Abstract: There may be provided a process for producing a polyimide siloxane solution composition having a further improved long-term viscosity stability; and a polyimide siloxane solution composition. In the process for producing the polyimide siloxane solution composition by polymerizing/imidizing a tetracarboxylic acid component and a diamine component consisting of (a) a diaminopolysiloxane, (b) a diamine having a polar group and (c) a diamine other than (a) and (b) in a solvent, the tetracarboxylic acid component and the diamine component excluding (b) the diamine having a polar group are polymerized/imidized to provide a reaction mixture solution, and then (b) the diamine having a polar group is added to the reaction mixture solution last, and the mixture is polymerized/imidized.

Abstract: Disclosed is a polymerizable composition comprising Component (a): a polythiocarbonate polythiol, Component (b): an episulfide compound, and optionally Component (c): an organic compound having a functional group that is reactive to the episulfide compound. The polymerizable composition can be cured to provide a polythioether having excellent optical properties (a high refractive index and a high Abbe's number) as well as excellent mechanical properties (a high bending distortion and a high glass transition temperature) and thus exhibiting excellent properties as an optical material.

Abstract: Disclosed is a polythiocarbonate poly(thio)epoxide in which a hydrogen atom in a mercapto group of a polythiocarbonate polythiol is substituted with a (thio)epoxy-containing group. By using this compound as a starting material, there can be obtained a polythioether or a sulfur-containing polyether having, in addition to excellent optical properties (a high refractive index and a high Abbe's number), excellent mechanical properties (a high bending distortion) and a high glass transition temperature.

Abstract: There may be provided a process for producing a polyimide siloxane solution composition having a further improved long-term viscosity stability; and a polyimide siloxane solution composition. In the process for producing the polyimide siloxane solution composition by polymerizing/imidizing a tetracarboxylic acid component and a diamine component consisting of (a) a diaminopolysiloxane, (b) a diamine having a polar group and (c) a diamine other than (a) and (b) in a solvent, the tetracarboxylic acid component and the diamine component excluding (b) the diamine having a polar group are polymerized/imidized to provide a reaction mixture solution, and then (b) the diamine having a polar group is added to the reaction mixture solution last, and the mixture is polymerized/imidized.

Abstract: Disclosed is a polymerizable composition comprising Component (a): a polythiocarbonate polythiol, Component (b): an episulfide compound, and optionally Component (c): an organic compound having a functional group that is reactive to the episulfide compound. The polymerizable composition can be cured to provide a polythioether having excellent optical properties (a high refractive index and a high Abbe's number) as well as excellent mechanical properties (a high bending distortion and a high glass transition temperature) and thus exhibiting excellent properties as an optical material.

Abstract: Disclosed is a polythiocarbonate poly(thio)epoxide in which a hydrogen atom in a mercapto group of a polythiocarbonate polythiol is substituted with a (thio)epoxy-containing group. By using this compound as a starting material, there can be obtained a polythioether or a sulfur-containing polyether having, in addition to excellent optical properties (a high refractive index and a high Abbe's number), excellent mechanical properties (a high bending distortion) and a high glass transition temperature.

Abstract: Disclosed is a polythiourethane having a high refractive index and low dispersion which is obtained through a reaction between a polythiol component containing one or more polythiocarbonate polythiol (preferably one having a —(CO—S—R—S)— structure (wherein R represents a divalent hydrocarbon group) and a number average molecular weight of 200-2,500) and a polyisocyanate component containing a polyisocyanate and/or a polyisothiocyanate. This polythiourethane is useful for plastic lenses, prisms, optical fibers, substrates for information recording, colored filters, infrared absorbing filters and the like.

Abstract: Disclosed is a polythiocarbonate polythiol including repeating units represented by the chemical formula (I): in which formula (I), R represents a divalent hydrocarbon group, which hydrocarbon group may have at least one substituent which does not take part in a reaction with the polyisocyante component and the carbon chain in the hydrocarbon group may include at least one member selected from hetero atoms and an —OCO— group, and the polythiocarbonate polythiol has a number average molecular weight of 200 to 2500.

Abstract: Disclosed is a polythiourethane having a high refractive index and low dispersion which is obtained through a reaction between a polythiol component containing one or more polythiocarbonate polythiol (preferably one having a —(CO—S—R—S)— structure (wherein R represents a divalent hydrocarbon group) and a number average molecular weight of 200-2,500) and a polyisocyanate component containing a polyisocyanate and/or a polyisothiocyanate. This polythiourethane is useful for plastic lenses, prisms, optical fibers, substrates for information recording, colored filters, infrared absorbing filters and the like.

Abstract: Disclosed is a polythiocarbonate polythiol including repeating units represented by the chemical formula (I): in which formula (I), R represents a divalent hydrocarbon group, which hydrocarbon group may have at least one substituent which does not take part in a reaction with the polyisocyante component and the carbon chain in the hydrocarbon group may include at least one member selected from hetero atoms and an —OCO— group, and the polythiocarbonate polythiol has a number average molecular weight of 200 to 2500.

Abstract: Disclosed is a method for preparing 2-mercaptothiazole, which comprises adding a dithiocarbamate salt represented by the formula (1): ##STR1## wherein M is a cation, to a chloroacetaldehyde solution in the presence of an acid.

Abstract: Disclosed is a process for preparing 1-ethyl-5-hydroxy-pyrazole, which comprises reacting an alkyl 3-alkoxy-acrylate represented by the following formula (1): ##STR1## wherein R.sup.1 and R.sup.2 are the same or different from each other and each represent a lower alkyl group, and in the formula represents either cis- or trans-configuration, with ethylhydrazine in an amount of 1- to 10-fold mole based on 1 mole of the alkyl 3-alkoxyacrylate in a weakly basic aqueous solvent.

Abstract: Disclosed is a process for preparing .epsilon.-caprolactone comprising using a percarboxylic acid solution obtained by oxidizing organic carboxylic acid in an organic solvent in the presence of hydrogen peroxide and a boric acid catalyst, and cyclohexanone, supplying 1 to 1.5 mole of percarboxylic acid, 0.012 mole or less of hydrogen peroxide and 0.04 mole or less of the boric acid catalyst per mole of cyclohexanone in a reaction system, and reacting said cyclohexanone with said percarboxylic acid to form .epsilon.-caprolactone.

Abstract: Disclosed is an ion exchange purification method of an aqueous caprolactam solution in a process for producing caprolactam and laurolactam by subjecting a mixture of cyclohexanone oxime and cyclododecanone oxime to Beckmann rearrangement in the presence of sulfuric acid and fuming sulfuric acid, which comprises, after neutralization of the rearrangement reaction products, and first extraction thereof with an organic solvent and second extraction of the first extract with water to obtain a second extract of an aqueous caprolactam solution, treating the aqueous caprolactam solution obtained by extraction with an organic solvent immiscible with water with a strongly acidic cation exchange resin, and subsequently with a weakly basic anion exchange resin or further with a strongly basic anion exchange resin.

Abstract: A process for preparing perpropionic acid solution comprising reacting propionic acid with hydrogen peroxide in the presence of a boric acid catalyst wherein the reaction is carried out by using an ethyl propionate as a reaction solvent, and water in the reaction solution is removed continuously by azeotropic distillation with the reaction solvent. Since the reaction is carried out while the concentration of the peroxide in an aqueous phase separated from the distillate by the azeotropic distillation is maintained at not more than 0.1% by weight, a perpropionic acid solution containing almost no unreacted hydrogen peroxide can be prepared.

Abstract: Disclosed is a process for stabilizing a percarboxylic acid characterized in that the percarboxylic acid is mixed with at least one pyridine derivative selected from the group consisting of picoline, ethylpyridine, conyrine, lutidine and N-oxide thereof.