Lactide is the lactone cyclic

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

derived by multiple

esterification In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

between two (usually) or more molecules from

lactic acid Lactic acid is an organic acid. It has the molecular formula C3H6O3. It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as wel ...

(2-hydroxypropionic acid) or other hydroxy carboxylic acid. They are designated as dilactides, trilactides, etc., according to the number of hydroxy acid residues. All lactides are colorless or white solids. The dilactide derived from lactic acid has the formula . This lactide has attracted interest because it is derived from abundant renewable resources and is the precursor to a biodegradable

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

Stereoisomers

The dilactide derived from lactic acid can exist in three different stereoisomeric forms. This complexity arises because lactic acid is

chiral Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek language, Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is dist ...

. These enantiomers do not racemize readily. All three stereoisomers undergo epimerisation in the presence of organic and inorganic bases in solution.

Polymerization

Lactide can be polymerized to

polylactic acid Polylactic acid, also known as poly(lactic acid) or polylactide (PLA), is a plastic material. As a thermoplastic polyester (or polyhydroxyalkanoate) it has the backbone formula or . PLA is formally obtained by condensation of lactic acid with ...

(polylactide). Depending on the

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

, syndiotactic or a heterotactic polymers can result. The resulting materials, polylactic acid, have many attractive properties. : Polylactide_synthesis_v

References

{{reflist Lactones Dioxanes Monomers Dimers (chemistry)