least 2 heavy metal salts and also bromine in an acid organic medium. The compounds can be employed for the preparation of partially fluorinated polycondensates, such as polyimides, polycarboxamides, esters of polyamidecarboxylic acids, polyamides and imide-oligomers.

Abstract: A process for producing a biphenyltetracarboxylic dianhydride which comprises the step of: heating phthalic anhydride at a temperature of from 135.degree. to 300.degree. C. in the presence of a palladium catalyst thereby to allow the phthalic anhydride to undergo a dimerization reaction. According to the process, biphenyltetracarboxylic dianhydride can be synthesized by the direct dimerization of phthalic anhydride.

Abstract: A method for reducing the formation of dust produced by solid aromatic anhydrides, and aromatic anhydride compositions that have a reduced tendency to emit aromatic anhydride dust, are disclosed. The method comprises treating the aromatic anhydride with low levels of suitable organic compounds.

Abstract: Poly(dianhydride) compounds having formulae (I) and (II): ##STR1## where m is 0 to 50. ##STR2## wherein n is 0 to 20 and X is bond junction, oxygen atom, sulfur atom, SO.sub.2, C(CF.sub.3), CO, C(CH.sub.3).sub.2, CF.sub.1 --O--CF.sub.2, CH.sub.2, and CHOH.The compounds are intermediates for certain resins.

Abstract: The invention relates to the preparation of novel dianhydrides of the formula: ##STR1## wherein R is a polyalkylated mononuclear aromatic radical, preferably a phenylene radical. The mononuclear aromatic radical may be substituted with from three to four lower alkyl radicals, preferably C.sub.1 -C.sub.4 alkyl radicals. The dianhydrides are preferably made by the reaction of a monoanhydride monoacid halide and a polyalkylated mononuclear aromatic in the presence of a Friedel-Crafts catalyst under Friedel-Crafts reaction conditions. These dianhydrides ae useful reactants in the preparation of polyimides and epoxy curing agents.