Abstract: A reprocessing process of spent nuclear fuels for roughly separating U and U—Pu from FP, TRU and the like in a nitric acid solution of spent nuclear fuels by utilizing phenomenon of cocrystallization of hexavalent U and Pu. For example, spent nuclear fuels are sheared and dissolved in nitric acid, and insoluble residues in the nitric acid solution are removed. Then, a nitric acid concentration in the solution is adjusted and a valence of Pu in the solution is adjusted to tetravalence. The solution is then cooled to crystallize uranyl nitrate hydrate crystals and separated into the crystals and a mother liquor, and the separated crystals are recovered as a U product. Then, a nitric acid concentration in the separated mother liquor is adjusted and a valance of U and Pu in the mother liquor is adjusted to hexavalence, and the mother liquor is cooled to crystallize uranyl-plutonyl nitrate hydrate crystals which are separated and recovered as a U—Pu mixed product.

Abstract: A reprocessing process of spent nuclear fuels for roughly separating U and U—Pu from FP, TRU and the like in a nitric acid solution of spent nuclear fuels by utilizing phenomenon of cocrystallization of hexavalent U and Pu. For example, spent nuclear fuels are sheared and dissolved in nitric acid, and insoluble residues in the nitric acid solution are removed. Then, a nitric acid concentration in the solution is adjusted and a valence of Pu in the solution is adjusted to tetravalence. The solution is then cooled to crystallize uranyl nitrate hydrate crystals and separated into the crystals and a mother liquor, and the separated crystals are recovered as a U product. Then, a nitric acid concentration in the separated mother liquor is adjusted and a valance of U and Pu in the mother liquor is adjusted to hexavalence, and the mother liquor is cooled to crystallize uranyl-plutonyl nitrate hydrate crystals which are separated and recovered as a U—Pu mixed product.

Abstract: A high molecular weight polyimidoylamidine having an intrinsic viscosity of from 0.25 dl/g to 0.60 dl/g and a high molecular weight polytriazine derived therefrom having an intrinsic viscosity of from 0.25 dl/g to 0.65 dl/g are disclosed. A polyimidoylamidine having a molecular weight in a wide range, including high molecular weight, can advantageously be obtained by reacting a perfluoropolyether dinitrile with ammonia and reacting the resultant reaction product with a specific amount of a perfluoropolyether dinitrile. A terminal-stabilized polytriazine and its preparation methods are also disclosed. A polytrizine, which contains a nitrile group at side chains thereof and has an intrinsic viscosity within a specific range, is particularly suitable as a precursor of a perfluoroelastomer having excellent mechanical and chemical properties.

Abstract: A process for the treatment of a quaternary onium salt is described. The process comprises the steps of (i) contacting an organic phase soaringly miscible in water containing a quaternary onium fluorine-containing carboxylate of RfCO.sub.2.sup.-+ AR.sup.1 R.sup.2 R.sup.3 R.sup.4 as defined in the present Specification with an aqueous phase containing a thiocyanate ion to form a quaternary onium thiocyanate in the organic phase and (ii) contacting the organic phase containing the quaternary onium thiocyanate with an aqueous solution containing a water-soluble oxidizing agent to decompose the thiocyanate ion and to form an easily ion exchangeable quaternary onium salt. Also, applications of this treatment to a process for preparing hexafluoropropylene oxide from hexafluoropropylene in a two-phase system of an aqueous phase and an organic phase by using a hypochlorite as an oxidizing agent in the presence of a quaternary onium salt as a catalyst are described.

Abstract: A process for epoxidation of a fluoro-olefin is disclosed. The process comprises epoxidizing a fluoro-olefin represented by the general formula (I): ##STR1## wherein X.sup.1, X.sup.2 and X.sup.3 each represents a substituent selected from (a)--F, (b) a perfluoroalkyl group having 2 to 20 carbon atoms and (c) --CF.sub.2 Y.sup.1, Y.sup.1 may be the same or different and represents a substituent selected from (d) a halogen atom selected from F, Cl, Br and I, (e) --OZ.sup.1 and (f) --Z.sup.1, wherein Z.sup.1 may be the same or different and represents a substituted or unsubstituted hydrocarbon group having not more than 20 carbon atoms, and X.sup.1, X.sup.2, X.sup.3 and Y.sup.1 may be combined with one another to form a cyclic compound, provided that all of X.sup.1, X.sup.2, X.sup.3 and Y.sup.1 do not represent --F; using a hypochlorite dissolved or suspended in an aqueous phase as an oxidizing agent in the presence or absence of an inorganic base.

Abstract: A process for epoxidation of a fluoro-olefin is disclosed. The process comprises epoxidizing a fluoro-olefin represented by the general formula (I): ##STR1## wherein X.sup.1, X.sup.2 and X.sup.3 each represents a substituent selected from (a) --F, (b) a perfluoroalkyl group having 2 to 20 carbon atoms and (c) --CF.sub.2 Y.sup.1, Y.sup.1 may be the same or different and represents a substituent selected from (d) a halogen atom selected from F, Cl, Br and I, (e) --OZ.sup.1 and (f) --Z.sup.1, wherein Z.sup.1 may be the same or different and represents a substituted or unsubstituted hydrocarbon group having not more than 20 carbon atoms, and X.sup.1, X.sup.2, X.sup.3 and Y.sup.1 may be combined with one another to form a cyclic compound, provided that all of X.sup.1, X.sup.2, X.sup.3 and Y.sup.1 do not represent --F; using a hypochlorite dissolved or suspended in an aqueous phase as an oxidizing agent in the presence or absence of an inorganic base.

Abstract: A process for producing hexafluoropropylene oxide from hexafluoropropylene is described. The process comprises epoxidizing hexafluoropropylene in a two-phase system of an aqueous phase and an organic phase by the use of a hypochlorite as an oxidizing agent, the hypochlorite being dissolved or dispersed in the aqueous phase, in the presence of at least one catalyst selected from the group consisting of (a) quaternary ammonium salts, (b) quaternary phosphonium salts, (c) quaternary arsonium salts, and (d) lipophilic complexing agents for cations contained in the hypochlorite, and also, in the presence or absence of an inorganic base.

Abstract: A process for producing hexafluoropropylene oxide from hexafluoropropylene is described. The process comprises epoxidizing hexafluoropropylene in a two-phase system of an aqueous phase and an organic phase by the use of a hypochlorite as an oxidizing agent, the hypochlorite being dissolved or dispersed in the aqueous phase, in the presence of at least one catalyst selected from the group consisting of (a) quaternary ammonium salts, (b) quaternary phosphonium salts, (c) quaternary arsonium salts, and (d) lipophilic complexing agents for cations contained in the hypochlorite, and also, in the presence or absence of an inorganic base.

Abstract: A polyamide elastomer having a structure of dehydration condensate between(A) a polycapramide having a number average molecular weight of 500-5,000 and having carboxyl end groups, which is derived from caprolactam and a dicarboxylic acid having 4-20 carbon atoms selected from aliphatic dicarboxylic acids, alicyclic dicarboxylic acids and aromatic dicarboxylic acids and (B) a polyoxytetramethylene glycol having a number average molecular weight of 800-5,000 or a modified polyoxytetramethylene glycol having a number average molecular weight of 800-5,000 and having, in the molecular chain, the units represented by the general formula--O--R--wherein R is a branched chain alkylene group having 4-20 carbon atoms or a straight chain alkylene group having 5-20 carbon atoms, the units content being 50% by weight or a less; the weight ratio of the component (A) to the component (B) being from 10:90 to 60:40. The said elastomer has a relative viscosity of 1.5 or above in m-cresol (0.5 weight/volume %) at 30.degree. C.

Abstract: A process for producing a polyether polyol with a content of 0.5 to 99.5% by weight of oxytetramethylene groups derived from tetrahydrofuran by copolymerizing tetrahydrofuran or a mixture of tetrahydrofuran and other cyclic ether copolymerizable therewith with a polyhydric alcohol having two or more hydroxyl groups per one molecule with the use of a heteropoly-acid and/or its salt as a catalyst, which comprises allowing 0.1 to 15 molecules of water per one heteropoly-anion to exist in the catalyst phase.The above-described polyether polyol is an industrially useful polymer which is a starting material for polyurethane to be used for spandex or a synthetic leather, etc.

Abstract: A process for purifying a polyalkylene ether, which comprises mixing a polyalkylene ether or a mixture of a polyalkylene ether and an organic solvent containing a heteropoly acid and/or its salt with at least one solvent for purification selected from hydrocarbons having 3 to 15 carbon atoms or halogenated hydrocarbons having 1 to 15 carbon atoms and separating by precipitation the phase composed mainly of the heteropoly acid and/or its salt, and a process wherein the polyalkylene ether or a mixture of a polyalkylene ether and an organic solvent containing a heteropoly acid and/or its salt is brought into contact with a solid adsorbent capable of adsorbing the heteropoly acid and/or its salt in the presence of at least one solvent for purification as described above, either further after the separation according to the process described above, or in the state unseparated.

Abstract: A polyacetal copolymer of continuous length is disclosed. The copolymer has an apparent density of 1.20 to 1.46 g/cm.sup.3, and a tensile modulus (X) of 19 GPA or more and a density change percentage (Y) of 85% or more. The relationship between the density change percentage (Y) and the tensile modulus (X) is defined by the following relationship:when 19.ltoreq.X.ltoreq.30, then Y.gtoreq.127.7-1.42X, and when X>30, Y.gtoreq.85.A method for producing this copolymer includes permitting a polymeric material in continuous length to pass through a pressurizing fluid and applying a substantially uniform pressure therearound. A drawing stress is applied to the material while heating it at a temperature not above its softening point, thus subjecting the material to high stretching.

Abstract: A process for producing a polyether polyol with a content of 0.5 to 99.5% by weight of oxytetramethylene groups derived from tetrahydrofuran by copolymerizing tetrahydrofuran or a mixture of tetrahydrofuran and another cyclic ether copolymerizable therewith with a polyhydric alcohol having two or more hydroxyl groups per one molecule with the use of a heteropoly-acid and/or its salt as a catalyst, which comprises allowing 0.1 to 15 molecules of water per one heteropoly-anion to exist in the catalyst phase.The above-described polyether polyol is an industrially useful polymer which is a starting material for polyurethane to be used for spandex or a synthetic leather, etc.

Abstract: A process for producing a polyoxytetramethylene glycol or a copolymerized polyetherglycol by polymerizing tetrahydrofuran or a mixture of tetrahydrofuran with other cyclic ethers copolymerizable therewith, which comprises using a heteropoly-acid as a catalyst and permitting 0.1 to 15 mol of water per mol of the heteropolyacid to be present in the catalyst phase.The above-described polymer and copolymer are industrially useful polymers which can be used as the primary starting materials for polyurethanes to be used for a spandex and a synthetic leather, solvents, pressured fluids, etc.

Abstract: In purifying methyl methacrylate by feeding a feed mixture containing methanol, methyl methacrylate and 0.

Abstract: A method for preparing a carboxylic ester by reacting an aldehyde with an alcohol in the presence of oxygen with a catalyst, characterized in that the catalyst is a solid catalyst comprising palladium and bismuth, which may form an intermetallic compound, and which catalyst may comprise an alkali metal compound or an alkaline earth metal compound. The aforesaid catalyst avoids decomposition reactions simultaneously with the desired reaction, and therefore, the desired compound can be obtained in a high yield.

Abstract: A process for producing methacrolein by oxidizing isobutylene or tertiary butanol with molecular oxygen, characterized by contacting a gaseous mixture of isobutylene or tertiary butanol, air or oxygen and optionally steam and an inert gas with a catalyst having the general composition:Mo.sub.12 Fe.sub.a Ni.sub.b Te.sub.c X.sub.d Z.sub.f Y.sub.g O.sub.hwherein a, b, c, d, f and g represent the numbers of atoms of the respective elements per 12 molybdenum atoms; X is Tl, Rb or Cs; Z is In or Ti; Y represents at least one element selected from the group consisting of Cu, Nd, Sm and Pb; a is a value of 0.2-6; b is a value of 0.2-6; a+b is a value of 1-10; c is a value of 0.1-4; d is a value of 0.1-3; f is a value of 0.1-3; g is a value of 0-5; and h is the number of oxygen atoms for satisfying the valencies of the existing elements. The use of this catalyst enables the selectivity for methacrolein to be improved to 90 or more and the yield based on the starting material to be increased to 89-91%.

Abstract: In a process for preparing an ether having a tertiary alkyl group by the reaction of a primary or secondary alcohol with the tertiary olefin in a tertiary olefin-containing mixed hydrocarbon, said reaction is carried out in the presence of an adduct of the starting alcohol with a heteropoly acid or salt thereof containing at least one member selected from the group consisting of P, Si, B, Ge, As, Se, Ti, Zr, Mn, F, U, Ce and Th as a central element, at least Mo and/or W as a coordinating element and at least one member selected from the group consisting of H, Li, Na, K, Rb, Cs, NR.sup.4 R.sup.5 R.sup.6 R.sup.7 wherein R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are hydrogen atoms or alkyl groups, Mg, Ca, Ba, Zr, Cr, Mn, Fe, Co, Mi, Cu, Ag, Zn, Cd, Hg, Al, Pb and Bi as cations, the ratio of the number of the coordinating elements to the number of the central elements being 2.

Abstract: A process for producing an ester of acrylic or methacrylic acid by oxidizing propylene or isobutylene in the liquid phase in the presence of a straight chain lower alcohol and molecular oxygen, characterized by carrying out the reaction in the presence of:(1) a catalyst consisting of palladium and at least one metal selected from the group consisting of lead, bismuth, thallium, tellurium and mercury, preferably an intermetallic compound of palladium and said metal;(2) at least one compound selected from the group consisting of mineral acids, heteropoly-acids, heteropoly-acid salts, molybdic acid and organic sulfonic acids, preferably heteropoly-acids or their salts; and(3) optionally, at least one compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds.According to this process, the activity of catalyst is high even in a reaction at low temperatures, the amount of by-product is small and the objective ester can be produced with a high selectivity.

Abstract: A method for preparing methacrolein by oxidizing isobutylene or tertiary butanol with molecular oxygen, characterized by contacting a gaseous mixture of isobutylene or tertiary butanol, air or oxygen and optionally steam and an inert gas with a catalyst having the general combination:Mo.sub.12 Fe.sub.a Ni.sub.b Te.sub.c Tl.sub.d Pb.sub.f X.sub.g O.sub.hwherein a, b, c, d, f and g represent the numbers of atoms of the respective elements per 12 molybdenum atoms; X is at least one element selected from the group consisting of Cu, Nd and Sm; a is a value of 0.2-6; b is a value of 0.2-6; a+b is a value of 1-10; c is a value of 0.1-4; d is a value of 0.1-3; f is a value of 0.1-5; g is a value of 0.1-5; and h is the number of oxygen atoms for satisfying the valencies of the existing elements. The use of this catalyst enables the selectivity for methacrolein to be improved to 90-94% and the yield based on the starting material to be increased to 89-91%.