Lactide
Structural formula | |||||||||||||||||||
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( R , R ) -lactide (top left), ( S , S ) -lactide (top right) and meso- lactide (bottom) | |||||||||||||||||||
General | |||||||||||||||||||
Surname | Lactide | ||||||||||||||||||
other names |
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Molecular formula | C 6 H 8 O 4 | ||||||||||||||||||
Brief description |
Colorless and odorless crystals |
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properties | |||||||||||||||||||
Molar mass | 144.13 g · mol -1 | ||||||||||||||||||
Physical state |
firmly |
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Melting point | |||||||||||||||||||
boiling point |
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solubility |
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safety instructions | |||||||||||||||||||
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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.