Lactide

• Dilactide
• (R, R ) -3,6 -dimethyl- 1 ,4-dioxane -2 ,5- dione
• (S, S ) -3,6 -dimethyl- 1 ,4-dioxane -2 ,5- dione
• ( meso ) -3,6 -dimethyl- 1 ,4-dioxane -2 ,5- dione
• (R, R ) -2,5 -dimethyl- 3 ,6- dioxo- 1 ,4-dioxane
• (S, S ) -2,5 -dimethyl- 3 ,6- dioxo- 1 ,4-dioxane
• ( meso ) -2,5 -dimethyl- 3 ,6- dioxo- 1 ,4-dioxane

• 95-96-5 (unspecified)
• 4511-42-6 [( S, S) -lactide ]
• 25038-75-9 [ (R, R ) lactide ]
• 13076-19-2 [( R, S) -lactide meso-lactide = ]
• 26680-10-4 ( mixture of stereoisomers of three isomers)

Color and odorless crystals

Fixed

• 95-97 ° C and [( S, S) -lactide, and (R, R ) lactide ]

• Hydrolyzed in water to lactic acid
• Soluble in chloroform, methanol,
• Slightly soluble in benzene

Attention

Template: Infobox chemical / molecular formula search available

Lactide is the cyclic diesters of lactic acid. To form an intermediate in the industrial preparation of polylactides ( polylactic acid ). In contrast to this, lactides ( plural) as a generic term cyclic diesters of α -hydroxycarboxylic acids ( lactic acid, α -hydroxybutyric acid, mandelic acid, etc.).

Extraction

Lactide can be prepared by catalytic condensation of lactic acid. Technically it is but nowadays usually obtained biotechnologically from glucose and molasses.

Isomerism

Since lactide has two substituted residues each analog stereo centers, there are three isomers of lactide:

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

The lactide of the natural L-lactic acid [ Synonym: (S)- lactic acid ] having (S, S )-configuration. ( R, R) -lactide, and ( meso ) -lactide having only minor importance in comparison to (S, S)- lactide.

Properties

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

Use

From the lactide [ precisely, the ( S, S) -lactide ], the L-lactic acid is prepared by ionic polymerization of polylactide. Moreover, it is in the polymerized state used as a biodegradable suture in operations ( self -dissolving stitches ).

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