Abstract: A method for producing a highly pure PMDA comprises at least the following steps: (1) a step of preparing a raw material solution by dissolving a raw material of a pyromellitic dianhydride in an acetic acid solvent, (2) a step of preparing a precursor pyromellitic dianhydride by recrystallizing the pyromellitic dianhydride in the prepared raw material solution and separating the acetic acid solvent, (3) a step of performing a degassing treatment on the precursor pyromellitic dianhydride by stirring the precursor pyromellitic dianhydride in a fluidized state while heating under reduced-pressure conditions, and (4) a step of taking out the pyromellitic dianhydride subjected to the degassing treatment.

Abstract: Disclosed is a film formation method, including vaporizing a plurality of raw material monomers in respective corresponding vaporizers, supplying the plurality of raw material monomers into a film formation apparatus, causing vapor deposition polymerization of the plurality of raw material monomers in the film formation apparatus to form an organic film on a substrate, and removing an impurity contained in at least one raw material monomer among the plurality of raw material monomers before the vapor deposition polymerization.

Abstract: The present invention is directed to a binder for a lithium ion battery electrode, comprising a polyimide precursor having a tetracarboxylic acid residue and a diamine residue and/or a polyimide, the polyimide precursor having a residue of a tetracarboxylic dianhydride selected from those represented by the following general formulas (1) and (2) as the tetracarboxylic acid residue, and a residue of a diamine selected from those represented by the following general formulas (3) and (4) as the diamine residue, the content of the acid residue being from 0.90 to 0.95 moles based on 1 mole of the diamine residue.

Abstract: A compound having a structure expressed by the following Structural Formula (1):

Abstract: Disclosed is a 5-alkyl-1,2,3,4-benzene tetracarboxylic-1:2,3:4-dianhydride which is represented by the general formula (1) and has excellent solubility with respect to various organic solvents. Depending on the diamine that is used, a polyimide with excellent heat resistance or a polyimide with good workability at a low melting point can be provided, and in addition, a polyimide that exhibits excellent characteristics for electronic materials or the like can be provided. (In the formula, R1 represents an alkyl group with carbon number 1-10.

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: A compound having a structure expressed by the following Structural Formula (1):

Abstract: A method oxidizes an organic compound with oxygen in the presence of a catalyst, in which the catalyst contains a N-hydroxy- or N-(substituted oxy)-imide compound derivable from at least one selected from a target product, a reaction intermediate, and a reaction byproduct, and the catalyst is produced from at least one component selected from the target product, reaction intermediate, and reaction byproduct each formed as a result of the reaction and is used in the oxidation reaction so as to make up for a loss of the catalyst due to denaturation in the reaction. The method can easily and inexpensively make up for a loss of the catalyst denaturated in the course of reaction.

Abstract: The present invention provides: a fixed-bed shell-and-tube reactor, which can stably produce an aimed product for a long period when a solid particulate material such as a catalyst is packed and used for each substance; and its usage. The fixed-bed shell-and-tube reactor comprises a plurality of reaction tubes that are packed with a solid particulate material and arranged in parallel, wherein the solid particulate material is weighed so as to be uniform volume, and is packed in each reaction tube in a packing time of not shorter than 30 seconds per liter.

Abstract: An object of the present invention is to provide a catalyst exhibiting excellent performance particularly in partial oxidation reaction. Another object is to provide a method for efficiently producing carboxylic acid or carboxylic anhydride through vapor-phase partial oxidation of an organic compound by use of an oxygen-containing gas in the presence of the catalyst. The catalyst contains (1) diamond; (2) at least one species selected from among Group 5 transition element oxides, collectively called oxide A; and (3) at least one species selected from among Group 4 transition element oxides, collectively called oxide B. The method for producing a carboxylic acid or a carboxylic anhydride includes subjecting an organic compound to vapor phase partial oxidation by use of an oxygen-containing gas in the presence of the catalyst, wherein the organic compound is an aromatic compound having one or more substituents in a molecule thereof, the substituents each including a carbon atom bonded to an aromatic ring.

Abstract: A method of producing pyromellitic dianhydride. The method includes a step of heating a crude pyromellitic acid in the absence of acetic anhydride to convert a part of pyromellitic acid to pyromellitic anhydride, and a subsequent step of heating the resultant mixture in the presence of acetic anhydride to complete the anhydrization of pyromellitic acid. The pyromellitic dianhydride by the method contains little pyromellitic monoanhydride and other monoanhydrides derived from impurities and is less discolored. The pyromellitic dianhydride has particle properties not causing plugging, etc. during its transportation, storage and use.

Abstract: A method of preparing a purified dianhydride is provided where said method comprises the steps of preparing a first mixture comprising water, at least one inorganic acid, and at least one dianhydride, said dianhydride comprising at least one impurity which is soluble in aqueous acid heating said first mixture until substantially all of said dianhydride is converted to a tetraacid comprised in a second mixture; filtering at least a portion of said second mixture to provide a solid tetraacid and a filtrate, said filtrate comprising at least a portion of said impurity; and heating the tetraacid provided in a solvent with concurrent distillation of water to provide a third mixture comprising a purified dianhydride and a solvent.

Abstract: A process which comprises reacting a 1,2,3,4-cyclobutanetetracarboxylic-1,2:3,4-dianhydride [1] with an alcohol [2] in the presence of an acid catalyst to obtain a compound [3], isomerizing the compound [3] with a base catalyst into a compound [4], reacting the compound [4] with an organic acid to obtain a compound [5], and reacting the compound [5] with a dehydrating agent to obtain a 1,2,3,4-cyclobutanetetracarboxylic-1,3:2,4-dianhydride: wherein R1 and R2 are each independently hydrogen, halogeno, alkyl of 1 to 10 carbon atoms, halogenated alkyl of 1 to 10 carbon atoms, cycloalkyl of 3 to 8 carbon atoms, phenyl, or cyano; and R3 is alkyl of 1 to 10 carbon atoms.

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: A method oxidizes an organic compound with oxygen in the presence of a catalyst, in which the catalyst contains a N-hydroxy- or N-(substituted oxy)-imide compound derivable from at least one selected from a target product, a reaction intermediate, and a reaction byproduct, and the catalyst is produced from at least one component selected from the target product, reaction intermediate, and reaction byproduct each formed as a result of the reaction and is used in the oxidation reaction so as to make up for a loss of the catalyst due to denaturation in the reaction. The method can easily and inexpensively make up for a loss of the catalyst denaturated in the course of reaction.

Abstract: In a method of producing pyromellitic acid by liquid-phase oxidizing 2,4,5-trimethylbenzaldehyde in a water solvent with molecular oxygen, a recrystallization mother liquor separated in a recrystallization step is recycled to the oxidation step after a part of the water solvent is removed. With this method, the loss of pyromellitic acid and the oxidation catalyst can be minimized and the burden of discharging the waste water is reduced without lowering the efficiency of the liquid-phase oxidation reaction.

Abstract: New spisulosine derivatives of use in treating tumors are of the formula (I) wherein: each X is the same or different, and represents H, OH, OR?, SH, SR?, SOR?, SO2R?, NO2, NH2, NHR?, N(R?)2, CN, halogen, C(?O)H, C(?O)CH3, CO2H, CO2CH3, substituted or unsubstituted C1–C18 alkyl, substituted or unsubstituted C2–C18 alkenyl, substituted or unsubstituted C2–C18 alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaromatic, or two groups X may together form ?O; Y is NR1, OR1, PR1, SR1, or halogen, wherein the number of substituents R1 is selected to suit the valency and each R1 is independently selected of H, OH, C(?O)R?, P(?O)R?R?, substituted or unsubstituted C1–C18 alkyl, substituted or unsubstituted C2–C18 alkenyl, substituted or unsubstituted C2–C18 alkynyl, substituted or unsubstituted aryl, and wherein the dotted line indicates an optional double bond; each Z is the same different, and represents H, OH, OR?, SH, SR?, SOR?, SO2R?, NO2, NH2, NHR?, N(R?)2, NHC(O)R?, CN, halogen, C(?O

Abstract: A multimetal oxide of the formula I Aga?bMbV2Ox*c H2O,??I where M is a metal selected from the group consisting of Li, Na, K, Rb, Cs, Tl, Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pb, Cr, Au, Al, Fe, Co, Ni and/or Mo, a is from 0.3 to 1.9 and b is from 0 to 0.5, with the proviso that the difference (a?b)?0.1 and c is from 0 to 20 and x is a number determined by the valence and amount of elements different from oxygen in the formula I, has a crystal structure giving an X-ray powder diffraction pattern which displays reflections at the lattice spacings d of 15.23±0.6, 12.16±0.4, 10.68±0.3, 3.41±0.04, 3.09±0.04, 3.02±0.04, 2.36±0.04 and 1.80±0.04 ?. Precatalysts and catalysts produced therefrom for the partial oxidation of aromatic hydrocarbons are also provided.

Abstract: The present invention has for its object to provide a production method of a pyromellitic anhydride which is not only conducive to an increased catalyst life and, hence, an enhanced operating rate of a plant (reduced downtime) and a reduction in catalyst cost but also conducive to reductions in byproducts and, hence, savings in the cost of after-treatments such as collection and purification. A production method of a pyromellitic anhydride comprising a step for catalytic gas-phase oxidation of a starting mixture gas consisting of a tetraalkylbenzene and/or a trialkylbenzaldehyde and a molecular oxygen-containing gas in a fixed-bed type reactor having a catalyst bed wherein the production method of a pyromellitic anhydride is carried out under the condition that the moisture content of said starting mixture gas to be introduced into the catalyst bed is not more than 2 volume %.

Abstract: A process for refined pyromellitic anhydride which comprises dissolving crude pyromellitic acid or crude pyromellitic anhydride in water, then cooling an aqueous solution thus obtained to perform crystallization as pyromellitic acid, then separating a crystal thus obtained from water, then anhydrating the crystal of pyromellitic acid thus separated with heating to produce pyromellitic anhydride, then vaporizing pyromellitic anhydride thus produced, cooling vapor of pyromellitic anhydride thus obtained, and thereby, recovering a refined crystal of pyromellitic anhydride.

Abstract: A method for producing crystals of pyromellitic dianhydride is disclosed which is characterized by setting the water content of an atmosphere used in handling the crystals of pyromellitic dianhydride at a temperature of not higher than 120° C. at a level of not more than 4 vol. %. Particularly by supplying an inert gas having a water content of not more than 4 vol. % to the step of production, it is made possible to prevent the conversion of pyromellitic dianhydride by hydration very efficiently.

Abstract: The present invention has for its object to provide a production method of a pyromellitic anhydride which is not only conducive to an increased catalyst life and, hence, an enhanced operating rate of a plant (reduced downtime) and a reduction in catalyst cost but also conducive to reductions in byproducts and, hence, savings in the cost of after-treatments such as collection and purification.

Abstract: A method for producing crystals of pyromellitic dianhydride is disclosed which is characterized by setting the water content of an atmosphere used in handling the crystals of pyromellitic dianhydride at a temperature of not higher than 120° C. at a level of not more than 4 vol. %. Particularly by supplying an inert gas having a water content of not more than 4 vol. % to the step of production, it is made possible to prevent the conversion of pyromellitic dianhydride by hydration very efficiently.

Abstract: The present invention has for its object to provide a production method of pyromellitic anhydride of high purity in good yield at low cost by catalytic gas-phase oxidation of a 2,4,5-trialkylbenzaldehyde with the aid of a suitable catalyst system. The present invention relates to a production method of pyromellitic anhydride comprising a step for catalytic gas-phase oxidation of a 2,4,5-trialkylbenzaldehyde with a molecular oxygen-containing gas in which said step for catalytic gas-phase oxidation is carried out in the presence of a catalyst such that a specific surface area of the catalytic active component thereof is not greater than 50 m2/g or in the presence of a catalyst containing vanadium as well as molybdenum and/or tungsten as a catalytic active component.

Abstract: The present invention relates to fluorine-containing 3,6-di(3′,5′-bis(trifluoromethyl)benzene)pyromellitic dianhydride as a monomer which can be used in preparing polyimides with high glass transition temperature, low dielectric constant and excellent processability, and preparing method thereof.

Abstract: A process for refined pyromellitic anhydride which comprises dissolving crude pyromellitic acid or crude pyromellitic anhydride in water, then cooling an aqueous solution thus obtained to perform crystallization as pyromellitic acid, then separating a crystal thus obtained from water, then anhydrating the crystal of pyromellitic acid thus separated with heating to produce pyromellitic anhydride, then vaporizing pyromellitic anhydride thus produced, cooling vapor of pyromellitic anhydride thus obtained, and thereby, recovering a refined crystal of pyromellitic anhydride.

Abstract: The present invention has for its object to provide a production method of pyromellitic anhydride of high purity in good yield at low cost by catalytic gas-phase oxidation of a 2,4,5-trialkylbenzaldehyde with the aid of a suitable catalyst system.

Abstract: A process for producing trimellitic anhydride which comprises performing liquid phase oxidation of pseudocumene containing 5% by weight or above of dimethyl bezaldehyde as a raw material for oxidation with air in aliphatic monocarboxylic acid having 1 to 5 carbon atoms as a solvent in the presence of a catalyst comprising both each metal of cobalt, manganese and zirconium and bromine to obtain trimellitic acid and then heat dehydrating trimellitic acid thus obtained or heat treating trimellitic acid thus obtained in the presence of a catalyst comprising 10 ppm or above of Ni thereby producing trimellitic anhydride.

Abstract: This invention relates to a process for preparing perylene pigment compositions by reaction of(a) a perylene tetracarboxylic compound;(b) about 0.01 to about 20% by weight, relative to the perylene tetracarboxylic compound, of a non-pigmentary cyclic anhydride or imide of formula (I) ##STR1## wherein W is O or NR.sup.1 (where R.sup.1 is hydrogen, a metal, or optionally substituted alkyl, cycloalkyl, aralkyl, or aryl), R.sup.2, R.sup.3, and R.sup.4 are various combinations of substituents and/or fused-on rings, and the dotted line is an optional double bond representing R.sup.2 --C.dbd.C--R.sup.3 ;(c) ammonia or a primary alkyl, aralkyl, or aryl amine; optionally in the presence of(d) a solvent and/or(e) one or more dispersants.

Abstract: Provided is a process for producing pyromellitic dianhydride by feeding 1,2,4,5-tetraalkylbenzene to a fixed bed multitubular type reactor charged with a catalyst layer to carry out catalytic vapor phase oxidation. This process is characterized by dividing the catalyst layer into at least two layers to charge a layer at an outlet side of reaction gas and a layer at an inlet side of raw material mixed gas with the following catalyst A and catalyst B respectively or dividing the catalyst layer into at least three layers to charge a layer at an outlet side of reaction gas, an intermediate layer and a layer at an inlet side of raw material mixed gas with the following catalyst A, catalyst B and catalyst C respectively:catalyst A: a catalyst containing V.sub.a (A).sub.b P.sub.c Ag.sub.d (B).sub.e O.sub.

Abstract: A carrier containing silicon carbide, inorganic bonding component, and at least one oxide selected from the group consisting of a niobium oxide, an antimony oxide, and a tungsten oxide carries at least one oxide selected from the group consisting of a vanadium oxide and a molybdenum oxide as catalytically active component. An inexpensive catalyst for catalytic oxidation use can be thus offered that does not change its properties over a period of time, that boasts stable catalytic activity over a period of time, and that is suitable for, e.g., manufacture of an acid anhydride and a nitrile compound by conducting a catalytic gas-phase oxidation reaction (partial oxidation reaction) on a hydrocarbon.

Abstract: The present invention relates to a process for preparing pyromellitic dianhydride via an oxidation in gas phase under normal pressure. The process is characterized in that a catalyst system is used, which catalyst system comprises a catalyst which is a mixture of vanadium and tungsten oxides; a catalyst support comprising rutile and at least one material selected from the group consisting of tungsten carbide, silicon carbide and a mixture thereof; and a cocatalyst comprising oxides of manganese, antimony, bismuth, phosphorus, copper, aluminum, titanium or a mixture thereof, an oxide of an element of the VIIIB group of the periodic table, and an oxide of an alkali metal and/or alkaline earth metal. In this process, pyromellitic dianhydride is produced from a feedstream containing 1,2,4,5-tetraalkylbenzene in a gas flow rate of 4,000.about.12,000 hr.sup.-1 via a selective oxidation at 300.about.450.degree. C. in the presence of air which acts as an oxidant.

Abstract: A method for preparing aromatic compounds including 1,4-difluoropyromellitic dianhydride represented by formula (12): ##STR1## and 1,4-difluoropyromellitic acid represented by formula (15): ##STR2## by dehydrating or hydrolyzing and dehydrating precursors.

Abstract: The present invention provides pyromellitic dianhydride derivatives represented as formula I: ##STR1## wherein, R is C.sub.1-24 alkyl.The pyromellitic dianhydride derivatives of the invention can be used as monomers for the synthesis of polyimides, ladder poly(imidazopyrrolone)s, crosslinked polyamides and polyesters. The present invention also provides a novel process for preparing the pyromellitic dianhydride derivatives as formula I.

Abstract: A process for producing anhydrides by passing a solution of the acid, preferably an organic polyacid, which is to undergo anhydridation over an acidified clay and a process for producing the catalysts therefor.

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: Cyclooctadiene derivative of the following formula (1): ##STR1## wherein A.sup.1, A.sup.2, A.sup.3 and A.sup.4 each independently represent COOR.sup.5 (where R.sup.5 represents a hydrogen atom, a C.sub.1 -C.sub.10 alkyl group, a phenyl group, a C.sub.7 -C.sub.12 aralkyl group or CONR.sup.6 R.sup.7 (where R.sup.6 and R.sup.7 each independently represent a hydrogen atom, a C.sub.1 -C.sub.10 alkyl group or a phenyl group), or A.sup.1 and A.sup.2, and/or A.sup.3 and A.sup.4 may be combined together to represent group(s) of: ##STR2## in which X represents an oxygen atom or NR.sup.8 {where R.sup.8 represents a hydrogen atom, a C.sub.1 -C.sub.10 alkyl group or a phenyl group),R.sup.0, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group and an C.sub.1 -C.sub.10 alkyl group,the symbol ------ represents a single or double bond, and when it is a double bond, then R.sup.1 and R.sup.

Abstract: A process for recovering phthalic anhydride as a liquid from a vapor phase oxidation product which comprises mixing the vapor phase oxidation product having a temperature in the range of about 130.degree. C. or greater with a first stream comprising maleic anhydride and/or at least one compound selected from the group consisting of: citraconic anhydride, benzoic acid and phthalic anhydride in a rectification tower such that a substantial portion of the phthalic anhydride contained within the vapor phase oxidation product transfers from the vapor phase to a liquid phase and the by-products contained in the first stream which are more volatile than phthalic anhydride transfer from the liquid phase to the vapor phase and wherein a vapor-to-liquid weight ratio in the range between about 5 to 20 is exhibited within the rectification tower, thereby forming a liquid phase phthalic anhydride product having a phthalic anhydride concentration in the range between about 50-100 wt. %, preferably 90-100 wt.

Abstract: A method for producing efficiently on a commercial scale pyromellitic anhydride having high purity and suffering only sparing coloration in a high yield from a raw material of high concentration is provided. By the use of a multilayer catalyst formed by packing on the reaction gas outlet side a first catalyst containing V and Mo and/or W and having an atomic ratio of Mo and/or W to V in the range of from 0.01 to 2, on the raw material mixed gas inlet side a second catalyst containing V, Mo and/or W and having an atomic ratio of Mo and/or W to V smaller than the atomic ratio of the first catalyst, and/or a third catalyst containing V and an alkali metal and having an atomic ratio of the alkali metal to V in the range of from 0.2 to 2.5, pyromellitic anhydride is produced by the vapor-phase oxidation of a tetraalkyl benzene with a molecular oxygen-containing gas.

Abstract: A compound of formula (I) possesses excellent potassium channel opening activity and is effective on various diseases arising from contractions of blood vessels, bronchial smooth muscles, etc., for example, ischemic heart diseases exemplified by angina pectoris, asthma, pollakisuria, sequela of subarachnoid hemorrhage, peripheral arterioinfarct, and so on. The compound has potent and long-lasting antihypertensive activity, with the onset of the action being slow, excellent activity in increasing renal blood flow, and high safety, and is therefore particularly useful as an antihypertensive. ##STR1## The substituents are as defined in the specification.

Abstract: The invention relates to a process for preparing pyromellitic dianhydride (PMDA) by heterogeneously catalyzed oxidation in the gas phase by means of a gas containing molecular oxygen. The process involves oxidizing benzaldehydes which are 2,4,5-trialkylated by C.sub.1 - to C.sub.3 -alkyl groups or mixtures of benzaldehydes which are 2,4,5-trialkylated by C.sub.1 - to C.sub.3 -alkyl groups and benzenes which are 1,2,4,5-tetraalkylated by C.sub.1 - to C.sub.3 -alkyl groups in the presence of a catalyst. The catalyst contains as active components 5% to 95% by weight of one or more transition-metal oxides of sub-group IV of the Periodic Table of the Elements, from 1% to 50% by weight of one or more transition-metal oxides of sub-group V of the Periodic Table of the Elements.

Abstract: The present invention relates to the compound A of the formula (A), the related compound B, carboxylic acid derived from acid anhydride group of these compounds and esters and salts thereof, microorganisms for producing the compounds, methods for producing the compounds A and/or B by using the microorganisms, and a treated or untreated fermentation broth obtained by culturing strains belonging to genus Zopfiella or Zopfiella curvata No. 37-3 strain. ##STR1## The present invention provides the compounds A and B, derivatives thereof, and treated or untreated fermentation broth obtained by culturing the strains belonging to genus Zopfiella or Zopfiella curvata No. 37-3 strain, which show an excellent activities as antifungal agent and anti-thrombotic agent.

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 process for producing anhydrides by passing a solution of the acid, preferably an organic polyacid, which is to undergo anhydridation over an acidified clay and a process for producing the catalysts therefor.

Abstract: A process for the production of carboxylic anhydrides from aromatic hydrocarbons in gas phase oxidation by using a high activity and high selectivity fluid catalyst, comprising 50 to 95% by weight calculated as TiO.sub.2 +SiO.sub.2 +B.sub.2 O.sub.3 of component (A) which comprises titanium oxide, silicon dioxide and boron oxide and5 to 50% by weight calculated as V.sub.2 O.sub.5 +M.sub.2 O (M represents an alkali metal) +SO.sub.3 of component (B) comprising vanadium oxide, an alkali metal oxide and sulfuric anhydride, wherein weight ratios of B.sub.2 O.sub.3 to TiO.sub.2 and SiO.sub.2 to TiO.sub.2 in said component (A) are in the range of 0.02 to 0.5 and 0.25 to 1.0, respectively, is provided.

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: Pyromellitic dianhydride, useful as raw material for the manufacture of polyimides, is prepared in high yield and purity by the reaction of benzene derivatives such as ethylbenzene, diethylbenzenes, and triethylbenzenes with an ethylating agent in the presence of a Friedel-Crafts catalyst, the separation of tetraethylbenzenes from the reaction products by distillation, the separation of 1,2,4,5-tetraethylbenzene from other tetraethyl benzenes by differential centrifugal precipitation at -10 to -30 degrees Celsius, and the catalytic vapor-phase oxidation of tetraethyl benzenes, using a catalyst containing vanadium pentoxide and titanium dioxide.

Abstract: Chemiluminescenct 3-aminobenzene-1,2,4,5-tetracarboxylic dihydrazides.

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: A process for the preparation of purified oxydiphthalic acid from impure oxydiphthalic anhydride, by treating with a mixture of water and propionic acid or butyric acid to produce oxydiphthalic acid. The acid may be treated to reform oxydiphthalic anhydride. The most effective composition range for the acid-water mixture is from about 25% acid to 75% acid.