Abstract: A process for the continuous production of polylactide polymers from lactic acid which incorporates removal of water or a solvent carrier to concentrate the lactic acid feed followed by polymerization to a low-molecular-weight prepolymer. This prepolymer is fed to a reactor in which a catalyst is added to facilitate generation of lactide, the depolymerization product of polylactic acid. The lactide generated is continuously fed to a distillation system as a liquid or vapor wherein water and other impurities are removed. The resultant purified liquid lactide is fed directly to a polymerization process.

Abstract: An ester is caused to act on a 2-substituted-3-hydroxycarboxylic acid ester as a racemate in the presence of hydrolase under substantially anhydrous conditions to effect a transesterification resulting in the resolution.The compound thus resolved is converted to an optically active 2,6-cis-2,5,6-substituted-1,3-dioxan-4-one and the resulting compound is recrystallized to give optically active 5,6-anti-2,5,6-substituted-1,3-dioxan-4-one and 5,6-syn-2,5,6-substituted-1,3-dioxan-4-one. Thus an optically active compound having plural chiral centers.Further, an optically active 2,5,6-substituted-1,3-dioxan-4-one obtained by transesterification and recrystallization is reacted with an alcohol to produce an optically active 2-substituted-3-hydroxycarboxylic acid ester.

Abstract: The invention relates to a new process for the preparation and purification of thermolabile compounds.

Abstract: A breathable, hydrolyzable, porous film which is obtained by the process comprising adding from 40 to 250 parts by weight of a finely-powdered filler having an average particle size of from 0.3 to 4 .mu.m to 100 parts by weight of a polylactic acid-based resin composition comprising from 80 to 100% by weight of polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer and from 0 to 20% by weight of a plasticizer, melting and film-forming the resultant mixture, and successively stretching the thus-obtained film 1.1 times or more at least in the direction of the axis; and which is consequently useful as a material for leakproof films of sanitary materials such as a paper diaper and packaging materials, and does not accumulate as wastes because of hydrolyzability in the natural environment in the case of being abandoned after use.

Abstract: The present invention is directed to a method for making lactide from aqueous lactic acid. The invention method comprises converting feed aqueous lactic acid to its vapor phase. The feed vapors then are passed through a reactor maintained at elevated temperature and in which optionally is disposed an alumina catalyst. Withdrawn from the reactor is product lactide, water, and unreacted lactic acid which are subjected to separation for recovery of the lactide product. The separated unreacted lactic acid is eligible for readmission to the process for making additional lactide. This cyclic process embodiment of the present invention comprises the steps of passing make-up aqueous lactic acid feed into a vaporization zone along with unreacted aqueous lactic acid filtrate from another step of the process and therein forming aqueous lactic acid feed vapors. The thus-generated vapors that are passed through a vapor phase reaction zone held at elevated temperature for forming lactide therein.

Abstract: This invention relates to a process for preparing 1,4-dioxane-2,5-diones comprising reacting an .alpha.-hydroxy acid oligomer or an ester of an .alpha.-hydroxy acid oligomer over a fixed bed catalyst system.

Abstract: A process of purifying and stabilizing a high molecular weight polylactide polymer by contacting solid polymer particles with methyl alcohol and subsequently acetone.

Abstract: Disclosed is a method for producing cyclic esters by the conversion of hydroxy carboxylic acids and their derivatives to their respective cyclic esters. Such cyclic esters, including lactide or glycolide, are particularly useful for producing polymers which can be used to make biodegradable materials, such as biodegradable packaging material. Various methods of cyclic ester production are disclosed, including liquid phase and vapor phase reactions. Also disclosed are various methods for recovering cyclic esters from product-containing streams.

Abstract: A highly selective dehydrogenation catalyst for the preparation of para-dioxanones is produced by impregnating copper and zinc on a promoter impregnated support. This catalyst is effective for the dehydrogenation of dialkylene glycols to produce a high purity 2-para-dioxanones.

Abstract: An improved process for converting oligomers of alphahydroxycarboxylic acids, such as glycolic and lactic acid, to dimeric cyclic esters, such as glycolide and lactide. The continuous process is conducted at reduced pressures and depolymerizing temperatures in a heated columnar depolymerization zone, coupled with an essentially unheated receiver for unconverted oligomer. By feeding the oligomer to the upper end of the column while coordinating the feed rate with the depolymerization temperature such that a fraction of the oligomer is converted to a vapor product stream containing the cyclic ester and another fraction of the oligomer exits the column at its lower end and passes to the receiver vessel, the dimeric cyclic ester is produced at high production rates and the oligomer is subjected to minimal thermal stress.

Abstract: The depolymerization of poly(hydroxyacids) in a liquid medium is enhanced by the presence of a quaternary ammonium compound. Poly(hydroxyacid) polymers containing a quaternary ammonium salt are more readily depolymerized.

Abstract: A process for the continuous conversion of crude lactic acid to a substantially purified lactide or polylactide including the steps of polymerizing the lactic acid to form a prepolymer with subsequent depolymerization to form a crude lactide in the presence of a catalyst. The crude lactide is purified in an improved distillation system in which at least three fractions are formed with the substantially purified lactide removed as an intermediate boiling sidedraw stream. The substantially purified lactide may then be polymerized.

Abstract: The present invention is directed to a method for making L-lactide from aqueous L-lactic acid. Aqueous lactic acid feed for present purposes comprehends an aqueous mixture of one or more of L.sub.1 A, L.sub.2 A, and L.sub.3 A, optionally with LD being present. L-lactic acid is the preferred feed configuration for making L-lactide, and is to be understood even though the configuration symbol is not used throughout this application. Aqueous lactic acid feed is treated for removal of water therefrom until a degree of polymerization (DP) not substantially above about 2 is reached. The treatment then is ceased to produce a crude LD product. LD then is separated from the crude LD product. A preferred treatment involves heating the feed at elevated temperature to remove water. LD can be separated from the crude LD product by a variety of techniques to produce an LD-depleted product.

Abstract: Depolymerizing high molecular weight polyhydroxy acid by reacting with an amine to produce an amide derivative.

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: Depolymerizing polyhydroxy acid by heating with the alcohol of 1-6 carbon atoms in the presence of an acid catalyst to produce an alkyl ester.

Abstract: Generally, polylactic acid is prepared by the ring opening polymerization of lactide. However, to obtain a high molecular weight polylactic acid it is necessary to start with a lactide having a high degree of purity. Lactide may be economically brought to the required degree of purity using melt recrystallization techniques.

Abstract: Rapid recovery from waste of high molecular weight polyhydroxyacid content by depolymerizing the PHA in acidic water.

Abstract: Polyhydroxyacid (PHA) is recovered by heating under pressure in the presence of a C.sub.1 -C.sub.6 alcohol, and optionally also water.

Abstract: A process for the continuous production of polylactide polymers from lactic acid which incorporates removal of water or a solvent carrier to concentrate the lactic acid feed followed by polymerization to a low-molecular-weight prepolymer. This prepolymer is fed to a reactor in which a catalyst is added to facilitate generation of lactide, the depolymerization product of polylactic acid. The lactide generated is continuously fed to a distillation system as a liquid or vapor wherein water and other impurities are removed. The resultant purified liquid lactide is fed directly to a polymerization process.

Abstract: There are provided novel and optically active 2,2-dimethyl-1,3-dioxin-4-ones which are useful as starting materials for physiologically active compounds, functional materials or the like. Furthermore, a method for preparing an optically active compound comprises reacting a racemic 1,3-dioxin-4-one with vinylacetate in the presence of lipase to resolve the racemic compound into optically active compound represented by the formula (3) ##STR1## and an optically active compound represented by the formula (4) ##STR2## which is an antipode of the compound represented by the formula (3).

Abstract: A process for the continuous production of substantially purified lactide and lactide polymers from an ester of lactic acid including the steps of forming crude lactide in the presence of a catalyst means to form a condensation reaction by-product and polylactic acid and depolymerizing the polylactic acid molecules followed by subsequent purification of the crude lactide in a distillation system. A purified lactide is then polymerized.

Abstract: A process for the continuous production of polylactide polymers from lactic acid which incorporates removal of water or a solvent carrier to concentrate the lactic acid feed followed by polymerization to a low-molecular-weight prepolymer. This prepolymer is fed to a reactor in which a catalyst is added to facilitate generation of lactide, the depolymerization product of polylactic acid. The lactide generated is continuously fed to a distillation system as a liquid or vapor wherein water and other impurities are removed. The resultant purified liquid lactide is fed directly to a polymerization process.

Abstract: A dimeric cyclic ester of an alpha-hydroxycarboxylic acid (lactide) is separated and recovered from a vapor product stream containing the cyclic ester, the corresponding lower-boiling hydroxycarboxylic acid (lactic), higher-boiling oligomeric hydroxycarboxylic acid and water without the use of solvents. More specifically, the vapor stream is condensed to obtain a condensate containing substantially all the cyclic ester, and the condensate is refined by distillation means alone to recover the cyclic ester substantially free of water, the alpha-hydroxycarboxylic acid and the higher-boiling oligomers.

Abstract: Recovery of polyhydroxy acids (PHAs) from waste containing high molecular weight polyhydroxy acid polymer by depolymerizing the PHA in water at elevated temperature and pressure.

Abstract: A process for preparing suture-grade .beta.-glycolide by purifying crude glycolide which comprises contacting the crude glycolide with a primary solvent which will dissolve the crude glycolide and residual impurities without dissolving primary impurities; removing the primary impurities; recovering the glycolide and residual impurities by evaporating the primary solvent at a temperature below 42.degree. C.; removing residual impurities by washing the glycolide with a washing solvent in which the residual impurities are soluble; and isolating the .beta.-glycolide crystals which remain.

Abstract: The invention relates to meso-lactide having a melting point of 52.8.degree. C. and to processes for its preparation.

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: The compounds of the formula: ##STR1## in which X, Y and Z are, independently, hydrogen, halogen, hydroxy, nitro, cyano, carboxyl, trifluoromethyl, phenyl, amino, alkylamino, dialkylamino, alkyl, alkoxy or phenylalkyloxy; R.sub.1 is alkyl, hydroxyalkyl, alkenyl, cycloalkyl, phenylcycloalkyl, 1-hydroxymethylphenethyl, 1-(t-butyl)dimethylsilyloxymethyl-phenethyl, 1-(t-butyl)dimethylsilyloxymethylisopentyl, 1-hydroxymethylisopentyl, phenyl, benzyl or substituted phenyl or benzyl, where the substituents are alkyl, alkoxy, halogen, cyano, trifluoromethyl, amino, alkylamino, dialkylamino, nitro or phenyl, benzyl, phenethyl or R.sub.1 is thienyl, imidazolyl, thiazolyl, pyridinyl, pyrimidinyl, pyrazinyl, benzamidazolyl, phenylalkylpiperidinyl or morpholino; R.sub.

Abstract: An improved process for the preparation of D,L-Lactide which can be used directly in polymerization reactions.

Abstract: A process for the continuous production of polylactide polymers from lactic acid which incorporates removal of water or a solvent carrier to concentrate the lactic acid feed followed by polymerization to a low-molecular-weight prepolymer. This prepolymer is fed to a reactor in which a catalyst is added to facilitate generation of lactide, the depolymerization product of polylactic acid. The lactide generated is continuously fed to a distillation system as a liquid or vapor wherein water and other impurities are removed. The resultant purified liquid lactide is fed directly to a polymerization process.

Abstract: Disclosed are new 1,3-dioxenones having the formulae ##STR1## in an optically pure state, a process for preparing same and the use thereof.

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 2-benzoylcyclic-1,3-dione derivative of the formula: ##STR1## wherein X represents methylene, oxygen, sulphur or --NR.sup.4 --, Y represents --C(R.sup.5) (R.sup.6)-- or oxygen, R.sup.1 represents hydrogen or alkyl optionally substituted by halogen or represents cycloalkyl, R.sup.2 represents hydrogen or R.sup.7 or R.sup.1 and R.sup.2 together represent alkylene, R.sup.3 represents halogen, hydroxy, carboxy, nitro, cyano or amino or carbamoyl (which may be substituted by one or two alkyl groups), alkoxycarbonyl, alkanoyl, or alkanoylamino, R, RO, RS, RSO or RSO.sub.2 in which R represents alkyl optionally substituted by halogen, R.sup.4 represents hydrogen or alkyl or alkoxycarbonyl, R.sup.5 represents hydrogen or alkyl or alkoxycarbonyl, R.sup.6 represents hydrogen or alkyl, R.sup.7 represents alkyl which may be substituted by halogen or alkylthio or by a group (R.sup.8).sub.n -phenyl-S-, or represents cycloalkyl or tetrahydrothiapyran-3-yl or represents a group (R.sup.8).sub.n -phenyl- in which R.sup.

Abstract: A process is provided for the production of lactones by the catalytic dehydrogenation of aliphatic diols containing from 3-7 carbon atoms and optionally one or more ether linkages in the diol chain. The reaction is conducted in the liquid phase with a copper chromite catalyst at a temperature of from about 150.degree.-250.degree. C. in the absence of added hydrogen, and preferably at reaction conditions where yields are about 99%.

Abstract: The present invention discloses the antimicrobial utility of certain iodonium ylide compounds. The particular iodonium ylide compounds are phenyl iodonium ylides having an ortho substituent that stabilizes the positive charge on the polyvalent iodine by a nonbonded electrostatic interaction. The polyvalent iodine is further stabilized by a cyclic 1,3-dicarbonyl anion.

Abstract: Catechol derivatives which relate to the production of nerve growth factor in particular tissues of brain are disclosed.Methods for the synthesis, data on the physiological activity, and data on the toxicity of these derivatives as well as examples of preparation for their administration are also disclosed.The disclosed derivatives provide preventive and remedial effect for regressive disorders in the central nervous system including senile dementia of Alzheimer type.

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: Process for preparing high purity solvent-free cyclic esters from alpha hydroxycarboxylic acids via an intermediate oligomer wherein a fluorocarbon or a mixture of fluorocarbons is employed to strip the ester from the oligomer as well as a refrigerant to quench lactide from a gaseous reaction stream comprising, besides cyclic ester, unconverted alpha-hydroxycarboxylic acid and water.

Abstract: A stereoconvergent process is described for preparing optically active alpha-arylalkanoic acids using as starting substance a diastereoisomeric mixture of ketals of formula ##STR1## in which the substitutents have the meanings given in the description. The described process leads to the formation of a single enantiomer.

Abstract: A method of synthesis of a partially retro-inverso peptide incorporating at least one malonyl residue of formula (III) ##STR1## wherein R represents the side chain of an .alpha.-amino acid, is described which is characterized in that said malonyl residue is incorporated by condensing a 5-substituted-2,2-dimethyl-1,3-dioxane-4,6-dione of formula (VI) ##STR2## wherein R' is the side-chain R wherein the functional groups, if any, are suitably protected, with an amino acid, amino acid amide, peptide fragment, or pseudo-peptide fagment wherein the terminal carboxyl group, if present, and the possible side-chain functionalities are suitably protected and the reactive amino group is tri-alkyl-silylated.The new compounds of formula (VI) and a process for the preparation of a partially retro-inverso tuftsin analog which involves use of said method and said intermediate are also described and claimed.

Abstract: 3-Methyl-3-(4-acetylaminophenoxy)-2,4-dioxabenzocyclohexanone-1, having formula I ##STR1## exhibits an high analgesic, antiinflammatory and antipiretic activity along with a prolonged action and an excellent gastric and systemic tolerability.

Abstract: A composition, in contact with a corrodable metal surface, comprising:a) an aqueous-based or oil-based system; andb) as an inhibitor for protecting the metal surface against corrosion, at least one compound having the formula I or II: ##STR1## in which R is C.sub.4 -C.sub.20 alkyl, C.sub.4 -C.sub.20 alkyl interrupted by one or more oxygen atoms, C.sub.4 -C.sub.20 alkenyl, C.sub.6 -C.sub.10 aryl, C.sub.7 -C.sub.15 alkaryl, C.sub.7 -C.sub.15 aralkyl or C.sub.5 -C.sub.12 cycloalkyl;R.sup.1, R.sup.2 and R.sup.3 are the same or different and each is methyl or, preferably, hydrogen;M is hydrogen, a metal ion, ammonium or substituted ammonium ion;a is 0 or 1;b is 0 or an integer from 1 to 6, preferably 0, 1, 2 or 3 especially 0 or 1; andc is an integer from 1 to 6; and/or at least one compound having the formula II: ##STR2## in which R, R.sup.3 and a are as defined above.

Abstract: The invention relates to a process for the preparation of lactide, in particular of optically pure L(-)- or D(+)-lactide, on an industrial scale.

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: An improved process for the preparation of D,L-Lactide which can be used directly in polymerization reactions.