Lactide

Structural formula
	( R , R ) -lactide (top left), ( S , S ) -lactide (top right) and meso- lactide (bottom)
General
Surname	Lactide
other names	Dilactide; 3,6-dimethyl-1,4-dioxane-2,5-dione; 2,5-dimethyl-3,6-dioxo-1,4-dioxane; LACTIDE ( INCI ) ;
Molecular formula	C 6 H 8 O 4
Brief description	Colorless and odorless crystals
External identifiers / databases
EC number	202-468-3
ECHA InfoCard	100.002.245
PubChem	7272
ChemSpider	7002
Wikidata	Q421313
properties
Molar mass	144.13 g · mol -1
Physical state	firmly
Melting point	95–97 ° C [( S , S ) -lactide and ( R , R ) -lactide]; 53 ° C [ meso- lactide];
boiling point	285.5 ° C [760 mm Hg, meso- lactide];
solubility	hydrolyzes in water to lactic acid ; soluble in chloroform , methanol ; sparingly soluble in benzene ;
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 319
	P: 305 + 351 + 338
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Lactide is the cyclic di ester of lactic acid and is used as a starting material in the technical production of polylactides (polylactic acids). In contrast to this, lactides ( plural ) are, as a generic term, cyclic diesters of α- hydroxycarboxylic acids (lactic acid, α-hydroxybutyric acid, mandelic acid, etc.).

Extraction

Lactide can be produced by the acid catalytic condensation of lactic acid. Technically nowadays it is mostly obtained biotechnologically from glucose and molasses .

Isomerism

Since lactide contains two stereocenters substituted by analogous radicals, there are three isomeric lactides:

( S , S ) -lactide,
( R , R ) -lactide and
meso- lactide.

The lactide of the natural L -lactic acid [synonym: ( S ) -lactic acid] has ( S , S ) -configuration. ( R , R ) -lactide and meso -lactide are of little importance compared to ( S , S ) -lactide.

properties

Lactide is a colorless, odorless powder that immediately hydrolyzes to lactic acid on contact with water .

use

From the lactide [more precisely: the ( S , S ) -lactide] of L -lactic acid, polylactide is produced by ionic polymerization . In addition, it is used in the polymerized state as a biodegradable suture material in operations (self-dissolving sutures).

The hydrogenation of L- lactide yields ( S ) - (+) - 1,2-propanediol .

Individual evidence

↑ Entry on LACTIDE in the CosIng database of the EU Commission, accessed on March 6, 2020.
↑ ^a ^b ^c ^d ^e Entry on lactide. In: Römpp Online . Georg Thieme Verlag, accessed on May 25, 2014.
^ A. Auras, Loong-Tak Lim, Susan EM Selke, Hideto Tsuji, Poly (lactic acid): Synthesis, Structures, Properties, Processing, and Applications, p. 11, John Wiley & Sons 2011
↑ guidechem.com: 1,4-Dioxane-2,5-dione, 3,6-dimethyl-, (3R, 6S) -rel- , accessed on February 7, 2018.
↑ ^a ^b Entry on Dilactid in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
↑ Ekambaram Balaraman, Eran Fogler and David Milstein: Efficient hydrogenation of biomass-derived cyclic di-esters to 1,2-diols , Chem. Commun. 48 (2012) 1111-1113.

[CosIng-1] Entry on LACTIDE in the CosIng database of the EU Commission, accessed on March 6, 2020.

[roempp-2] Entry on lactide. In: Römpp Online . Georg Thieme Verlag, accessed on May 25, 2014.

[3] A. Auras, Loong-Tak Lim, Susan EM Selke, Hideto Tsuji, Poly (lactic acid): Synthesis, Structures, Properties, Processing, and Applications, p. 11, John Wiley & Sons 2011

[4] uidechem.com: 1,4-Dioxane-2,5-dione, 3,6-dimethyl-, (3R, 6S) -rel- , accessed on February 7, 2018.

[GESTIS-5] Entry on Dilactid in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .

[Balaraman-6] Ekambaram Balaraman, Eran Fogler and David Milstein: Efficient hydrogenation of biomass-derived cyclic di-esters to 1,2-diols , Chem. Commun. 48 (2012) 1111-1113.