Abstract: An atmospheric pressure process for the continuous production of polyester is disclosed wherein a melt of bis(3-hydroxy propyl) terephthalate, or its low molecular oligomers, obtained by esterifying terephthalic acid or transesterifying dimethyl terephthalate with propylene glycol, is intimately contacted with an inert gas to facilitate polymerization and removal of the reaction byproducts. The propylene glycol evolved and the inert gas are recycled.

Abstract: An atmospheric pressure process for the continuous production of polyester is disclosed wherein a melt of dihydroxy ethyl terephthalate, or its low molecular oligomers, obtained by esterifying terephthalic acid or transesterifying dimethyl terephthalate with ethylene glycol, is intimately contacted with an inert gas to facilitate polymerization and removal of the reaction by-products. The ethylene glycol evolved and the inert gas are recycled.

Abstract: An atmospheric pressure process for the continuous production of polyester is disclosed wherein a melt of dihydroxy ethyl terphthalate, or its low molecular oligomers, obtained by esterifying terephthalic acid or transesterifying dimethyl terephthalate with ethylene glycol, is intimately contacted with an inert gas to facilitate polymerization and removal of the reaction by-products. The ethylene glycol evolved and the inert gas are recycled.

Abstract: An improved process for the recovery of lactide or other dimeric cyclic ester from a gas stream containing the cyclic ester and such hydroxylic impurities as water and open-chain hydroxycarboxylic acids, by scrubbing the gas stream with a water immiscible solvent, such as, a non-polar hydrocarbon, a cycloaliphatic hydrocarbon or a halogenated hydrocarbon solvent, at a temperature at which the cyclic ester and the open-chain hydroxycarboxylic acids are scrubbed from the gas stream and any water present in the gas stream is carried away. The crude cyclic ester-acid composition is separated from the solvent and purified by extracting the acid impurities therefrom. The acid impurities are recovered and recycled.

Abstract: A distillation process for converting lactic acid oligomer to lactide wherein the oligomer is depolymerized in the presence of a co-vaporizable solvent at a temperature and pressure which forms a vapor fraction comprising water, lactide, lactic acid and solvent, and the vapor fraction is condensed and the lactide is recovered from the condensate.

Abstract: A continuous catalyzed vapor phase process for the production of dimeric cyclic esters which comprises converting the corresponding alpha-hydroxy-carboxylic acid or ester in the vapor phase over a solid catalyst, such as a silica-alumina, preferably a silica-alumina having a high silica content, in the presence of a carrier of gas.

Abstract: Processes are described for recovering lactic acid from impure lactide and the residue produced in the depolymerization of polylactic acid to lactide. Lactic acid is recovered from the impure lactide by a dual solvent extraction process and, from the polylactic acid residue by hydrolysis. The lactic acid recovered from the impure lactide and the depolymerization residue is recycled to provide for a high yield lactide process.

Abstract: An improved process for the recovery of lactide or other dimeric cyclic ester from a gas stream containing the cyclic ester and such hydroxylic impurities as water and open-chain hydroxycarboxylic acids by scrubbing the gas stream with a nonpolar water-immiscible solvent at a temperature at which the cyclic ester is removed from the solvent and any water present in the gas stream is vaporized from the solvent. The cyclic ester is recovered from the solvent in a high state of optical purity.

Abstract: A gas-assisted process for the rapid conversion of oligomers of alpha-hydroxycarboxylic acids, esters or nitrogen salts thereof to cyclic esters in high yields and high states of purity. An inert gas is intimately contacted with the oligomer so as to create a large interfacial area. The large interfacial area permits removal of the cyclic ester substantially as fast as the cyclic ester is formed.

Abstract: A continuous, gas-assisted atmospheric process for preparing cyclic esters of alpha-hydroxycarboxylic acids, such as lactide, which comprises feeding the reactants into a reactor having means for introducing an inert gas at the operating temperature, forming a reaction mass having cyclic esters in the reactor, passing a flow of said inert gas through said reactor whereby cyclic esters are swept from the reaction mass into a gaseous product stream, and recovering the cyclic esters therefrom.

Abstract: A gas-assisted continuous process for the rapid conversion of oligomers of alpha-hydroxycarboxylic acids, esters or salts thereof to cyclic esters in high yields and high states of purity.

Abstract: This invention relates to a gas-assisted vaporization process for purifying cyclic esters such as glycolide, lactides and mixtures thereof which enables the cyclic ester to be rapidly separated from its impurities as a vapor component of a gas stream. The process includes a solvent-scrubbing step for recovering the cyclic ester from the gas stream.

Abstract: This invention relates to an improved process for preparing highly pure cyclic esters by heating a polymer of the corresponding .alpha.-hydroxy acid or its ester or a copolymer of .alpha.-hydroxy acid or its ester and a thermally stable polyether in the presence of an inert gas at atmospheric pressure. The cyclic ester is carried from the reaction with the inert gas to a solvent system.

Abstract: 2-VINYL-5-METHYL-1,3-DIOXANE IS PROVIDED AS A NEW CYCLIC ACETAL WHICH, WHEN HYDROFORMYLATED, HYDROLYZED AND HYDROGENATED PROVIDES HIGH YIELDS OF A MIXTURE OF 1,4-BUTANEDIOL AND 2-METHYL-1,3-PROPANEDIOL.

Abstract: 2-Vinyl-5-methyl-1,3-dioxane is provided as a new cyclic acetal which, when hydroformylated, hydrolyzed and hydrogenated provides high yields of a mixture of 1,4-butanediol and 2-methyl-1,3-propanediol.

Abstract: 2(2'-PROPANAL)-5-METHYL-1,3-DIOXANE AND 2(3'-PROPANAL)-5-METHYL-1,3-DIOXANE ARE PROVIDED AS NEW CYCLIC ACETAL-ALDEHYDES WHICH, WHEN HYDROLYZED AND HYDROGENATED, PROVIDE HIGH YIELDS OF A MIXTURE OF 1,4-BUTANEDIOL AND 2-METHYL-1,3-PROPANEDIOL.