Abstract: In the process of the present invention for producing diol compounds by esterifying a carboxylic acid mixture collected from a reaction product mixture of a liquid phase oxidation of cyclohexane with air and hydrogenate-decomposing the resultant esterification product mixture with hydrogen, the hydrogenate-decomposition is carried out by using a combined catalyst which includes a catalyst (A) including, as principal components, copper oxide and zinc oxide and a catalyst (B) including copper oxide and iron oxide carried on aluminum oxide, does not include chromium, has a high catalytic activity and can be easily separated by filtering, and the combined catalyst is collected from the hydrogenate-decomposition reaction product mixture by filtering it.

Abstract: A monoalkylether of a dihydric phenol compound is produced at a high conversion and selectivity by catalytically dehydration reacting a dihydric phenol compound with a lower monohydric alcohol in the presence of a catalyst comprising at least one inorganic substance of the empirical formula (I):Al.sub.a P.sub.b Ti.sub.c Si.sub.d X.sub.e O.sub.f (I):wherein X is an alkali metal (Group Ia) atom, alkaline earth metal (Group IIa) atom or a metal atom of Group VIII of the Periodic Table, a, b, c, d, e and f are the numbers of Al, P, Ti, Si, X and O atoms respectively, and provided that a =1, b =1.0 to 1.9, c =0 05 to 0.5, d=0.05 to 0.2, e=0 to 0.9 and f=4.2 to 8.1, and collecting the resultant reaction product from the reaction system.

Abstract: A monoalkylether of dihydric phenol compound is produced by bringing a feed gas comprising a mixture gas of a dihydric phenol compound with a monohydric alcohol compound into contact with an active catalyst component comprising at least one member selected from phosphorus compounds, and mixtures and reaction products of phosphorus compounds with boron compounds and carried on an inert solid carrier consisting of, for example, .alpha.-alumina, .gamma.-alumina, activated carbon or titania grains, and preferably having a pore volume of 0.1 ml/g or more and a specific surface area of 1 m.sup.2 /g or more, at a temperature of 200.degree. C. to 400.degree. C., and collecting the resultant reaction product from the reaction mixture.

Abstract: There is provided a process for the continuous preparation of a diester of oxalic acid, which comprises a first step of reacting carbon monoxide with an ester of nitrous acid in the gaseous phase; a second step of condensing the gaseous reaction mixture to separate a non-condensed gas from a condensed liquid containing the diester of oxalic acid; a third step of introducing the non-condensed gas of the second step to a regeneration column, thereby contacting it with a gas containing molecular oxygen and an alcohol, and recycling the resulting gas containing an ester of nitrous acid to the reactor of the first step; a fourth step of distilling out an alcohol containing a diester of carbonic acid formed as a by-product of the first step and obtaining a liquid diester of oxalic acid; and a fifth step of introducing the distillate of the fourth step to a hydrolysis column thereby hydrolyzing the diester of carbonic acid in the gas and recycling the alcohol as an alcohol source for the third step.

Abstract: There is provided a process for the continuous preparation of a diester of oxalic acid which comprises a first step of reacting carbon monoxide with an ester of nitrous acid in the gaseous phase; a second step of condensing the gaseous reaction mixture to separate a non-condensed gas from a condensed liquid containing the diester of oxalic acid; a third step of introducing the non-condensed gas of the second step to a regeneration column and thereby contacting it with a gas containing molecular oxygen and an alcohol to regenerate nitrogen monoxide in the non-condensed gas into an ester of nitrous acid so as to bring the concentration of nitrogen monoxide in the gas at the outlet of the column to a level of from 2 to 7% by volume; and a fourth step of recycling the gas of the third step containing the ester of nitrous acid and from 2 to 7% by volume of nitrogen monoxide to the reactor of the first step.

Abstract: There is disclosed a process for continuously preparing ethylene glycol, which comprises (1) a first step of contacting a gas containing carbon monoxide and an ester of nitrous acid with a solid catalyst of platinum group metal series in the gaseous phase thereby to obtain a product containing a diester of oxalic acid, (2) a second step of condensing the product of the first step thereby to separate a non-condensed gas containing nitrogen monoxide formed by the catalytic reaction of the first step from a condensed liquid containing the diester of oxalic acid, (3) a third step of contacting the non-condensed gas of the second step with a gas containing molecular oxygen and an alcohol, and recycling the resulting gas containing an ester of nitrous acid to the first step, (4) a fourth step of contacting the condensed liquid of the second step containing the diester of oxalic acid and hydrogen with a catalyst for hydrogenation in the gaseous phase thereby to obtain a product containing ethylene glycol, (5) a fift

Abstract: There is disclosed a novel process for the preparation of an ester of formic acid which comprises subjecting hydrogen, carbon monoxide and an ester of nitrous acid to a catalytic vapor phase reaction in the presence of a platinum group metal or a salt thereof. The product obtained by the process according to the present invention does not substantially contain water and free formic acid. The ester of formic acid formed by the process according to the present invention can be separated and purified in a simple manner, e.g., by conventional distillation procedure.

Abstract: A process for preparing a diester of a dicarboxylic acid having two more carbon atoms than the unsaturated hydrocarbon used as a starting material, which comprises subjecting an unsaturated hydrocarbon, carbon monoxide and an ester of nitrous acid to catalytic vapor phase reaction at a temperature of 50.degree. to 200.degree. C. in the presence of a platinum group metal or a salt thereof and a halogen compound.

Abstract: A process for preparing a diester of oxalic acid which comprises bringing carbon monoxide into contact with an ester of nitrous acid or with an alcohol and a nitrogen oxide or a hydrate of the nitrogen oxide in the gaseous phase in the presence of a solid catalyst containing metallic palladium or a salt thereof, a gas containing molecular oxygen being introduced into the reaction system in cases where said nitrogen oxide or a hydrate of the nitrogen oxide requires molecular oxygen together with the alcohol to form an ester of nitrous acid.

Abstract: A process for separating and purifying biphenyltetracarboxylic dianhydride isomers from a mixture of these isomers by fractional crystallization in aliphatic acid anhydrides or acetone. The isomeric mixture is obtained by heating biphenyltetracarboxylic acids, optionally in the presence of an aliphatic acid anhydride. The biphenyltetracarboxylic acids are obtained by oxidizing coupling dimers of o-xylene or by hydrolyzing coupling dimers of dimethyl phthalate. 2,3,3',4'-biphenyltetracarboxylic acid dianhydride which can be isolated from the above mixture can be used to form polyimide.

Abstract: A process for separating and purifying biphenyltetracarboxylic dianhdride isomers from a mixture of these isomers by fractional crystallization in aliphatic acid anhydrides or acetone. The isomeric mixture is obtained by heating biphenyltetracarboxylic acids, optionally in the presence of an aliphatic acid anhydride. The biphenyltetracarboxylic acids are obtained by oxidizing coupling dimers of o-xylene or by hydrolyzing coupling dimers of dimethyl phthalate.

Abstract: A process for preparing a diester of oxalic acid which comprises bringing carbon monoxide into contact with an ester of nitrous acid or with an alcohol and a nitrogen oxide or a hydrate of the nitrogen oxide in the gaseous phase in the presence of a solid catalyst containing metallic palladium or a salt thereof, a gas containing molecular oxygen being introduced into the reaction system in cases where said nitrogen oxide or a hydrate of the nitrogen oxide requires molecular oxygen together with the alcohol to form an ester of nitrous acid.