Applications of DL-Lactide

DL-Lactide(C3H4O2) is a odorless, colorless liquid at room temperature and pressure, which is hygroscopic and is a type of acid anhydride. It is miscible with water, ethanol, glycerin, and insoluble in chloroform, carbon disulfide and petroleum ether.

DL-Lactide is the optically inactive internal diester of DL-lactic acid. The same comments apply here as for the L-form. Unlike the parent acid, DL-lactide is an odorless solid. Frinton Laboratories, DL-Lactide appears as a free-flowing crystalline powder, melting at about 125°C and with purity higher than 99%. This as well as the optically active L-lactide are used in medical practice, after polymerization to polylactide, a biodegradable and bioactive thermoplastic aliphatic polyester, one of the largest consumed bioplastics in the world. DL-Lactide is often used as a protective layer in wound coatings, or as anchors, screws or mesh in surgery, since it degrades in about six months to the innocuous lactic acid.

Fig 1. Chemical structure formula and three-dimensional structure of DL-Lactide

DL-Lactide is used to produce 2-hydroxy-propionic acid 1-(1-phenyl-ethoxycarbonyl)-ethyl ester. It acts as an important raw material and an intermediate used in organic synthesis, pharmaceuticals, agrochemicals and dyes. It is involved in enzymatic alcoholysis to produce both alkyl (R)-lactates and alkyl (S,S)-lactyllactates[1,2].
 
References

[1] Dong, H.; Dai, W.; Ju, H.; Lu, H.; Wang, S.; Xu, L.; Zhou, S. F.; Zhang, Y.; Zhang, X. Multifunctional Poly(dl-lactide)-Polyethylene Glycol-Grafted Graphene Quantum Dots for Intracellular MicroRNA Imaging and Combined Specific-Gene-Targeting Agents Delivery for Improved Therapeutics. ACS Appl. Mater. Inter. 2015, 7 (20), 11015-11023.
[2] Zuza, E.; Lejardi, A.; Meaurio, E.; Sarasua, J. R. Phase behavior and interactions in poly(dl-lactide)/poly(styrene-co-vinylphenol) blends. Eur. Polym. J. 2015, 63, 58-66.