Lactic acid O-carboxyanhydride (lac-OCA) is an organic compound. It is used as a monomer equivalent to lactic acid or lactide in the preparation of poly(lactic acid). When this monomer undergoes ring-opening polymerization, one equivalent of carbon dioxide gas is released for every lactic acid unit incorporated into the polymer:^[1]

Lactic acid O-carboxyanhydride

Names
IUPAC name 5-Methyl-1,3-dioxolane-2,4-dione
Identifiers
CAS Number	17578-13-1
3D model (JSmol)	Interactive image
ChemSpider	11239219
ECHA InfoCard	100.116.276
EC Number	605-761-8
PubChem CID	22227598
InChI InChI=1S/C4H4O4/c1-2-3(5)8-4(6)7-2/h2H,1H3 Key: JLXQJNCZXSYXAK-UHFFFAOYSA-N InChI=1/C4H4O4/c1-2-3(5)8-4(6)7-2/h2H,1H3 Key: JLXQJNCZXSYXAK-UHFFFAOYAX
SMILES O=C1OC(=O)OC1C
Properties
Chemical formula	C4H4O4
Molar mass	116.072 g·mol−1
Melting point	28 °C (82 °F; 301 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

This compound is prepared by treatment of lactic acid or its salts with phosgene or one of its equivalents, e.g. diphosgene.^[1]