Abstract: The invention relates to methods for producing a lactic acid based polymer, which comprises co-polymerisation of lactide with cyclic dimer of another ?-hydroxy-acid as co-monomer of opposite ?-carbon chirality.

Abstract: A process for preparing cyclic esters by means of a transesterification reaction in the gas phase, comprises the steps of: (i) vaporizing a liquid solution of alpha-hydroxy esters, (ii) passing the ester vapors through a reaction zone containing a solid catalyst and (iii) recovering the cyclic esters from the gaseous product stream; and wherein the solid catalyst comprises at least one metal of titanium (Ti) and Zirconium (Zr), and a SiO2 support, and wherein said metal is chemically bound to the SiO2 support through M-O—Si chemical bonds.

Abstract: A process for preparing cyclic esters by means of a transesterification reaction in the gas phase, comprises the steps of: (i) vaporizing a liquid solution of alpha-hydroxy esters, (ii) passing the ester vapors through a reaction zone containing a solid catalyst and (iii) recovering the cyclic esters from the gaseous product stream; and wherein the solid catalyst comprises at least one metal of titanium (Ti) and Zirconium (Zr), and a SiO2 support, and wherein said metal is chemically bound to the SiO2 support through M-O—Si chemical bonds.

Abstract: The invention relates to a process for preparing a cyclic ester or a cyclic amide, comprising the step of: contacting at least one hydroxycarboxylic acid and/or at least one amino-carboxylic acid; or an ester, or salt thereof; wherein said hydroxycarboxylic acid is a 2-hydroxycarboxylic acid, or a 6-hydroxycarboxylic acid; and wherein said amino carboxylic acid is a 2-amino-carboxylic acid or a 6-amino-carboxylic acid; with at least one acidic zeolite comprising: two or three interconnected and non-parallel channel systems, wherein at least one of said channel systems comprises 10-or more-membered ring channels; and a framework Si/X2 ratio of at least 24 as measured by NMR; or three interconnected and non-parallel channel systems, wherein at least two of said channel systems comprise 10-or more-membered ring channels; and a framework Si/X2 ratio of at least 6 as measured by NMR; wherein each X is Al or B, and wherein the process is performed at a pressure between 0.5 and 20 bar.

Abstract: The invention relates to a process for preparing a cyclic ester or a cyclic amide, comprising the step of: contacting at least one hydroxycarboxylic acid and/or at least one amino-carboxylic acid; or an ester, or salt thereof; wherein said hydroxycarboxylic acid is a 2-hydroxycarboxylic acid, or a 6-hydroxycarboxylic acid; and wherein said amino carboxylic acid is a 2-amino-carboxylic acid or a 6-amino-carboxylic acid; with at least one acidic zeolite comprising: two or three interconnected and non-parallel channel systems, wherein at least one of said channel systems comprises 10- or more-membered ring channels; and a framework Si/X2 ratio of at least 24 as measured by NMR; or three interconnected and non-parallel channel systems, wherein at least two of said channel systems comprise 10- or more-membered ring channels; and a framework Si/X2 ratio of at least 6 as measured by NMR; wherein each X is Al or B, and wherein the process is performed at a pressure between 0.5 and 20 bar.

Abstract: A process for preparing a cyclic ester or a cyclic amide includes contacting hydroxycarboxylic acid and/or amino-carboxylic acid, an ester thereof, or a salt thereof, with acidic zeolite. The hydroxycarboxylic acid is a 2- or 6-hydroxycarboxylic acid, and the amino carboxylic acid is a 2- or 6-amino-carboxylic acid. The zeolite may include two or three interconnected and non-parallel channel systems, in which a channel system includes 10- or more-membered ring channels, and in which a framework Si/X2 ratio is at least 24 as measured by NMR. X is Al or B. The zeolite may include three interconnected and non-parallel channel systems, in which at least two channel systems include 10- or more-membered ring channels, and in which a framework Si/X2 ratio is at least 6 as measured by NMR. The process may be performed at a pressure between 0.5 and 20 bar.

Abstract: A process for preparing a cyclic ester or a cyclic amide includes contacting hydroxycarboxylic acid and/or amino-carboxylic acid, an ester thereof, or a salt thereof, with acidic zeolite. The hydroxycarboxylic acid is a 2- or 6-hydroxycarboxylic acid, and the amino carboxylic acid is a 2- or 6-amino-carboxylic acid. The zeolite may include two or three interconnected and non-parallel channel systems, in which a channel system includes 10- or more-membered ring channels, and in which a framework Si/X2 ratio is at least 24 as measured by NMR. X is Al or B. The zeolite may include three interconnected and non-parallel channel systems, in which at least two channel systems include 10- or more-membered ring channels, and in which a framework Si/X2 ratio is at least 6 as measured by NMR. The process may be performed at a pressure between 0.5 and 20 bar.