Abstract: A method for preparing an unsaturated carboxylic acid comprising (a) preparing an aqueous solution comprising an ammonium salt of hydroxycarboxylic acid and a salt of inorganic acid; (b) contacting the aqueous solution with a cation exchange resin to prepare a conversion aqueous solution comprising a hydroxycarboxylic acid and an inorganic acid; and (c) dehydrating the hydroxycarboxylic acid using the inorganic acid as a catalyst is provided.

Abstract: A process of continuous production for polyester, comprising continuously supplying an esterification or transesterification product comprising ester oligomers with an acid value of less than 100 meq/kg to a liquid phase polymerization reactor, wherein the esterification or transesterification product is produced by esterification or transesterification of a polycarboxylic acid or an alkyl ester thereof and a polyhydric alcohol; and performing a liquid-phase polymerization at a temperature of 200 to 270° C. and at a pressure of 0 to 5 torr in a liquid-phase polymerization reactor to produce the polyester with an intrinsic viscosity of 0.4 dl/g or higher.

Abstract: Provided is a two-step method of producing a compound of chemical formula 1 in the presence of an alcohol solvent and a Group 3B metal catalyst or a salt thereof, comprising a first step comprising alkylation or isomerization of an aldohexose-containing substrate to obtain an intermediate, and a second step comprising dehydration of the intermediate to produce a compound of chemical formula 1. Preferably, additional solvent and/or catalyst are not added in the second step.